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2. 20 kpsi 13 8 kPa Tool Diameter 3 625 in 9 21 cm Tool Length 16 9 ft 5 15 m Sampling Interval 50m Max Logging Speed Stationary Vertical Resolution N A Deployment Notes The WST is run alone and placed at stations at regular intervals At each station a seismic shot is produced at the sea surface using either air or water guns provided by TAMU Schlumberger provides a blast hydrophone for synchronizing the gun pulse with the system timer The WST and other downhole seismic tools are sensitive to pipe noise and ringing of pipe following a shot Efforts should be made to reduce pipe noise at each station If time and resources permit a drill string packer may be deployed to dampen the banging motion of the pipe against the borehole Also it is always prudent to leave 50 to 75 m distance between the tool and the bottom of pipe For FY 99 the WST is a standard tool and can be deployed on any leg The WST requires TAMU involvement to provide air or water guns as the energy source At the beginning of each leg meet with the TAMU techs to ensure that the guns can will be ready for use Typically one week s notice is required before the guns can be used If a WST tool deployment is not initially scheduled plan on meeting with the co chiefs to let them know that running the WST will require at least 7 days notice prior to deployment The CSES should not be used with the WST for thr
3. m 8 8 M Screen shot of the Data Manager application within IESX T 74 5000 751000 75 30 00 8 Ld rt tears si twat Tor sont CR 1 1 1 Screen shot of the Basemap application within IESX File Displou EET 41 zi a LA El BI i to add points 2 to undo MB3 For break options Double click MBI on interpretation to start data nar W Screen shot of the Seis2DV application within IESX Synthetics Define Tools a g Et 9 T al EU a Screen shot of the Synthetics application within IESX F i 2 E 4 2 019 Screen shot of the Geoviz application within IESX Object selector ziz Track selector PRE Remove spikes and extend log data to the sea floor i e you make up your own Bulk shift data Re sample data to even spacing 3 zu al 5 ES 2 25006 Save edited log curve Screen shot of the Well Edit application within IESX Aude Gyeqeceubepy woudcdg apun 6689 1 8 Velocity Vel e T BE mm E a 55 t m 5 El a aja E E f3 m T a Ou gps na
4. Am Be radioisotope or an electrical generator source to bombard the formation with neutrons After the neutrons collide with molecules of like mass in the formation such as H sufficient energy devices e g Paler er ab T1990 fui and 1990 Images can be visually used to compare logs with cores for bedding orientation and to study fracturing structure and borehole shape Temperature tools Temperature logging typically involves measuring a continuous profile of borehole fluid temperature as a proxy for the in situ formation
5. Logging Manual Any opinions findings and conclusions or recommendations expressed this document are those of the author s and do not necessarily reflect the views of the National Science Foundation Joint Oceanographic Institutions Inc or ODP member countries Welcome to the Logging Manual How to use this manual What is downhole logging Home Index of Topics Logging Manual How to use this manual HOME i What is downhole logging How to use this manual Welcome to Version 2 0 of the ODP Logging Services Electronic Manual There are several ways to navigate through this manual Clicking on the Home page will take you to a Table of Contents organized along rough chronological lines Four main groups of issues are presented Pre cruise Planning Data Acquisition amp Shipboard Operations Data Processing amp Analysis and Data Presentation amp Post Cruise Activities In addition a separate Index of Toolstrings and Tools is provided on this page A navigation banner containing a link to the Home page is provided at the top of most of the pages in this manual Also in this banner are links to the Acronyms page a Glossary of Logging Terms page and an Index of Topics page The latter is particularly useful when you are seeking information about a specific topic but may not be sure where to find it in the chronological menu Version 2 of this manual include
6. Index Toolstrings amp Tools Triple Combo FMS Sonic Specialty Tools Other Equipment HOME ACRONYMS GLOSSARY INDEX OF TOPICS CONTACT US INDEX OF TOPICS GLOSSARY ACRONYMS HOME Data Acquisition amp Transfer The objective of this chapter is to provide a short description of how the loggers collect data onboard the JOIDES Resolution It focuses on the techniques and formats employed to produce proprietary also called field and customer also called field edit tapes and how both data and the information necessary for its processing are transmitted via satellite to ODP Logging Services at the Lamont Doherty Earth Observatory For further information about these procedures contact the following personnel Data Handling and Processing Satellite Transmission e Cristina Broglia e James Murray Data Services Supervisor Database Assistant Tel 845 365 8343 Tel 845 365 8639 Fax 845 365 3182 Fax 845 365 3182 chris 1deo columbia edu jmurray deo columbia edu e Trevor Williams e Greg Myers Log Analyst Technical Operations Manager Tel 845 365 8626 Tel 845 365 8772 Fax 845 365 3182 Fax 845 365 3182 trevorQ ldeo columbia edu gmyers Q ldeo columbia edu Customer Proprietary amp Backup Tapes Once the Schlumberger log data have been acquired they are routinely loaded on DAT tapes Three types of DAT tapes are produced onboard Proprietary tapes also call
7. 0050 3 cLossarY ACRONYMS HOME Logging While Drilling Hesistivity at the Bit Tool LWD RAB Description The Resistivity at the Bit LWD RAB tool makes lateral resistivity measurements As formation evaluation tool its application is limited to conductive muds It may be run in several configurations and provides up to five resistivity measurements The RAB tool contains a scintillation gamma ray detector which supplies a total gamma ray measurement An azimuthal positioning system allows the gamma ray measurement and certain resistivity measurements to be acquired around the borehole Additional measurements are chassis temperature and radial and longitudinal shocks The RAB tool has a nominal 6 75 in diameter it is meant to be run in 8 5 in holes Designed to be a flexible component of the bottomhole assembly the RAB tool may be connected directly behind the bit or further back in the bottomhole assembly The tool may be configured for packed or pendulum assemblies When connected directly to the bit the RAB Resistivity at the Bit tool uses the lower portion 8 in of the tool and the bit as a measure electrode In this configuration it provides a bit resistivity measurement RBIT with a vertical resolution just a few inches longer than the length of the bit A 1 5 in tall cylindrical electrode located 3 feet from the bottom of the tool provides a focused lateral resistivity measurement RING with a 2 in
8. In smooth boreholes with very homogeneous bedding the depth of investigation is about 10 in 25 cm The vertical resolution is 0 2 in 5 mm lt Sixteen electrode arrangement for the four pad tool Applications e Mapping of bedding planes fractures faults foliations and other formation structures and dip determination e Detailed correlation of coring and logging depths e Precise positioning of core sections where core recovery is less than 100 e Analysis of depositional environments Environmental Effects To produce high quality FMS images the pads must be pressed firmly against the borehole wall The maximum extension of the caliper arms is 15 0 inches In holes with a diameter larger than 15 inches the pad contact will be inconsistent not all four pads touching the wall and the FMS images can be blurred The maximum borehole deviation where good data can be recorded with this tool is 10 Irregular borehole walls will also adversely affect the images because the pads can not make sufficient contact with the borehole wall Log Presentation FMS images can be plotted with identical vertical and horizontal scales to see features without exaggeration However due to physical constraints different vertical and horizontal scales are commonly used To display the images we use an oriented plot also called an azimuthal plot because the images are positioned according to their orientation in the boreho
9. 1 1 1 1 1 h 1 1 n Thonum 1 ppm Uranium V Qe s 1 1 PA A we M s Y r Y hn pee 10 40 50 60 B 90 100 110 130 140 180 ODP Logging Manual 1 How to use this manual pus I uu o x What is downhole logging Downhole logging is the process of measuring physical chemical and structural properties of penetrated geological formations using logging tools that are either lowered into the borehole on a wireline cable wireline logging or placed just behind the drill bit as part of the drill pipe itself logging while drilling The tools employ various acoustic nuclear and electrical measurement techniques to acquire downhole logs of properties such as sonic velocity density and electrical resistivity The wireline cable provides real time communication between the tools and the surface logging while drilling tools typically record the logs in downhole memory devices which are subsequently downloaded when the tool returns to the ship The downhole logs are rapidly collected are continuous with depth and measure in situ properties They can be interpreted in terms of the formation s stratigraphy lithology and mineralogy The sampling interval is typically 15 cm with a vertical resolution of about 35 cm Some tools have a higher sampling interval and resolutio
10. 19 9 ft 6 07 m 310 Ibs 141 kg 5 in 12 7 cm with short arms 19 in 48 3 cm with long arms Stationary N A 3 axis One per axis 5 gimbaled 10 Hz 60 dB Sensitivity per axis Low cut frequency Low cut slope High cut frequency High cut slope Digitization Sampling rate ADC resolution Autoranger steps Preamplifier gain Dynamic range per waveform shot Total dynamic range Input noise level Anti aliasing filters Data format Deployment Notes 83 V m sec or 80 V in sec at 25 C 0 2 Hz 18 dB per octave 250 Hz for 1 ms or 125 Hz for 2 and 4 ms sampling 36 dB per octave Downhole 1 2 or 4 ms selectable 11 bit sign Five 6 dB steps 40 160 dB by 6 GB steps for each axis 90 dB 156 dB 2uV 330 Hz 24 dB per octave 16 bit FP 12 bits mantissa 4 bits exponent The WST 3 can be used in both checkshot and offset vertical seismic profile experiments A remote seismic source is required for an offset survey while a traditional check shot survey can be completed with existing equipment on the JOIDES Resolution For each type of experiment the deployment routine for the WST 3 is approximately the same The main difference is simply the location of the source and the handling of the trigger pulse For a check shot a 120 in air gun is suspended by buoys at a depth of 3 mbsl offset 48 5m from the hole on the portside The WST 3 is clamped against th
11. Density tools use a gamma ray source usually a bombard the formation with gamma rays that are scattered through the rock and gradually lose energy Sensors pressed against the borehole wall measure the energy flux of gamma rays returned to a scintillation counter and crystal detector which captures photons emitted by Compton scattering The radiation returned is directly related to the electron density in the forma tion which in turn is related to the bulk density of the rock Doveron 1986 Elis 1987 The electron density is low for most pore filling fluids and can therefore be used as an indicator of rock composition The depth of inves ligation into the borehole wall of density tools depends on the density of the formation greater density reduces the penetration of emitted gamma rays inte the borehole wall In porous and permeable formations densities typically measured to approximately 0 5 m into the bore hole wall and the vertical resolution of the measure ment is approximately 0 4 m Neutron tools employ either Am Be radioisotope or an electrical generator source to bombard the formation INDEX OF TOPICS GLOSSARY ACRONYMS 35 3 REVIEWS OF GEOPHYSICS is transferred to slow the neutrons down enough to drop below 0 1 eV energy constituting the epithermal thermal neutron transition Neutron responses are therefore strongly affected by the porosity and pore fluids in the formation and by minerals such as cla
12. Pressure Rating 20 kpsi 13 8 kPa Tool Diameter 3 625 in 9 2 cm Tool Length 8 58 ft 2 61 m Sampling Interval 6 in 15 24 cm Max Logging Speed 900 ft hr Vertical Resolution 75 1 ft 20 31 cm Depth of Investigation 1 5 ft 46 cm Output SGR Standard total Gamma Ray GAPI CGR Corrected Gamma Ray GAPI THOR Thorium ppm URAN Uranium ppm POTA Potassium dec fraction WING Window 1 0 2 0 5 MEV Counts cps W2NG Window 2 0 5 1 1 MEV Counts cps W3NG Window 3 1 1 1 59 MEV Counts cps W4NG Window 4 1 59 2 0 MEV Counts cps WSNG Window 5 2 0 3 0 MEV Counts cps Deployment Notes Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME The Pre Cruise Meeting Pre cruise meetings usually last two days and are always held at ODP TAMU in College Station Texas The goal of the pre cruise meeting is to prepare a detailed scientific and planning prospectus for the upcoming leg This prospectus is available on the relevant page of the Science Operator s web site The scientific prospectus contains the following information 1 Leg objectives 2 Operations plan including Operation details of each site to be drilled Coring logging tools to be deployed Specific objectives to be achieved at the site Sampling plan if any 3 A time table for the leg operat
13. 387 430 Brewer T S Pelling R Lovell M A amp Harvey P K 1992 The validity of whole rock geochemistry in the study of ocean crust a case study from ODP Hole 504B Jn Parson L M Murton B J amp Browning P eds Ophiolites and their modern ocean analogues Geological Society of London Special Publication No 60 263 278 Brewer T S Harvey P K Lovell M A Haggas S Williamson G amp Pezard P 1998 Ocean floor volcanism constraints from the integration of core and downhole logging measurements In Harvey amp Lovell M A eds Geological Society of London Special Publication No 136 341 362 Doveton J D 1991 Lithofacies and geochemical facies profiles from nuclear wireline logs new subsurface templates for sedimentary modelling Franseen E K Watney W L Kendall C J amp Ross W eds Sedimentary modelling computer simulations and methods for improved parameter definition Kansas Geological Society Bulletin 233 101 110 Ellis D V 1987 Well logging for earth scientists Elsevier Amsterdam Hassan M Hossin A amp Combaz A 1976 Fundamentals of the differential gamma ray log interpretation technique SPWLA 17th Annual Symposium Transactions Paper 8 1 7 Heslop A 1974 Gamma ray log response of shaly sandstones Trans SPWLA McAllen Texas Hurst A 1990 Natural gamma ray spectrometry in hydrocarbon bearing sandstones from the Norwegian Continental Shelf Hu
14. ALKALI Orthoclase KAIS30 252 69 2 9 2 220 16 Anorthoclase KAIS3Og 2 59 2 9 7 4 220 16 Microline 2 53 2 9 220 16 FELDSPARS PLAGIOCLASE Albite NaAISi40g 2 59 49 85 17 44 7 5 Anorthite CaALSi5Og 2 74 45 31 86 25 MICAS Muscovite KAL Si4AIO Q OH 2 82 49 20 17 f Ko 7 Mg Fe gt Al Glauconite 64 2 86 4 8 14 21 Biotite 22 999 5 E 30 CLAYS Kaolinite Al4S14049 OH g 2 41 1 8 4 4 80 130 14 K i SAl4 S17 65 1 5 Illite DS 250 300 Oy OH Halite NaCl 4 7 Gypsum 4 0 Pyrite FeS 4 99 39 2 62 1 17 85 90 Mean value which may vary for individual samples INDEX OF TOPICS GLOSSARY ACRONYMS Logging While Drilling Azimuthal Density Neutron Tool LWD ADN Description The Azimuthal Density Neutron tool ADN is the latest generation density neutron LWD tool provided by Anadrill it supplants the CDN which suffered from poor support and tool availability problems It is deployed in similar fashion to the CDN and is combinable with other LWD tools Unlike the CDN the ADN can be configured to provide real time apparent neutron porosity formation bulk density and photoelectric factor data to characterize formation porosity and lithology while drilling These nuclear measurements are borehole compensated for improved accuracy standoff and photoelectric factor measurements while drilling 360 degre
15. Porosity Indicator Ratio CHY CCA CSI Potassium wet wt Pad 1 Relative Bearing degrees LDS Long spaced Bulk Density g cm3 Bulk Density g cm LDS Corrected Bulk Density g cm Low Resolution Susceptibility ppm Spherically Focused Log ohm m Spectroscopy Gamma Ray API units APS Formation Capture Cross Section cu Spontaneous Potential mv APS Computed Standoff Receiver Coil Temperature C NMRS differential Temperature Thorium ppm Thermal Neutron Ratio Transit Time 10 spacing usec Transit Time 8 spacing Transit Time 12 spacing usec Transit Time 10 spacing usec Uranium ppm Compressional Wave Velocity Short Spacing or Mean Transit Time km s Compressional Wave Velocity Long Spacing or Median Transit Time km s Compressional Wave Velocity from DTCO km s Shear Wave Velocity from DTSM km s Stonely Wave Velocity from DTSM km s POINTS AL203 AL203MIN AL203MAX CAO CAOMIN CAOMAX CA203 CA203MIN CA203MAX CCA CCHL CFE CGD CHY CSI CSIG CSUL CTB CTI FEO FEO MIN FEO MAX FE203 FE203MIN FE203MAX GD GDMIN GDMAX Number of Transmitter Receiver Pairs Used in the Processing Top ADDITIONAL ACRONYMS AND UNITS PROCESSED LOGS FROM GEOCHEMICAL TOOL STRING Computed dry weight Computed 1 standard deviation dry weight 96 Computed A150 standard deviation dry weight Computed CaO dry weight Computed C
16. Pressure Rating 20 kpsi 13 8 kPa Tool Diameter 3 625 in 9 2 cm Tool Length 13 ft 3 96 m Sampling Interval 6 in 15 24 cm Max Logging Speed 1 800 ft hr Vertical Resolution 2 in 5 08 cm Output APLC Near Array Limestone Porosity Corrected decimal fraction STOF Computed Standoff SIGF Formation Capture Cross Section cu AFEC Far Detector Count Rate cps ANEC Near Detector Count Rate cps Deployment Notes Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index IN DEX OF TOPICS GLOSSARY ACRONYMS HOME Array Seismic Imager ASI Description The Array Seismic Imager ASI consists of an array of five seismic shuttles linked by a bridle to a signal conditioning cartridge Each shuttle sensor package contains three mutually orthogonal geophones fixed relative to the sensor package geometry One geophone lies along the axis of the package z axis the other two geophones x and y axes form a 45 angle relative to the clamping direction This design allows the ASI tool to operate in wells with a 90 deviation while not exceeding the 45 limitation of the X and Y geophones For the study of anisotropy and analysis of split shear these features make the ASI tool reliable in both vertical and deviated wells with consistent X and Y component response The ASI tool is unique in that it ensures consistent lengthy coupl
17. and structural orientation in the vicinity of the hole In addition these data may be used to distinguish fractures that are transmissive from those that are not Environmental Effects Laboratory measurements and mathematical modeling have been used to define the density and photoelectric response and to quantify environmental effects These effects include gamma ray streaming mud weight tool standoff and photoelectric effects of formation and mud on density A reliable density measurement requires good contact between stabilizer and formation Because a statistical caliper measurement 15 made during the recording it is possible to check the quality of the contact Contact also affects the neutron log response the formation signal particularly for the epithermal count rates tends to be masked by the borehole signal with increasing hole size Log Presentation This tool has not yet been deployed by ODP Logging Services so we have no examples at this point Specifications Tool weight 2000 Ibm 907 kg Tool length 21 7 ft 6 62 m Min Max temp 13 300 F 25 150 C Collar OD 6 75 in API tolerances Stabilizer OD 8 25 to 9 875 in F 74 000 000 L2 Ibm where L is the distance between stabilizers in feet Maximum overpull no bending 330 000 Ibf Maximum operating pressure 20 000 psi Maximum flow rate 800 gal min Maximum weight on bit Output RHOB Bulk Density g cm Bulk Densi
18. deep azimuthal TEC SS ae Al M2 1 0 1 M a 1 2 LL and azimuthal electrical standoff ae 1 Image Horizontal Scale 1 17 Orientation North 120 240 36G ig Conduct ve DT4P DSIPASS1 10 BO 105 55 ohm rn ust E DTS DSIPASS2 E 180 BD ae m ust 4 i f 1 T f J 1 L ia 1 on f E Y 1 i 1 E f i er 1 T T f pu um A 5 m T l D f z i 4 i l m i i B f a 1 F im m A 1 mm m LJ MYAT WV Ram LT ay Wi TW BAUR Py M Uo LE MS P MAN Or Vu Y v 11 y 3 1 WP porto oU 22 15 3 42 42 ku LA LPT ooo 1 T im S E NAE B s e cg 2 MIT TUM wits h Mad 5 ug 0 MUR DR Computed Gamma Total Ra y Y y adis guo uc 5 2 E amp 150 150 160 160 170 170 180 180 190 190 Figure 2 selection of the geochemical logging results from ODP Hole 950A Downhole
19. valve in the open position Lockable flapper valve in the closed position The LFV presents an obstacle for the logging operation as a closed LFV could snag a tool string as it is withdrawn from the open hole into pipe The LFV is engineered to pass tools through a diameter of 3 5 8 3 625 but to lock open or release with the passage of a 3 3 4 3 75 tool For this reason a go devil an attachment at the end of the tool string is deployed to open the valve as the tool passes through downward As the tool is withdrawn to the surface the go devil again closes the LFV Certain tools the GHMT for example can work as a go devil because their diameter is very close to 3 3 4 Remember when the RCB BHA is used the LFV is not an issue In logging operations the bit is released either in the hole or on the seafloor or is removed at the surface so logging tools pass through pipe with no other obstructions There are two methods for running the go devil Go devil SSS 1 The go devil is attached to the bottom of each toolstring except the GHMT which acts as its own go devil and the LFV is opened and closed for each logging run The disadvantage of this is that it sometimes takes a few attempts to get the go devil through the LFV 2 The go devil is pumped down on its own before logging and the LFV stays open for all logging runs until closed by the GHMT passing upwards though it the WST would either have to be
20. 80 cm and 40 cm respectively The Nuclear Resonance Magnetometer Sonde NMRS is a high precision nuclear magnetic resonance device which accurately measures the total magnetic induction in the borehole Its depth of investigation is theoretically infinite most of the Earth s field is generated in the Earth s core and its vertical resolution is about 45 cm TOOL Applications Magnetostratigraphy In order to obtain a magnetic reversal sequence the total induction and the susceptibility are processed and combined to reveal the polarity of the remanent magnetization in the sediment Normal polarity is in the direction of the present Earth s magnetic field reverse polarity is in the opposite direction The magnetic reversal sequence be correlated to the geomagnetic polarity time scale GPTS for absolute formation dating giving a formation depth to age conversion and sedimentation rates Paleoclimate Magnetic susceptibility is often a good indicator of climatically induced lithological changes It has been used in studies of sediment cyclicity and usually represents either varying terrestrial sediment input or varying dilution by for example carbonate Core log correlation Magnetic susceptibility measurements on both core and log are reliable and often display correlatable peaks troughs and trends Thus it is a good parameter to use for correlation between core and log Environmental Effects The method
21. ALL search CAND for the selected Gate jor clear form of sejecaoos 409PM PT Netscape Communicator 4 7 x T file Edit View Go Bookmarks Communicator Help Netscape Query Subtable Peet Netscape fret Security Pew m ko at FATT www Met coh sine Oba 0474 46 24 p Tht Query Subtable TO VIEW DATA Simply cick Ge highlighted bole aumber from Ge ble below New are Coming Online Ge Please note that proprietary data requires password which is made to shipboard parties 5 holes met your search criteria Search Type OR 116 100 Peace 1 of 1 SCHLUMBERGER CONVENTIONAL Description Porosity metry Year Leg Location bic M dai mcd ma ct hoca pei opa Mia S po Ho aue Caliper Density GCeochkemical Resolution 1114 11124 Return to data search page EMAIL peo Of ete fuf LO us sh muta 7 BAY 2 ODES WD GR ETE D e ao o Qa v mmm LDEO High T Temperature Tool sub Closure collar seal supports Female connector Male connector Upper chassis sub Insulating stopper Pressure case Dewar sup
22. Correlation Tying in Hole C so that all holes are in the composite Depth Scale The splice complete to 34 mcd Splicer version 2 0 Cufrent splice ends at the bottom of core 4 To continue the splic must move to a new core from the hole 2 core from different hole 3 lt TS selected A tie point is chosen for switching over 2 12 An overlapping core from hole is chosen to extend the splice Solicer version 2 0 The tie is now added and B4 isin the splice 3 Tie point where lt splice jumps from A4 to B4 2 This is good E After the tie point is chosen the splice continues in the B hole 3 162 site 364 hohe A Core magnetic susceptibility data is loaded from three different ODP holes A B C at Site 984 and appears vs mbsf E Display Process Help ELD Tool Core magnetic susceptibility Hole Core data from and holes 65 Select Core Downhole log magnetic Clear Last Tle Sa susceptibility data the hole Tie Applies To Susceptibility Auto Pair Off suu Log Core magnetic susceptibility data from three holes are compared to downhole magnetic susceptibility from the B hole File Display Process Hel
23. PC Mac and Unix 7 o omies 1S amp Cof platforms All data are in ASCII format except the FMS images which are stored as GIF files In addition to being available with each volume CD ROMs are available directly from ODP Logging Services For further information contact Jim Murray at jmurray Q ldeo columbia edu The log data CD ROM organizes the data by site and typically includes along with relevant documentation Processed conventional logs Processed FMS images Processed Dipmeter data Processed GHMT data Processed temperature data Sonic waveforms In addition to the log data on the CD a subset of core data are also included for integration with the log data set The following data types are routinely included as part of the core data set GRAPE gamma ray attenuation porosity evaluation Moisture and density system Magnetic susceptibility Natural gamma Paleomagnetic data Compressional wave velocity Screen shot showing opening windows of a representative log data CD ROM Log summary figures are available as postscript PS or portable document format PDF files Log summary figure displayed as a portable document format PDF file At the request of the Co Chief Scientists additional information such as third party tool data can also be included on the CD ROM subject to space availability Other data sets are included as available on a leg by leg basis ODP Logging Services i
24. ROLE OF DOWNHOLE MEASUREMENTS IN MARINE GEOLOGY AND GEOPHYSICS David Goldberg Borehole Research Group Lamont Dolwerty Earth Observatory Palisades New York Abstract During the last 25 years downhole measure ments have been increasingly used for scientific applica tions in marine geology and geophysics particularly in deep sea drilling operations Used mostly by the oil industry to map promising formations for exploration and production of hydrocarbons a variety of instru ments have been developed that can be lowered down drill holes to extract information about the subsurface geology In the last decade advances im computers software and data transmission have greatly increased the amount and quality of data that such instruments can provide Relatively new instruments that image the hore hole wall with high resolution can reveal layers and faults that previously could be seen only in core sections Downhole measurements play a crucial role in linking INTRODUCTION The scientific use of downhole measurements in ma rine geology and geophysics has become increasingly important im recent years The methods and tools are derived largely from those developed for oil and gas exploration and are applied to recent scientific problems in the Earth s oceans The purpose of this review is twofold first to present applications of state of the art downhole measurements in recent marine science prob lems and second to review both ex
25. Source Operation Time From One Set of Batteries Deployment Notes 8 895 ft 2 71 m 3 25 in 8 26 cm 105 C 220 F 2g to 2g 1 mm s 4 Hz 8 Hz 4 C to 85 C 0 005 C 10 000 psi 1 psi 0 1 FS 1 Hz 5 hrs 8 hrs 8 alkaline batteries D type approx 40 hrs The TAP tool can be deployed in two modes memory mode and telemetry mode memory mode the TAP is deployed in the same fashion as the superseded TLT This requires the logger to initialize the tool approximately 1 2 hour prior to rig up of the lower most Triple Combo tool typically the DIT Once initialized the TAP tool should be placed on the deck outside of the DHML to be picked up by the roughnecks The logger then must connect it to the bottom of the triple combo using a pin and rotating ring assembly When the Triple Combo is retrieved to the rig floor the Lamont logger must remove the TAP tool wash it off and download the data When the telemetry cartridge is completed in mid FY 00 the TAP tool may be run in telemetry mode which precludes from running it with the triple combo In telemetry mode the TAP tool will be deployed in a similar fashion as a Schlumberger tool The tool will be placed outside the DHML door for rigging by the rig floor crew A tugger will hoist the tool for insertion into pipe where it will be held by the Schlumberger make up plate From here the Schlumberger cable head will be fastened to the TAP tool with
26. Tool LWD CDN Logging While Drilling Compensated Density Neutron Tool LWD CDR Logging While Drilling Compensated Dual Resistivity Tool LWD RAB Logging While Drilling Resistivity at the Bit Tool MCD Mechanical Caliper Tool M_ Miscellaneous NGT Natural Gamma Ray Spectrometry Tool N_ Natural Gamma Ray Spectrometry Tool SDT Digital Sonic Tool 5_ Digital Sonic Tool SP Spontaneous Potential UBI Ultrasonic Borehole Imager WST Well Seismic Tool ee Well Seismic Tool 3 Component ACRONYMS FOR THIRD PARTY TOOLS BHTV Borehole Televiewer MCS Multichannel Sonic Tool SST Shear Sonic Tool TAP High Resolution Temperature Acceleration Pressure Tool TLT Temperature Logging Tool ACRONYMS AND UNITS USED FOR SCHLUMBERGER LOGS AFEC APS Far Detector Count Rate cps APLC APS Near Array Limestone Porosity Corrected decimal fraction Cl Caliper in from FMS C2 CALI CFEC CFTC CGR CNEC CNTC DEVI DIFF DRH DRHO DT DTCO DTL DTLF DTLN DTSM DTST ENPH ENRA FINC FNOR FX FY FZ GR HALC HAZI HBDZ HBHK HCFT HCGR HCNT HD HDEB Caliper 2 in from FMS Caliper in from HLDT Corrected Far Epithermal Counts cps Corrected Far Thermal Counts cps Computed Th K Gamma Ray API units Corrected Near Epithermal Counts cps Corrected Near Thermal Counts cps Hole Deviation degrees Difference Between MEAN and MEDIAN in Transit Time Proc usec ft HLDS Bulk Density Correction g cm3 Bulk Dens
27. When the tool is run in memory mode the stored data are dumped to the third party DAS upon the tool s return to the rig floor At a meeting in January 1999 the Scientific Measurements Panel SCIMP recommended that BRG LDEO use the TAP tool routinely for the purpose of acquiring acceleration data and testing the efficiency of the WHC under different cable length and heave conditions The Co Chief scientists must be informed at the pre cruise meeting at TAMU of the potential use of this tool and additional logging time that may result from the use of the tool Thus the TAP tool must be run routinely in every hole The acceleration log can aid in deconvolving heave effects post cruise and it has proven at times to be critical data In almost ALL cases the 5 ft of log data that is missed can be compensated by drilling a rat hole below the target horizon If hole depth is so tightly constrained that this is not possible then a truly compelling reason should be provided e g fault at TD etc Applications Geothermics The recording of temperature provides an insight into the thermal regime of the formation surrounding the borehole The vertical heat flow is estimated from the vertical temperature gradient combined with the measurements of the thermal conductivity from logs or core samples Hydrogeology Crust at mid ocean ridge crests must be permeable to a considerable depth to allow for the efficient removal of heat by hydrotherm
28. a standard Schlumberger field joint The Logging Staff Scientist will then be responsible for conducting the entire logging operation for this tool This includes coordination with the winch shack rig floor and Schlumberger engineer Detailed instructions for the telemetry mode deployment will be available following prototype field testing Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME Well Seismic Tool WST Description The WST is a Schlumberger single axis check shot tool 1 used for zero offset vertical E I5m Prid seismic profiles VSP The WST consists of a single geophone pressed against the borehole wall that 1 used to record the acoustic waves generated by an air gun located near the sea surface A 120 in3air gun is suspended by buoys at a depth of 3 mbsl Offset 48 5 m from the hole on the portside The WST is clamped against the borehole wall at intervals of Geophone 1 11 approximately 50m and the air gun fired five to seven times The resulting Tool zero waveforms are stacked and a WST traveltime is determined from the median of the first breaks in each trace These check shot experiments attempt to reproduce the seismic reflection profiling by simulating a similar geometry and source frequency In general the acoustic velocities and resulting depth traveltime pairs determined from the sonic tool differ significantly from the
29. a variety of applications although spreadsheet and graphing programs are most often used Image data such as the FMS are provided as GIF files The easiest way to view these files is in a web browser such as Netscape Navigator or Internet Explorer They can also be imported into graphics programs or included in word processing documents Along with these files the log database contains explanatory documentation and log summary plots The documentation provides an overview of operations for each hole as well as information about processing procedures and quality control The file dictionaries provide a list of data file names for each hole and the corresponding data type contained within it The log summary plots show various types of log data and core recovery plotted versus depth They are available only for the more recent legs Leg 155 and later For one year after the drilling leg log data from the leg can be accessed by members of the shipboard scientific party only a username and password unique to each leg are distributed about two weeks after the leg After a one year moratorium the password is lifted and the data become available to the rest of the scientific community Post Cruise Data On line Log Data Meetings Distribution Data CD ROM INDEX TOPICS GLOSSARY ACRONYMS HOME Log Data CD ROM ODP Logging Services creates a CD ROM for distribution with each ODP Initial Reports volume The CD is readable on
30. and photoelectric effect index are input parameters to some of the geochemical processing algorithms used onshore Environmental Effects A reliable density measurement requires good contact between pad and formation Because a caliper measurement is made during the recording it is possible to check the quality of the contact In the lithodensity tool the presence of mudcake and hole irregularities are automatically accounted for using a spine and ribs chart based series of laboratory measurements The spine is the locus of the two counting rates short and long spacing without mudcake and the ribs trace out the counting rates for the presence of mudcake at a fixed formation density The short and long spacing readings are automatically plotted on this chart and corrected for their departure from true value These corrected data are typically located in the DRHO data column Log Presentation The primary curves are bulk density RHOB in g cc photoelectric effect PEF in barns electron density correction DRHO in g cc and caliper CALI in in They are usually displayed along with the neutron curve NPHI Also DPHI density porosity can be computed and displayed by assuming a constant grain density of the matrix is useful for quality control of the data if the tool is operating correctly it should be less than 0 1 g cc Specifications Temperature Rating 260 500 F Pressure Rating 25 kpsi 1
31. azimuthal Maximum flow rate Maximum operating pressure Maximum weight on bit Maximum jarring load 1200 10 1 ft 13 300 F 25 150 C 6 75 in 8 125 in 800 gal min 18 000 psi 74 000 000 L2 Ibm where L is the distance between stabilizers in feet 330 000 Ibf Output PGRD Gamma ray average API PGR UP Gamma ray up quadrant API PGR RT Gamma ray right quadrant API PGR DN Gamma ray down quadrant API LT Gamma ray left quadrant API GTCK Gamma ray tick RTCK Resistivity tick RPM RAB rotational speed rpm 5 Rate of penetration ft hr RTAB Ring time after bit hr or min RTMP RAB chassis temperature F C RB3 Relative bearing deg PINO3 1 north deg P1AZ azimuth deg HAZI Azimuth deg Deployment Notes Along with the LWD collars additional equipment such as jars must be included Responsibility for providing this equipment is discussed at the pre cruise meeting LWD deployment illustration LWD deployment photo trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index The number two crane is used in all LE WD ops Pipe Hacker Casing Hold Door Tools stored on casing hold doors batteries installed here and tools initialized here After batteries are installed the tools are staged on top of CT shack using the 2 crane When ready for logging is l
32. by the log analyst The resulting depth shifts are then applied to the other logs on the tool strings The depth reference is then shifted from the rig floor to sea floor which is determined from the step in the natural gamma log seen at the sediment water interface Environmental corrections Environmental corrections are designed to remove any effect from the borehole size roughness temperature tool standoff or the drilling fluids that may partially mask or disrupt the log response from the formation Onshore only the natural gamma NGT logs are generally corrected The logs from the HNGS HLDS and APS tools are corrected in near real time during log acquisition Sonic log corrections Sonic slowness logs from the SDT LSS and DSI 2 sonic tools are routinely edited to remove noise and cycle skips that are often present in the raw log The travel times are converted into sonic velocities Quality control and documentation The quality of the data is assessed in terms of reasonable values for the logged formation repeatability between different passes of the same tool and correspondence between logs affected by the same formation property e g the resistivity log should show similar features to the sonic velocity log Invalid data at the top affected by the bottom hole assembly and bottom of the logs are removed Depth adjustments corrections and data quality are documented in the processing report Data delivery
33. discussion The following summary of downhole logging measurements is included only to present a general overview of the methods used and the range of data and their measurement resolutions Typically logs made downhole fall into three general categories electrical nuclear and acoustic In addition borehole imaging temperature and various other in situ properties can be measured downhole using wireline logging tools Although the accuracy resolution and applications differ for each type of measurement to gether they provide a comprehensive data set that can be used as a proxy for the subsurface geology Each type of measurement is discussed briefly below summary of the vertical resolutions of several common devices which range from a few millimeters to over a meter is pre sented in Figure 4 see Table 1 for abbreviations Most typical logging devices have vertical resolution of at least 0 5 m so that beds thinner than this are difficult to study er al 1988 Tunnan 1991 To maximize the vertical resolution of logging data it is important to minimize effects that may introduce additional uncertainties in the correlation between the recorded data and depth such as motion due to ship heave In 1988 a hydraulic heave compensator that moves the wireline opposite to heave motion while log ging was first developed and used on the ODP drill ship Goldberg 1990 measured the effectiveness of this wire line heave compen
34. easy to detect since in a tight hole the effective weight of a tool string varies from several hundred pounds to zero compared to 5 10 000 pounds cable weight Solution If logging down with Schlumberger tools setdown is easy to see on the oscilloscope as a sudden straight lining of log responses However straight lining of the deepest tool on the string will not be visible until about 15m of excess cable is unspooled because of recording delay With specialty tools or when not logging while going down setdown is detected only on the tension meter especially on the increment dial Fortunately bridges are most likely on the first run seismic stratigraphic combo and the gamma ray can be monitored while the winch operator watches the tensiometer The increment dial must be watched carefully through the last 200m of pipe and BHA if the CSES is in use Mud plugs are likely and pipe diameter is so narrow compared to open hole that even a few meters of excess cable can cause a kink Back to Stuck Lost Tools Data Loggin Stuck Lost Shipboard Acquisition Operations Tool Policy Reports 05 MEST C TOOL ZERO Table 1 Specifications of downhole tools employed during Leg 178 Tool String Triple Combo total length 32m FMS Sonic total length 26m GHMT WST Tool Output HNGS HSGR HCGR UNIS Approx Tool Measurement In Vertical Resolution cm HNGS Natural Gamma 15 45 APS Porosi
35. fluctuations in 5102 and shown with calculated errors reflect regular variations in the lithology 750 770 Abundant tephra horizons in the core 790 800 ch a SiS Ca 810 TT Fel Si Ca HiSi Ca 820 830 840 Figure 3 Elemental yield ratios from ODP Hole 999B Increases in all the data but particlulrly the porosity indicator H S1 correlate with the occurrence of abundant tephra horizons in the core Depth Depth mbsf mhsf UNIT 2 Olivine hearing gabbro with intervals of Fe Ti oxide gabbro UNIT 3 Olivine gabbro UNIT 4 Fe Ti oxide rich gabbro Very high Fet max 34 and TiQ2 max 9 PERMEABLE UNIT 5 Relatively uniform olivine gabbro with a paucity of Fe Ti oxides Figure 4 Geochemical results from ODP Hole 735B clearly show a unit of iron titanium oxide rich gabbro in the formation LIEU eS VALAE LIUIVW UE oxide rich gabbro in the formation CFE CHY CE ALUM m a 1 1203 Tio Applications of gamma ray logs Depth correlations and core log integration Total gamma ray log curves which are acquired with every toolstring combination are normally used to depth match all of the logs obtained in any one hole The HSGR log from the Triple Combo is used as the base curve and the SGR logs from all the other to
36. ft hr 550 m hr Resistivity Range 0 2 to 100 000 ohm m Vertical Resolution 8 in Output ARI output plot Deployment Notes The ARI may be deployed in the Triple Combo where it replaces the Dual Induction Tool DIT E in several other combinations or deployed independently However the ARI must be used with the GPIT for image orientation as is the case for the FMS tool Repeat passes of the ARI may be useful to obtain consistent azimuth measurements Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME Cyclicity in Logs Introduction Milankovitch orbital cycles eccentricity at periods of 95K 123K and 410K obliquity at 41K and precession at 19K and 23K are expected in logs of pelagic sediments for the following reasons Orbital changes cause global or regional climatic changes 2 Climatic changes affect the mineralogy or porosity of the sediments 3 Logs detect mineralogy and porosity changes See figure The cycles may appear on different logs in different regions so far we have had success with gamma density resistivity magnetic susceptibility and sonic logs and it is possible that different logs from the same well will show energies at different Milankovitch periods The climate system also varies on sub orbital time scales and this climate variability is similarly reflected in th
37. generate seismic waves that did not have sufficiently high peak pressures to cause damage to marine fauna In addition explosive sources created a so called bubble effect an undesirable artifact in a seismic record caused by oscillations of gas bubbles generating repetitions of first arrivals Because of the consistency of the water medium it is possible to generate energy within the frequency band used for seismic exploration by a more controlled release of gas pressure air gun or by other means of producing a sudden volume increase within the water column water gun while at the same time minimizing the bubble effect The requirements for a marine seismic source are 1 Ability to generate a discrete powerful pulse or signal that can be subjected to later compression in time 2 A rechargeable or repeatable system which can be used in a sequence of operations at short intervals of time 10 seconds or so 3 relatively simple system that will operate consistently trouble free and have long life between overhauls 4 A system that can be used in constant depth below the water surface and results in minimum drag on the vessel carrying it 5 A system that does not injure marine life 6 A system that minimizes the bubble effect Seismic guns currently available on the JOIDES Resolution 3 80 cu in SSI water guns 2 200 cu in Hamco water guns 1 400 cu in SSI water gun 1 1500 Bolt Airgun capable of 120 to 10
38. in the image logs and are critical to recognize the extent of the deformation front along a tectonic front Conversion of RAB images into relative porosity using Archie s equation Archie 1942 can be used in combination with density and porosity data to help define the azimuthal distribution of porosity and overpressurized zones which may contribute to fluid flow along planes of structural weakness Environmental Effects The button measurements have a shallow depth of investigation by design in order to be sensitive to shallow invasion When the RAB tool is centralized in a 8 5 in hole the buttons are 0 1875 in from the formation Controlling this standoff insures correct measurements Therefore proper centralization is recommended The RAB processing automatically corrects the resistivity measurements for frequency effects and the effects of the borehole Routines to derive Rt from the multidepth measurements are being developed In impermeable zones such as shales and zones where insufficient time has passed for any significant invasion to take place the measurements from the Ring Deep Button and Medium Button will match all reading Rt Log Presentation RAB output Comparison of RAB and Formation MicroImager Specifications Tool weight Tool length Min Max temp Drill collar nominal outside diameter Drill collar maximum outside diameter slick Drill collar maximum outside diameter
39. is being employed primarily for post cruise work However a pilot study is underway Legs 194 and 196 to determine the effectiveness of using this tool on the drillship The log and seismic data are organized into GeoFrame projects usually one project for each ODP leg The user must log in to the project to gain access to the data and the application modules that are used to load process and view the data Within IESX are the following applications e IESX Data Manager for loading seismic data into the project e Basemap for viewing maps of the survey lines and site locations e Seis2DV for viewing and interpreting seismic data and adding downhole log data e Synthetics for generating synthetic seismograms e Geoviz for viewing and interpreting data in 3 dimensions Initially the available seismic navigation and trace SEG Y data for the area are loaded into the project The latitude and longitude of existing and proposed sites are also entered The examples shown in the links above are based on ODP Leg 119 Prydz Bay Antarctica and the 1982 BMR Australian Bureau of Mineral Resources seismic surveys of the area The log and core physical property data can also be imported into the project A synthetic seismogram can be generated to provide the link between the logs and and the seismic section The basic idea is to achieve match between the reflections that we expect the formations to create the synthe
40. makes it a less than optimum washover shoe The wireline attempt 15 not recommended in a cased reentry hole where chances of successful overshot fishing are excellent In a single bit hole however a free fall funnel FFF and reentry into an uncased hole are required with greatly reduced chances of reaching the fish in a clean hole It is therefore an on the spot judgment call and a wireline attempt before pulling out of the hole may be the more prudent course of action ODP stocks grapples in 2 1 2 fishing neck and 3 3 8 tool body sizes for logging tools for the Bowen 9 1 2 overshot The overshot is installed in place of a bit a reentry is made and the entire drill string is lowered over the tool to engage the grapple Circulation is maintained through this process and successful engagement is signaled by increased pump pressure Situation 3 calls for a pipe stripping operation by means of the Bowen ropesocket method The cable must be cut at the rig floor and that portion in the pipe is thereby sacrificed Once the pipe has been stripped into the hole to just above the fish the circulating head is installed and the washover operation is conducted as with the CSES The logging tool and cable then can be recovered by the logging winch In situation 4 without the CSES the only alternative is to pull on the logging tool until it comes free or the weak point fails If the weak point fails a core barrel with slip type core catcher ca
41. margins have not been included but can be by increasing the fixed time necessary for certain operations e g item 3 above or by decreasing logging speeds ODP Logging Selecting Estimating Pre Cruise Staff Scientist Toolstrings Log Times Meeting INDEX OF TOPICS GLOSSARY ACRONYMS HOME lt Geochemical Tool GLT Note the GLT is no longer in use in the ODP logging program This page is included to provide assistance to investigators working with GLT data Description The Geochemical Logging Tool GL T uses three separate modes of gamma ray spectroscopy to obtain measurements of most of the major oxides which make up sedimentary and igneous rocks Initial measurements provide estimates of Si A Fe Ca K U and Th together with and Cl Estimates of Ti S and Gd are obtained later with further processing The GLT provides gross geochemical information about the formation which is particularly useful when combined with other logs The data can be used directly for the characterization of geological sequences and phenomena and are excellent for geotechnical zoning Al However due to its relatively low measurement precision see Environmental Effectssection below the GLT is best employed in environments where there is a marked variation in the geochemistry of the rocks E Th 17 The GLT consists of four components At the top is a Natural Gamma Ray Tool NGT Beneath this is a Compensated Neutron Poro
42. occurs at a slowness near that of the frequency of peak excitation after filtering The estimate is therefore biased slower than the true shear and must be corrected The bias depends on the time signature of the source excitation the filter characteristics the borehole size and shear slowness In slow formations the correction is less than 10 and usually much less In fast formations where the dispersion of the flexural mode is greater a large correction is required only in large gt 17 in boreholes In a fast formation with a moderate hole size lt 12 in very little or no bias is found 2 Depth derived borehole compensation One way to obtain borehole compensation is to derive slowness delta t measurements from both upward and downward propagating waves The effects of borehole size changes tend to have an opposite effect on the slownesses derived from each The standard BHC tool accomplishes this by having a transmitter above and below the receivers The Long Spaced Sonic LSS tool though simulates this with depth derived borehole compensation The DSI 2 employs the same depth derived technique Instead of having transmitters above and below the array it constructs a pseudo transmitter array from several tool positions as it moves up the hole The pseudo transmitter array looks like an array of transmitters with one receiver above This approximates a single transmitter on top with a receiver array below Depth of Inve
43. of electrons which is roughly proportional to the bulk density The source and detector are on a skid which is pressed against the borehole wall Compensated density logging tools include a secondary detector which responds more to the mud cake and small borehole irregularities the response of the second detector is used to correct the readings of the main detector Depth of investigation The radius about a logging sonde within which material contributes significantly to the readings from the sonde Dipmeter A well log from which the magnitude and azimuth of formation dip can be determined The resistivity dipmeter includes a three or more microresistivity readings made using sensors distributed in azimuth about the logging sonde b a reading of the azimuth of one of these c a reading of the hole deviation or drift angle d its bearing and e one or two caliper measurements The microresistivity curves are correlated to determine the differences in depth of bedding markers on different sides of the borehole and dip calculations are based on such correlations E Eccentralize To push a logging tool from the center of the borehole to the borehole wall This is often accomplished by a mechanical arm in the logging tool actuated at the beginning of the upward logging run Nuclear logging tools for example need to eccentralized to make correct measurements Environmental Corrections Log data are adversely influenced by downh
44. of hydrofractures may occur within fault zones Variations in fault displacement and fluid activity can be related to the in situ measurements to investigate the degree to which these processes are active The ADN measurements of porosity and estimations of fluid pressure can illustrate the nature of the pressure seals as well as the physical processes responsible for fluid migration and redistribution along a fault zone The determination of the Vp and bulk modulus using ISONIC and ADN data can also contribute to the understanding of the mechanical strength of the rocks within and near a fault zone These LWD azimuthal measurements can be used to provide information regarding the spatial variation of physical properties around the borehole The ADN measurements can also provide porosity information as a function of borehole azimuth To estimate strain from in situ porosity lithological effects on these measurements must be first distinguished from the porosity effects For this purpose RAB resistivity and gamma ray measurements can be used to estimate any significant changes in clay mineralogy within a fault zone Laboratory porosity measurements and thin sections of core samples allow observations of interstitial pore structures and can serve as a correlation tool for more refined calculations of continuous porosity records from the log data The porosity and resistivity image data can provide information about fracture density fracture aperture
45. preliminary report is meant to supply operational details and highlights of the data which is recovered Operational details that are usually presented include BHA depth tools used and depths logged during each pass number of passes problems encountered highlights of the recovered data and its potential utility e g potential for core log integration cyclicity related to climate good magnetics that allow reversal stratigraphy etc Data Loggin Stuck Lost Shipboard Acquisition Operations Tool Policy Reports INDEX OF TOPICS GLOSSARY ACRONYMS HOME ACRONYMS e Acronyms for Schlumberger Tools e Acronyms for Third Party Tools e Acronyms and Units used for Schlumberger Logs e Additional Acronyms and Units ACRONYMS FOR SCHLUMBERGER TOOLS ACT Aluminum Clay Tool APS Accelerator Porosity Sonde ARI Azimuthal Resistivity Imager ASI Array Seismic Imager BHC Borehole Compensated Sonic Tool CNT Compensated Neutron Tool CALI Caliper CA_ Caliper DIT Dual Induction Tool DLL Dual Laterolog DSI 2 Dipole Sonic Imager FMS Formation GHMT Geological Magnetic Tool GLT Geochemical Tool GPIT General Purpose Inclinometer Tool GR Natural Gamma Ray GST Induced Gamma Ray Spectrometry Tool HLDS Hostile Environment Lithodensity Sonde HNGS Hostile Environment Gamma Ray Sonde LDT Lithodensity Tool LSS Long Spacing Sonic Tool LWD ADN Logging While Drilling Azimuthal Density Neutron
46. seismic velocities because of frequency dispersion e g the sonic tool works at 10 20 kHz vs 50 100 Hz in seismic data and because the sound is forced to travel along the borehole wall a path this is quite different from the one taken by the air gun signal generated during a seismic reflection survey In addition sonic logs are not obtained above the bottomhole assembly and the traveltime to the uppermost logging point has to be estimated by some other means WST Well Seismic Tool Applications Depth traveltime pairs determined from check shots can be used to produce a depth traveltime plot and to calibrate the sonic logs and determine accurate drilling depths and their relative position with respect to targets on the seismic reflection profiles Log Presentation The first arrival times are plotted against depth the time vs depth data derived from core and log sonic velocity measurements can be displayed on the same plot The interval velocities gradients of the time vs depth plot between WST stations can be plotted in the same track as the sonic velocity log Velocities are given in km sec arrival times are measured in either milliseconds or seconds If the WST waveforms have been processed as a zero offset VSP by the Schlumberger engineer on the Maxis the resulting seismogram can be plotted vs two way time alongside the seismic section and the synthetic seismogram Specifications Temperature Rating 350 F 175
47. some instances velocities derived from resistivity logs can be used to depth tie seismic reflectors e Lithologic boundary definition and textural changes Resistivity along with acoustic and velocity logs is a very valuable tool in defining lithologic boundaries over intervals of poor core recovery In a particular example the decrease in resistivity toward the top of a carbonate unit coupled with a decrease in velocity allowed one to interpret this unit as a fining upward sequence in mostly carbonatic sediments Similar saw tooth patterns in the resistivity response can also be observed in oceanic basalt units where they are related to porosity changes towards the top of each unit Environmental Fffects The Phasor Dual Induction tool provides a set of corrections for different environmental effects which can be performed in real time during logging These include corrections for adjacent formations borehole signal and invasion In general invasion is not a problem in the boreholes logged in the Ocean Drilling Program because seawater is used as drilling fluid but it can occur in land wells In fact depending on the type of drilling mud used and on the permeability of the formation invasion of the mud filtrate into the formation adjacent to the borehole can lead to differences in the response of shallow and deeper resistivity devices On the other hand invasion can provide useful information about formation permeability and por
48. sour the mood on the ship considerably Don t lose the GHMT either as there are only two of them in existence In summation losing a tool is awkward and unpleasant Try very hard not to do it Conical side entry sub CSES The CSES makes it less risky to log under unstable hole conditions however it can increase the logging time by 50 or more and cannot be used in shallow water depths A more detailed discussion can be found in the CSES section on the Other Equipment page Dedicated logging holes The more time spent coring a hole the wider and more unstable it will become For this reason a fresh hole should provide better logs However the time involved is usually prohibitive Logging APC XCB vs RCB holes The logging tools can pass through the APC XCB bit whereas the RCB bit has to be dropped at the bottom of the hole before logging tools can pass through The hole cannot be deepened or bridges tagged after the RCB bit has been dropped The RCB bit is about 2 inches narrower than the APC XCB bit so the RCB hole is less likely to be wide and consequently better for the FMS The go devil It is important to understand the principles behind the deployment and operation of the go devil For details see the go devil section on the Other Equipment page Third Party Tool Support ODP Logging Services provides support for broad aspects of third party downhole tool deployment Third party tools are designed and deve
49. spectroscopy tools The next two tools in the string allow the measurement of the Al concentration The 252Cf source in the Compensated Neutron Porosity Tool causes the neutron activation of Al in which the natural isotope 27 absorbs thermal neutrons and produces the isotope 28 which decays with a half life of 2 24 minutes and emits 1 78 MeV gamma rays The aluminium activation clay tool measures the gamma spectrum of the activated formation and the Al component is determined by subtracting the input from the natural gamma ray tool spectrum There is some spectral interference in the aluminium measurement from silicon which is corrected during the land based processing The gamma ray spectrometry tool can operate in two timing modes inelastic which mainly measures the neutron reactions in the high energy range and capture tau mode which employs prompt neutron capture reactions to measure elemental concentrations This report describes how the gamma ray spectrometry tool functions in capture tau mode which is how it is normally used in the ODP For an example of its use in inelastic mode the reader should refer to the Leg Summary for ODP Leg 164 gamma ray spectrometry tool uses minitron tritium source to bombard the formation with pulsed 14 MeV neutrons Through scattering reactions with the atoms in the formation the neutrons progressively lose energy until they reach a thermal energy at which they can be c
50. the data if the tool is operating correctly they should be less than 0 1 g cc and 1 in respectively Gamma ray GR log in API units is also plotted Specifications Tool weight 2000 Ib 907 kg Tool length with savers 30 6 ft 9 3 m Min Max temp 13 300 F 25 150 C Maximum weight on bit 63 000 000 L2 Ibm where L is the distance between stabilizers in feet Maximum flow rate 600 gal min Maximum operating pressure 18 000 psi 12 4 kPa Available collar sizes 6 75 in 8 25 in Available stabilizers 8 50 in 9 75 in Output DCAL Differential Caliper in DRHO Bulk Density Correction g cm3 PEF Photoelectric Effect barns e ROMT Max Density Total g cm3 from rotational processing TNPH Thermal Neutron Porosity DTAB CDN Density Time after Bit hr NTAB CDN Neutron Time after Bit hr Deployment Notes Along with the LWD collars additional equipment such as jars must be included Responsibility for providing this equipment is discussed at the pre cruise meeting LWD deployment illustration LWD deployment photo trademark of Schlumberger Triple Combo FMS Sonic Specialty Other X Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS Cogging While Drillin Compensated Dual Resistivity LWD CDR Description The LWD CDR is an electromagnetic propagation and spectral gamma ray tool built into a drill collar It has many similarities to dual induct
51. the most important requirement to obtain reliable porosity measurements This is not routinely performed in ODP boreholes because of the increased risk of getting the tool stuck in the drill pipe The lack of contact of the tool with the borehole wall during the recording results in the attenuation of the formation signal by the borehole fluid and in turn the overestimate of the true porosity of the formation Hole size also affects the neutron log response the formation signal particularly for the epithermal count rates tends to be masked by the borehole signal with increasing hole size In liquid filled holes the influence of the borehole fluid depends on its salinity chlorine is a strong neutron absorber and density the addition of weighting additives such as barite will yield a lower porosity reading In the Ocean Drilling Program the neutron tool is sometimes recorded through the drilling pipe and the bottom hole assembly Because iron is a strong neutron absorber the effect will be of an increased porosity reading depending on the thickness of the pipe Log Presentation The CNT G is recorded in linear porosity units for a particular lithology limestone sandstone dolomite The thermal porosity curve NPHI or TNPH is usually displayed When the CNT G is run in combination with the lithodensity and spectral gamma ray tool the neutron and density curves are usually displayed in the same track with Gamma Ray and Caliper
52. the mud usually have relatively high frequency content they are sometimes called fluid waves One or more modes of high amplitude low frequency tube waves sometimes called Stonely waves are usually very distinct arrivals 3 More generally an elastic wave or seismic wave Advanced Piston Corer APC A coring device used to obtain near complete core recovery when sediments are very soft usually the uppermost 100 200 m of section API Units 1 A unit of counting rate for the gamma ray log The difference between the high and low radioactivity sections in the API calibration pit is defined as 200 API units 2 A unit of counting rate for the neutron log The reading in the Indiana limestone portion of HOME the API neutron log calibration pit which has 19 porosity and is saturated with fresh water is defined as 1000 API units Auxiliary Measuring Sonde AMS A Schlumberger tool that can be added to any digital string yielding measurements of hole temperature and head tension Borehole effect A distortion of a well log because of the size and influence of the borehole or sometimes the invaded zone Bottom Hole Assembly BHA The lowest 70 100 m portion of the drillstring made of thicker steel with a smaller inner diameter than normal pipe Different BHAs are used for coring and coring Bridge A hole constriction too small for the logging tool to pass through caused sometimes by clay swelling and sometim
53. to an increase in terrigenous clays Figure 3 Spectral gamma ray data from Hole 11720 showing high U values in an organic bearing claystone unit between 622 640 mbsf MD HSGR HTHO HFK HURA 0 API 10010 2010 510 10 High U values 600 605 610 615 620 625 630 associated with increased total 635 i organic carbon 640 645 650 655 660 back to gamma applications Figure 4 Spectral gamma ray data from Hole 11710 showing high values due to the presence of glauconite MD a 2 a 1 b El h D 0 10010 2010 510 ppm 10 High K values 250 255 260 265 270 0 275 due to glauconite 280 285 290 High K values 295 due to glauconite 300 305 310 back to gamma applications Power Figure 5 Spectral gamma ray data A and preliminary spectral analysis B and C from 1170D The power spectrum show the results of spectral analysis over the entire logged section B and the interval where the Th and K data show the most pronounced cyclicity C 550 600 650 700 750 N OO no wo a rer rites 20 0 0 01 02 0 3 0 4 0 5 0 6 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 frequency cycles m frequency cycles m Power YI we Vg 9 5 9 9 9 0 U frequency cycles m frequency cycles m back to gamma applications INDEX OF TOPICS GLOSSARY ACRONYMS THE
54. total time is automatically calculated See Table 2 2 immediately below All the variable inputs to the spreadsheet are separated from the detailed outline of logging operations This detailed outline can be tailored for or changed according to the specifics of an individual leg or from experience of actual logging times as a leg progresses TABLE 2 2 Variable Input Tool Speed Rep Rep Logs Deployed Repeat Yes No m hr Speed Interval Triple m Combo Variables Pipe Depth FMS Sonic Yes 250 Yes 250 250 GHMT Yes 500 Yes 500 100 BHTV 150 UBI No 250 Yes 250 100 Hole Depth GLT Yes 183 Yes 183 100 D Yes 180 No NA N A Yes 180 No N A Station Interval Time Station meters min WST Yes 50 20 1800 Can CSES be used uu NM 200000 Wee to use CSES Estimation Concerns Prior to Leg 112 the major uncertainty in logging time estimates involved delays associated with bridges A bridge is a constricted hole interval that the logging tool may not be able to get past when it is on its way down through open hole Nearly all ODP bridges are found in sedimentary sequences and are caused by clay swelling after drilling With the routine use of sepiolite muds the clay swelling problems have significantly diminished Bridges can also form in heavily fractured formations but thes
55. vertical resolution independent of the location of the RAB tool in the bottomhole assembly In addition the RAB sub has three longitudinally spaced button electrodes that provide staggered depths of investigation As the tool rotates azimuthal Bus re mar at meaa poe cmt 5 T rr DAE me im E measurements are acquired from the button electrodes The RAB measurements have a high vertical and azimuthal resolution To make the most of the vertical resolution the optimal sampling density is greater than one sample every inch At the maximum sampling interval of 10 sec the optimal sampling density can be achieved for rates of penetration up to 30 ft hr Achieving this vertical sampling is most important when imaging Applications The RAB tool provides four depth of investigation measurements to detect early invasion of borehole fluids into the formation a sensor at the bit to ensure minimum invasion azimuthal resistivity images of the borehole to detect resistivity heterogeneity and a gamma ray sensor for lithology characterization The RAB tool can also provide a close look at structural information within a fault zone or an active tectonic are with a resolution of 15 30 cm The RAB measures oriented resistivity images of the borehole wall similar to an FMI or FMS wireline tools These fracture orientations and distributions can be observed as resistivity contrasts
56. works best when the sediment s remanent magnetization is strong The working range of the NMRS is from 27100 to 69400 nTesla The magnetic field in some areas off South America is below this range When the Earth s field inclination is or 35 degrees approximately or 20 degrees of latitude the susceptibility effect is zero and the polarity cannot be determined Log Presentation Magnetostratigraphy is compiled from the susceptibility and total induction measurements and is usually plotted to show the correlation or anticorrelation between the susceptibility and the remanence effects Magnetostratigraphy plot Specifications Temperature Rating Pressure Rating 20 kpsi 13 8 kPa Tool Diameter 4 in 10 2 cm Tool Length 27 4 ft 8 34 m Weight 286 Ib Range Full Scale NMRS from 27100 to 69400 nT 0 1 nT SUMS 0 000005 Deployment Notes As of Leg 189 the GHMT can be combined with the DSI 2 The main advantages of this combination are 1 it adds weight to the GHMT 2 it avoids using the FMS in high heave and difficult hole conditions and 3 it saves rig up time if the DSI 2 is run twice Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME Other Equipment cont Fluid Seal and Torpedo The fluid seal is used to prevent drilling fluid from being released in large quantitie
57. 00 cu in Shoulder bed effect Effect of adjacent beds log reading Also called the adjacent bed effect For example high resistivity beds adjacent to a low resistivity bed may result in more current flowing in the low resistivity bed than if the high resistivity bed were not present thus changing the apparent resistivity of the low resistivity bed Sonic log A well log of the travel time for acoustic waves over a unit distance and hence the reciprocal of the longitudinal wave P wave velocity Also called acoustic velocity log and continuous velocity log Usually measured in microseconds per foot Especially used for porosity determination by the Wyllie relationship The interval transit time is integrated down the borehole to give the total travel time For the compensated sonic log two transmitters are pulsed alternately averaging the measurements tends to cancel errors due to sonde tilt or changes in hole size Spontaneous Potential SP Also called self potential 1 A well log of the difference between the potential of a movable electrode in the borehole and a fixed reference electrode at the surface The SP results from electrochemical SP and electrokinetic potentials which are present at the interface between permeable beds adjacent to shale In impermeable shales the SP is fairly constant at the shale base line value In permeable formations the deflection depends on the contrast between the ion content of the for
58. 1 8 30 A M Coffee Curation amp Sampling Computers Publications Photography Noon Lunch 1 00 P M Scientific Prospectus ODP Logging Selecting Staff Scientist Toolstrings Logging Information Heike Delius ODP Logging Staff Scientist Brad Julson ODP TAMU Supervisor of Logistics amp Technical Support Pat Thompson ODP TAMU Material Services Team Aaron Woods ODP TAMU Coordinator for Public Information Tom Davies ODP TAMU Manager Science Services Karen Graber Paul Wallace Staff Researcher Staff Scientist John Firth ODP TAMU Curator Science Services Ken Emery ODP TAMU Supervisor Computer Network Development amp Support Ann Klaus ODP TAMU Manager Publication Services John Beck ODP TAMU Senior Photographer Paul Wallace Mike Coffin Fred Frey Estimating Pre Cruise Log Times Meeting INDEX OF TOPICS GLOSSARY ACRONYMS HOME Selecting Logging Tools Introduction The selection of specific downhole logging tools for a particular leg is an Principal Application ongoing procedure that starts with the proponents and usually ends when the Program Plan is approved The standard toolstrings Triple Combo and FMS Sonic are always on the ship often accompanied by one or more of the specialty toolstrings GHMT ARI etc Specialty tool use is dictated by the scientific objectives of the cruise leg and inevitably by the size of the year s budget for sp
59. 3 and 5 apart as well as the spacings T5 R4 and T5 R The transit time of the compressional wave in the formation measured in microseconds per foot is given by dt 1 2 T4 R5 T4R 4 T5R5 T5R4 Long Spacing Sonic LSS The LSS relies on the depth derived borehole compensation principle because the sonde would be too long if it used the same configuration as the BHC tool Two transmitters spaced two feet apart are located eight feet below two receivers which are also two feet apart Hole size compensation is obtained by memorizing the first DT reading and averaging it with a second reading measured after the sonde has been pulled up to a fixed distance along the borehole The LSS provides an improved measurement of the sonic travel time Thanks to its longer spacing 10 12 feet the sonde has a deeper investigation depth and the measurement is not influenced by the altered zone close to the borehole In fact drilling operations in the altered zone produce a decrease of acoustic velocity below that of the virgin zone Full waveforms are always recorded for each receiver Shear velocity can be recorded with delay beyond P wave arrival during a separate run Array Sonic SDT In a fast formation where shear velocity is faster than the velocity of the drilling fluid the SDT obtains direct measurements for shear compressional and Stoneley wave values In a slow formation the SDT obtains real time measurements of compressiona
60. 7 25 kPa Tool Diameter 3 5 in 9 cm Tool Length 23 08 ft 7 03 m Sampling Interval 6 in 15 24 cm Max Logging Speed 1 800 ft hr Vertical Resolution 1 25 ft 38 cm Depth of Investigation see last paragraph of Description section Output RHOM Corrected Bulk Density g cm DRH Bulk Density Correction g cm Long spaced Photoelectric Effect barns e Bulk Density g cm Deployment Notes Typically run with IPLT components HNGS APS Can be combined with DIT DLL and ASI The Density section is capable of measuring internal temperature which may be useful in high temperature holes Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS The ODP Logging Staff Scientist The role of the ODP Logging Staff Scientist encompasses a number of responsibilities e Coordination of all leg related logging activities pre cruise cruise and post cruise e Training of any new logging scientists sailing on the cruise e Interfacing with the Co Chief Scientists TAMU Staff Scientist and the Operations and Drilling Superintendents e Pre cruise cruise and post cruise reporting of logging objectives and operations e Participation in and supervision of at sea logging operations Logging scientists aboard ODP Leg 188 HOME Formation of the Project Team Shortly after th
61. AMS to monitor borehole fluid temperatures High Temperatures In high temperature environments i e hydrothermal systems or lower crustal settings temperature logs can be recorded using the wireline slim hole Hi T Temperature Tool HTT developed at LDEO for operation at the TAG hydrothermal mound in 1994 or the University of Miami third party GRC memory temperature tool Tools LDEO High T Temperature Tool HTT The HTT can be used in temperature conditions of up to 275 C although the Teflon insulation in the wireline will begin to degrade beyond 232 C Generally this can present a problem after extended use in temperature conditions exceeding 235 C however the HTT measuring system is only frequency dependant Therefore the tool can still transmit reliable measurements even after the cable has been considerably degraded GRC Ultra High T Temperature Tool The GRC was developed with NSF funds by the University of Miami Although this tool is available arrangements need to be made for maintenance if it is desired for future use This tool can be deployed on the sandline if temperatures exceed 232 C as occurred during Leg 169 when the tool was successfully deployed in Hole 858G However since this is a memory tool the loggers will be unable to monitor temperature or tool problems in real time Operations Following drilling circulation operations must occur to cool the hole At this point the Triple
62. ARI provides a remote image of the formation in a similar way to that of the BHTV de LJ ia a The ARI electrode array operates at 35 Hz for the deep readings and focuses currents that flow from the 12 electrodes to the grounded logging cable The sum of these 12 readings produces a high resolution measurement equivalent to a single laterolog electrode of the same height To correct for tool eccentralization and variations in borehole shape a shallow auxiliary measurement of electrical resistivities is performed at a much higher frequency of 71 kHz This measurement responds primarily to the volume of borehole fluid affecting each electrode If the borehole fluid resistivity is independently measured then borehole size and shape can be deduced from the auxiliary array measurements While the vertical resolution of the standard laterolog readings is about 0 60 m the high resolution array can reduce this by up to a factor of 6 depending on the formation resistivity Preliminary processing of ARI images may be accomplished using GeoFrame software package developed by Schlumberger and GeoQuest in a similar manner to FMS image processing Comparison of image data from different logging tools can also be displayed using this software which may provide information about fracture and fault orientation and aperture formation dip and heterogeneity and borehole shape As the FMS is less sensitive to features nea
63. BHA then a hammer is sent down to fire the crimper which crimps the logging cable against the BHA A successful crimp must be observed by the Schlumberger engineer by checking for an electrical short inside the cable If successful the cutter 15 dropped and the cut logging cable is reeled in The tool is held inside the BHA and recovered by pulling pipe to the rig floor Crimping and cutting works well for situation 4 but is no guarantee of success During Leg 175 the Kinley crimper was used to secure the tool in the pipe but it failed to adequately crimp the cable As the tool and drill pipe were being pulled to the surface the toolstring dislodged itself and fell to the seafloor where it could not be retrieved 5 Additional strategies In 1988 Glen Foss Operations Superintendent at ODP TAMU put together a detailed memo on wireline stripping operations This is highly recommended reading The part relevant to recovery of stuck tools is given In addition ODP Logging Services has compiled a list of to avoid when logging along with strategies to avoid and cope with them To some degree each stuck lost tool situation is unique and it is impossible for any guidelines we give to always be appropriate Thus the recommendations given in the following table should be considered as suggestions only not requirements CSES SOLUTIONS PROBLEM COMMENTS pull cable to failure cut amp crimp strip amp cut 1 Stu
64. Capillary Suction Tester CST CD ROM of log data Conical Sidewall Entry Sub CSES Core Barrel Temperature Tool CBTT Core Log integration Splicer amp Sagan software packages Customer tapes Cyclicity in logs Data acquisition amp transfer Data distribution Data processing overview Dipole Shear Sonic Tool DSI 2 Downhole Measurements Lab DHML Drill String Acceleration Tool DSA Dual Porosity Compensated Neutron Log CNT G Dual Laterolog DLL E Estimating logging times F Fluid seal FMS processing FMS Sonic toolstring Formation Microscanner FMS G General Purpose Inclinometry Cartridge GPIT Geochemical Tool GLT Geological High Resolution Magnetic Tool GHMT processing Glossary of terms Go devil GRC Ultra High T Temperature Tool H High T Temperature Tool HTT High temperature logging operations Hole finder Hostile Environment Gamma Ray Sonde HNGS Hostile Environment Lithodensity Sonde HLDS How to use this manual IESX Core Log Seismic Integration Initial Reports Explanatory Notes Initial Reports Logging Chapter Initial Reports Seismic Stratigraphy Chapter J JOIDES Logger K Kinley crimper cutter L Lockable Flapper Valve LFV Log plots Schlumberger Log processing Log Seismic Integration IESX Logging operations Logging Staff Scientist Logging times estimation of Logging tool response in sediment
65. Combo 5 5 Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME emperature Acceleration Pressure Tool TAP Description The TAP High Resolution Temperature Acceleration Pressure tool was designed to acquire borehole temperature tool acceleration and hydrostatic pressure data It is the successor tool to the Lamont Temperature Tool TLT The TAP tool may be run in either memory mode where the tool is fastened to the bottom of the Triple Combo and data stored in the onboard memory or it may be run in telemetry mode where the tool is run alone and data is recorded in real time by the third party DAS data acquisition system Fast and slow response thermistors are mounted near the bottom of the tool to detect borehole fluid temperatures at two different rates The thinner fast response is able to detect small abrupt changes in temperature the thicker slow response thermistor is used to estimate temperature gradient and thermal regimes more accurately One pressure transducer is included to turn the tool on and off at specified depths when used in memory mode Typically data acquisition is programmed to begin 100m above the seafloor A 3 axis accelerometer is also included to measure tool movement downhole These data are expected to be instrumental in analyzing the effects of heave on a deployed tool string which will lead to the fine tuning of the WHC wireline heave compensator
66. Combo with the AMS can be deployed If the AMS records temperatures in the 175 C range then the tool string must be retrieved immediately to avoid damage In this case additional hole cooling operations must occur and a deployment using a modified string with only the Hostile Environment Natural Gamma Sonde HNGS and the Hostile Environment Litho Density Tool HLDT can be attempted The tool s built in temperature sensors must be monitored carefully in order to avoid exposing the electronics to harmful temperatures In additions downhole magnetic field measurements are also possible with the German BGR third party three component fluxgate magnetometer This tool measures the three orthogonal components of the magnetic field up to 100 microTesla with a resolution of 0 1 nT The tool also contains two inclinometers that measure tilt with a resolution of 0 1 The probe is mounted inside a dewar flask and contains heat sinks that allow measurements at temperatures of up to 300 C This magnetometer was previously used during ODP Leg 148 however as it is the case with most third party tools any future deployments must obtain additional funds prior to the cruise for maintenance shipping and training Back to Toolstring Selection ODP Logging Selecting Estimating Pre Cruise Staff Scientist Toolstrings Log Times Meeting INDEX OF TOPICS GLOSSARY ACRONYMS Hostile Environment Gamma Ray Sonde 5 Description The Hostil
67. D Isonic DLL MGT GHMT UBI m HTT WST LWD ADN WST 3 component Triple Combo Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME m WHC Fluid Seal Hole Finder Torpedo Cable Heads ui Wireline DHML Sheaves CSES Sources Miscellaneous Triple Combo FMS Sonic Specialty Other Toolstring Index OF TOPICS GLOSSARY ACRONYMS HOME Formation MicroScanner Description The Formation MicroScanner sonde FMS consists of four orthogonal imaging pads each containing 16 microelectrodes which are in direct contact with the borehole wall during the recording The button current intensity is sampled every 0 1 in 2 5 mm The tool works by emitting a focused current from the four pads into the formation The current intensity variations are measured by the array of buttons on each of the pads Processing transforms the current intensity measurements which reflect the microresistivity variations of the formation into high resolution gray or color images of variable intensity Black and white darkest or lightest color indicate low and high microresistivity respectively The tool also includes a General Purpose Inclinometry Cartridge GPIT which provides accelerometer and magnetometer data in order to allow one to define the tool position and spatial orientation of the data
68. PICS GLOSSARY ACRONYMS HOME hasor Dual Induction Spherically Focused Resistivity Tool DIT E Description The Phasor Dual Induction Spherically Focused Resistivity tool amp Adapter Head DIT E provides measurements of spontaneous potential SP and three amp Telemetry Cartridge different resistivity values IDPH deep induction IMPH medium induction and SFLU shallow spherically focused resistivity Since the solid constituents are orders of magnitude more resistive than pore fluids in most rocks resistivity is controlled mainly by the conductivity of the pore fluids and by the amount and connectivity of the pore space The spontaneous potential is a measure of the streaming potential generated by differences between Induction Sande borehole and pore fluid electrical properties these result in both membrane and liquid junction potentials due to differences in the 7 Nose Standoff mobility of ions in the pore and drilling fluids The induction sonde consists of a series of transmitter and receiver coils mounted on the sonde axis The high frequency alternating current of constant intensity sent through the transmitter coil produces an alternating magnetic field which in turn induces currents in the formation around the borehole These currents flow in circular ground loops coaxial with the sonde Because the alternating current sent by the transmitter coil is of constant frequency
69. R tool However because of shoulder bed effects Rps and Rad will read too low in a thin resistive bed with conductive shoulder beds and a small correction for bed thickness is required to obtain true resistivity Rt A major advantage of the CDR tool is its ability to measure Rt in thin beds before invasion occurs Once thin beds are deeply invaded there is no reliable method for obtaining true resistivity Applications Resistivity Porosity estimate In sediments that do not contain clay or other conductive minerals the relationship between resistivity and porosity has been quantified by Archie s Law Archie s Law relates the resistivity to the inverse power of porosity This relationship has also been used to estimate apparent porosity in oceanic basalts Density and velocity reconstruction Archie s equation has been used effectively to create pseudodensity and or pseudovelocity logs from porosity over intervals where no such logs were recorded or were totally unreliable In some instances velocities derived from resistivity logs can be used to depth tie seismic reflectors Lithologic boundary definition and textural changes Resistivity along with acoustic and velocity logs is a very valuable tool in defining lithologic boundaries over intervals of poor core recovery In a particular example the decrease in resistivity towards the top of a carbonate unit coupled with a decrease in velocity allowed one to interpret this
70. S images are usually made available to the scientific party within 48 hours of acquisition They are stored as ASCII files usually one file per logging run and can be opened by any spreadsheet application such as Synergy Software s KaleidaGraph or Microsoft Excel Before placing the data on the Uservol server the Logging Staff Scientist converts the depths to meters below sea floor mbsf and uses the gamma ray curves to perform a preliminary depth matching between successive runs More accurate depth correction is available with the return of the processed data about a week later For more information see the section on data processing FMS images are now also made available on the Uservol server in the form of GIF images produced by the Logging Scientist after preliminary processing with GeoFrame These images usually produced at several different scales to maximize their utility can be opened in any graphic application such as Adobe Photoshop or browser Because the interpretation of FMS images is greatly enhanced by the ability to identify and characterize structural features with Geoframe shipboard scientists are encouraged to familiarize themselves with this software package in order to be able to perform their own interpretation and correlation on the Downhole Measurements Lab workstation provided they don t interfere with the critical work of the logging scientists of course Schlumberger Log Plots Playbacks Sch
71. Solution Spend very little time trying to break through the second bridge If unsuccessful after 5 minutes give up and POOH pull out of hole In fact when there are two bridges within a short interval there are probably many more deeper in the hole Alternative solutions a switch to using the CSES b do a wiper trip then set pipe beneath the two bridges for further logging c if the bridges are near the bottom of the hole give up logging the deeper portion with this tool string do a wiper trip and start logging with the next tool string Tool stuck near hole bottom Getting the tool stuck between the bottom of the hole and a bridge near the bottom of the hole or getting stuck by cavings at the bottom of the hole Solution Whether or not any deep bridges exist spend as little time as possible near the bottom of the hole As soon as bottom is reached while logging down start moving upward slowly and continue upward during the time it takes for the Schlumberger engineer to set parameters for the upcoming run When ready go back down to bottom and immediately start logging up Remember cavings will almost always be accumulating at the bottom of the hole Getting trapped downhole by a bridge Getting trapped downhole by a bridge forming after you ve already gone down through it Solution This is always a risk and is not easily avoided Bridges usually take 2 5 hours to form so if you break down through a bridge try
72. The processed data are saved as ASCII files and transmitted via satellite back to the ship They are also put in the on line database the Initial Reports CD ROM and are archived to tape in LIS DLIS format FMS Processing Processing is required to convert the 64 electrical current traces recorded by the FMS into a color scale image representative of the conductivity changes in the formation BorEID corrections Several corrections are applied using the BorEID module of GeoFrame 1 Speed Correction The data from the z axis accelerometer are used to correct the vertical position of the data for variations in the speed of the tool speed correction including stick and slip In addition image based speed correction is also applied to the data based on reducing any offset between the data from two rows of button electrodes on each FMS pad 2 Equalization The responses of the button electrodes on the pads of the tool are equalized to correct for various tool and borehole effects which affect individual buttons differently 3 Button Correction If the measurements from a button electrode are unreasonably different from its neighbors e g dead buttons the defective trace is replaced by traces from adjacent good buttons 4 EMEX voltage correction During logging the voltage that drives the current is continuously regulated so that current flows even through very resistive formations The button response is divided by
73. aO standard deviation dry weight Computed CaO standard deviation dry weight Computed CaCO dry weight Computed standard deviation dry weight Computed CaCO standard deviation dry weight Calcium Yield decimal fraction Chlorine Yield decimal fraction Iron Yield decimal fraction Gadolinium Yield decimal fraction Hydrogen Yield decimal fraction Silicon Yield decimal fraction Capture Cross Section capture units Sulfur Yield decimal fraction Background Yield decimal fraction Titanium Yield decimal fraction Computed FeO dry weight Computed FeO standard deviation dry weight Computed FeO standard deviation dry weight Computed Fe5O dry weight Computed standard deviation dry weight Computed Fe5O standard deviation dry weight 96 Gadolinium dry weight 96 Gadolinium standard deviation dry weight 96 Gadolinium standard deviation dry weight 96 2 K20 SIO2 SIO2MIN SIO2MAX THORMIN THORMAX TIO2 TIO2MIN TIO2MAX URANMIN URANMAX VARCA Computed Fe5O dry weight Computed Fe5O standard deviation dry weight 96 Computed SiO dry weight 96 Computed SiO standard deviation dry weight 96 Computed SiO standard deviation dry weight 96 Thorium standard deviation ppm Thorium standard deviation ppm Computed TiO dry weight 96 Computed TiO standard deviation dry weight 96 Computed TiO standard deviation dry weight 96 Ura
74. ability depend strictly on porosity variations and on the geometry of the pore space In the presence of clays or hydrous alteration minerals a correction is required to account for the presence of bound water Lithologic determination Because the hydrogen measured by the tool is present not only as free water but also as bound water in clay minerals the porosity curve often combined with the density log can be used to detect shaly intervals or minerals such as gypsum which have a high hydrogen index due to its water of crystallization Conversely the neutron curve can be used to identify anhydrite and salt layers which are both characterized by low neutron readings and by high and low bulk density readings respectively Environmental Effects A reliable density measurement requires good contact between stabilizer and formation Because a statistical caliper measurement 15 made during the recording it is possible to check the quality of the contact Contact also affects the neutron log response the formation signal particularly for the epithermal count rates tends to be masked by the borehole signal with increasing hole size Log Presentation The primary curves are bulk density ROMT in g cc photoelectric effect PEF in barns electron density correction DRHO in g cc and caliper DCAL in in They are usually displayed along with the neutron curve TNPH in porosity units DRHO and DCAL are useful for quality control of
75. al 1998 More quantitative attempts have been made to derive a mineralogy from the spectral gamma ray log which generally involve cross plotting Th against K Quirein 1982 PEFL against K Schlumberger 1991 or PEFL against Th K Schlumberger 1991 However the validity of these methods is questionable Hurst 1990 and it is unlikely that they are applicable in a wide variety of sedimentary environments Cyclostratigraphic analysis Spectral gamma ray data can also be used for cyclostratigraphic analysis of the formation to help identify the frequency of paleoceanographic and or climatic change Figure 5 Data acquired by the recently developed Lamont Multisensor Gamma ray Tool will be particularly valuable for time series analysis due to its very high resolution 8 cm nu ns ir P 1 Mm qp nv mini 2 nf 3 os 4 68 ima zaras frequency Figure 5 Spectral gamma ray data preliminary spectral analysis from 1170D power spectrum show the results of spectral analysis over the entire logged section B and the interval where the Th and K data show the most pronounced cyclicity C References Adams J A amp Weaver C E 1958 Thorium uranium ratios as indicators of sedimentary processes example of concept of geochemical facies Bulletin American Association of Petroleum Geologists 42 2
76. al systems Temperature logs in such an environment can clearly differentiate between the advective hydrothermal and conductive heat transfer regimes Environmental Effects Drilling and circulation operations considerably disturb the temperature distribution inside the borehole thus preventing equilibrated temperature conditions The amount of time elapsed between the end of drilling fluid circulation and the beginning of logging operations is not long enough to allow the borehole to recover thermally Therefore the data recorded is not representative of the thermal equilibrium of that environment In addition the thermistors may become fouled with sediment from the drilled formation which reduces the sensitivity and accuracy of the recorded temperature data Log Presentation Temperature data acquired by the fast and slow thermistors may be presented with resistivity density and porosity log data Temperature data may also be imported into GeoFrame for inclusion in plots made during the leg Specifications Tool Length Tool Diameter Temperature Rating Acceleration Measurement Range Acceleration Resolution Acceleration Sampling Rate Low Resolution Mode LR High Resolution Mode HR Temperature Measurement Range Temperature Resolution Pressure Measurement Range Pressure Resolution Pressure Measurement Precision Temperature Pressure Sampling Rate Total Data Recording Time HR mode LR mode Power
77. al to noise ratio and allows successful logging of extremely slow formations and greatly enlarged holes Improved waveform processing techniques have greatly improved vertical resolution New answer products utilize Stoneley slowness to evaluate fractures and indicate permeability In addition to the new dipole features acquisition of the Stoneley wave velocity utilizes a low frequency monopole energy pulse for highest quality Stoneley measurements Stoneley derived permeability is useful for evaluating fractures as well as investigating deeply into the formation A new technique for detecting compressional wave arrival digital first motion detection DFMD provides measurements that are compatible with previous sonic logs in addition to a 6 in vertical resolution compressional sonic Processing with the MAXIS wellsite unit displays a full wave and its component characteristics Its high speed array processor uses the slowness time coherence STC method to determine compressional shear and Stoneley slowness values choice of band pass filters permits utilization of the optimum frequency range within a mode The process reliably provides unambiguous transit times even in difficult borehole conditions The resulting values are useful inputs for mechanical properties formation evaluation and seismic applications Tool Components 1 Transmitter section The transmitter section contains three transmitter elements one omni
78. an happen inadvertently if the winch operator is not watching cable tension and neither the Logging Scientist nor the Schlumberger engineer notices the tension increase on the dial or oscilloscope log display It can happen deliberately if you get stuck on a bridge or at the base of pipe and try too hard to pull your way out Solution Watch the log oscilloscope display while logging up for any quick ramping up of tension When entering the pipe watch the tension gauge instead of the oscilloscope because there is a substantial delay before tension data are displayed on the scope Remember that many pulls will weaken the weak point Breaking the tool when turning on the WHC Turning on the WHC wireline heave compensator when the tool is in the air or barely lowered into the pipe can break the tool Very rarely the WHC will jerk when it is turned on and this jerk can sever the tool at the weak point Solution Wait until the tool is several hundred meters down the pipe but not in the BHA or well into open hole not barely past the bit before turning on the WHC Jamming the BHA with mud When using the CSES the bottom hole assembly becomes jammed with mud while lowering pipe with the logging tool in open hole Solution The tool must always be up in pipe when lowering the pipe Severing the cable by rotating the pipe while the cable is clamped to the CSES When rigging up the LDT combo with the CSES in place the rig han
79. and amplitude they are directly proportional to the formation conductivity They also produce a magnetic field which induces a voltage in the receiver coil which is in turn proportional to the ground loop currents and therefore to the resistivity of the formation 7 Induction Carmidge 7 amp Fin Standoff Sensor Geometry In homogeneous formations with resistivity higher than 100 ohm the average radial depth of investigation is about 5 ft 1 5 m and 2 5 ft 76 cm for the deep and medium induction curves respectively and 1 25 ft 38 cm for the SFL This drops to 4 ft 122 cm and 2 2 ft 66 cm at 0 1 ohm m resistivities The thin bed resolution over a full range of formation conductivities has been greatly improved due to an enhanced signal processing technique and real time correction for the effect of adjacent formations shoulder effect Applications e Porosity estimate In sediments that do not contain clay or other conductive minerals the relationship between resistivity and porosity has been quantified by Archie s Law Archie s Law relates the resistivity to the inverse power of porosity This relationship has also been used to estimate apparent porosity in oceanic basalts e Density and velocity reconstruction Archie s equation has been used effectively to create pseudodensity and or pseudovelocity logs from porosity over intervals where no such logs were recorded or were totally unreliable In
80. and azimuthal borehole images are acquired over the entire drilled interval providing data over the critical section and 2 data is either saved in memory or transmitted during drilling hence data can be obtained without dismantling the drill string and the chances of borehole wall collapse are reduced MBSF meters below sea floor MBRF meters below rig floor Measurement While Drilling MWD Drilling and logging technology very similar to LWD Logging While Drilling MWD data is telemetered to a surface acquisition system in real time while LWD data is stored in downhole memory until the tool is pulled to the surface and the data retrieved The MWD tools are now routinely used in industry often together with LWD tools to monitor drilling parameters in real time A significant advantage of measuring downhole weight on bit is that it allows for changes in the rate of penetration to be quantified in terms of formation strength through a simple transform When P calibrated to shear strength measurements on core this estimate of downhole formation strength together with LWD and core measurements of porosity density and lithology provides an improved determination of the pore pressure and effective stress at depth N Neutron Activation Radioactive sources in density and porosity tools emit neutrons into the formation as part of the routine density and porosity measurements If a toolstring with radioactive sources is station
81. aptured by elemental nuclei in the rock When this occurs the nucleus emits a gamma ray at a unique energy characteristic for each element The emitted gamma rays are measured by a spectrometer consisting of a sodium iodide detector and a 256 channel analyzer During logging the gamma ray spectrometry tool provides estimates of Si Fe Ca Cl and H In ODP boreholes the Cl and H relate virtually entirely to the sea water in the borehole Later land based processing permits the removal of Cl and H from the spectra and the additional extraction of estimates for Ti S and Gd The elements measured by the GLT account for the bulk of the chemistry of most common rocks the only significant elements not measured are Na Mg and possibly Mn Under favorable circumstances an estimate of these missing elements may be obtained by comparing a calculation of the photoelectric factor from the elements measured above with the direct measurement of P made by the Hostile Environment Lithodensity Tool HLDS The difference in these P values is within limits of error due to the unmeasured elements and may be recast as either Na or Mg or some combination where a fixed ratio of the elements has to be assumed Applications Lithology In basement variations in elemental concentrations will help delineate flow boundaries and characterize alteration vein filling In sedimentary environments where there is a reasonable chemical variation in the rock
82. arate waveforms simultaneously stack these waveforms from more than one firing and then transmit the signals uphole Threshold detectors for recording amplitude threshold crossing times for each waveform are also present These are for compressional first motion detection and allow derivation of compressional slowness in a manner similar to the analog threshold detection scheme used in conventional sonic tools Explanation of Acoustic Wave Propagation 1 Monopole compressional and shear Compressional and shear waves sometimes referred to as p and s waves are excited in the formation along with various modes in the borehole by a monopole source operating at high frequencies typically 10 20 kHz They propagate as body waves in the formation and along the borehole As they do so they leak energy refract back into the borehole creating headwaves in the borehole fluid Compressional waves propagate along the borehole in the direction of the borehole axis with minute vibrations or displacements of the formation in the same direction Shear waves propagate in the direction of the borehole axis with minute radial vibrations of the formation Monopole shear waves have a lower velocity higher t generally a larger amplitude and a slightly lower frequency than the compressional waves Shear waves have a larger refraction angle than the compressional waves The mud speed is usually nearly constant so that the refraction angle depends
83. ary in the hole for any amount of time residual neutrons will remain in the borehole for a small period of time in the location adjacent to source This neutron activation does not usually last more than a few hours but it is detectable with the gamma tool and can be falsely interpreted as a high gamma count interval Neutron log A porosity well log which measures mainly hydrogen density Fast neutrons emitted by a source in the tool are slowed to thermal speed by collisions with mainly hydrogen atoms The thermal neutrons are then captured by atomic nuclei of the surrounding material mainly chlorine atoms at which time a characteristic gamma ray of capture is given off Porosity calculated from the neutron log is affected somewhat by the formation matrix and by the presence of gas Neutron logs are used in crossplots to detect gas and determine lithology Neutron logs are sometimes scaled in API units sometimes in porosity units assuming a limestone matrix The neutron log can be recorded in cased holes O Permeability A measure of the ease with which fluid can pass through the pore spaces of a formation Measured in millidarcy 1 1000 darcy units The permeability constant k is expressed by Darcy s law as uq dp dx where p is fluid viscosity q is linear rate of flow and dp dx is the hydraulic pressure gradient Pigtail A 4 foot long piece of logging cable modified with electrical connectors at each end which converts the rop
84. ary minerals table Logging While Drilling Azimuthal Density Neutron Tool LWD ADN Logging While Drilling Compensated Density Neutron Tool LWD CDN Logging While Drilling Compensated Dual Resistivity Tool LWD CDR Logging While Drilling Isonic Tool LWD Isonic Logging While Drilling Resistivity at the Bit Tool LWD RAB Long Spacing Sonic LSS Lost tools LWD deployment of Measurement While Drilling MWD Minimum Configuration MAXIS system MCM Milankovitch cycles Multi Sensor Spectral Gamma Ray Tool MGT Top Natural Gamma Ray Tool NGT O On line data Phasor Dual Induction Spherically Focused Resistivity Tool DIT E Post cruise meetings Pre cruise meeting Project team Proprietary tapes 2 Sagan software package Satellite data transmission Schlumberger log plots playbacks Sheaves Shipboard reports Sidewall Entry Sub CSES Sources Specialty tools index of Splicer software package Stuck tools T Temperature Acceleration Pressure Tool TAP Third party tool support Toolstring selection Toolstrings index of Torpedo Triple Combo toolstring U Ultrasonic Borehole Imager UBI V W Well Seismic Tool WST Well Seismic Tool 3 Component WST 3 Well Seismic Tool deployment of Winch Wireline descriptions and types Wireline Heave Compensator WHC X Y Top Mailing Address E Mail Fax W
85. atch boron LD Recommended Depth Matching 9350 Stretch Compress mbstimed Ratio 0 938 2 39 Log Offset 0 793 966 1 Al Apply Undo Dismiss 0 ld The user chooses the preferred correlation File Display Process The core log depth map is applied to all holes Susceptibility mbsf SUMT Core Help ELD Tool Hole Core Select Core Tie Applies To Auto Pair Off Once this is applied to the core data they can now be shown versus estimated log depth eld jem Back to Sagan text Figure 1 Regional correlation of major lithostratigraphic units using total gamma ray data from Leg 189 100 HOLE 1171D HOLE 1168A HOLE 1172D 150 150 200 200 250 6 250 Oligocene to Quaternary 300 300 pelagic carbonates 350 sce eel ui id uud i 400 400 Palaeocene to late Eocene 450 450 shallow water siliciclastics 500 500 550 550 600 600 650 650 700 700 750 750 A i 0 40 80 120 160 HSGR API 850 850 40 80 120 160 900 HSGR API ODP Leg 189 0 40 80 120 160 HSGR API back to gamma applications Figure 2 Spectral gamma ray data from Hole 1124C showing high Th values in a mudstone unit between 420 430 mbsf ____HSGR_ 0 ____HTHO 0 sgl 0 1000 X 0 pm K pum 395 400 405 410 415 420 425 430 435 440 445 450 back to gamma applications High Th values due
86. aterologs are used to measure higher resistivities 7100 ohm m that may occur in the calcareous and igneous rocks encountered in ocean drilling Most mea surements of electrical resistivity are made by induction tools with vertical resolutions ranging between 0 5 m and 2 0 m The varying spacing between electrodes on these tools measures resistivity at different depths in the borehole wall If drilling fluids have invaded significantly into the formation these measurements not equal and their difference allows one to make an estimate of formation permeability Acoustic logging tools Acoustic tools record corn pressional shear and surface waves in the borehole environment much like a seismic refraction experiment that operates in the kilohertz frequency range e g Paillet et al 1992 Energy generated by one or more Sources acoustic instrument is transmitted into the borehole fluid and then propagates as refracted and surface waves at the borehole wall Energy is received at ene or more sensors on the logging tool at a transit time proportional to their distance from the source Wave velocities can he determined comparing arrival times of different waves Using asymmetric acoustic sources in the borehole acoustic tools now be used to estimate shear wave velocities most marine environments e g Zemanek et al 1991 Compressional and shear wave velocily measurements can be used together to compute th
87. ayed in the pipe racker then moved Drillers Shack to the hole The same procedure for the ADN The bitis added then the sources Once the sources are added the ADN collar must not come above the rotary tabla Rig down occurs in the reverse sequence Draw works IN DEX OF TOPICS GLOSSARY ACRONYMS HOME Measurement While Drilling MWD Description The MWD tool is an in line drill collar that records at the bit drilling parameters and telemeters the drilling parameter data as well as data from other LWD tools to the surface in real time MWD measurements include weight on bit WOB rate of penetration ROP torque and pump pressure The tool uses a continuous mud wave or siren type telemetry method and incorporates design features and software that enable it to approach data transmission rates of 6 to 10 bits per second It measures downhole weight and torque on the bit to help the driller maintain optimal weight on bit or torque and improve the penetration rate The use of MWD equipment in ODP is anticipated to improve core quality and increase core recovery by reducing the variability of weight on bit WOB Examples of improved core quality include reduced biscuiting reduced core breaks and recovery of difficult lithologies Mud pulse siren Turbine Specifications 8 25 in normal flow API collar size 6 75 in 8 25 in Collar OD 6 89 in 8 41 in Collar ID 5 109 in 5 109 in Makeup len
88. brid flask non magnetic Lacking sleeve Spring loaded plunger Payload lock screw 1 25 OD battery housing 1 25 OD electronics housing extension wire 1 25 OD pressure transducer Connection Autoclave to 1 16 tube adapter Wiring piping hold down screws RTD quick connects RTO Sheath 1000 ohm wire Pressure tubing Primary metal seal O rings Plug Pre loading sleeve Stainless Belleville springs Thermowell Bull nose Pressure pick up nozzle Sensors Electronic Neutron Source Near epithermal detector Array epithermal Array thermal Far epithermal detector Measurements and features Near array ratio porosity Hydrogen index measurement Reduced lithology effect No thermal neutron absorber effects Reduced environmental effects Improved vertical resolution Epithermal slowing down time Standoff determination Thermal neutron decay rate Formation capture cross section of invaded zone Near far ratio Lithology indicator Stand alone gas indicator in clean formations o Depth mbaf 50 60 80 100 140 150 180 bulk den E 26 gum 36 HLDS tool APS tool core zt 9 xrosity APLC SIGE 20 10 capture unit 40 3 fraction km 10 anm rn IMF H 5550 3 LLy and
89. ces and plane waves sometimes a point source Synthetic seismograms sometimes show primary events only primaries plus selected multiples or primaries plus all multiples they may be constructed by analog digital or manual methods T Tadpole Plot A type of plot of dipmeter or drift results also sometimes called an arrow plot The position of a dot gives the dip angle versus depth and a line segment pointing from the dot gives the direction of dip using the usual map convention of North being up Telemetry Communication with a remote acquisition system Logging tools usually transmit acquired data in real time via wireline telemetry Temperature log A well log of temperature often made with a resistance thermometer thermistor Used for locating cement behind the casing because the setting of cement is exothermic and hence raises temperature intervals which are producing gas because the expansion of gas as it enters the borehole lowers the temperature and fluid flows particularly behind the casing Total depth Final depth achieved during drilling operations U V Vertical Seismic Profile VSP A VSP differs from a conventional reflection profile in that the receiver is clamped successively at different borehole depths within the Earth The seismometer records both the direct downgoing waves and upgoing waves reflected from acoustic impedance changes below the clamping depth Interval velocities may be calculated from t
90. ches the winch on the JOIDES Resolution is powered by electricity not a diesel motor This affords much smoother slow speed operation The winch contains several cable sensing mechanisms including two calibrated wheel depth encoders which measure deployed cable length and cable speed It also contains a tension gauge for surface cable tension K K KK K Calibration Equipment Prior to the logging of each hole the logging tools are subjected to calibrations to ensure that reliable quantitative data are obtained from the tools The Schlumberger engineer will place sleeves on some tools to expose the sensors to known values of radiation electrical resistance distance etc Other tools are placed within a tank for the calibration process Seen in the picture are the radiation calibration tanks with tools inserted The tools are routinely subjected to calibrations during the course of a leg A master calibration is performed at the beginning of the leg and subsequent standard calibrations are performed before each logging run Schlumberger engineer performing Density calibration tank di calibration tests K KK KK Lockable Flapper Valve and Go Devil The lockable flapper valve LFV is a component of the APC XCB Bottom Hole Assembly BHA It is hinged and sprung on one side and is designed to prevent fluids from backflowing up the drill pipe Close up view of the lockable flapper
91. cialty Other Toolstring Index INDEX EX TOPICS GLOSSARY ACRONYMS HOME Other Equipment Wireline Heave Compensator WHC The wireline heave compensator WHC is an extremely important component in the wireline logging program due to its role in preventing degraded data as a result of ship s heave The WHC is a large hydraulic ram with a wireline sheave on one end and is designed to reduce the effect of ship s heave on the downhole tool As the ship heaves with the billowing sea an accelerometer located near the ship s center of gravity measures the movement and feeds the data in real time to the WHC The WHC responds to the ship s heave by adding or removing cable slack to decouple the movement of the ship from the desired movement of the toolstring The WHC can adequately compensate in seas of 10 meters or less Aborting the logging effort should be considered if the seas are greater than 10 meters as the WHC could reach the end of its operating limits and automatically shut down This could place the toolstring at risk Should you be caught in a situation where the ship s heave is greater than 10m and a tool is downhole you should increase logging speed to 1500 ft hr to prevent the tool from traveling too far downward as the ship reaches the wave trough The WHC is LDEO property and therefore its status should be known and monitored by the logger However during logging events the assistant drill
92. ck in bridge and YES cuttings 2 Cannot pull past a _ 3 Stuck in _ YESa YESbf YESe d base of pipe 4 Cannot get E YES ED into pipe NO CSES 1 Stuck in bridge and cuttings 3 Stuck in YES YESe d base of pipe 4 Cannot get _ ves wae into pipe if a feasible technique can be worked out b after pulling the CSES on deck and detaching it from the drill string c first figure out what is hanging up circulate while trying especially with lockable flapper rotate the drillstring half a turn and keep trying to pull out a centralizer or bow spring can sometimes be snapped deliberately by repeated trials d first try circulating to free the tool with a slightly slack cable e a last resort if cutting and stripping is rejected hopefully the tool will break free before failure or if not be so well stuck that it will be pulled up with the BHA f if the tool is too far into the pipe the crimper will not be able to seat Data Loggin Stuck Lost Shipboard Acquisition Operations Tool Policy Reports INDEX OF TOPICS GLOSSARY ACRONYMS HOME Shipboard Reports 1 Logging Chapter Initial Reports The scientific results of the cruise are initially presented in the Initial Reports IR volume which is organized by site The Logging Staff Scientist is responsible for presenting the results of any downhole measureme
93. correct oxide factor assumptions In the ODP shipboard data particularly petrographic chemical and diffraction can often be used to minimize these errors One limitation of the GLT is its relatively low spatial resolution The volume sampled by the GLT approximates to a sphere with a radius varying from around 0 3 1 0 m depending on lithology porosity composition of the pore fluids and the elemental spectra being determined At each measurement point every 15 cm a number of these spherical samples are averaged The raw data from the GLT have therefore already undergone a certain amount of smoothing This accentuates the shoulder effect on the logs which tends to smooth the log responses over sharp lithological boundaries Comparisons between GLT derived oxide estimates and similar data obtained from conventional geochemical analyses e g XRF on core samples should be treated with extreme caution The two techniques measure substantially different volumes of rock Furthermore it is always difficult to precisely match the depths of the core samples with those of the log values especially when core recovery is low Log Presentation Following data acquisition the elemental concentrations measured by the GLT are expressed as decimal fractions and the elements are normalized to unity Further processing sometimes referred to as the oxide closure procedure converts the major elements Si Al Ca Fe S Ti K Cl and H to weigh
94. ct from the lithodensity tool Mineralogy Carbonates usually display a low gamma ray signature an increase of potassium can be related to an algal origin or to the presence of glauconite while the presence of uranium is often associated with organic matter Ash layer detection Thorium is frequently found in ash layers The ratio of Th U can also help detect these ash layers Additional applications of gamma ray logs Environmental Effects The NGT response is affected by borehole size mud weight and by the presence of bentonite or KC in the mud In ODP boreholes KCl is sometimes added to the mud to stabilize freshwater clays which tend to swell and form bridges This procedure takes place before logging operations start and even though is probably diluted by the time the tool reaches total depth it can still affect the tool response All of these effects are accounted for during the processing of the NGT data onshore Log Presentation The NGT log is routinely recorded for correlation between logging runs To this purpose SGR total gamma ray in API units and CGR computed gamma ray SGR minus Uranium component in API units are usually displayed along with other curves resistivity sonic density etc A full display of the data with SGR CGR and THOR in ppm URAN in ppm and POTA in wet wt is usually provided separately Output plot of NGT data Specifications Temperature Rating 149 300
95. curves in a separate track CNT G output plot Specifications Temperature Rating 400 F 205 C Pressure Rating 20 kpsi 13 8 kPa Tool Diameter 3 375 in 8 6 cm Tool Length 16 6 ft 5 06 m Sampling Interval 6 in 15 24 cm Max Logging Speed 1 800 ft hr Vertical Resolution 1 5 ft 46 cm Depth of Investigation See text in Description section Deployment Notes Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME Dual Laterolog DLL Description The Dual Laterolog DLL provides two resistivity measurements with different depths of investigation into the formation deep LLd and shallow LLs In both devices a current beam 2 ft thick Ag is forced horizontally into the formation by using focusing also called bucking currents A A A j A two monitoring electrodes are part of a loop that adjusts the focusing currents so that no current flows in the borehole between the two electrodes For the deep measurement both measure and focusing currents return to a remote electrode on the surface thus the depth of investigation is greatly improved and the effect of borehole conductivity and of adjacent formations is reduced In the shallow laterolog instead the return electrodes which measure the bucking currents are located on the sonde and therefore the current
96. d global scientific investigation using downhole insiru TENS to measure in situ properties of the Earth The scope af this review focuses on past present and future scientific applications that have used or will usc short term experiments that is measurements that themselves do not require instruments to be deployed for more than several hours or days in the subseafloor Such measurements can be repeated over longer periods for time series studies This class of downhole measure ments is commonly referred to as logging and is dis tinet from the class of instruments deployed below the sealloor for long term studies The latter class may be referred to as in situ observatories and is discussed in less detail the reader is referred to recent workshop reports by 1991 and Carson et af 1994 for an overview of and further references to a variety of downhole observatory applications in marine research The reason for this distinction is methodological not scientific as both types ol deployments are complemen tary The short term logging measurements that are pri marily addressed include 1 measurements made borchole by instruments lowered on a wireline 3 mea surements made while drilling and 3 measurements repeated over time A short background is given first to define the current types and range of measurements that be made by logging Then a discussion of strategies for downhole m
97. d the Logging Staff Scientist will be more involved in the collection and interpretation of seismic profiles and thus will have a more active role in the production of the stratigraphy chapter of the IR volume Geological information derived from the stratigraphic sequences is used to define in detail the geological or tectonic setting of the leg to design the leg operation and to tie seismic boundaries with core and log depths both during the leg and post cruise Proper use of the results of seismic sequence analyses can help in the integration of core log and seismic data and can enhance the spatial interpretation of high resolution profiles of structural physical and chemical properties from the core and log data 3 Explanatory Notes Initial Reports The purpose of the explanatory notes chapter of the IR volume is to provide the reader with the technical and operational background for the wireline logging operations conducted during the leg Although there are an infinite number of ways to present this material a typical downhole logging section of the Explanatory Notes would contain the following sections Introduction This section should introduce the reader to what wireline logging is and how it is conducted e g the in situ measurement of physical chemical and structural properties It is tailored to the science relevant to the leg under discussion and may include general principles of how these measurements can con
98. d basalt sediment sequence in ODP Hole 857C near the Juan de ridge in the north eastern Pacific irom ODP Leg 139 Xcieritif e Drilfing Party 1942 Core recos ery black zones is partial and ix arbitrarily set at the top of cach core section biasing any subsequent geologic interpreta ton The complete interpretation dotted zones are basalt is za __ 1 LAWS In 1927 and Schlumberger made the first well log near Paris It was a simple electrical current experi ment that used an electrode placed at a series of hori zontal points on the ground to make measurements and detect variations in geological structure below the sur de 857C near the Juan de ridge in the morth eastern Pacific from Leg 139 Scientifie Drilling Party 1992 Core recov ery black z nes is partial and is arbitrarily set at the top of each core hiasing amy subsequent geologic interpreta tin The complete interpretation dotted zones are basalt is based on the logi Depth is in meters below sea floor bsf Goldberg DOWNHOLE MEASUREMENTS HOT 1 0 ee 1975 18 1585 Year Too Introduced 1990 face During the 1930s they evolved this method into a simple tool consisting of an electrode and a current source that made continuous measurements of the sub surface resistivity with each lowering into a borehole Depth was det
99. d the field of the metal drill pipe are subtracted from the total magnetic field log MAGB to isolate the field anomaly caused by the local formation 2 The local field anomaly is caused by the induced and remanent magnetizations of the local formation see figure The induced anomaly can be calculated from the magnetic susceptibility log MAGS and so the remanent anomaly can also be isolated Prior to this step the logs are smoothed so that they have comparable vertical resolutions 3 The induced and the remanent anomalies are correlated over depth intervals of varying heights correlation analysis If the induced and remanent anomalies correlate then the magnetic polarity of the formation is normal if they anti correlate the polarity is reversed below left This polarity interpretation can then be related to the geomagnetic polarity timescale below right 5a pasia a fees he ee ee 4 processed data are included along with a summary diagram in the on line database and the Initial Reports CD ROM Processing of Other Log Data Temperature data Time vs temperature logs recorded by Lamont s TAP tool are merged with time vs depth data recorded during logging by the Schlumberger MCM unit to give the variations of borehole temperature with depth The temperature data are added to the Initial Reports CD ROM Sonic waveform data During logging s
100. d uranium The high energy part of the spectrum is divided into three energy windows each covering a characteristic peak of the three radioactivity series The concentration of each component is determined from the count rates in each window Because the high energy region contains only 1046 of the total spectrum count rates the measurements are subject to large statistical variations even using a low logging speed The results are considerably improved by including the contribution from the low energy part of the spectrum Filtering techniques are used to further reduce the statistical noise by comparing and averaging counts at a certain depth with counts sampled just before and after The final outputs are the total gamma ray a uranium free gamma ray measurement and the concentrations of potassium thorium and uranium Energy hte Schlumberger The radius of investigation depends on several factors hole size mud density formation bulk density denser formations display a slightly lower radioactivity and on the energy of the gamma rays a higher energy gamma ray can reach the detector from deeper in the formation The vertical resolution on the log is about 1 5 ft 46 cm Applications Clay typing Potassium and thorium are the primary radioactive elements present in clays because the result is sometimes ambiguous it can help combining these curves or the ratios of the radioactive elements with the photoelectric effe
101. depth scale Build continuous sediment section by splicing overlapping cores o Enter and compare stratigraphic data from various holes down the splice o Output data on the new composite depth scale mcd as well as mbsf o Output a continuous spliced records for further analysis o Tie the downhole spliced record to reference data such as insolation or isotope curves Sagan The addition of the Sagan program now allows the composite sections output by Splicer to be mapped to their true stratigraphic depths unifying core and log records and providing a crosscheck on the completeness of the composite section Sagan generates a single metafile that defines a set of precise depth correlations between core and log datasets at any given site This metafile provides the foundation for core log data integration as it establishes the unique mapping function linking the two independent depth scales The program performs the core log depth merging using physical parameters which are measured on both cores by logs e g natural gamma bulk density porosity magnetic susceptibility sonic velocity The core log depth correlations are conducted either manually e g core by core from single or multiple holes or automatically Sagan can also perform smoothing decimation and culling procedures to modify the data The program can manage up to 10 holes of core data 5 data types nearly an infinite number of cores and data points and
102. dex INDEX OF TOPICS GLOSSARY ACRONYMS HOME 7 46 NT Seven conductor armored cable designed and specially manufactured for use in well logging The armor wires are high tensile galvanized improved plow steel pre formed and pre stressed The armor is coated with an anticorrosion compound 20 AWG copper 6 0 014 6 0 36 mm Teflon insulation 0 073 1 85 mm 20 AWG copper 7 0 013 710 32 mm Teflon insulation 0 070 1 78 mm Conductive Neoprene Compressed Diameter 0268 Temm Inner armor 24 0 039 24 0 99 mm Outer armor 24 0 049 24 1 24 mm Nominal Diameter 0 464 11 79 mm trademark of Dupont ELECTRICAL DC Resistance 68 F or 20 Insulation Resistance Capacitance Voltage Rating MECHANICAL Calculated Weight Temperature Rating Break Strength Triple Combo Nominal Properties Maximum end to end variation Conductor 10 9 ohm kFt Armor 1 2 ohm kFt at 500 VDC 15000 M ohm kFt at 1 KHz 55 pf Ft 560 Vrms In air 350 Lbs kFt In fresh water 277 Lbs kFt Min 40 450 Ends fixed 16700 Lbf Ends free 11600 Lbf 0 010 Inch FMS Sonic Specialty Other 36 ohm km 4 ohm km 5000 M ohm km 180 pf km 560 Vrms 521 kg km 412 kg km 40 260 74 52 0 254 mm Toolstring Index Assembled Length 105 0 Ultra High Temperature Multi Sensor Memory Tool Flask Length 98 1 Payload Length 80 5 2 2 outside diameter Hy
103. ding on the complexity of the processing to perform the initial processing of a hole logged with a full suite of logs complete FMS GHMT and geochemical data processing are performed at a later date Shipboard Data Availability amp Utility Logging data are made available to the entire scientific shipboard party immediately after the acquisition and preliminary processing are completed The digital data are placed on the centralized data disk called UserVol and paper copies are available for the Core Lab and Science Lounge The resistivity gamma ray magnetic susceptibility and density logs are useful to sedimentologists and petrologists for reconstruction of gaps in the lithostratigraphy especially in cases of poor core recovery compiling a complete stratigraphic sequence in the area of interest and determining the thickness of individual units The FMS and BHTV images allow structural geologists to orient the structural features observed in the cores and relate these features to the current principal stresses associated with the present tectonic environment The DSI 2 VSP porosity and density logs allow geophysical properties specialists to correlate core and log results with seismic properties and improve the interpretations of regional and local seismic data The GHMT logs provide paleomagnetists with the capabilities of producing continuous magnetostratigraphic and polarity inversion records All data except FM
104. directional monopole ceramic transducer and two unidirectional wide band electrodynamic dipole transducers oriented perpendicular to each other Wide band transducers are preferable to a single narrow band source because they allow examination of the entire frequency spectrum without phase matching problems at their resonant frequencies and are not subject to reduced output because of aging A low frequency pulse drives the monopole transducer for Stoneley wave excitation and a high frequency pulse drives it for compressional and shear measurements A low frequency pulse drives each dipole transducer for the creation of shear waves In addition a new low frequency source option provides excitation below 1 kHz for extremely large holes and for very slow formations and shear waves 2 Isolation joint The isolation joint is a mechanical filter that keeps the transmitter signals from traveling up the tool 3 Receiver section The receiver section contains eight receiver stations spaced 6 in apart and spanning 3 5 ft Each station contains two hydrophone pairs one oriented in line with the upper dipole transmitter and the other in line with the lower dipole transmitter The outputs from each pair are differenced for dipole reception and summed for monopole reception Receivers are carefully matched during manufacture 4 Acquisition cartridge The acquisition cartridge contains the circuitry to perform automatic gain control digitize eight sep
105. ds twist the pipe string to join it to the CSES Because the LDT bow spring prevents free rotation of this tool in pipe rotating the pipe while the cable is clamped to the CSES will unravel and possibly sever the cable Yet the pipe must be rotated to tighten the threads between pipe and CSES Solution There is no easy solution at present Fortunately the LDT is seldom used now that we have the HLDT and most of the other tools do not drag on pipe the neutron eccentralizer could be a problem but it too is seldom used Option 1 is to put the swivel into the top of the tool string Before logging ask the Schlumberger engineer whether there is a working swivel aboard filled with oil The disadvantage of a swivel is that sometimes it will short out downhole Option 2 is to make up the pipe to the CSES horizontally with the pigtail unclamped at the CSES so that it can rotate freely to avoid torquing the cable Then clamp the pigtail and pick up everything joining the drillstring to this pipe joint Excess cable spooling after the tool has set down Sometimes cable continues to spool out inadvertantly after the logging tool has set down on a bridge At 600 m hr a one minute delay in detecting tool setdown means 10m of excess cable that will accumulate just above the logging tool The cable may fold so that it cannot get back into pipe or it may kink causing a short or greatly decreasing breaking strength Yet tool setdown is not always
106. e 1994 Reviews of current downhole technologies are also periodically published in industry journals i Snyder and Fleming 1985 Prensky 1994 Sm a a a me ee ee 2 2 2 m ma Copyright 1997 by the American Geophysical Union Reviews of Geophysics 15 3 August 1997 HOME DSDP they have been made in more than 56 of the also periodically published in industry journals ei holes drilled by ODP This dramatic increase Snyder and Fleming 1985 Prensky 1994 M Reviews of Geophysics 15 3 August 992 pages 315 342 Paper number 97 RGOO221 Copyright 1997 by the American Geophysical Union 8755 1209 97 97RC 002215 1 5 00 a 315 3164 Goldberg DOWANHOLE MEASUREMENTS Continental scientific chilling programs have also sut cessfully used downhole measurements to achieve their objectives Downhole experiments support and enhance core r lated studies of the subsurface almost every environment and in nearly every scientific discipline During the last decade several continental scientific drilling programs conducted by Germany Japan Swe den the United States Russia and Ukraine have relied on the extensive use of downhole measurements Zoback a 1994 Often the results of these efforts complement the goals of the ODP in advancing new scientific applications of downhole measurements and together these programs are moving researchers towar
107. e Environment Natural Gamma Ray Sonde HNGS utilizes two bithmus germanate BGO scintillation detectors to Phateamulbplier measure the natural gamma tube 1 ray radiation of the formation The larger detector volume and higher Detectar 1 gamma ray stopping power of BGO makes the HNGS a very effective spectral gamma tool The HNGS makes similar measurements to the NGT however the HNGS is more accurate and capable of making measurements in difficult hole conditions The HNGS employs a larger and better scintillation detector than the NGT which affords better nuclear decay statistics The HNGS measures total gamma and 256 window spectroscopy to resolve the detected spectrum into the three most common components of naturally occurring radiation potassium thorium and uranium The high energy part of the spectrum 15 divided into three energy windows each covering a characteristic peak of the three radioactivity series The concentration of each component is determined from the count rates in each window Because the high energy region contains only 1096 of the total spectrum count rates the measurements are subject to large statistical variations even using a low logging speed The results Stabilization source Detector 2 Prato multiplier tube 2 HOME are considerably improved by including the contribution from the low energy part of the spectrum Filtering techniques are used to further reduce the statistical
108. e and downhole log data These graphically oriented and intuitive products are for use on the ship or on shore based Unix workstations Splicer current version 2 2 and Sagan current version 1 2 have expanded data handling flexibility considerably allowing for access to a variety of non standard data types and formats in addition to current Janus database output files Splicer Splicer is installed on Sun workstations on the JOIDES Resolution and allows interactive depth shifting of multiple holes of core data to build composite sections using an optimized cross correlation approach Multiple data types can be compared simultaneously in order to quickly determine the best correlation for all variables On legs where it is important to recover complete spliced sediment sections a Stratigraphic Correlator will be staffed in order to provide real time feedback on the completeness of the recovered sediment record to help determine operational and drilling plans Splicer has been used routinely on the JOIDES Resolution to build continuous sediment records since Leg 151 1993 Metadata files generated by this program are now formally included in the JANUS database Splicer also allows the composite section to be compared or tied to reference records such as insolation and isotope curves Some example applications are o Simultaneous comparison of multiple data types from multiple holes o Tying holes together to build a common composite
109. e borehole wall at intervals of approximately 50m and the air gun fired five to seven times The resulting waveforms are stacked and a travel time is determined from the median of the first breaks in each trace These check shot experiments attempt to reproduce the seismic reflection profiling by simulating a similar geometry and source frequency The WST 3 is always the last tool run and it is always run alone At each selected station seismic shot is produced at the sea surface using either air or water guns provided by TAMU Schlumberger provides a blast hydrophone for synchronizing the gun pulse with the system timer The WST 3 and other downhole seismic tools are sensitive to pipe noise and ringing of pipe following a shot Efforts should be made to reduce pipe noise at each station If time and resources permit a drill string packer may be deployed to dampen the banging motion of the pipe against the borehole In addition it is always prudent to leave at least 50 to 75 m distance between the tool and the bottom of pipe The WST 3 must be powered with a 400hz power supply to avoid 60hz noise generated when a 60hz power supply is used The CSES should not be used with the WST 3 for three primary reasons 1 If the bottom of pipe is kept near the tool it is likely that the tool will measure ringing in the pipe each time the gun is fired 2 If a significant amount of pipe is downhole there is a possibility that the pipe could g
110. e composition and physical properties of the sediments In regions where the sedimentation rate is high enough or conversely in logs with sufficient vertical resolution the millennial scale variability can also be documented There are several prerequisites to successfully identifying any climate cycle through spectral analysis First log display makes a difference A log plot that shows broad compaction trends may obscure fine scale Milankovitch cycles Second accurate sedimentation rates are needed for confirmation that any detected periodicity is at Milankovitch frequencies Reversal stratigraphy gives more accurate sedimentation rates than paleontology because the latter has errors at both datums that blow up when calculating a sedimentation rate Lacking precise sedimentation rates one will need to detect at least two Milankovitch periods preferably in more than one log before any confidence can begin to be placed in them Third a high sedimentation rate is needed for logging tools with 0 5 vertical resolution to detect high frequencies e g 19K 23K and 41K Fourth beware of cycles caused by local sedimentary phenomena e g turbidites rather than climate the depth period of the latter will change with the sedimentation rate but not the former Keep in mind that the 41K cycle is the only truly constant period for all ages Eccentricity strength varies somewhat between 95K and 123K as a function of time and precession stren
111. e drillship schedule has been set by SCICOM at the August meeting ODP Logging Services appoints a Logging Staff Scientist for each scheduled leg Following the appointment the Logging Staff Scientist will contact the Co Chief Scientists when named and the TAMU Staff Scientist to introduce himself and explain his role on the drilling leg The Logging Staff Scientist is considered to be the leader of the Logging Services project team In addition to any people sailing the team usually consists of o Manager of Technical Services Greg Myers for tool deployment and engineering issues o Engineering Assistant Walt Masterson for shipping issues o Manager of Information Services Cristina Broglia for data handling issues Log Analysts Trevor Williams and Caroline Philippot for log processing services CD ROM coordinator Jim Murray for issues involving the Log Data CD o Systems Analyst Ted Baker for any computer or software issues In addition there may be other engineering or scientific personnel involved if special projects are planned for the cruise The Deputy Director of Operations Mary Reagan is responsible for coordinating the activities of the leg project managers She and the Director Dave Goldberg are available to assist as needed Following the initial consultations between the Logging Staff Scientist the Co Chief Scientists and the TAMU Staff Scientist there should be general agreement on the following issue
112. e elastic properties of a formation such as the Pois son s ratio which depend on lithology and porosity Wave amplitudes can be measured directly at cach sen sor or between sensors and primarily reflect the coupling r FMS LOT CNL GST LSS SFL ILM WD Figure 4 Intrinsic vertical resolution of various wireline tools representing ihe minimum depth interval for which a mean ingful hog measurement can he ohtained after deMenoca er 1992 data from er al 1988 See Table 1 for List of abbreviations velocity measurements can be used together to compute the elastic properties of formation such as the Fois son s ratio which depend on lithology and porosity Wave amplitudes can be measured directly at each sen sor or between sensors and primarily reflect the coupling of energy between the formation and the borehole In fractured and heterogeneous formations the coupling of energy decreases and wave amplitudes can be used to 320 Goldberg DOWNHOLE MEASUREMENTS indicate fracturing and heterogeneity at the scale of centimeters to meters in the formation Most acoustic logging tools measure compressional waves which pen ctrate 0 1 0 5 m into the borehole wall with vertical resolutions of 0 5 1 5 m Other instruments that clamp geophones downhole and record energy from seismic sources om the surface penetrate through hundreds of meters of the formation Such vertical seismic p
113. e fluid electrical conductivity Differences in the temperature of drilling fluid compared to undisturbed formation temperatures can also generate this effect as conductivity in ionic fluids such as seawater is strongly temperature dependent Log Presentation Deep ILD or IDPH and medium ILM or IMPH induction and spherically focused resistivity SFLU are usually plotted in ohm m on a logarithmic scale along with gamma ray and caliper logs Output plot of DIT E data Specifications Temperature Rating 350 175 Pressure Rating 20 kpsi 13 8 kPa Tool Diameter 3 375 in 9 21 cm Tool Length 31 3 ft 9 6 m Sampling Interval 6 in 15 24 cm Max Logging Speed 10 000 ft hr 5 6 ft 1 5 m and 7 8 ft 2m for medium and deep Vertical Resolution induction logs 2 5 ft 76 cm for spherically focused log Depth of Investigation see discussion in Description section Formation Ohm Limits 0 150 ohm m Output ILD Deep Induction ohm ILM Medium Induction ohm IDPH Phasor Deep Induction ohm IMPH Phasor Medium Induction ohm SFLU Spherically Focused Log ohm ITEM Internal Temperature C Deployment Notes Typically run with IPLT components the DIT can be substituted for the DLL or ASI if additional funding is available The DIT has an internal temperature measurement which may be useful in high temperature environments Stuck lost tool information trademark of Schlumberger Triple
114. e images of density and porosity result from the rotation of the tool s sensors through four quadrants top bottom left right Along with the azimuthal data average values for each parameter are also available ADN tool Neutron Density Density Ultrasonic source source gensors caliper E E oF Neutron Fishing Tini In line ro detectors head Stabilizer Applications The ADN provides azimuthal borehole compensated formation density neutron porosity and photoelectric factor measurements Given present technological capabilities estimations of bulk porosity and HOME permeability are best made in situ borehole measurements preferably at scales large enough to average the effects of irregular fracture porosity and matrix porosity ADN measurements allow both for determining matrix and fracture porosity and locating overpressure zones The Power Pulse MWD tool can measure parameters such as annulus pressure torque and penetration rates Together MWD and ADN can render reliable measurements of effective pressure through both normal and overpressurized zones If overpressurized zones exist within a fault zone the magnitude and effects of fluid pressure on fault displacement and fluid flow can be assessed by estimating the amount of fluid expulsion porosity reduction in the immediate vicinity of the borehole Fault collapse and strain hardening active fluid flow fault fluid interactions and the formation
115. e of magnetostratigraphy from ODP Leg 165 The figure above shows the derivation of magnetostratigraphy from the susceptibility and total induction measurements The analysis column shows the correlation black or anticorrelation green between the susceptibility and the remanence effects in three sliding windows of different sizes Correlation indicates normal magnetic polarity zones anti correlation indicates reverse magnetic polarity zones The interpretation column is then compared to a standard geomagnetic polarity time scale Battery Test Azimutha l Lower transmitter gamma ray 5 Upper transmitter Ring electrode Field replaceable stabilizer Optional uphole connector Batteries Upper sensor Middle sensor containing focused ring electrode Azimuthal gamma ray Field replaceable stabilizer Lower sensor Flaat valve bore Built into a near bit stabilizer for rotary BHAs Earliest possible resistivity measurement while drilling Data sent to MWD by tool bus or by EMAG telemetry up to 150 ft Bit resistivity measurement F E ETT HEU IHR UB UELUT HMM E a LWD Image Wireline Image TOP BOTTOM TOP TOP BOTTOM TOP Depth 4ft Comparison of LWD Resistivity at the Bit RAB tool and wireline electrical imaging FMI tool measurements of dense fracturing in consolidated sediments Both images of the interior of the borehole wall are ori
116. e socket Schlumberger cable termination via the torpedo to the Gearhart Owen G O cablehead used the specialty tools Processed Data Logging data that has been processed using a specific log analysis system such as GeoFrame or Logos Processing includes depth shifting environmental corrections quality control and the creation of ASCII files for the online database Proprietary Data The entirety of logging data collected by the Schlumberger acquisition system aboard the JOIDES Resolution Proprietary Tape A tapes containing the original log data recorded by the Schlumberger engineer as well as the calibration counts necessary for some onshore processing of the original count rates Pull Out of Hole POOH A term used to describe the upward trip of either a logging tool or the drillstring Most commonly it refers to the distance from the bottom of the hole to the drill floor but distances to specific depths below the seafloor can also be specified e g POOH to 70 mbsf means raising pipe from the bottom of the hole to 70 mbsf Q R Rotary Core Barrel Used after the APC XCB core barrels to drill hard rocks Logging tools cannot pass through an RCB bit therefore the bit must be removed prior to logging Resistivity The property of a material which resists the flow of electrical current Also called specific resistance The ratio of electric field intensity to current density The reciprocal of resistivity is c
117. e types of situations have been much rarer Deep basalt holes rarely exhibit bridging Bridging is very difficult to predict before a leg begins Even after drilling and before logging the likelihood of bridges cannot always be estimated reliably The drilling engineers and operations superintendent usually have a good feel for hole conditions prior to logging from their observations during the wiper trip If a bridge is encountered that stops the logging tool there are two options 1 simply log the interval above the bridge and cancel plans to log beneath the bridge or 2 pull the logging tool out of the hole and up onto the ship set pipe through the bridge then lower the logging tool again Nearly always the much heavier drill pipe can punch through bridges that had stopped the lighter logging tool This second option requires about 3 4 hours for each bridge To prevent lost time or lost logs associated with bridges the JOIDES Resolution has the capability of using a conical sidewall entry sub CSES during logging When inserted into the drill string the CSES allows for the addition or removal of drill pipe while a logging tool is downhole The CSES strategy is to lower pipe to near the bottom of the hole lower the logging tool into open hole just beneath the pipe then log up while simultaneously pulling pipe at the same speed In this way open hole logs are obtained by minimizing the time between pipe removal and logging so substan
118. ear receivers The acoustic data is usually presented as compressional Vp velocity and where available as shear velocity Vs in km s Output plot of acoustic data shallow depth Output plot of acoustic data deep water Max Logging Speed Specifications Temperature Rating 17976 0350 Pressure Rating 20 kpsi 13 8 kPa Tool Diameter 3 625 in 9 2 cm Tool Length 37 9 ft 11 6 m Acoustic Bandwidth 5 kHz to 18 kHz Waveform Duration 5 ms nominally 10 ms maximum Sampling Interval 6 in 15 24 cm 1 700 ft hr for eight receiver array Deployment Notes Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME Azimuthal Resistivity Imager ARI Description The Azimuthal Resistivity Imager i ARI is a new generation of laterolog tool that makes deep measurements and azimuthal resistivity images around the borehole Using these data it is possible to analyze features and details that escape conventional resistivity measurements thin beds down to 8 inches borehole formation heterogeneity formation dip resistivity in dipping beds and fracture position and orientation The ARI produces images similar to the FMS with coarser vertical resolution but complete azimuthal coverage Whereas FMS electrodes are pad mounted and in contact with the borehole surface the
119. easurements is presented followed by a discussion of various scientific achievements of down hole measurements over the past several years Within this last section two broad disciplinary arcas are dis cussed the Earth s crust and Earth s environment The applications of many different downhole measurements fall into these two categories both of which contain several subdisciplines that illustrate the broad range of questions which can be addressed using downhole meth ods The scientific objectives for the future of marine scientific drilling have recently been outlined the ODP Long Range Plan Jot Ceeamographtic fnstituans Inc 1996 This plan describes the directions for ma rine scientific drilling from now through 2008 and the new technologies that will be required to accomplish them The plan relies heavily on downhole experiments INDEX OF TOPICS GLOSSARY ACRONYMS 35 REVIEWS OF GEOPHYSICS an ODP borehole is a scientific legacy it is not a mere relie of a acquisition procedure Scientific measure ments boreholes and on recovered core should be planned on the basis of their incorporation into a re gional or global model their future reinterpretation and in some cases the reoccupation of the drill site for further investigations Given these views of the future the summary provided here of recent scientific applica tions and new methods for downhole measurements leads to the conclusio
120. eb How to contact us Borehole Research Group Lamont Doherty Earth Observatory Rt 9W Palisades NY 10964 845 365 8132 845 365 8674 Director 845 365 8672 Deputy Director 845 365 8772 Manager Technical Services http www ldeo columbia edu BRG ODP INDEX OF TOPICS GLOSSARY ACRONYMS HOME Data Processing Overview The main purpose of shore based log processing is to provide scientists with a comprehensive quality controlled downhole log data set This data set can then be used for comparison and integration with core and seismic data from each ODP leg the Sagan in house software is used to put cores and logs on the same depth scale and IESX software is used to analyze seismic sections and generate synthetic seismograms from the logs Shore based log processing comprises o Depth adjustments to remove depth offsets between data from different logging runs o Corrections specific to certain tools and logs o Documentation for the logs with an assessment of log quality o Conversion of the data to a widely accessible format ASCII for the conventional logs GIF for the images and summary diagrams o Assembling the data for inclusion in the ODP Logging Services on line and tape databases Log analysts at ODP Logging Services carry out the processing mostly using Schlumberger GeoQuest s GeoFrame software package Conventional log data natura
121. ecialty tools The operational plan for logging is determined at the pre cruise meeting usually held 6 to 8 months before the cruise and is included in the cruise prospectus Confirmation of the logging plan and time estimates are made onboard before each site at the pre site meetings The Triple Combo is always run first because it collects most of the basic petrophysical and lithological logs It also measures borehole width an important indicator of borehole and log quality The FMS Sonic is usually run next the FMS resistivity image reveals the fine details of the formation and the sonic velocity completes the basic logs Then the specialty tools are run usually in order of scientific importance The WST is usually the final tool to be run because the fact that it is clamped against the borehole wall means it can destabilize the hole and it is perhaps the one tool most prone to getting stuck When time is short or when there are adverse logging conditions the Logging Staff Scientist has the responsibility of preserving the integrity of the logging plan and making appropriate changes to it if necessary He will keep in regular contact with the Operations Superintendent and the Co Chiefs so as to be up to date with the latest operational developments Shipboard scientists should understand that it is the Logging Staff Scientist s job to act as an advocate for the logs based on their scientific merit not just because th
122. ed Low frequency components traveling near the shear slowness become well separated from the slower higher frequency components Often the nondispersive shear headwave is detectable in fast formations In slow formations the flexural mode is again dispersive but to a much lesser extent Typically the ratio between the high and low frequency limiting values of the flexural slownesses is about 1 2 or less The flexural arrival is shorter in time duration and the spectral content is concentrated at lower frequencies As in the figure a higher frequency compressional arrival is often visible in slow formations and in large boreholes and very slow formations can become the largest amplitude event A distinct shear headwave arrival cannot be detected in slow formations Slowness Time Coherence STC Analysis Acquisition Software Slowness Time Coherence examines each waveform set for coherent arrivals across the array It does this by stepping a time window of fixed duration through a range of times across the waveforms and a range of slowness across the array For each time and slowness step the waveforms within the window are added or stacked and the corresponding stacked or coherent energy is computed When the window moveout or slowness aligns with a particular component moveout across the array the waveforms within the window add in phase maximizing the coherent energy Coherent arrivals are thus identified by maxima in the coherent en
123. ed field tapes 2 Customer tapes also called field edit tapes and 3 Backup copies of the proprietary tapes Proprietary tapes field tapes contain the original log data recorded by the Schlumberger engineer as well as the calibration counts necessary for some onshore processing of the original count rates The original proprietary data are not depth shifted because 1 depth shifting can alter the sonic and geochemical waveforms recorded with the other data and 2 accurate depth shifting is performed on shore Customer tapes field edit tapes contain the data necessary to perform the processing and preliminary interpretation Backup tapes are produced for each leg and kept on the ship for a maximum of six months The Logging Staff Scientist makes sure that the backup copy copies of the proprietary data are safely stored onboard in case the tapes brought onshore get lost or damaged during transport to LDEO BRG Every six months these backup tapes are brought back or sent to LDEO BRG to be included in the permanent archive Satellite Data Transmission Digital log data are routinely transmitted via satellite to LDEO BRG after the completion of logging operations at each hole This allows log analysts at the LDEO BRG Log Analysis Center to perform routine processing of the conventional logs and transmit the data back to the ship in ASCII format along with documentation of the processing performed It currently takes 2 5 days depen
124. ee fall of the tool may be enough to snap the weak point Once the tool is free you can pull it well into pipe raise pipe and go back down to resume logging 3 Cutting and stripping Cutting and stripping involves clamping the cable at the drill floor cutting it then either adding or removing a stand of pipe For every 30m of pipe added or removed the cable must be threaded in or out of the pipe and re clamped For sticking types 1 or 2 one would add pipe to break through the bridge For sticking types 3 and 4 one would remove pipe eventually pulling the tool on deck with the bottom hole assembly One disadvantage of cutting and stripping is that all of the cut cable will be discarded perhaps 1000 3000m and this may not leave enough cable on the spool for subsequent logging The Logging Staff Scientist is responsible for making this determination Cutting and stripping is also not the most favorable alternative because it is time consuming Cutting and stripping is not needed for situations 1 and 2 if the CSES is in the string but a modified type of cutting and stripping may be possible with situations 3 and 4 with the CSES 4 Using the Kinley crimper cutter The Kinley crimper and cutter system greatly increases the safety of downhole tool recovery operations The crimper cutter procedure is extremely sequence sensitive The crimper slides down the wireline and stops about 10m above the base of the bottom hole assembly
125. ee primary reasons 1 If the bottom of pipe is kept near the tool it is likely that the tool will measure ringing in the pipe each time the gun is fired 2 If a significant amount of pipe is downhole there is a possibility that the pipe could generate noise in the data as the pipe bangs in the hole 3 The WST is inherently risky to run because the tool is routinely stationary in a deteriorating borehole and must be clamped to the borehole creating additional risks Use of the CSES may only exacerbate these risks by providing access to a hole that may be unsafe for the WST Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Other Toolstring Index INDEX i OF TOPICS GLOSSARY ACRONYMS HOME November 22 1988 To Operations Superintendents From Glen Foss Subject Wireline stripping operations There are four basic scenarios for the recovery of a logging tool stuck in open hole The side entry sub is in the string and the cablehead weak point has not failed 2 The cablehead weak point has failed CSES not relevant in this situation 3 The CSES is not deployed and the cablehead weak point has not failed 4 Both the tool and drill string are stuck presence of CSES is very relevant Though there are risks to the tool in all the above situations situation 1 is by far the least undesirable The hazard to the tool is minimized the cable is saved and very little operating ti
126. eeds usually result in better counting statistics for nuclear tools such as the NGT AACT and GST Faster logging speeds on the other hand usually lead to less tool sticking that adversely affects all logs Table 2 1 shown immediately below provides some guidelines regarding the logging speeds commonly used for logging on the JOIDES Resolution High resolution logs neutron porosity and bulk density data sampled every 2 and 1 inches respectively can only be obtained by logging at the lower logging speeds typically 900 ft hr or less The currently available logging winch onboard the JOIDES Resolution as of January 1995 is capable of stable minimum logging speeds of 600 ft hr However even at speeds of a few hundred feet per hour the effect of only partially compensated ship s heave achieved by the WHC system may lead to the tool string undergoing significant oscillatory motion in the hole during logging TABLE 2 1 Typical Logging Speeds Ted mhr fuhr fuhr mir fuhr Triple 549 1800 335 1100 274 900 183 600 137 450 91 300 FMS Sonic 549 1800 488 1600 274 900 GHMT 549 1800 488 1600 274 900 A spreadsheet logtime xls has been created to facilitate standardized estimation of logging times for all loggers and logging proponents The spreadsheet provides the means for calculating times for both standard and specialty tools Some borehole experiments with s
127. ence of bentonite or KCI in the mud In ODP boreholes KCI is sometimes added to the mud to stabilize freshwater clays which tend to swell and form bridges This procedure takes place before logging operations start and even though is probably diluted by the time the tool reaches total depth it can still affect the tool response All of these effects are accounted for during the processing of the MGT data onshore Specifications Temperature Rating 85 C operational 100 C maximum Pressure Rating 10 000 psi 6 8 km Tool Length Telemetry module 9 0 ft 2 75 m MGT module 9 5 ft 2 90 m Tool Outer Diameter 3 375 in 8 6 cm Maximum logging speed 900 ft hr Energy Measurement Range 0 2 0 3 MeV Deployment Notes The MGT is always run at the top of the Schlumberger toolstring The downhole switch in the MGT telemetry module provides switching of the signal and power lines between the MGT and the Schlumberger logging system Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME Natural Gamma Ray Tool NGT Description The Natural Gamma Ray Tool NGT utilizes a sodium iodide scintillation detector to measure the natural gamma ray radiation of the formation and 5 window spectroscopy to resolve the detected spectrum into the three most common components of the naturally occurring radiation potassium thorium an
128. enerate a noise in the data as the pipe bangs in the hole 3 The WST 3 is an inherently risky tool to deploy because the tool is held in a stationary position in a deteriorating borehole Use of the CSES may only exacerbate these risks by providing access to a hole that may be unsafe for the WST 3 Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index Testing the WST hydraulic arms during rig up Leg 183 Raw Image After BorEID Static Normalization i Resiste FMS 4 im Candactve t Raeistwe FMSAIM Canductwe PEN Basement Sediment A 4 29 5 9 2 j 5 4 13 FMS images after successive processing steps Showing how the Remanent Anomaly Bi in the borehole is related to the remanent magnetization J of the formation for the case 67 5 S Site 1096 and Jy 0 1 Formation Borehole EAD x North y a gt Bir Jy Induced magnetization 11407 z down K Bg ug B projection z along B 80 nT 60 6 3 a y I dir Remanent magnetization reversed case 0 1 A m Magnetic susceptibility lig permeability of non magnetic material Bo main geomagnetic field Remanent vs Induced field anomaly 400 420 mbsf Hole 1096 covering a transition from reversed to normal polarity The gradient is positive for nor
129. ented to the top and bottom of the deviated hole Although the LWD tool has inferior bed resolution by a factor of 30 it offers the advantage of data coverage around the entire circumference of the borehole and measurements within minutes after the hole has been drilled INDEX OF TOPICS GLOSSARY ACRONYMS 7 46 P Seven conductor armored cable designed and specially manufactured for use in well logging The armor wires are high tensile galvanized improved plow steel pre formed and pre stressed The armor is coated with an anticorrosion compound 20 AWG copper 6 0 014 6 0 36 mm EPC insulation 0 102 2 59 mm 20 AWG copper 7 0 013 7 0 32 mm EPC insulation 0 098 2 49 mm Filler rods filler compound amp tape binder 0 288 7 32 mm Compressed Diameter Inner armor 24 0 039 24 0 99 mm Outer armor 24 0 049 24 1 24 mm Nominal Diameter 0 464 11 79 mm ELECTRICAL DC Resistance 68 F or 20 Insulation Resistance Capacitance Voltage Rating MECHANICAL Calculated Weight Temperature Rating Break Strength Nominal Properties Conductor Armor at 500 VDC at 1 KHz In air In fresh water Min Max Ends fixed Ends free Maximum end to end variation Triple Combo FMS Sonic Specialty 10 9 ohm kFt 1 2 ohm kFt 15000 M ohm kFt 40 pf Ft 880 Vrms 335 Lbs kFt 264 Lbs kFt 40 F 300 F 16700 Lbf 11600 Lbf 0 010 Inch Other 36 ohm km 4 ohm km 5000 M o
130. er or Coretech will operate the WHC so the logger will not always be directly involved Also ODP Logging Services employs SEDCO mechanic to perform routine maintenance on the unit Hole Finder The hole finder is a solid rubber extension that may be run at the end each tool string excluding the GHMT to assist the tool past ledges Experience has shown that it only provides a real benefit in deviated holes as it closely follows the curves of the borehole and guides the tool down The Schlumberger engineer is responsible for maintaining and deploying this device It is important to note that the TAP and TLT cannot be run when the hole finder is deployed Cableheads Cableheads are used by all wireline logging tools to make a physical connection between the wireline and the tool string Several different cablehead models exist including ones with a cablehead tension measurement The LEH QT is the most widely used cablehead with tension measuring capability Tension data are only available when the cablehead is connected to digital tools therefore tension data is not available for the WST Wireline In ODP wireline logging operations three types of logging cable are typically used All are 15 32 in diameter and all contain 7 copper conductors Differences in the cable insulation determine temperature rating The standard 7 conductor cable used in ODP is the For moderately high temperature boreholes a short len
131. ere an important objective The log database is useful not only for scientific research but also for cruise planning If a proponent is writing a proposal for drilling in an accretionary prism for instance the keyword feature can be used to search for all holes logged in accretionary prisms and determine what tools were used in each The links to the on line logging summaries would reveal that the traditional coring and logging techniques used in the early cruises were not very successful Recent cruises such as Legs 170 and 171A that used logging while drilling LWD techniques however delivered very satisfactory results Links are also available to a Guide to Logging section where in depth information on the tools is provided and to Proponent s Helper a section that provides assistance in completing the required site forms While the log database is an important asset to most ODP research its value is greatly enhanced when the data can be integrated and compared with core data For this reason a link is provided from each listing of log data collected in a hole to the corresponding core data set at the TAMU web site The ODP log database consists of profiles and images of geophysical measurements e g density gamma ray porosity resistivity and acoustic properties recorded as a function of depth in a drill hole There are two basic data formats currently available on line ASCII and GIF ASCII can be opened in
132. ergy The STC module is used to find and extract slowness Dt and other information about various coherent arrivals in the sonic waveforms Then the STC computation performs a sequence of operations on a set of waveforms aimed at identifying coherent arrivals in the set and extracting their slownesses The following steps taken are Waveform filtering Waveform stacking Peak searching and Labeling An additional step is needed to identify and separate the desired arrivals flexural compressional shear or Stoneley from any others This is done by the labeling algorithm part of the STC computation The slowness arrival time and coherence of each arrival are examined and compared with the propagation characteristics expected of the compressional shear or Stoneley waves for the given physical conditions Classifying the arrivals in this manner gives a continuous log of wave component slowness versus depth STC processing of high frequency monopole waveforms generally results in compressional and shear slowness estimates in fast formations Narrow band filtering is applied to low frequency monopole Stoneley waveforms since this mode is dispersive and we want to estimate slowness within a consistent band of frequencies In slow formations no shear slowness estimate is available from monopole waveforms 1 Dipole labeling bias correction In STC processing of dipole waveforms a coherence peak corresponding to the dispersive flexural mode
133. ermined by measuring the length of the cable run into the hole s it is today The interpretation of these continuous logs for oil exploration helped to determine bed thicknesses identify clay rich and hydro carbon bcaring zones and provided a rough estimate of formation permeability all qualities that could be cor related between holes In the 1940s Archie 1932 linked laboratory measurements of resistivity to the amount of water and hydrocarbon in pore space which greatly improved log interpretation In various modifications his empirical relationship is still used to calculate porosity and fluid saturation from resistivity logs In the mid 19406 through the 1970s rapid technological advances made it possible to estimate porosity using nuclear acti vation gamma radiation and acoustic techniques The resolution of the logging measurements also improved with the development of sensors that extended close to the borehole wall In the 19805 continued advances in digital data acquisition and signal processing have made it possible to evaluate logging data as they are collected so that decisions can be made on site to enhance data quality and interpretation With these improvements logging has become the standard for evaluating subsur face geology in the oil industry it is now often the sole source of data used for geological interpretation because of the difficulty and expense of routine coring Over the past 10 years researchers i
134. es by caving of fractured formations Bridle 1 The insulation covered lower portion of the cable to which a logging tool is connected 2 To connect in parallel a group of amplifiers to a common input 3 An arrangement for towing a seismic streamer Caliper A tool used for measuring the diameter of borehole The measurements displayed as a caliper log Open hole caliper logging tools often have four or more arms Casing Tubes or pipes used in boreholes to keep them from caving in Usually made in pieces of ten feet lengths that screw together Cement bond log A well log of the amplitude of the acoustic wave which indicates the degree of bonding of cement to the casing and formations If the casing is poorly cemented energy which travels through the casing at the fast speed of acoustic waves in steel is strong and little energy travels in the formation if the casing 15 well cemented the casing signal nearly disappears and the formation signal is strong The log may consist of 1 an amplitude log CBL which represents the amplitude of a portion of the longitudinal acoustic wave train or 2 a display of the acoustic wave train such as the character log 3 D microseismogram VDL or acoustic signature log Check Shot Survey Seismic sources shot into a borehole where a seismic recording tool records travel times for checking results of integrating a continuous velocity or sonic log Compensated log A well log made w
135. etailed comparisons with other data core log comparisons and definitions of stratigraphic intervals Finally the results of any analysis or scientific highlights of the logs will be presented This section may be included in each of the tool results sections if it is not significant enough to merit an independent section 2 Seismic Stratigraphy Chapter Initial Reports Occasionally the Logging Staff Scientist will collaborate with other shipboard scientists in producing the seismic stratigraphy chapter of the Initial Reports volume Seismic sequence analysis is usually outlined in this chapter to describe the structural boundaries between layers of different ages and to provide scientific context for the proper interpretation of drilling and logging results The seismic profiles included in this chapter are usually collected during pre cruise site surveys occasionally seismic profiles from industry sources are also available The quality and density of the seismic data are usually a function of the scientific objectives of the drilling leg For legs on which seismic stratigraphic sequence analysis is most important multichannel seismic MCS data are frequently available for the others single channel seismic SCS data are usually the norm The specifications for the seismic data are usually given in this chapter including acquisition and processing On certain legs such as those on which vertical seismic profiling is performe
136. ey are part of the logging plan in the prospectus The principles to keep in mind when prioritizing toolstrings are 1 To get the logs most relevant to the leg s scientific objectives 2 To run the toolstrings most likely to get good results 3 To minimize the risk of harming the tools or getting them stuck down the hole The scientific environmental and technical issues relevant to toolstring selection are described briefly below Science Issues Lithology The natural gamma magnetic susceptibility and PEF logs yield information on aspects of the chemical and mineralogical composition of the formation which can be used to infer lithology see individual tool summaries This information can then be used to fill gaps in the core record to pinpoint boundaries etc The absence of gaps in the logs makes them particularly useful for studies of sediment cyclicity where a complete record is essential Petrophysics The porosity density resistivity and sonic velocity logs collect petrophysical and geotechnical information about the penetrated formations In sediments the general trend in these logs is of consolidation with depth Deviations from this trend are caused by lithological change lithification cementation under consolidation due for example to high fluid pressure or a framework provided by microfossils or the presence of gas hydrates Hydrate in the pore space increases resistivity and sonic velocit
137. for porosities ranging from 0 to 30 the depth of investigation varies from 2 ft 61 cm to about 6 in 15 cm The vertical resolution is 1 5 ft 46 cm Applications Porosity In reservoir engineering its importance is quite evident in the study of the volcanic rocks that make up the upper oceanic crust a good in situ porosity measurement is most important to the correct understanding of the crustal structure first because it samples both the small scale microcrack vesicle porosity seen in the cores and the large scale fractures not sampled by drilling and secondly because other properties such as density seismic velocity and permeability depend strictly on porosity variations and on the geometry of the pore space In the presence of clays or hydrous alteration minerals a correction is required to account for the presence of bound water Lithologic determination Because the hydrogen measured by the tool is present not only as free water but also as bound water in clay minerals the porosity curve often combined with the density log can be used to detect shaly intervals or minerals such as gypsum which has a high hydrogen index due to its water of crystallization Conversely the neutron curve can be used to identify anhydrite and salt layers which are both characterized by low neutron readings and by high and low bulk density readings respectively Environmental Effects Eccentralization of the tool by a bow spring is
138. for third party tool support at LDEO include o PC based data acquisition system at LDEO and on the JOIDES Resolution o Multiple power supplies in a wide variety of voltage and amperage outputs o Crossover for connecting third party tools to a Schlumberger style cablehead Telemetry connection to a depth measurement system Access to pressure test vessel capable of 10 000 psi Access to 740 foot test hole at LDEO 22 000 feet of 7 46 wireline with terminations Assistance during the development of third party tools is provided through ODP Logging Services personnel and the facilities available at LDEO On site facilities are available to assist in manufacturing assembly and pressure and field testing Interested investigators should contact ODP Logging Services Technical Services Manager Greg Myers at gmyers ldeo columbia edu ODP Logging Selecting Estimating Pre Cruise Staff Scientist Toolstrings Log Times Meeting INDEX OF TOPICS GLOSSARY ACRONYMS HOME Itrasonic Borehole Imager UBI Description The UBI Ultrasonic Borehole Imager features a high resolution transducer that provides acoustic images of the borehole Critical borehole stability and breakout information can be derived from the accurate borehole cross section measured by the tool The high resolution image from the transducer 1 also 14 1 Compensating device Motor assembly e Gear box assembly for measuring casing inte
139. gth 23 ft without WOB 23 ft without WOB Collar weight 1330 Ibm 2590 Ibm UH connection bending strength ratio 200 2 DH connection bending strength ratio nd Moment of inertia 77 4 in 212m 5 deg 100 ft 4 4 deg 100 ft Soller does rotating at 100 rpm rotating at 100 rpm 15 deg 100 ft 12 deg 100 ft Max collar dogleg sliding sliding Flow range 225 800 gpm 300 800 gpm Marron operating 12 000 ft Ibf 23 000 ft Ibf torque Maximum weight on bit 71 000 L2 194 000 L2 Maximum tensile load 550 klbf 865 klbf Deployment Notes Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME ulti Sensor Spectral Gamma Ray Tool MGT Description The Multi Sensor Spectral Gamma Ray Tool is a new third party tool developed by the Lamont Doherty Borehole Research Group to improve the vertical resolution of natural gamma ray logs This is achieved in the MGT by using an array of short detector modules with approximately 2 ft spacing Each module comprises a small 2 x4 Nal detector a programmable 256 channel amplitude analyzer and Am calibration source The spectral data are later recalculated to determine the concentration of potassium thorium and uranium radioisotopes or their equivalents The spectral data from individual modules are sampled 4 times per second and stacked in real time based on the
140. gth of is spliced to the main wireline For detailed specs click on the relevant cable type 4 Breaking Insulation Capacitance trength Temp Rating Propylene 40 16 700 Lbf 300 F Teflon 55 16 700 Lbf 450 F 450 F 500 F up to 2 hrs Fluoropolymer 55 16 700 Lbf Sheaves Sheaves or pulleys are used during the logging operation to route the wireline around bends and curves on the rig floor Sheaves are located at the WHC at the crown block and adjacent to the pipe racker It is extremely important that these be given plenty of clearance when rigged to avoid personal injury Logging tool string with rigged up Another view of a sheave This is sheave a night photo Sources Chemical and electrical radioactive sources are commonplace in ODP logging Sources include N ame Type Uses Chemical LithoDensity tool and LWD CDN Compensated Neutron Porosity tool and LWD CDN Chemical Geochemical tool Electrical Accelerator Porosity tool and Geochemical tool Sources are handled only by the Schlumberger engineer including all permitting and paperwork Should a tool containing a radio source become stranded or lost downhole appropriate actions such as tool fishing and well abandonment would occur Please see the iquipment Continued Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TO
141. gth varies between 19K and 23K although ideally one would find separate eccentricity peaks and separate precession peaks Also the shortest periods are the most likely to be smeared by small changes in sedimentation rate within a log interval Spectral analysis is the most common means of characterizing periodicity in logs and can be undertaken with either depth or age as the independent variable Ultimately however a conversion from depth scale to age must be performed in order to understand the driving forces behind the variability There are a large number of programs available on various platforms that easily allow spectral analysis to be performed Perhaps the easiest and most commonly employed and accepted method is to use the Macintosh program Analyseries to perform the analysis In order to generate power spectra in Analyseries you need to do the following 1 Generate a tab delimited text data file for the mac with the first column as depth or age 2 Import it to Analyseries open it from within the application 3 Select click on the data you wish to analyze and choose a method from the Math menu Blackman Tukey is the most common method used by geologists paleoceanographers but a variety of methods should be compared to insure that the results are robust The Blackman Tukey method is nice because unlike some other methods it gives confidence estimates for the results 4 The resulting frequency vs power spectra out
142. h of this mation is probably stopped by friction between the tool and the borehole wall however recent corrections the control of the heave compensator further reduce the effects of heave by a factor of 2 3 eliminating the possibility that wireline motion could be reversed for most logging operations As a result downhole logs obtained at diferent times are consistent under most sea conditions and the residual heave effects on vertical resolution arc negligible for most downhale tels Electrical resistivity logging tools Devices that gather data on a formation s electrical properties mea sure currents that propagate through the borehole and pore fluids in the surrounding rock and sediment layers Water is ubiquitous and conductive fluid underground its electrical conductivity increases with the concentra of and CT ions and with temperature which increases the mobility of the ions Electrical resistivity measurements in a formation therefore allow one to estimate its porosity fluid content and often the degree of fracturing Clays also contribute to the measured electrical conductivity because of the negative ions com monly associated with the molecular structure of various Al bearing minerals found in many clays Effrs 1986 Self potential devices measure the electrical potential generated by ions flowing between the borehole and pore fluids This measurement is related to clay content formation it h
143. hal resistivity imager ARI can provide images of the same features Crustal stress and anisotropy Borehole televiewers measure the shape of the borehole which can be interpreted in terms of crustal stress the borehole is deformed according to the maximum horizontal stress direction The FMS caliper arms will tend to follow the major and minor axes of the borehole if it is elliptical and thus can also be used to infer stress orientation The Dipole Sonic Imager DSI 2 can reveal sonic S wave anisotropy which may be due to crustal stress or a preferential rock fabric Magnetic polarity The GHMT total field and magnetic susceptibility measurements processed to find the magnetic polarity of the remanent magnetization of the sediment which can then be used for magnetostratigraphic dating Note that the GHMT can log when descending the hole as well as while going up the hole unlike the other toolstrings Heat flow fluid flow The Temperature Acceleration Pressure TAP tool records the temperature of the borehole fluid which increases downhole The borehole fluid temperature equilibrates towards the actual formation temperature over the course of the logging run and thus gives a lower limit to the actual formation temperature Where formation fluids locally enter the borehole they will cause an anomaly in the temperature log Environmental Issues The state of the hole for logging can be assessed from the conditions ex
144. hat describes any post cruise work performed with the logging data or with samples obtained for physical properties or chemical analyses If the Logging Scientist or any other shipboard scientist obtains samples for post cruise work ODP requirements stipulate that a manuscript must be submitted on the work performed with the samples Collaborations and scientific discussions between the Logging Staff Scientist and other shipboard participants are an integral part of the second post cruise meeting At this time preliminary manuscript titles for publication in the Scientific Reports volume should be provided to the ODP TAMU Staff Scientist Shore based investigators with an approved sample or data request are also usually invited to participate in the second post cruise meeting where they too present their results and submit manuscript titles Post Cruise Data On line Log Data Meetings Distribution Data CD ROM INDEX OF TOPICS GLOSSARY ACRONYMS HOME Data Distribution Shipboard Participants Shipboard data distribution Log data are distributed onboard the JOIDES Resolution to all shipboard scientific participants both digitally and in paper format Details can be found in the shipboard data availability section of the data acquisition page Shipboard integration of logs with core data and seismic sections is possible using the Sagan software package more information on data processing and analysis can be found on the data proces
145. he measurements may be summarized This will essentially amount to a paragraph about each tool If new tools were used or conventional tools employed in an unconventional way then a more detailed explanation of the tool and the way it makes its measurements will be provided Data Quality Any environmental borehole conditions excessive heave etc or technical problems encountered on the leg will be discussed here in the context of how they affect data quality Data Processing This section is somewhat optional but it is usually included especially if the logging operation employed new tools new techniques or data were applied in new ways The basics of depth shifting and correlation between the passes are briefly presented Then details of how particular estimates are derived from the data will be given For example these may include the onboard generation of a magnetostratigraphy using the GHMT or clay typing using natural gamma ray and photoelectric effect The above sections are meant to provide guidelines for the type of information to be conveyed in the Explanatory Notes As the specific operations and science of each leg is different it may be beneficial to refer to previous examples of explanatory notes from legs with similar scientific objectives and or tool deployments e g 162 167 172 175 for paleoceanography or 118 140 148 or 176 for hard rock environments 4 Logging Operations Preliminary Report The
146. he difference in arrival time of the direct wave between receiver depths Processing techniques can be applied to separate the upgoing and downgoing wavefields which can then be analyzed for attenuation properties of rock prediction of acoustic properties below the bottom of the hole and correlation with borehole lithology wireline logs and events on conventional seismic reflection profiles W Washout A borehole feature where the gauge of the hole increases substantially due to caving or erosion during the drilling processes Wavelet A seismic pulse usually consisting of 1 1 2 to 2 cycles Wiper Trip The action of pulling pipe from the bottom of the hole to logging depth then lowering pipe back to bottom or the opposite Wiper trips are always pipe round trips to clean the hole logging usually at a much slower speed than normal pipe trips to avoid damaging the hole Wireline A cable comprising one or conductors which is lowered into a borehole and provides for real time communication between a tool and the surface X Y Top INDEX OF TOPICS GLOSSARY ACRONYMS Index of Topics in this Manual ABCDEFGHIJKLM A Accelerator Porosity Sonde APS Acronyms used in logging Acoustic wave propagation explanation of Array Seismic Imager ASI Array Sonic SDT Azimuthal Resistivity Imager ARI Backup sonic tools Backup tapes Borehole Compensated Tool BHC C Cableheads Calibration equipment
147. he mud cake is a flushed zone from which almost all of the formation water and most of the hydrocarbons have been displaced by filtrate The invasion process alters the distribution of resistivities and other properties and consequently the value which logs read The depth of invasion is the equivalent depth in an idealized model rather than the maximum depth reached by filtrate In oil bearing intervals the filtrate may push a bank of formation water ahead of it to produce a relatively low resistivity annulus which is especially important with deep investigation induction logs J K L Logging While Drilling LWD Process by which downhole geophysical logs are acquired during drilling operations LWD acquires data from sensors integrated into the drill string immediately above the drill bit LWD records data minutes after cutting the hole closely approximating in situ conditions This forefront industry technology provides high quality logging information in environments where standard wireline systems previously acquired either no data or poor quality data Specifically LWD provides excellent quality results in deviated holes or unstable environments that may preclude wireline log runs In addition to the acquisition of logging data in potentially unstable boreholes where high quality wireline data cannot be acquired LWD measurements also offer at least two other operational advantages over standard coring and wireline operations 1 in situ logs
148. he tool string along with the position from the bottom of the string of the different sensors 2 Logs This is a display vs depth of the main curves recorded The Logging Staff Scientist can follow every step of the recording on the screen of the MCM unit and thus has the option of choosing the best type of display Should she decide to change the type of display the data can be played back on the screen at the end of logging operations before producing final blueprints Logs are usually displayed with depth referred to the rig floor mbrf 3 Trailer The bottom portion of the blueprints includes the after and before survey calibration summary as well as the shop calibration a list of the sensor measure points for each tool and a list of logging parameters Data Loggin Stuck Lost Shipboard Acquisition Operations Tool Policy Reports INDEX OF TOPICS GLOSSARY ACRONYMS HOME Logging Operations When the total depth of a hole scheduled for logging has been reached a series of activities 15 initiated to prepare the hole and rig floor for the logging operation The borehole is conditioned by pumping a viscous mud into the hole to flush remnant cuttings from the borehole running the bit up and down to break through any bridges or swelling clays and finally filling the hole with a drilling mud such as sepiolite to stabilize the hole Based on data collected from the capillary suction test CST the hole may be fil
149. hed to the bottom of the DIT E These two tools are placed in the pipe and successive tools are added to the top After the tool string is assembled the cablehead is attached and the tool zero point is established by pulling the bottom of the DIT E to the level of the rig floor The tool string is then lowered the fluid seal is fastened and the tool is run into the hole The tool descent speed is typically 10 000 ft hr Once the sea floor is reached the tool string is held stationary for 2 3 minutes to allow the TAP tool to equilibrate The tool is run down to the bottom of the hole and then pulled up at a constant rate to complete the first pass A second pass can be completed if desired As the first toolstring is being pulled back to the surface the Schlumberger engineer may slow the ascent speed as the tool string crosses the mud line to measure the depth of the sea floor accurately The first toolstring is rigged down and the TAP tool is cleaned by the logger and returned to the Downhole Measurements Lab for the retrieval of the data The next toolstring typically the FMS Sonic is then prepared The same logging procedure is followed for running the FMS Sonic toolstring The third toolstring deployed may be a specialty tool such as the GHMT WST or other During the logging process the Logging Staff Scientist is involved in many steps including 1 Taking detailed operations notes on the Logging Event forms and including all listed depth
150. hm km 131 pf km 880 Vrms 498 kg km 393 kg km 40 150 74 52 0 254 mm Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS 7 46 NA Seven conductor armored cable designed and specially manufactured for use in well logging The armor wires are high tensile galvanized improved plow steel pre formed and pre stressed The armor is coated with an anticorrosion compound 20 AWG copper 6 0 014 6 0 36 mm PFA insulation 0 073 1 85 mm 20 AWG copper 7 0 013 7 0 32 mm PFA insulation 0 070 1 78 mm Conductive Neoprene 0 288 7 32 mm Compressed Diameter Inner armor 24 0 039 24 0 99 mm Outer armor 24 0 049 24 1 24 mm Nominal Diameter 0 464 11 79 mm trademark of Dupont ELECTRICAL DC Resistance 68 F or 20 Insulation Resistance Capacitance Voltage Rating MECHANICAL Calculated Weight Temperature Rating Break Strength Maximum end to end variation Triple Combo Nominal Properties Conductor Armor at 500 VDC at 1 KHz In air In fresh water Min Max Ends fixed Ends free FMS Sonic Specialty Other 10 9 ohm kFt 1 2 ohm KFt 15000 ohm kFt 55 pf Ft 560 Vrms 350 Lbs kFt 277 Lbs kFt 40 450 F 500 F up to 2 hrs 16700 Lbf 11600 Lbf 0 010 Inch 36 ohm km 4 ohm km 5000 M ohm km 180 pf km 560 Vrms 521 kg km 412 kg km 40 260 74 52 0 254 mm Toolstring In
151. hole and drilling problems e Casing and mechanical wear An additional run in the hole to monitor the internal surface of the casing can be avoided by acquiring data while pulling the UBI tool out of the hole after an openhole survey Log Presentation The UBI presentation usually consists of an amplitude image on the left and a borehole radius image on the right on a 1 40 depth scale Dynamic normalization usually over 1 m interval is applied to both images to highlight borehole features Dark colors represent low amplitudes and large radii indicating borehole rugosity enlargements and attenuative material These center tracks display dynamically scaled images The two edge tracks show the upper 25 median and lower 25 values of the amplitude and radius information at each depth The colored areas on the edge tracks indicate the range of amplitude and radius data represented by the image color scales at each depth With advanced processing techniques choice of operating frequencies and low sensitivity to eccentralization the UBI tool offers unequaled quality of amplitude and precision of radius measurements for high resolution acoustic borehole images Specifications Temperature Rating 350 175 Pressure Rating 20 kpsi 13 8 kPa Tool Diameter varies according to subassembly 3 6 to 112 in Weight varies according to Sonde 188 210 Ibm subassembly Tool Length sonde and 20 ft 8 in 6 3 m cartr
152. idge only Maximum Mud Weight Water base mud 16 Ibm gal in vertical sampling rate 2100 ft h Recommended Logging Speed 0 4 in vertical sampling rate 800 ft hr 0 2 in vertical sampling rate 400 ft hr Hole Size Range 5 5 12 5 in 250 kHz operating frequency 0 4 in Approximate Image Resolution Deployment Notes The UBI is run only with the NGT and after the Triple Combo Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME Component Description 4 LEH GT 1 The WST 3 is a Schlumberger three axis check shot tool used for both zero offset check shot wsTa n 3 Axis Well Semit Ial and offset vertical seismic profiles VSP The WST 3 consists of three geophones which press against the borehole wall and record the acoustic Hydraulic clamping arms waves generated by an air gun located near the sea surface The tool was designed specifically for use in an offset VSP experiment where a remote seismic source ger would be fired from a second ship The tool is compatible with Schlumberger s latest data acquisition system and data WST 3 output is in SEG Y format Applications Offset VSP data acquired by the WST 3 are useful for e Providing seismic interval velocities which can be compared to the rock sequence inte
153. igh where resistivities are low In most ocean drill holes however seawater fills both bore hole and pore space and the self potential measurement is poor Induction devices are used to measure lower 100 ohm m resistivities current menerating devices 3 6 eni B e oo ous s E gni 2 0 41 5 m 3 1 0 081 cm a F oy am i B n n 5 6 0 Sp FMS LOT ONL GST LSS SFL ILM ILD Figure 4 Intrinsic vertical resolution of various wireline tools representing ihe minimum depth interval for which mean INDEX OF TOPICS GLOSSARY ACRONYMS HOME Goldberg DOM NIHOLE MEASUREMENTS 319 TABLE 1 Abbreviations for Downhole Tools and Logs Definition AIT Array Induction Imager Tool BHTY Borchole Televiewer CNL Compensated Neutron Log DIL Dual Induction Log D I Dipole Shear Sonic Imager FMS Formation MicroScanmer Fullbore Formation Microlmager GST Gamma Ray Spectroscopy Tool HDT High Resolution Dipmeter Tool ILD Induction Log Deep ILM Induction Log Medium IPLT Integrated Porosity Lithology Tool LDT Litho density Tool 155 Long Spacing Sonic Tool Formation Dynamics Tester NGT Natural Gamma Ray NME Nuclear Magnetic Resonance Tool RAB ResistivitysAt Hit Tod SDT Sonic Digital Array Sonic Tool SFL Spherically Focussed Resistivity Tool SHOT Stratigraphic Dual Dipmeter Tool Trademark of Schlumberger l
154. ilizes an in line eccentralizer to maintain consistent contact with the borehole wall The eccentralizer is vital in preventing poor contact of the tool with the borehole wall which can lead to attenuation of the formation signal by the borehole fluid and in turn the overestimation of the true porosity of the formation Hole size also affects the neutron log response the formation signal particularly for the epithermal count rates tends to be masked by the borehole signal with increasing hole size In liquid filled holes the influence of the borehole fluid depends on its salinity chlorine is a strong neutron absorber and density the addition of weighting additives such as barite will yield a lower porosity reading In the Ocean Drilling Program the neutron tool is sometimes recorded through the drilling pipe and the bottom hole assembly Because iron is a strong neutron absorber an increased porosity reading will result its degree depending on the thickness of the pipe Log Presentation The APS is recorded in linear porosity units for a particular lithology limestone sandstone dolomite The Near Array Limestone Porosity Corrected APLC is usually displayed When APS is run in combination with the lithodensity and spectral gamma ray tool the porosity and density curves are usually displayed in the same track with gamma ray and caliper curves in a separate track Specifications Temperature Rating 175 C 350 F
155. illing purposes Rotational processing provides an important correction in oval holes and yields a differential caliper Applications Density Measurement Porosity estimate If grain density is known porosity can be calculated from the density log Alternatively porosity and density logs can together be used to calculate grain density Seismic impedance calculation The product of velocity and density can be utilized as input to synthetic seismogram computations Lithology and rock chemistry definition In combination with the neutron log the density log allows for the definition of the lithology and of lithologic boundaries Because each element is characterized by a different photoelectric factor this can be used alone or in combination with other logs to determine the lithologic type Both density and photoelectric effect index are input parameters to some of the geochemical processing algorithms used onshore Applications Neutron Porosity Measurement Porosity In reservoir engineering its importance is quite evident in the study of the volcanic rocks that make up the upper oceanic crust a good in situ porosity measurement is most important to the correct understanding of the crustal structure First because it samples both the small scale microcrack vesicle porosity seen in the cores and large scale fractures not sampled by drilling and secondly because other properties such as density seismic velocity and perme
156. ing periods during downhole seismic acquisition both in vertical and deviated wells This feature makes the ASI tool ideal for 2D and 3D time lapse borehole seismic surveys reservoir monitoring applications and amplitude variation with offset AVO calibration walkaways Applications The ASI can acquire three dimension walkaway vertical seismic profile VSP surveys in both vertical and deviated wells One of the primary benefits to ODP is its low deployment time since multiple geophones are deployed simultaneously Specifications Temperature Rating 350 F 175 Pressure Rating 20 kpsi 13 8 kPa Tool Diameter 3 375 in 8 57 cm Minimum Tool Length 280 ft 85 m Sampling Interval 1 2 and 4 msec Max Logging Speed Stationary Vertical Resolution N A Deployment Notes The standard ASI tool can be used in cased holes without special equipment Adding a bowspring assembly allows surveying of open holes from 8 1 2 to 13 in Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME Backup Sonic Tools Description Borehole Compensated Tool The BHC sonde measures the time required for a compressional sound wave to travel through one foot of formation The BHC consists of an upper and lower transmitter arranged symmetrically on either side of two pair of receivers The spacings and T R are
157. ion tools it responds to conductivity rather than to resistivity operates in water or oil base muds and provides two depths of investigation It has better vertical resolution but a shallower depth of investigation than dual induction tools The tool broadcasts a 2 Mhz electromagnetic wave and measures the phase shift and the attenuation of the wave between two receivers These quantities are transformed into two independent resistivities that provide the two depths of investigation The phase shift is transformed into a shallow resistivity Rps for resistivity from phase shift shallow the attenuation is transformed into a deep resistivity Rad for resistivity from attenuation deep The LWD CDR has upper and lower transmitters that fire alternately HOME The average of these phase shifts and attenuations the upward downward propagating waves provides a measurement with borehole compensation similar in principle to that of the Borehole Compensated Sonic Tool BHC Borehole compensation reduces borehole effects in rugose holes improves the vertical response increases measurement accuracy and provides quality control for the log An electrical hole diameter is computed from the CDR data and is used as an input to hole size corrections tool Receivers LI a Li gt Li Li t Gamma ray Transmitters Detection of 3 in 7 5 cm beds is possible with the CD
158. ion on physical prop erties and age Downhole core and seismic data used jointly also contribute to the confidence each individ ual data set Unlike measurements on core samples which are often disturbed during the process of recovery downhole data provide a set of continuous bogs of infor mation and sample a larger volume of rock than core measurements Because logs have much greater vertical resolution than surface data but itle lateral resolution the combination of the two defines subsurface geological structures far better than either data type can alone The difference in the scale of physical phenomena affecting each type of measurement may be extreme The scale ratio from core to log may be greater than 2 10 the ratio from log to seismic section may be 10 to 10 times larger In mest integrated scientific applications there HOME Miia Taia sat ee hes a cdd Long Range Plan Join Oceanograpftic institutions Inc 1996 This plan describes the directions for ma rine scientific drilling from now through 2008 and the new technologies that will be required to accomplish them The plan relies heavily on downhole experiments to achieve its scientific objectives It also maintains the historical premise that Worthington et al 1987 p 135 dem difference in the scale of physical phenomena affecting each type of measurement may be extreme The scale ra
159. ions Applications Porosity In reservoir engineering the importance of porosity measurements is quite evident In the study of the volcanic rocks that make up the upper Oceanic crust a good in situ porosity measurement is critical to the correct understanding of the crustal structure for two reasons first because it samples both the small scale microcrack vesicle porosity seen in the cores and the large scale fractures not sampled by drilling and second because other properties such as density seismic velocity and permeability depend strictly on porosity variations and on the geometry of the pore space In the presence of clays or hydrous alteration minerals a correction is required to account for the presence of bound water Lithologic determination Because the hydrogen measured by the tool is present not only as free water but also as bound water in clay minerals the porosity curve often combined with the density log can be used to detect shaly intervals or minerals such as gypsum which has a high hydrogen index due to its water of crystallization Conversely the neutron curve can be used to identify anhydrite and salt layers which are both characterized by low neutron readings and by high and low bulk density readings respectively Environmental Effects Eccentralization of the tool by a bow spring is the most important requirement to obtain reliable porosity measurements The triple combo string ut
160. ions 4 A list of scientific participants At the pre cruise meeting the Logging Staff Scientist will make a presentation on the tools available for logging the rationale for tool selection and the estimated logging times for specific sites to be drilled on the leg Typically this presentation follows those of the Co Chief Scientists on general scientific objectives and the Operations Superintendent on operations and engineering issues Other topics covered by additional speakers include sampling and curatorial procedures computing equipment and services and publications policy and procedures A sample agenda for a pre cruise meeting can be found at the end of this page The Logging Staff Scientist will contact the Co Chief Scientists several weeks prior to the pre cruise meeting in order to learn what issues the Co Chiefs would like to have addressed at the meeting The Logging Scientist s contribution can range from minimal a short talk on time calculation to comprehensive a crash course on logging Typically the Logging Scientist will have several overheads describing recent applications of particular tools and or measurements from recent legs ideally from legs in similar geologic environments or legs with similar scientific objectives Overheads showing the standard tool strings available along with alternative tool combinations will also be available The ODP TAMU Drilling Superintendent will also prepare a prelimina
161. iption Acoustic waveforms are acquired while drilling with the Anadrill Isonic tool One transmitter and four receivers are positioned within a drill collar just above the bit to collect compressional transit times just seconds after the rock has been cut As with all Logging While Drilling tools formation data are collected before the borehole alteration or invasion occurs The data are stored in memory and dumped upon collar retrieval or they are pulsed in real time if an MWD sub is in use Isonic data are then utilized in the tradional manner for sonic porosity synthetic seismogram and correlation with wireline logs Receivers Transmitter Applications Porosity and pseudodensity log The sonic transit time can be used to compute porosity by using the appropriate transform and to estimate fracture porosity in carbonate rocks In addition it can be used to compute a pseudodensity log over sections where this log has not been recorded or the response was not satisfactory Seismic impedance The product of compressional velocity and density is useful in computing synthetic seismograms for time depth ties of seismic reflectors Sonic waveforms analysis If a refracted shear arrival is present its velocity can be computed from the full waveforms and the frequency content and energy of both compressional and shear arrivals can also be determined Fracture porosity Variations in energy and frequency content are indicati
162. is to interpret bell shaped gamma curves as a fining upwards sequence and funnel shaped gamma curves as a coarsening upward sequence Serra amp Sulpice 1975 However these methods are only likely to be of use in simple sandstone shale formations and are subject to error when a significant proportion of the gamma ray radioactivity originates from the sand sized detrital fraction of the rock see Heslop 1974 and Rider 1990 Gamma ray data may also be used to help interpret the environment of deposition Unconformities can result in the accumulation of phosphatic nodules which may be evident in the spectral gamma log as an anomalous spike in U Increased U values and in particular low Th U ratios may also be associated with marine condensed sequences Myers amp Wignall 1987 Doveton 1991 used Th U ratios to estimate paleo redox conditions at the time of deposition which he used to identify generally transgressive and regressive intervals Mineralogy Geochemistry The concentrations of the three main radioactive elements in the formation can often be used to give an indication of the mineralogy and or geochemistry For example high Th values may be associated with the presence of heavy minerals particularly in channel sand deposits overlying an erosional unconformity Increased Th values may also be associated with an increased input of terrigenous clays Hassan et al 1976 Figure 2 High Th duc ka Figure 2 Spectra
163. isting and mew meth odologies for downhole measurements with new scien tific directions During the last 25 years the Deep Sea Drilling Propect DSDP and its successor since 1984 the Ocean Drilling Program ODP have been progressively expanding the role of downhole measurements These programs have successfully fulfilled their scientific mis sions by drilling holes in nearly all the different geologic settings of the world s oceans A total of 170 drilling expeditions or legs around the world s oceans have been successfully completed at the time of this writing More than 1000 drill holes have been cored after which many have in turn been logged using downhole instru ments While downhole measurements were conducted in less than 14 of all marine holes drilled during the DSDP they have been made in more than 56 of the holes drilled by ODP This dramatic increase ODP s core data with regional geophysical surveys and pro viding data where core sections could not be obtained Examples of recent scientific applications and ap proaches are presented that address previous problems with data quality and changes in properties over time after a hole is drilled The role of downhole measure ments is discussed for two broad areas of research the structure and composition of the Earth s crust most of which is formed at mid occan ridges and past changes in Earth s environment recorded in the deep sea sediments overlying the crus
164. it Pleistocene climate transition 40K to quity cyclicty The period prior to 790 Kya red shows dere uar less spectral B00 in the eccentricity bangi iad obliquity peak s the menst prominent eem amend aut due io the sedimentation rate that occur throughout this interval 0 0 1 0 2 0 3 0 4 0 5 n amp Frequency 0 10 20 30 40 5060708090 bae Turbidite sequences are imaged here by the FMS data Red sine waves on the images trace bedding planes The corresponding tadpole plot shows the average dip is roughly 40 degrees to the west Interpretive work of the FMS data can be performed either on the ship or onshore with the GeoFrame software FMS Image Horizontal Scale 1 17 LLC M DT4P DSIPASE Orientation North Elem 10 24D 880 aon m uam Resistive Conductive ea _ DOTS DSIPASS2 40 8010 80 ust 463 2 HM 3 1 464 E 465 n 1 4 mL 2 466 SR RTD NN e AE pum du 467 74 E I 6 m 5 2 468 n i i iL f i gt 2 Fo 483 Depth mbsf 260 280 200 320 340 Susceptibility effect n T 2 3 4 5 40 50 80 Remanence effect Interpretation GPTS 21 23 Exampl
165. ith a sonde designed to correct unwanted effects The compensated density log uses the signal from a secondary detector to correct for the effect of mud cake and small irregularities in the borehole wall The compensated sonic log uses a special arrangement of the transducers to correct for irregularities in the borehole size and sonde tilt Continuous velocity log A sonic log a log of formation velocity against depth The quantity recorded and graphed is usually the reciprocal of the velocity the travel time over a short interval often expressed in usec ft Customer tape Tape containing the data used in the processing of standard logs Cycle skipping In acoustic or sonic logging the first arrival is sometimes strong enough to trigger the receiver closest to the transmitter but not the farthest receiver which may then be triggered by a later cycle resulting in an erroneously high transit time This situation is called cycle skipping Its onset is characterized by an abrupt deflection corresponding to an added cycle of travel between receivers Short cycle skipping where the near receiver is triggered by a cycle too late also can occur resulting in an abnormally short travel time D Density log A well log which records the formation density The logging tool consists of a gamma ray source e g Cs 7 and a detector so shielded that it records backscattered gamma rays from the formation This secondary radiation depends on the density
166. ity Correction g cm Short Spacing Transit Time 10 8 spacing usec ft Compressional Wave Transit Time Long Spacing Transit Time 12 10 spacing usec ft Long Spacing Transit Time 12 10 spacing usec ft Short Spacing Transit Time 10 8 spacing usec ft Shear Wave Transit Time usec ft Stoneley Wave Transit Time usec ft Epithermal Neutron Porosity 96 Epithermal Neutron Ratio Magnetic Field Inclination degrees Magnetic Field Total Moment oersted Magnetic Field on X Axis oersted Magnetic Field on Y Axis oersted Magnetic Field on Z Axis oersted Natural Gamma Ray API units High Res Near Array Limestone Porosity Corrected decimal fraction Hole Azimuth degrees High Res Bulk Density Correction g cm HNGS Borehole Potassium dec fraction High Resolution Corrected Far Thermal Counts HNGS Computed Gamma Ray GAPI High Resolution Corrected Near Thermal Counts Hole Diameter in High Res Enhanced Bulk Density g cm HFLC HLCA HLEF HNEC HNPO HNRH HPEF HRHO HROM HSGR HSIG HSTO HTHO HTNP HURA IDPH ILD ILM IMPH LCAL LDOC LIR LLD LLS LTTI LTT2 LTT3 LTT4 MAGB MAGC MAGS High Resolution Density Correction g cm High Res Far Detector Count Rate cps HNGS Formation Potassium dec fraction High Res Near FarLimestone Porosity Corrected decimal fraction High Res Caliper in High Res Long spaced Photoelectric Effect ba
167. ium dec fraction Deployment Notes The HNGS is always run near the top of the triple combo tool string Several passes are made with the HNGS past the mudline for improved depth control Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME ostile Environment Litho Density Sonde HLDS Description The Hostile Environment Litho density sonde HLDS consists of a Cs 37radioactive source and two detectors mounted on a shielded skid which is pressed against the formation by a hydraulically activated eccentering arm The 662 keV gamma rays emitted by the source into the formation experience two types of interaction with the electrons in the formation Compton scattering and photoelectric absorption Compton scattering is an elastic collision by which energy is transferred from the gamma ray to the electrons in the formation This interaction forms the basis of the density measurement in fact because the number of scattered gamma rays which reach the detectors is directly related to the number of electrons in the formation the tool responds to the electron density of the rocks which is in turn related to the bulk density Photoelectric absorption occurs when the gamma rays reach a low energy lt 150 keV level after being repeatedly scattered by the electrons in the formation The photoelec
168. l Stoneley and mud wave velocities Shear wave values can then be derived from these velocities The multireceiver sonic tool with its linear array of eight receivers provides more spatial samples of the propagating wavefield for full waveform analysis than the standard two receiver tools This arrangement allows measurements of wave components propagating deeper into the formation past the altered zone Mud At Measurement Section Eight ad Ceramic Receivers Two Ceramic Receivers Two Ceramic Transmitters The depth of investigation cannot be easily quantified it depends on the spacing of the detectors and on the petrophysical characteristics of the rock such as rock type porosity granular vacuolar fracture porosity and alteration For source detector spacings of 3 5 ft 8 10 ft and 10 12 ft the depth of investigation ranges from 2 in to 10 in altered invaded and undisturbed formation respectively 5 in to 25 in and 5 in to 30 in The vertical resolution is 2 ft 61 cm Applications Porosity and pseudodensity log The sonic transit time can be used to compute porosity by using the appropriate transform and to estimate fracture porosity in carbonate rocks In addition it can be used to compute a pseudodensity log over sections where this log has not been recorded or the response was not satisfactory Seismic impedance The product of compressional velocity and density is useful in c
169. l char acteristics of the rock The images are always oriented to magnetic reference measured downhole Electrical imaging provides approximately 5 mm resolution of the borehole wall by sensing contrasts between high and low conductivity features such as water filled fractures or fine scale bedding variations Sera 1989 Devices such as the Formation MicroScanner FMS and Full bore Formation Microlmager FMD measure the borehole s surface conductivity on four pads pressed against the borehole wall with vertical resolution 10 times finer than most other downhole measurements see Figure 4 Optical imaging also offers high vertical resolution but is limited to holes containing transparent borehole fluids Ultrasonic imaging devices generate complete 360 image of the reflectivity of the borehole wall an advantage over the four pad electrical method with a vertical resolution of 2 3 cm The dip strike width and depth of geological features intersecting a borchole may be measured using any of these imaging devices e g Paler er al T1990 funi and Souhaite 1990 Images can be visually used to compare logs with cores for bedding orientation and to study fracturing structure and borehole shape Temperature tools Temperature logging typically HOME typically measured to approximately 0 5 m into the bore hole wall and the vertical resolution of the measure ment is approximately 0 4 m Neutron tools employ
170. l gamma radioactivity resistivity density porosity sonic velocity magnetic susceptibility logs are transmitted via satellite from the ship processed and returned to the ship usually within a week of logging Processing of other log data FMS images GHMT magnetic polarities etc is done after the cruise either because the file sizes are too large to transmit via satellite and or the processing time is longer For details on the various types of processing click on the appropriate link o Log Processing o Core Log Integration Splicer amp Sagan o Log Seismic Integration IESX Data Processing Log Core Log Integration Log Seismic Overview Processing Splicer amp Sagan Integration IESX INDEX OF TOPICS GLOSSARY ACRONYMS HOME C Log Processing Conventional Log Processing Depth adjustments The main processing task is to remove depth discrepancies between the different logging runs Such discrepancies are caused by cable stretch incomplete heave compensation and by tides The natural gamma ray log SGR and HSGR is generally used to match between the logging runs as this log is recorded on all toolstrings One gamma log is chosen as the reference on the basis of the length of the logged interval and data quality The other gamma logs are matched to the reference using an automatic routine the match of each log is checked to make sure distinctive peaks and troughs line up and the match is adjusted as necessary
171. l gamma ray data from Hole 1124C showing Th values a mudstone unit between 420 430 mbsf Increases in U are frequently associated with the presence of organic matter For example particularly high U concentrations gt 5 ppm and low Th U ratios lt 2 occur in black shale deposits Adams amp Weaver 1958 In the Ocean Drilling Program a correlation can often be observed between the U log and the total organic carbon values measured in the core Figure 3 Figure 3 Spectral gamma ray data from Hole 11720 showing high U values an organic bearing claystone unit between 622 640 mbsf In sandstones high K values may be caused by the presence of potassium feldspars or micas Humphreys amp Lott 1990 Hurst 1990 Glauconite usually produces a very distinctive almost diagnostic spike in the K log Figure 4 High values dos co glamennite Figure 4 Spectral gamma ray data from Hole 1171D showing high K values due to the presence of glauconite In ocean floor volcanics K can become significantly enriched in secondary alteration minerals which are typically found where the formation is more permeable and intense fluid rock interactions can occur Brewer et al 1992 An example of this can be seen in ODP Hole 896A where the lowest values occur in relatively impermeable massive flows whereas higher and more variable K concentrations can be correlated with the more permeable pillow lavas and breccias Brewer et
172. le with N in the center and S on both edges Images from two passes of the tool can be merged and plotted together The calipers or other curves can be plotted alongside the images as well With an additional processing step on the VAXstation dipmeter calculations can be made Standard dipmeter plots consist of borehole drift calipers dip angle and direction tadpoles azimuth frequency plots and pad traces FMS output plot Specifications Temperature Rating 175 350 F Pressure Rating 20 kpsi 13 8 kPa Tool Diameter 3 625 in 9 2 cm Tool Length 25 3 ft 7 72 m Sampling Interval 0 1 in 2 5 mm Max Logging Speed 1 800 ft hr Vertical Resolution 0 2 in 5 mm Depth of Investigation 10 in 25 cm Deployment Notes Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME Dipole Shear Sonic Tool DSI 2 Description The Dipole Shear Sonic DSI 2 tool combines high speed 13 ft telemetry with simultaneous 12 bit dynamic range digitization of an eight 18 receiver array The sonde incorporates Receiver section both monopole and in crossed dipole transmitters with oe r 4 eight station array of EE 11 ft to Cartridge to dus upper dipole electronically 35ft joint monopole ud 4 transmitter configurable 115 ft to lower dip
173. led with fluids containing potassium chloride to inhibit the swelling of re hydrated clays The next step is determined by the type of bottom hole assembly BHA used If the APC XCB BHA and core barrel assembly is deployed logging can commence directly through the bit with the use of a go devil and the lockable flapper valve LFV If the RCB BHA and core barrel are deployed the drill bit must be removed using one of three methods listed below 1 The drill bit may be dropped at the bottom of the hole if hole deepening will not occur 2 The drill bit may be dropped at the seafloor but a reentry cone or Free Fall Funnel FFF is required to reenter the hole 3 A pipe trip may be used to remove the bit at the rig floor and the hole reentered assuming a reentry cone or FFF is deployed Next the base of drill pipe is placed at a depth of 50 80m below the sea floor to provide confining pressure to the upper regions of the hole and to prevent the pipe from pulling out of the hole Once the pipe is set the rig floor is converted from drilling operations to logging operations To prepare the rig floor for logging the top drive is pushed back and the wireline is threaded through the derrick winch and wireline heave compensator WHC The first logging string typically the Triple Combo is now prepared for rig up The tools are assembled from the bottom up therefore the DIT E is rigged up first then the Lamont TAP tool is attac
174. litude modulation in both the data and the inferred forcing are necessary to evaluate the validity of the timescale Shackleton et al 1995 re Cruise INDEX OF TOPICS GLOSSARY ACRONYMS HOME ual Porosity Compensated Neutron Log Description In the Dual Porosity Compensated Neutron log CNT G a radioactive source mounted on the sonde emits fast neutrons which are scattered and slowed down by collisions with the nuclei in the formation Whenever they reach the thermal energy level they are captured by the nuclei of atoms such as hydrogen chlorine and silicon and gamma rays of ource 16 curie AmBe capture are emitted Two pairs of detectors measure Epithermal both epithermal Detectors intermediate and thermal slow neutrons The epithermal detectors are spaced closer to the source 4 than the thermal detectors in order to maintain a good statistical precision in the count rates A new data processing method utilizing the individual count rates rather than their ratios is used to derive porosity This technique minimizes the environmental effects on the response of the epithermal detectors due to their closer spacing from the source and provides better porosity measurements in shaly formations Thermal Detectors The depth of penetration of the neutrons is inversely related to the porosity of the formation but also depends on the source detector spacing In general we can say that
175. log in API units A full display of the Natural Gamma Spectroscopy data with SGR total gamma ray in CPS CGR computed gamma ray SGR minus Uranium component in CPS and THOR in ppm URAN in ppm and POTA in wet wt is usually provided separately Specifications Tool weight 2000 Ib 907 kg Tool length with savers 22 ft 6 7 m Min Max temp 13 300 F 25 150 C F 63 000 000 L Ibm where L is the Maximum weight on bit B 5 distance between stabilizers in feet Maximum flow rate 600 gal min Maximum operating pressure 18 000 psi 12 4 kPa Available collar sizes 6 75 in 8 25 in Available stabilizers 8 50 in 9 75 in Output GR Gamma Ray API Units SGR Total Gamma Ray API units CGR Computed Gamma Ray API units POTA Potassium wet wt THOR Thorium ppm URAN Uranium ppm ATR Attenuation Resistivity deep ohm m PSR Phase Shift Resistivity shallow ohm m GTIM CDR Gamma Ray Time after Bit sec RTIM CDR Resistivity Time after Bit hr Deployment Notes Along with the LWD collars additional equipment such as jars must be included Responsibility for providing this equipment is discussed at the pre cruise meeting LWD deployment illustration LWD deployment photo trademark of Schlumberger Triple Combo FMS Sonic Specialt Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME Logging While Drilling Isonic Tool LWD Isonic Descr
176. logging speed This approach increases vertical resolution by a factor of 3 4 over conventional Schlumberger tools used in the ODP e g the NGT while preserving comparable counting efficiency and spectral resolution The radius of investigation depends on several factors hole size mud density formation bulk density denser formations display a slightly lower radioactivity and the energy of the gamma rays a higher energy gamma ray can reach the detector from deeper in the formation The tool also includes an accelerometer channel to improve data stacking by the precise measurement of logging speed A specialized telemetry system developed for the MGT allows it to be combined with Schlumberger toolstrings in a single logging operation minimizing the required rig time to acquire the log Applications Spectral gamma ray logs provide one of the best means to investigate the mineralogy of thin bedded sedimentary sequences to correlate among different logging runs and to compare logging data and core measurements Increasing vertical resolution over currently available tools provides new opportunities for log analysis in reservoirs with rapidly changing lithology and for finer resolution of thin layering and in areas with low sedimentation rates The added resolution provided by the MGT will be of particular use in paleoclimate studies Environmental Effects The MGT response is affected by borehole size mud weight and by the pres
177. loped by investigators at other institutions involved with ODP and are reviewed by the JOIDES Scientific Committee SCICOM and the Scientific Measurements Panel SCIMP for deployment on the JOIDES Resolution ODP Logging Services provides support to third party investigators in the areas of data acquisition systems and software tool design and manufacturing assistance and tool testing Recently successful deployments of the Lamont Shear Sonic tool SST and the WHOI Vertical Seismic Profile tool have been completed The need for custom designed surface instrumentation acquisition systems and specialized power supplies has been addressed through the development of a multipurpose data acquisition system installed in the Downhole Measurements Lab DHML This system offers numerous benefits including a standard computer platform from which to launch acquisition software several power supplies and a work space in the acquisition area devoted to third party equipment Data telemetry software currently available includes modules utilizing a Windows 3 11 LabView4 0 graphic environment for acquisition of the following data types Temperature Acoustic Depth and Heave Acceleration O Third party tool support also includes the design and production of a cablehead crossover that allows third party tools to connect to the Schlumberger cablehead via an inexpensive modified off the shelf connector Hardware components currently available
178. lumberger prints out detailed expanded scale log plots for use by shipboard scientists These images complement the regular page scale plots commonly used to define broad trends and general log units The fine scale resolution of the larger plots aids in detailed stratigraphic correlation with the core Schlumberger plots are particularly valuable to the shipboard sedimentologists stratigraphers and physical properties specialists who use them to help reconstruct the complete stratigraphic sequence of the cored material and estimate how much and what type of material is missing from the recovered section For example cyclic sequences with periodic or fining upward lithologies that are difficult to recover completely with coring can be well defined by the addition of the detailed log information In addition when a number of sites are logged in a given region these plots are useful for inter site correlation and can be used to map the lateral continuity of individual beds and units The Schlumberger log plots are produced by the Schlumberger engineer after completion of logging operations Each playback consists of three parts Header Logs and Trailer 1 Header The header includes information such as the hole location latitude and longitude water depth the interval drilled and logged type of drilling fluid etc which are all used later during processing The new Minimum Configuration MAXIS presentation also includes a sketch of t
179. lying noise filtering Transit times are converted to borehole radius information using the velocity of the ultrasonic signal in mud measured by the tool on the way down The images are oriented with inclinometry data from the combinable GPIT inclinometry tool and then enhanced by dynamic normalization and displayed as an image for visual interpretation Amplitude and radius image data can be loaded on a geology workstation for analysis and interpretation Major events can be automatically extracted from the radius data for wellbore stability evaluation Applications e High resolution geological interpretation The high resolution of openhole borehole wall images with 360 coverage makes the UBI tool suitable for fracture evaluation even in oil base mud e Accurate shape analysis Borehole stability problems can lead to stuck pipe lost time and even the loss of equipment or part of the well resulting in added drilling costs The UBI radius and the cross section analysis accurately report the shape of the borehole enabling a clear and detailed analysis of the problem e Mechanical properties evaluation The UBI tool indications of stress anisotropy and orientation characterize borehole deformations such as breakouts for predicting perforation stability in unconsolidated formations Shear sliding along a fracture or bedding plane can be detected with UBI radius measurements and cross section plots providing strong evidence of potential bore
180. mal polarity and negative for reversed polarity this forms the basis of the Correlation Analysis method for determining polarities In some cases such as this one the polarity is also given by the sign of the remanent anomaly 400 mbsf 100 xy 2 1 Qe A 404 Pa 50 hc Normal polarity 404 407 y Gradient 1 63 0 93 m gt t8 30 4 7 50 60 70 80 90 Induced Anomaly B nT calculated from susceptibility a 9 re e Reversed polarity 410 413 mbsf Gradient 2 51 0 99 100 SNL m c 1 NNR SK p B 2 WA 150 413 9 Comparison of magnetic polarity from GHMT logs and core paleomagnetism Hole 1096C Leg 178 Antarctic Peninsula Remanent Anomaly nT Correlation Remanent Core paleomag Polarity Timescale from total magnetic field Analyses Anomaly nT Inclination Kent 1995 gradient 200 150 150 360 380 2 4 gt Gauss Gilbert 420 I A E 440 a T 469 480 500 520 can in 200 O 200 Induced Anomaly nT susceptibility Polarity Black normal polarity Green reversed polarity Splicer version 20 A point chosen toink B4 to 4 Independent depth scale yellow Tying Hole B to Hole A Splicer version 20 Tying in the hole
181. mation water and the drilling fluid the clay content the bed thickness invasion and bed boundary effects etc In thick permeable clean nonshale formations the SP has the fairly constant sand line value which will change if the salinity of the formation water changes In sands containing disseminated clay shale the SP will not reach the sand line and a pseudostatic SP value will be recorded The SP is positive with respect to the shale base line in sands filled with fluids fresher than the borehole fluid 2 The DC or slowly varying natural ground voltage observed between nearby nonpolarizing electrodes in field surveying In many mineralized areas this is caused by electrochemical at the electrically conducting sulfide body Stand A 30 meter segment of pipe made up of 3 10 meter pipe joints This is the usual increment for adding or removing pipe Stoneley wave 1 A type of seismic wave propagated along an interface 2 A surface wave in a borehole Synthetic Seismogram An artificial seismic reflection record manufactured from velocity log data by convolving the reflectivity function with a waveform which includes the effects of filtering by the Earth and recording system Used to compare with an actual seismogram to aid in identifying events or predicting how stratigraphic variation might affect a seismic record Often constructed from sonic log data alone although density data may also be incorporated Generally assumes plane interfa
182. me is consumed in the freeing of the tool Pipe is simply added at the rig floor to bring the end of the drill string to the top of the stuck tool The circulating head is installed and the drill string is washed over the logging tool to free it Care must be exercised to avoid putting too much tension on the cable if the tool does not enter the pipe easily This can be tricky if there is any amount of vessel heave involved Normally it is prudent to start the tool into the pipe and then hold the pipe stationary and try to work the tool loose with the winch That minimizes chances of damaging the tool or pulling out the weak point as the drill string is lowered past bow springs retractable arms etc Situation 2 is to be avoided if possible but if the weak point has failed in the open hole an open hole fishing job is required Depending on the circumstances a wireline fishing job may be attempted before the more drastic round trip reentry step is taken In one case an expensive logging tool was recovered by washing over the tool with the bit release top connector and then engaging the fishing neck of the tool with a Larson slip type core catcher There are risks of damaging the logging tool by applying too much string weight deforming the fishing neck jeopardizing subsequent fishing attempts or bypassing the tool with the BHA and pushing it into the side of the hole The conformation of the lower end of a bit release top connector
183. mmediately but needs a fair amount of work to get off sometimes it refuses to release and we either cannot log or have to wash a new hole for logging Induction log An electrical conductivity resistivity well log based on electromagnetic induction principles A high frequency alternating current of constant intensity induces current flow in the formation This Foucault current flowing in the formation ground loop causes an alternating magnetic field which produces a current in a receiving coil The receiving coil current is nearly proportional to the conductivity of the formation Induction sondes may have several transmitting and receiving coils to produce a highly focused log An induction log can be recorded where the borehole fluid is conductive or nonconductive as in oil base muds gas A dual induction log measures different depths of penetration Interval transit time The travel time of a compressional sonic seismic wave over a unit distance hence proportional to the reciprocal of P wave velocity Measured in the sonic log usually in microseconds per foot Invaded zone The portion about a wellbore into which drilling fluid has penetrated displacing some of the formation fluids Invasion takes place in porous permeable zones because the pressure of the mud is kept greater than that of the formation fluids A mud cake builds on the formation wall limiting further flow of mud fluid filtrate into the formation Directly behind t
184. n for example the FMS can electrically image sub cm scale features Logging tools are generally designed to measure formation properties some distance into the formation in order to minimize the effects of variable borehole diameter and roughness Logs also provide the major link between borehole and seismic section sonic velocity logs and checkshots improve depth to travel time conversion and synthetic seismograms may be compared directly to the seismic section While downhole logs are complementary to core measurements they also offer certain advantages In a hole where there is only limited core recovery the depth location of the incomplete cores can be uncertain logs provide a continuous depth record of formation properties Where there is preferential recovery of a certain rock type for example basalt pillows can be more easily recovered than breccia the logs can reveal a more realistic stratigraphy The in situ nature of the downhole measurements 1 in contrast to measurements on recovered core when material is no longer under the high pressure conditions that exist at depth it can physically expand and gas hydrates can dissociate The core may also be degraded by the coring process rotary coring can grind up sediment resulting in biscuits of coherent sediment in a ground up matrix Readers interested in an in depth introduction to the role of downhole measurements in marine geology and geophysics with examples are invi
185. n MAXIS MCM system Downhole Measurements Lab DHML The logger s scientific domain aboard the JOIDES Resolution is the Downhole Measurement Lab DHML Located atop the lab stack the DHML contains two Mac Computers one PC for data acquisition one Sun Ultra Sparc and Laserjet printer The third party data acquisition system 1s housed in the DHML as well as additional rack space for other equipment deployments Hand tools and supplies are furnished by LDEO BRG Conical Sidewall Entry Sub CSES The CSES was tested successfully on Leg AMET Lour nt 108 When inserted into the drill string it allows one to add or remove drill pipe while a logging tool is downhole The CSES strategy is to lower pipe to near the bottom of the hole lower the logging tool into open hole just beneath the pipe then log up while simultaneously pulling pipe at the same speed In this way open hole logs are obtained without allowing enough time between pipe removal and logging for bridges to form Drill String Acceleration Tool Core Barrel Temperature Tool The Drill String Acceleration tool DSA is a modular downhole tool designed to acquire data near the bit in memory The DSA is attached to virtually any core where it measures drillbit acceleration and vibration signals while drilling The DSA tool contains a single axis high sensitivity accelerometer for heave measurements a three axial high frequency acceler
186. n academia and industry have steadily improved the accuracy and sophis lication of geophysical and geochemical logging mea surements Most downhole experiments use technology developed by industry a small vet significant number use technologies developed for scientific research The recent history of advances in all of these technologies parallels advances in data transmission and computer capabilities which have led to remarkable Increase in en ee oo a m m ah Cable telemetry BO KEita aec Bi Digital iuisenetry 88 Kbits mez INDEX OF TOPICS GLOSSARY ACRONYMS 35 3 REVIEWS OF GEOPHYSICS mmm Dp 00 Se Figure 3 Telemetry rates for common wireline teols showing the steady increase in data rates over the past Z5 years after Prensky 1994 data from Schlumberger See Table 1 for bisa af abbreviations 18525 of a number of commercial instruments over the past 10 years Advances in acquiring scientific data for marine geology and geophysics have followed closely from these new technological developments Prensky 1994 provides an excellent summary of cur rent downhole technologies Deverom 1986 Serra 1987 Ellis 1987 and the Borehole Research Group 1990 among others have summarized the principles of downhole measurements and the interpretation of log ging data in scientific applications The interested reader is referred to these publications for a more detailed
187. n be run into open hole to attempt to engage the fishing neck More pull can then be exerted with the coring line than with the logging line If the CSES is installed the situation is serious With the current equipment and techniques it would be necessary to pull on the cable until the weak point fails pull the logging line until the torpedo connection reaches the CSES packoff and then drop the Kinley cutter and cut the logging line at the SES The drill pipe severing tool could then be lowered as far as the logging line inside the pipe would permit to salvage as much drill pipe as possible The logging tool would be lost Note that this is the case even if the logging tool is not stuck but the pipe is The weak point simply does not enter into the operation as there is no way to pull on it Back to i Stuck Lost Tools Data Loggin Stuck Lost Shipboard Acquisition Operations Tool Policy Reports INDEX OF TOPICS GLOSSARY ACRONYMS HOME Dangerous Logging Situations Tool trapped between two closely spaced 30m bridges If the troolstring breaks through one bridge and then encounters another one less than about 30m beyond the first cavings will accumulate between the two bridges while it is trying to get through the second bridge The cavings can fill up the short interval between the two bridges Then it is extremely difficult to even pull up again through the upper bridge because there is nowhere to displace the cavings
188. n that downhole data are irreplace able assets in marine geology and geophysics planning and use of downhole experiments in the future should expand both while drilling and in existing holes The scientific legacy of new downhole data will undoubtedly continue to advance marine science several disci plines BACKGROUND During the previous decade downhole measurements have become viewed as essential and complementary to measurements made on recovered core They are critical for measurements such as temperature that must be mace in situ The scientific objectives at most study sites are addressed with a multidisciplinary strategy imtegrat ing measurements made core samples with those made downhole and placing both in the context of te gional geophysical and seismic studies Worthington et al 1991 summarize this multiscale approach to drilling investigations and suggest that data integration will be the hallmark of the gecsciences in the 1994 Figure 1 shows their illustration of the range of experimental scales of investigation used today The multiple scales of investigation used with seismic downhole and core data acquired in the same geological environment comple ment cach other extremely well Seismic sections are the basis for a regional description downhole measurements are of an intermediate scale and give continuous infor mation in the region surrounding the borehole and core samples provide detailed informat
189. nium standard deviation ppm Uranium standard deviation ppm Variable CaCO4 CaO calcium carbonate oxide factor INDEX OF TOPICS GLOSSARY ACRONYMS GLOSSARY ABCDEFGHIJKLM A Acoustic log A generic term for well logs which display any of several aspects of acoustic wave propagation In some acoustic logs sonic log continuous velocity log the travel time of the compressional wave between two points is measured In others amplitude log the amplitude of part of the wave train is measured Other acoustic logs character log three D log VDL log microseismogram log signature log display part of the wave train in wiggle or variable density form Still others cement bond log fracture log are characterized by the objective of measurements rather than their form The borehole televiewer is also an acoustic log Acoustic wave 1 Sonic wave An elastic wave train sometimes restricted to propagation through a fluid 2 The wave train generated and detected by a sonic logging sonde The wave train is a composite of various modes of energy transfer The first arrival usually results from compressional P or longitudinal waves traveling in the formation the inverse of its velocity is measured by the sonic log A second arrival is sometimes identified as shear S wave travel in the formation it represents a pseudo Rayleigh wave which travels at approximately the velocity of S waves Compressional waves traveling through
190. noise by comparing and averaging counts at a certain depth with counts sampled just before and after The final outputs are the total gamma ray a uranium free gamma ray measurement and the concentrations of potassium thorium and uranium The radius of investigation depends on several factors hole size mud density formation bulk density denser formations display a slightly lower radioactivity and the energy of the gamma rays a higher energy gamma ray can reach the detector from deeper in the formation Only the high energy gamma rays are used in the analysis thereby eliminating sensitivity to mud barite content The MAXIS system provides real time corrections for borehole size and the borehole potassium contribution Applications e Clay typing Potassium and thorium are the primary radioactive elements present in clays because the result is sometimes ambiguous it can help combining these curves or the ratios of the radioactive elements with the photoelectric effect from the lithodensity tool e Mineralogy Carbonates usually display a low gamma ray signature an increase of potassium can be related to an algal origin or to the presence of glauconite while the presence of uranium is often associated with organic matter e Ash layer detection Thorium is frequently found in ash layers The ratio of Th U can also help detect these ash layers Additional applications of gamma ray logs Environmental Effects The HNGS resp
191. ns policy html Post Cruise Data On line Log Data Meetings Distribution Data CD ROM INDEX OF TOPICS GLOSSARY ACRONYMS HOME On line Data Over the last four years ODP Logging Services has undertaken a major effort to create an easily accessible on line database of the log data collected by the Ocean Drilling Program Currently the ODP Log Database contains the majority of the log data collected by ODP and in the future will provide access to all ODP log data It can be accessed and searched through the internet providing a convenient method for downloading large amounts of data as well as educational and technical information about the applications of log data to scientific problems The ODP Log Database can be accessed at http www ldeo columbia edu BRG ODP DATABASE The ODP Log Database provides access to log data 24 hours a day 7 days a week from any computer in the world Using the database a user has the ability to search by leg hole location ocean sea or tool en ree 24 O DATA SEARCH The Data Search screen on the The Search Results screen Data ODP Logging Services web site are organized by hole number A keyword search will soon be available as well This feature will greatly enhance the search capability of the database For example scientists will be able to search for all holes where basement was penetrated or search for all the holes where fluid processes w
192. nsibilities Logging Staff Scientist e Schlumberger data acquisition supervision and quality control e Specialty tool data acquisition and processing e Data reformatting e Systems management e Downhole Measurements Lab supervision Shared between Logging Staff Scientist and JOIDES Logger e Daily sampling shift Authorship of Initial Reports chapters and Scientific Results data scientific report Seismic interpretation linked to core and log data Detailed interpretation of specialty logs Quantitative mineralogy from logs and its interpretation Interaction with physical properties scientists sedimentologists and seismic stratigraphers Qualitative interpretation of lithologic units Qualitative interpretation of specialty tool data Comparison of log and laboratory measurements Inter site correlation via logs Generation of synthetic seismograms ODP Logging Selecting Estimating Pre Cruise Staff Scientist Toolstrings Log Times Meeting Capture 5 Cross usec ft usec ft Section SILICATES Quartz SiO 2 64 56 88 1 8 4 8 4 3 SiO HO 1209 ue 5 0 Garnet Fe3Al Si04 3 4 31 11 48 45 3 20 438 815 60 19 18 1518055 gt CARBONATES Calcite 2 1 49 88 4 5 1 13 8 Dolomite CaCO4MgCO 2 85 44 72 3 1 9 Siderite FeCO 3 89 47 15 57 52 OXIDATES Hematite 5 18 42 9 79 3 21 111 101 Magnetite Fe304 5 08 73 22 113 103 FELDSPARS
193. ntroduction Logging times are calculated by the Logging Staff Scientist prior to her initial contact with the Co Chief Scientists and are revised if necessary before the pre cruise meeting At the meeting the Logging Staff Scientist will discuss the logging plan and logging time estimates with the Co Chiefs TAMU Staff Scientist and other cruise participants as part of the leg planning process The logging time estimates together with time estimates for drilling transit and other operations are commonly published in the leg scientific prospectus which is distributed among the leg participants and is also available on the prospectus page of the Science Operator web site During the cruise the Logging Staff Scientist will continuously monitor and modify logging time estimates Drilling and logging plans are commonly altered during the course of the leg in order to accommodate changes in the original plan due to unforeseen hole conditions or the dynamics of the scientific drilling process The purpose of this document is to provide shipboard scientists with the basic information the Logging Staff Scientist incorporates in the course of preparing logging time estimates Logging Time Calculation Logging time depends on several variables such as water depth length of logged interval logging speed and type and number of tool strings used Logging speed is an important variable because it may affect logging data quality Slower logging sp
194. nts made during the leg Any site for which logging operations are conducted requires a chapter on downhole measurements In this section the Logging Scientist will 1 Present the operational details for the site If more than one toolstring is run then the operations will be summarized in a table organized by toolstring with the following information start and stop time logging speed pipe depth mudline measured depth interval logged for each pass and the tools on the string The text will also contain general information about the site such as total penetration core recovery muds that were circulated etc Finally the conditions of the hole during logging will be discussed as well as any obstacles or difficulties encountered which affect data quality 2 Present the results of the logging This section is usually similar to the data results of a paper in which log data are presented in plot form and the pertinent features described The presentation of results will be tailored to the science of the leg and integrated as much as possible with the results from other groups physical properties sedimentology biostratigraphy magnetics geochemistry etc Frequently a summary figure containing all of the log curves caliper curve stratigraphy sedimentology etc is presented This is then followed by a breakdown of each of the records describing them in the context of the other data including plots where necessary 3 Discuss the d
195. odes The DSI 2 tool has several data acquisition operating modes any of which may be combined to acquire digitized waveforms over each 6 in logging interval For waveforms eight channels are digitized simultaneously with a 12 bit dynamic range 1 Upper and lower dipole modes Eight dipole waveforms from firings of either of the dipole transmitters 40 sec per sample 512 samples waveform 2 Crossed dipole mode Standard acquisition of 32 total waveforms in line and cross line from both transmitters 3 Stoneley mode Eight monopole waveforms from firings of the monopole transmitter driven with a low frequency pulse 40 sec per sample 512 samples wave form 4 P and S mode Eight monopole waveforms from firings of the monopole transmitter driven with a high frequency pulse 10 sec per sample 512 samples waveform 5 First motion mode Eight sets of monopole threshold crossing data from firings of the monopole transmitter driven with a high frequency pulse primarily for compressional first arrival applications Features New fast tool bus and data reduction techniques have allowed double the maximum logging speed most instances A switchable power regulator has enabled a one third reduction in power needs resulting in broader combinability with other tools Additional human interface engineering has improved field acquisition quality and efficiency A new low frequency transmitter driver improves sign
196. ole hydrophones for transmitter monopole and dipole idee reception The MAXIS Transmitter section wellsite unit acquires and processes these data The DSI 2 tool combines new dipole based technology with the latest monopole developments into one system providing the best method available today for obtaining borehole compressional shear and Stoneley slownesses Slowness is the reciprocal of velocity and corresponds to the interval transit time measured by standard sonic tools Dipole technology allows borehole shear measurements to be made in soft rock as well as hard rock formations Limited by borehole physics monopole tools can detect only shear velocities that are faster than the borehole fluid velocity or in hard rocks only Dipole tools overcome this fluid velocity barrier The DSI 2 is a multireceiver tool with a linear array of eight receiver stations a monopole transmitter and two dipole transmitters The receiver array provides more spatial samples of the propagating wavefield for full waveform analysis The arrangement of the transmitters and receivers allows measurement of wave components propagating deeper into the formation The DSI 2 tool is distinguished from the DSI by an upgraded receiver section The upgrade improves the shear measurements in slow formations The unimproved DSI is no longer available on board the JOIDES Resolution The DSI 2 can be combined with most ODP tools Tool Operation M
197. ole Size 21 in 53 3 cm Tool Length 51 ft 15 5 m Maximum Logging Speed One eight waveform set 3600 ft hr single mode All six modes simultaneously without 6 in delta t LOOO tuli All six modes simultaneously with 6 in delta t Digitizer Precision 12 bits Digitizer Sampling Interval Limits Ween per sample Digitized Waveform Duration Up to 15 000 samples all Limits waveforms Acoustic Bandwidth Dipole and Stoneley 80 Hz to 5 kHz High frequency Monopole 8 to 30 kHz MAXIS tools any resistivity tool Deployment Notes Stuck lost tool information trademark of Schlumberger Triple Combo Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME Geological High Resolution Magnetic Tool GHMT Description i igh i Geological High Resolution 4 Magnetic Tool GHMT 10 81m TCC BF TET Telemetry Cartridge provides magnetic susceptibility B Bam and total magnetic induction Defector Beim Haua Gamma Tool measurements The main use of the GHMT is to provide a magnetic reversal sequence in 73m GHMT Nuclear Porsi sediment The GHMT consists of two SUMS sedicn sondes The Susceptibility Measurement Sonde SUMS makes an induction type measurement to record a signal NMRS section related to formation susceptibility Its depth of investigation and vertical resolution are about
198. ole conditions such as pressure salinity drilling mud filter cake etc The effects of these environmental conditions on the data may be eliminated post cruise though environmental correction software Extended Core Barrel XCB A thin bit which extends beyond the normal bit for high core recovery when sediments are too firm for use of the advanced piston corer Flowmeter A device that measures the flow of fluid in the borehole casing at specified depth intervals Sometimes the flowmeter is lowered through the flow stream in a borehole and sometimes it is set in one spot with a packer G Gamma ray log A well log which records the natural radioactivity 1 In sediments the log mainly reflects shale content because minerals containing radioactive isotopes the most common of which is potassium tend to concentrate in clays and shales Volcanic ash granite wash and some salt deposits also give significant gamma ray readings The log often functions as a substitute for the SP for correlation purposes in cased holes in conductive muds in open holes and for thick carbonate intervals H Hydraulic Bit Release HBR Equipment inserted next to the bit while making up putting together an RCB bottom hole assembly to permit dropping the bit for logging A go devil is sent down the pipe to release bit latches and seal the bit opening then the bit is pumped off by applying hydraulic pressure The HBR usually does not release i
199. olstrings are interactively matched to it The depth shift applied to each SGR curve is propagated to all other logs acquired by that toolstring Gamma ray data can also be used for core log integration by correlating the natural gamma results from the whole core multisensor track WC MST with the HSGR and SGR curves Furthermore because the gamma ray log responds principally to fluctuations in the formation s mineralogy rather than physical properties such as lithification it is particularly useful for making regional inter hole comparisons between major lithostratigraphic units Figure 1 HOLE 11710 HOLE 11684 HOLE 11720 shalhew waier alimclastics ores ree eee x mo orm ie ISOR ODP Leg 189 TET Figure 1 Regional correlation of major lithostratigraphic units using total gamma ray data from Leg 189 Identification of lithology facies and depositional environment Naturally radioactive elements tend to have a far greater concentration in shales than in other sedimentary lithologies and therefore the total gamma ray log and in particular the corrected gamma ray log HCGR and CGR and the Th log are frequently used to derive a shale volume see Ellis 1987 and Rider 1996 In addition the shape of the gamma log curve may be used to reconstruct downhole fluctuations in grain size and infer changes in sedimentary facies the standard approach
200. ometer for drillbit vibrations and a high resolution pressure sensor For ease of deployment the DSA has been designed as a removeable extension of the APC XCB RCB core barrels Using standard threaded connections the DSA will be attached to the top of a selected core barrel by a Core Tech prior to core barrel deployment Except for the connection and disconnection of the DSA coring activities will not be affected by the presence of the DSA Upon DSA core barrel retrieval the DSA will be disconnected and the data downloaded to the third party data acquisition system in the DHML for immediate analysis The modular design of the DSA allows for customization of the sensor packages The acceleration and pressure measurements may be swapped for high fluid temperature measuring equipment In the high temperature fluid temperature monitoring mode the tool name changes to the Core Barrel Temperature Tool CBTT Many additional measurement possibilities exist but have not been designed and implemented do date Other Equipment Continued Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX TOPICS GLOSSARY ACRONYMS HOME Other Equipment cont Miscellaneous Winch The winch is located at the aft end of the pipe racker and 15 controlled by either the assistant driller AD or the core tech CT An intercom link is used between the MCM and winch during logging operations In contrast to most oilfield win
201. omputing synthetic seismograms for time depth ties of seismic reflectors Sonic waveforms analysis If a refracted shear arrival is present its velocity can be computed from the full waveforms and the frequency content and energy of both compressional and shear arrivals can also be determined Fracture porosity Variations in energy and frequency content are indicative of changes in fracture density porosity and in the material filling the pores In some cases compressional wave attenuation can also be computed from the full waveforms Environmental Effects One common problem is cycle skipping a low signal level such as that occurring in large holes and soft formations can cause the far detectors to trigger on the second or later arrivals causing the recorded dt to be too high This problem can also be related to the presence of fractures or gas Transit time stretching appears when the detection at the further detector occurs later because of a weak signal Finally noise peaks are caused by triggering of detectors by mechanically induced noise which causes the dt to be too low Reprocessing programs that can eliminate the aberrations described above are available both at sea and onshore Log Presentation DT and DTL are interval travel times in microseconds per foot for the near and far receiver pairs respectively In very slow formations DTL provides the more reliable measurement as the refracted wave is not seen at the n
202. on the phase velocity of the body wave in the formation As the shear t becomes large soft formations less shear energy is refracted back into the hole If the shear t surpasses the mud slowness typically 190 sec ft none of the shear waves will be detected by the receivers 2 Monopole Stoneley At low frequencies perhaps a few kHz where typical wavelengths in the mud are greater than the borehole size monopole signals are dominated by the Stoneley wave a dispersive mode of the borehole Stoneley waves are guided waves associated with the solid fluid boundary at the borehole wall and their amplitude decays exponentially away from the boundary in both the fluid and formation At extremely low frequencies the slowness of this mode approaches that of the tube wave while at higher frequencies it approaches that of the Scholte planar interface wave It is most easily excited using a low frequency monopole source For all frequencies the Stoneley slowness is determined predominantly by the mud and to a lesser extent by the formation compressional and shear slownesses formation permeability and other variables 3 Dipole shear In a dipole shear sonic tool a directional dipole source and directional receivers are employed The source is operated at low frequencies usually below 4 kHz Compressional and shear waves are excited along with a dispersive flexural mode of the borehole The slowness of this mode has the same high fre
203. onductivity Resistivity logs Well logs which depend on electrical resistivity normal lateral laterolog and induction log Most resistivity logs derive their readings from 10 to 100 ft of material about the sonde Microresistivity logs on the other hand derive their readings from a few cubic inches of material near the borehole wall Rigup RU To assemble a toolstring or piece of equipment in preparation for deployment Rigdown RD To disassemble a toolstring following deployment ROP Rate of penetration Run Into Hole The opposite of POOH 5 Schlumberger Workshop room on JOIDES Resolution immediately beneath the logging winch containing Schlumberger supplies and the ozalid machine for paper copies of logs Scintillation Counter An instrument for measuring radioactive radiation especially from gamma rays Gamma radiation impinging on a sensitive phosphor causes it to emit light scintillations which is measured by a photo multiplier tube Secondary porosity Porosity resulting from the alteration of the formation such as by fractures vugs solution channels dolomitization etc Seismic Source The sound source used for the collection of seismic reflection data In the early days of seismic exploration of watered covered areas the source was always a form of unconfined explosion However an unacceptable level of environmental damage resulted from this method and it was soon clear that there was a pressing need to
204. onic travel times are picked from the waveform data acquired by the DSI 2 and LSS sonic tools these picks are used in the conventional log processing It is anticipated that the waveform data from the DSI 2 sonic tool can be reprocessed after the leg using newly acquired GeoFrame waveform processing modules to derive compressional shear and Stonely wave velocities and seismic anisotropy data WST checkshot and VSP data WST data both individual shot records and the stacks for each station are archived in DLIS format First arrival times are picked on the ship and are not generally re picked onshore Where there are enough stations for a vertical seismic profile a corridor stack can be produced and compared to the synthetic seismogram and seismic section Other data Processing of data from tools that are used or have been used only occasionally Geochemical tool GLT Borehole televiewer BHTV Azimuthal Resistivity Imager third party logging tools etc is determined on a per leg basis and may be outsourced Data Processing Log Core Log Integration Log Seismic Overview Processing Splicer amp Sagan Integration IESX INDEX OF TOPICS GLOSSARY ACRONYMS HOME Core Log Integration Splicer amp Sagan Introduction The Core Log Integration Platform CLIP software provides the ODP community with a set of graphic interactive data analysis products for depth merging and integrating cor
205. onse is affected by borehole size mud weight and by the presence of bentonite or KCI in the mud In ODP boreholes KCl is sometimes added to the mud to stabilize freshwater clays which tend to swell and form bridges This procedure takes place before logging operations start and even though is probably diluted by the time the tool reaches total depth it can still affect the tool response All of these effects are accounted for during the processing of the HNGS data onshore Log Presentation The HNGS log is routinely recorded with each logging string for correlation between logging runs To this purpose HSGR total gamma ray in API units and HCGR computed gamma ray HSGR minus Uranium component in API units are usually displayed along with other curves resistivity sonic density etc A full display of the data with HSGR HCGR and HTHO in ppm HURA in ppm and HFK dec fraction is usually provided separately Output plot of HNGS data combined with DIT E and TLT data Specifications Temperature Rating 260 500 F Pressure Rating 25 kpsi Tool Diameter 3 75 Tool Length 8 5 ft Sampling Interval 6 in Max Logging Speed 3600 ft hr Accuracy Thorium 2 Accuracy Uranium 2 Accuracy Potassium 5 Output HSGR Standard total Gamma Ray GAPI HCGR Computed Gamma Ray GAPI HFK Formation Potassium dec fraction HTHO Formation Thorium ppm HURA Uranium ppm HBHK Borehole Potass
206. ontinuous logs so that preferential recovery of particular rock types be documented In Figure 2 nonrepresentative section of interlayered basalt and sediment near the Juan de Fuca ridge in the northeastern Pacific would have been inter preted from the recovered core alone but the continu ous log profiles reveal layers of sediment between basal that were not recovered through coring Despite such successes complete recovery of continuous log profiles is still mot possible With current wireline technology the interval immediately below the seafloor is not logged because the drill pipe must be lowered 80 100 m to ensure hole stability in the softest sediments for logging to begin To benefit from core log correlation the strati graphic interpretation from logs is limited to below this depth and only where high quality data are recorded Downhole Measurements Logging In 1927 C and M Schlumberger made the first well log near Paris It was a simple electrical current experi ment that used an electrode placed at a series of hori zontal points on the ground to make measurements and nm mmus b um nit gt ohm m counta d 16 155 0 2 an a _ TTE on _8 How 8570 Figure 2 Logs of electrical resistivity and natural gamma radiation in a layere
207. p ELD Tool 99 Hole Core Core Log Auto Correlate vues To automatically correlate core Evaluate Core Log Data data to log depths use the autocorrelation tool Select Core Applies Susceptibility med d SUMT togimi adi Auto Pale Of Core Log Core data versus mcd and downhole log data before correlation Core Log Depth Matching _ Define Pretiminary Core Log Depth Matching Parameters Stretch Compress Core Data Between 9520 and 95 20 Zat Slide LogUp Down Between 7519 m and EAT RUNS 5 Correlation Depth Step 015 Select Hole s c n Yi invert Core Variable es Hole D Calculate Optimal SUSCEPTIBILITY SUMT Working hole B Core Log Depth Match Interupt LD Recommended Depth Matching Stretch Compress mbsimed Ratio 0 938 Log Offset m Undo Dismiss Help 0 0 Susceptibility mbsf mod odd SUMT A hole is chosen for correlating core data to the logs and the best overall correlation is calculated Continue gt File Display Process Help ELD Manually picking Mole Core a tie c 19 Select Cancel Core Clear Last Tie Saved Show List Tie Applies To Correlation Param Apply Tie s nd Auto Pair Off Susceptibility mbsf do SUMT log Manually tying the core data to the logs
208. pecialty tools such as vertical seismic profiling case inspection logs CORKS and others may require consultation with the scientists involved in order to accurately estimate the times Invariably real time decisions have to be made in response to changes in conditions uphole and downhole thus knowing how the condition changes affect the estimates is important In considering the time required for operations it is important to note that the Operations Superintendent assumes that hole preparation time including mud circulation wiper trip bit release and pulling pipe to logging depth is not included in the logger s estimate In this spreadsheet note that Logging Time is counted as the time between the positioning of the base of the bottom hole assembly at the logging depth and the time when tools and wireline are rigged down and the pipe can begin to be pulled out of the hole The spreadsheet has been continually updated It allows for easy calculation of the logging times for an individual hole as well as for input of different logging speeds retrieval speeds and the addition of repeat logging runs The input variables are outlined in Table 2 2 The user simply inputs the values for water depth pipe depth hole depth tool strings run and their respective logging speeds whether the is used or not whether the bit is released or not bit 15 released only when is used in drilling and the tool retrieve speed in pipe and the
209. penetrated basement of the Southwest Indian Ridge which between 50 400 mbsf can be subdivided into four distinct units see figure The geochemical data clearly delineate Unit 4 which is a Fe Ti oxide rich gabbro Generally low and uniform FeO and TiO values occur in Unit 5 which is a relatively uniform olivine gabbro Quantitative Mineralogy and lithology The oxide data in combination with data from other logs if appropriate can be inverted to estimate the proportions of the main minerals in the rock This information which can be displayed as mineralogical logs can often be used to derive other physical properties of the formation such as magnetic susceptibility or cation exchange capacity CEC Environmental Effects During data acquisition the signal to noise ratio of the gamma ray measurement can be affected by the following o Logging speed This is normally between 400 and 600 ft hr with measurements being made every six inches The slower the logging speed the greater the measurement precision Borehole fluids and porosity Due to the large capture cross section of chlorine and hydrogen more than half of the gamma ray spectrometry tool signal may come from the borehole fluid normally seawater This can adversely affect the measurement precision of the other element yields High porosity rocks can have a similar affect on precision and it is recommended that the GLT only be used in rocks with less than 40 poro
210. perature conditions When in a high temperature environment such as a hydrothermal ridge system careful attention is paid to the temperature channels on for example the DIT E It is important not to exceed the tool temperature ratings Circulating water in the hole immediately prior to logging will cool the hole for a period of time Some measurements are temperature dependent e g resistivity Technical Issues Logging tool limitations The logging operation is limited to downhole tools with a diameter of 3 75 inches or less All tools listed in the tool section of this document can be deployed in a standard bottom hole assembly BHA The absolute maximum tool diameter which can be run ina standard BHA is 3 81 inches but this is pushing the tolerances to unsafe limits To run tools up to 4 0 inches in diameter the BHA can be modified by removing the Kinley crimper landing sub This is strongly discouraged and formal approval would be necessary since this action would severely limit stuck tool recovery efforts Stuck lost tools This issue is discussed in more detail on the stuck lost tools page Needless to say every effort should be made to avoid getting any of the tools stuck in the hole The loggers are required to fish for any tool that is stuck or lost It is particularly undesirable to lose the HLDT as that tool contains a radioactive source losing it would require cementing of the hole a process that would take days and
211. perienced during coring Before logging the Logging Staff Scientist will confer with the Operations Superintendent and drillers about the general condition of the hole and whether there are any tight spots or likely washouts The Schlumberger Engineer the Operations Superintendent the Drilling Superintendent the drillers and the core techs all have a wealth of experience in dealing with adverse hole conditions and should be able to advise on specific matters such as how long to spend trying to break through bridges what the risk to tools might be how to retrieve stuck tools and so on Logging while drilling LWD tools may be assigned to legs where hole conditions are anticipated to be unsuitable for conventional logging Available LWD tools include the Azimuthal Density Neutron Tool ADN the Compensated Dual Resistivity Tool CDR and the Resistivity at the Bit RAB Tool In cases where real time acquisition of downhole data are required Measurement while drilling MWD tools may be utilized Time limited logging Although adequate time for logging is usually allocated in the leg prospectus it is not uncommon for unforeseen events bad weather difficult formations slowing the pace of coring etc to reduce the actual time available for the logging program at a given hole In this case the Logging Staff Scientist will discuss with the Co Chiefs the relative merits of allocating extra time to carry out the original
212. port Spacer rod Spring carrier spring Smalley retaining ring Dowel pin Hypertronics discrete contacts Dewar Electronics area Insulated stand off Battom sub Thermistor 2 a lt Natural Gamma Ray HNGS Click on tool name for further information Porosity APS Measurement Tool j dJ I o E O I o 2 aldu High Resolution Gamma Ray Fluid Temperature TAP Acoustic DSI 2 LSS Electrical Imaging F5 JUOS SINS Magnetic Field Susceptibility GHIMT Caliper HLDT HLDS FMS High Fluid Temperature HTT Acoustic Imaging UB te o E LE c E S 2 s o E MEET i o Ayeisads Logging While Drilling L V D ORBITAL PERIODIC GLOBAL LOCAL MINEROLOGY RESPO ean Wm Eccentricity 95 000 yrs Obliquity 41 000 yrs 23 000 yrs grain size 19 000 yrs wind patterns mineral type temperature upwelling Precession and abundance Site 1063 Natural Gamma Log high gamma values correspond to clay rich cold glacial periods 100 cyclicity 4OK cyclicity Clay rich colder glacial 50 100 150 200 250 300 depth mbsf Blackman Tuckey spectral analysis of the intervale before and after the Mid Obliqu
213. preadsheets 5 Prepare a logging template for the leg 6 Prepare a short presentation with overheads on the tools to be deployed and the respective time requirements Division of Responsibilities bewteen the Logging Staff Scientist and JOIDES Logger The other shipboard participant with whom the Logging Staff Scientist has extensive contact is the JOIDES Logging Scientist This position is selected by the co chiefs The person who is selected may or may not have had previous logging experience ODP Logging Services offers to provide pre cruise training to any JOIDES logger who wants it an invitation is issued by the Deputy Director of Operations The Logging Staff Scientist will contact the JOIDES Logger before the cruise to discussed planned operations shipboard responsibilities and post cruise research interests The division of responsibilities between the Logging Staff Scientist and JOIDES Logger is quite flexible and is usually worked out between the individuals involved on a leg by leg basis A general summary of the respective responsibilities is given below The rule of thumb is that the Logging Staff Scientist is responsible for data acquisition with both Schlumberger standard tools and specialty tools and preliminary processing Log interpretation responsibilities are shared between the Logging Staff Scientist and JOIDES Logger and should be divided in a mutually agreed upon manner Here is the typical division of respo
214. program cutting back on repeat runs or even forgoing a toolstring entirely The Triple Combo will still be run first but the others should be prioritized according to the leg objectives Bridged holes Some holes may contain constrictions bridges that slow the toolstring s descent into the hole The heavier toolstrings Triple Combo and FMS Sonic have a better chance of passing through a bridge than the lighter toolstrings GHMT WST therefore these are run first One cause of bridges is swelling clays this phenomenon can be combated by adding KCI to the drilling mud although this will degrade the natural gamma potassium log The capillary suction test equipment should be employed when swelling clays are suspected Blocked holes There are various options if the toolstring cannot penetrate beyond a certain depth in the hole If the blockage is near the base of the hole it is probably best to just log the open interval above the blockage If the blockage is midway down the hole several options exist 1 log only above the blockage 2 dismantle the logging cable and lower the BHA to tag the blockage then raise the BHA back to the original position or 3 tag the blockage and only log below it If the blockage is near the top of the hole it is likely that there will be similar blockages further down and the hole is unloggable but dismantling the wireline cable and re reaming the hole is always an option Wide holes Wide holes can
215. put can be copied and pasted into any spreadsheet program or plotted directly in Analyseries Example of spectral analysis figure Click to enlarge Tuning Once Milankovitch cycles have been positively identified in the logs the regular pacing of these records can be used to refine or tune the timescale by correlating the climate driven cycles to the astronomical forcing Such correlations are capable of producing much more accurate and highly resolved age models than are obtainable by other methods Furthermore with a high resolution timescale it becomes possible to make phase estimates for the relative responses of the different components of the climate system and to determine the rates of various geologic processes The SAGAN program designed to correlate core and downhole log records is also capable of automatically by maximizing coherence or manually by graphical selection of tie points correlating logs to insolation records In this way it is possible to generate a highly resolved age depth model for a well in a matter of minutes However any age model generated by tuning in this fashion should be considered tentative because although a high coherence is good for estimating the success of tuning it is not necessarily an indication of the degree of common amplitude modulation a basic test of whether the tuning is correct Instead other methods such as complex demodulation which assesses the relationship between amp
216. quency limit as the Stoneley wave but at low frequencies it approaches the formation shear slowness rather than the tube wave slowness The amplitudes of both the flexural and the shear wave are peaked in frequency the flexural generally peaking higher They fall off very rapidly toward low frequencies and more gradually toward high frequencies The flexural mode dominates the response down to very low frequencies where the shear wavelength is several times the borehole diameter At such low frequencies the direct shear wave is the only appreciable feature on the waveform However the amplitude of the waves at these frequencies below 1 kHz for a typical slow formation is very low and noise is likely to be a problem A practical frequency range is 1 4 kHz In this range the flexural mode dominates the signals but travels at nearly the shear slowness A continuous shear log then is obtained by measuring the flexural slowness at as low a frequency as is practical and applying a small correction In very fast formations the dipole compressional signal is usually very weak and may not be visible The flexural mode is very dispersive in fast formations there being as much as a factor of two difference in slowness between low frequencies shear slowness and high frequencies Scholte slowness approximately the mud slowness The flexural arrival is therefore quite long in duration and spreads rapidly as the transmitter receiver spacing is increas
217. r Processed Resistivity Spherically Focussed Resistivity Geologic Magnetic Tool Magnetic Susceptibility limited range Low Resolution Magnetic Susceptibility wider range Earth Conductivity Earth Total Magnetic Field Digital Sonic Tool Transit times 10 8 12 10 ft spacings Slowness 12 minus 10 ft travel times Slowness 10 minus 8 ft travel times trademark of Schlumberger gAPI gAPI ppm ppm fraction fraction c units inches g cm barns e inches g cm ohm m ohm m ohm m ppm ppm ppm nT usec usec usec INDEX OF TOPICS GLOSSARY ACRONYMS HOME Accelerator Porosity Sonde APS Description The APS sonde is the key module in the Triple Combo s IPL components The powerful bis unie m ED Perea ty electronic neutron source Heyn rauca 1 minitron allows epithermal neutron measurements and et es detector shielding resulting in Ti 5 porosity values that are less influenced by environmental conditions The near array ratio i epithermal porosity is the primary porosity measurement Its source to detector spacing 15 optimized to yield a formation hydrogen index measurement that is essentially free of formation matrix density effects Five detectors provide information for porosity gas detection shale evaluation improved vertical resolution and borehole correct
218. r the borehole than the FMS such as drilling induced fractures the origin and lateral extent of such features may be determined from the comparison of FMS and ARI images Applications Fractures The response of each of the 12 electrodes is strongly influenced by conductive fluid filled fractures and each log trace is affected by its position and orientation in relation to the fractures Deep fractures can be clearly identified and are differentiated from the shallow drilling induced cracks to which the tool is insensitive Formation heterogeneity Average resistivity can be strongly affected by formation heterogeneities In such cases the azimuthal images from the ARI tool help interpret the resistivity log Formation dip ARI images can give a good estimate of formation dip although they cannot provide dipmeter accuracy They may detect unexpected structural features such as unconformities and faults and they help confirm expected features Resistivity in dipping beds electrodes facing along the strike of the formation dip are barely affected by anistropy of the apparently dipping layers Selecting the readings from these electrodes gives a much more accurate resistivity in thin dipping formations Specifications Temperature Rating 350 F 175 Pressure Rating 20 kpsi 13 8 kPa Tool Diameter 3 625 in 9 21 cm Tool Length 33 2 ft 10 12 m Sampling Interval 6 in 15 24 cm Max Logging Speed 1800
219. rate at 16 5 cm Neutron sensors 12 84 m Meutron source Density source Density sensors 10 94 m which the neutrons slow down Gamma ray 5 89 to epithermal and thermal energies Neutrons are Transmitters detected in near and far O istivity spacing detectors and ratio receivers 2 71 processing is used for borehole compensation The energy of the detected neutrons has an Total Length epithermal component because yil Bit 16 24 a high percentage of the 25 cm incoming thermal neutron flux is absorbed as it passes through the 1 in 2 5 cm steel wall of the drill collar Also a wrap of cadmium under the detector banks shields them from thermal neutrons arriving from the inner mud channel This mainly epithermal detection practically eliminates adverse effects caused by thermal absorbers in the borehole or formation The density section of the tool uses 1 7 Ci 137 Cesium gamma ray source in conjunction with two gain stabilized scintillation detectors to provide a high quality borehole compensated density measurement The tool also measures the photoelectric effect Pe for lithology identification The density source and detectors are positioned behind a full gauge clamp on stabilizer which excludes mud from the path of the gamma rays greatly reducing borehole effect In deviated and horizontal wells the stabilizer may be run under gauge for directional dr
220. ration IESX INDEX OF TOPICS GLOSSARY ACRONYMS HOME Post Cruise Meetings The first post cruise meeting is usually held in College Station about three to six months after the leg is completed Prior to the meeting the Logging Staff Scientist reviews all text and figures generated for the ODP Initial Reports volume During the meeting the Logging Staff Scientist revises the text figures and tables as needed Corrections and additions are made to the IR Explanatory Notes and Site chapters in order to finalize these sections for publication All figures include depth shifted log plots and any additional processing performed immediately after the cruise The Co Chiefs and TAMU Staff Scientist will generally review the text and figures and discuss any potential changes with the Logging Staff Scientist i ls z Ri i x IE I i E a a 1 1 E ja F 1 H a T Ai 3 r 4 i t Mis 1 t AL 1 Typical IR figure of downhole logs Typical IR figure of FMS image and core recovery column with downhole logs The second post cruise meeting focuses on the preparation of the ODP Scientific Reports volume and the coordination of publishing strategies in other scientific journals During this meeting the ODP Logging Staff Scientist as well as the JOIDES Logging Scientist prepares a 10 15 minute presentation t
221. result in poor contact between the tool sensor and the borehole wall and hence degraded logs Affected tools are the HLDS and APS max caliper extension 18 the FMS max 16 and the WST max 18 The borehole width is measured by caliper during the first Triple Combo run Depending on the scientific objectives it is sometimes preferable to run the GHMT which is relatively insensitive to borehole width before the FMS Sonic High heave conditions The wireline heave compensator WHC reduces the effect of ship heave on tool motion but higher heave conditions lead to increased uncertainty in the downhole tool depth particularly if the heave is too great more than 6m for the WHC to be used Increased tool motion up down oscillation poses a risk to those tools with caliper arms e g the HLDT and FMS as there may be downward tool movement even when logging upwards higher logging speeds will help Additionally high heave makes the process of bringing the tools back into the pipe from the open hole after logging more difficult There is an increased risk of the wireline cable slipping on the cable reel when lowering the tools down though the pipe especially at the start of the descent because initially there is only a small weight to provide tension in the cable Tools must be lowered slowly adding to the logging time particularly in deep waters The risk of cable slip is worse with the lighter toolstrings GHMT WST High tem
222. rnal geometry The rotating cm transducer incorporated in the UBI sonde is both a transmitter and a receiver _ The transducer subassembly CINE is available in a variety of sizes for logging the Rotating shaft with complete range of normal builtin electronics openhole sizes The subassembly is also selected to optimize the distance traveled by the ultrasonic re Transducer sound pulse in the borehole Interchangeable fluid by reducing attenuation rotating sub in heavy fluids and maintaining a good signal to noise ratio For openhole gg 7 5 applications UBI tool is logged with the transducer operating at either 250 or 500 kHz The higher frequency has better image resolution but the lower frequency provides more robust measurement highly dispersive muds The UBI tool measures amplitude and transit time An innovative processing technique improves accuracy avoids cycle skips and reduces echo losses which makes the UBI transit time measurement as reliable as that of the amplitude The tool is relatively insensitive to eccentralization up to 1 4 in and yields images that are clean and easy to interpret even in highly deviated wells Processing software available both in MAXIS surface units and at Data Services Centers further enhances UBI images by correcting amplitude and transit time information for the effects of logging speed variations and tool eccentering and by app
223. rns e High Res Near Detector Count Rate cps High Resolution Enhanced Thermal Nutron Porosity 96 High Resolution Bulk Density g cm High Resolution Photoelectric Effect barns e High Resolution Bulk Density g cm3 High Res Corrected Bulk Density g cm HNGS Standard total Gamma Ray GAPI High Res Formation Capture Cross Section cu High Res Computed Standoff HNGS Thorium ppm High Resolution Thermal Neutron Porosity 96 HNGS Uranium ppm Phasor Deep Induction ohm m Iron Indicator Ratio CFE CCA 4CSTI Deep Resistivity ohm m Medium Resistivity ohm m Phasor Medium Induction ohm m HLDS Caliper in HLDS Density quality Indicator Lithology Indicator Ratio CSI CCA4CSTI Laterolog Deep ohm m Laterolog Shallow ohm m Transit Time 10 usec Transit Time 8 usec Transit Time 12 usec Transit Time 10 usec Earth s Magnetic Field nTes Earth Conductivity ppm Magnetic Susceptibility ppm MEDIAN MEAN NMST NMSV NPHI NRHB 1 7 PEF PEFL PIR POTA RB RHL RHOB RHOM RMGS SFLU SGR SIGF SP STOF SURT SXRT THOR TNRA TI TT2 TT3 TT4 URAN VP1 VP2 VPCO VPSH VPST Median Transit Time Recomputed usec ft Mean Transit Time Recomputed usec ft Magnetometer Temperature C Magnetometer Signal Level V Neutron Porosity LDS Bulk Density g cm Pad 1 Azimuth degrees Photoelectric Effect barns e LDS Long spaced Photoelectric Effect barns e
224. rofiles VSPs typically provide acoustic velocity and amplitude profiles with vertical resolution of 5 0 50 m Nuclear logging tools This class of instruments measures naturally occurring radioisotopes and mineral constituents of the formation as well as the fluid content in pore space They are sophisticated devices that rely on statistical counting of subatomic particles and advanced computer analysis for interpretation Three types of nu clear measurements are typically used in marine scien tific applications natural gamma activity gamma scattering amd neutron scattering Gamma ray activity tools are perhaps the most com mon nuclear measurement instruments and detect the radioactive decay of natural isotopes of potassium ura nium and thorium using a scintillation counter and a crystal detector The response of the detector is a simple function of the concentration by weight of the radioiso topes and the formation density The average depth of penetration of the measurement into the borehole wall is about 0 5 m and vertical resolution is approximately 0 3 m alien er al 1988 The natural gamma ray log usually responds to clay content in a formation where naturally radioactive elements concentrate or to alter ation minerals that have these minerals present within oxides and other compounds The concentration of the natural radioisotopes is therefore largely controlled by depositional environments and diagenesis
225. rsected by the borehole e Placing the borehole results in their proper setting with respect to the seismically defined structure of the oceanic crust and mantle e Correlating borehole lithology with the up going seismic reflected wavefield e Predicting structure and lithology changes below the drill hole e Estimating physical properties of rock on seismic scales by studying particle motion and downhole seismic attenuation In check shot mode the WST 3 data can be used to produce a depth traveltime tie and to calibrate the sonic logs and determine accurate drilling depths and their relative position with respect to targets on the seismic reflection profiles Log Presentation The WST 3 has not yet been run in the Ocean Drilling Program so no examples of data output are available yet It is scheduled for deployment during Leg 194 beginning January 2001 Data from the WST and WST 3 are similar in check shot mode however the WST 3 s offset VSP mode is quite different Updated information on the WST 3 will be posted to the ODP Logging Services web site as soon as it is available Specifications Mechanical Temperature Rating Pressure Rating Tool Diameter Tool Length Tool Weight Min Hole Diameter Max Hole Diameter Max Logging Speed Vertical Resolution Sensors Axis Geophone Geophone type Geophone frequency Damping 350 175 20 kpsi 13 8 kPa 3 625 in 9 21 cm
226. rst A Lovell M A amp Morton A C eds Geological Application of Wireline Logs Geological Society of London Special Publication No 48 211 222 Humphreys B amp Lott G K 1990 An investigation into nuclear log responses of North Sea Jurassic sandstones using mineralogical analysis n Hurst A Lovell M A amp Morton A C eds Geological Application of Wireline Logs Geological Society of London Special Publication No 48 223 240 Quirein J Gardner J S amp Watson J T 1982 Combined natural gamma ray spectral lithodensity measurements applied to complex lithologies SPE 11143 57th Annual Fall Technical Conference and Exhibition of SPE and AIME New Orleans Sept 26 29 Rider M 1990 Gamma ray log shape used as a facies indicator critical analysis of an oversimplified method Hurst A Lovell M A amp Morton A C eds Geological application of wireline logs Geological Society of London Special Publication No 48 27 37 Rider M 1996 The Geological Interpretation of Well Logs Caithness Whittles Publishing Schlumberger 1991 Log interpretation charts SMP 7006 Schlumberger Wireline amp Testing Serra O amp Sulpice L 1975 Sedimentological analysis of shale sand series from well logs Transactions of the SPWLA 16th Annual Logging Symposium paper W Depth mbsf 40 50 g B B 1 130 140 160 caliper LCAL n iB n Mur
227. run before the GHMT or after with another go devil attached to it The disadvantage here is that the hole cannot be deepened because the go devil is sitting at the bottom of it Capillary Suction Tester The Capillary Suction Testing CST equipment is used to measure the propensity of a clay to swell once it is introduced to fresh water A slurry consisting of a portion of the core catcher with distilled water is prepared This slurry is placed in the small stainless steel beaker seen in the picture at right A piece of blotting paper is located underneath the beaker and below the clear plastic frame which includes two electrodes The slurry makes contact with the blotting paper and front moves outward from the beaker The liquid front passes the first electrode and starts a timer the black box seen in the picture The liquid front passes the second electrode and stops the timer The recorded time is directly related to the sample s swelling potential the greater the time the higher the swelling potential is This time can be reduced by adding KCI to the slurry In samples where the clays are predicted to swell KCl may be added to the drilling fluid in a percentage determined by the CST to inhibit swelling The Operations Superintendent may ask the logger to conduct a CST on several samples to determine the likelihood of encountering a swelling clay during logging Triple Combo 5 Spe
228. ry timetable prior to the pre cruise meeting In that table he will also often include the logging times The Logging Staff Scientist will work closely with both the Drilling Superintendent and the Co Chiefs prior to the pre cruise meeting to make sure all is well coordinated and everyone is on the same page more or less before the meeting begins During the meeting there will normally be discussion of how to fit the program into a single leg by reducing the target depth for example or by cutting down the number of holes and or sites or cutting down the logging program less runs no runs The Logging Staff Scientist will provide detailed information on the utility and rationale of logging measurements for each scheduled hole on the leg but will also be prepared to re compute logging times if necessary At the end of the meeting the Logging Staff Scientist will write the logging section of the prospectus OCEAN DRILLING PROGRAM Pre Cruise Meeting Draft Agenda Leg 183 Kerguelen Plateau ODP Conference Room 106 Texas A amp M Research Park College Station Texas April 20 21 1998 April 20 8 30 A M Introduction Coffee Paul Wallace ODP TAMU Staff Scientist Science Overview Mike Coffin Fred Frey Co Chiefs Operations and Mike Storms ODP TAMU Engineering Discussion Operations Superintendent Lunch 1 00 P M Technical Support Logistics Public Relations Science Staffing Scientific Prospectus April 2
229. s At what sites logging is required The general science plan for the leg What tools are funded for the leg The preliminary details of the logging plan At this point the science and logging plans undergo refinement through numerous discussions with LDEO BRG TAMU Schlumberger and the Co Chief Scientists Meanwhile the Logging Staff Scientist in consultation with the Logging Services project team prepares a logging presentation for the pre cruise meeting It is at the pre cruise meeting that the involved parties discuss every detail of the leg and the time allocation for each drill site The Logging Staff Scientist represents the ODP logging program therefore she will describe the available toolstrings and the integration of the logging plan with the overall science plan The result of the pre cruise meeting is the creation of a comprehensive Scientific Prospectus which serves as the operational guide for the leg Prior to the pre cruise meeting the Logging Staff Scientist will 1 Contact the members of the Logging Services project team to begin acquiring specific information about the leg 2 Contact the Co Chief Scientists once named to review the current plan 3 Be apprised of tool condition and availability and toolstring deployment details specific to the leg Greg Myers serves as the liaison between ODP Logging Services and Schlumberger 4 Generate logging time estimates using the estimation s
230. s GLT data can be used as an effective indicator of changes in the lithostratigraphy Cyclically interbedded lithologies can be identified and analyzed using geochemical logging and changes in the provenance of sediments can be shown For example the FeO SiO and results from ODP Hole 950A on the Madeira abyssal plain show distinct downhole alternations see figure Horizons which are generally rich in FeO rich in SiO and poor in CaCO show the position of clay rich organic and volcanic distal turbidites sourced from volcanic islands and the African margin to the east of the drill site Horizons generally poor in FeO poor in SiO and rich show the position of calc turbidites sourced from a chain of seamounts to the west of the plain The ratio of certain elemental yields can also be used to emphasize fluctuations or distinct marker horizons in the stratigraphy For example elemental yield ratios were used to analyze data from ODP Hole 999B drilled beneath the Caribbean Sea The lithology Si Si Ca iron Fe Si Ca and porosity H Si Ca indicator ratios all help to highlight the position of tephra horizons within the formation see figure Geochemistry Downhole fluctuations in the elemental yields reflect gross variations in geochemistry which can be used to help categorize the formation The GLT results from Hole 735B logged during Leg 118 show a good example of this This hole
231. s and times 2 Discussing toolstring configurations with the Schlumberger Engineer 3 Initializing the Lamont TAP tool and operating the data acquisition system 4 Connecting the TAP tool to the bottom of the DIT E 5 Disconnecting cleaning and downloading the data from the TAP tool 6 Remaining with the Schlumberger engineer to monitor tool progress and to inspect the data in real time Data Logging Stuck Lost Shipboard Acquisition Operations Tool Policy Reports Introduction Stuck and lost tools are a normal occupational hazard of logging In spite of our best efforts to avoid tool loss Schlumberger strings have been lost on Legs 101 113 117 122 and 175 These strings are expensive and therefore are insured against loss in a hole however the shipboard loggers obviously try their best to avoid sticking a tool to recover a stuck tool and to fish for a lost tool If a tool is lost downhole a reasonable effort must be made to recover it in order to satisfy obligations to Schlumberger and the insurance provider The recovery effort should follow accepted practices and include multiple recovery attempts if technically feasible The shorebased ODP Logging Services representative must be notified of the stuck or lost tool situation by the Logging Staff Scientist or the drilling superintendent If all reasonable efforts have been made to recover a stuck or lost tool without success then the decision to abandon the tool mu
232. s currently investigating new and innovative log data visualization software for use in future CD ROMs st Cruise Data Log Data leetings Distributi Data CD ROM INDEX OF TOPICS GLOSSARY ACRONYMS HOME adle LEHOTA Gablehead w tension zb 56m DTC A NEN FAS Detector 24 9am T Telemetry Cartridge Detector 24 76m m HHGS Hostile Environment Natural Gamma Sonda 23 16m ILD E Eccentralizer 5 20 72m Detectors 18 28 17 08 m APS Accelerator Porosity Sonde 9 16 78m NPLC Nuclear Porosity Lithology Cartridge 14 34m HLDS HLDT Hostile Environment Litho Density Tool C Detector 10 28m Caliper DIT Dual Induction Tool SP 3 15m Deep 2 80m SFL 1 88m Medium 1 83 1 20m m High Resolution Temperature TOOL ZERO Acceleratian Pressure Tool Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS 20 17m i LEH GT 1 X Cablehead w tension 29 50m 1 DTC A Telemetry Cartridge 27 06m DTA A Telemetry Cartridge 25 far Detector 25 46 Ee WNatural Gamma ray Tool 23 24m DSI DSST Di pole Shear Toal 10 23m 2 3 23m 7 68m FMSi MEST H Formation MicroScanner 155 SDT Backup Sonic Tools 1 Pad Contact 0 46m TOOL ZERO Triple Combo FMS Sonic Specialty Other Toolstring Index Standard HOME INDEX OF TOPICS GLOSSARY ACRONYMS HOME gt gt ARI LWD CDR 9 gt ASI LWD RAB CNT G LW
233. s on the rig floor The device consists of rubber packing element surrounded by a steel enclosure The logging cable is passed through the seal prior to logging and the tool string is then rigged up Following the completion of tool rigup the seal is slid down the cable and fastened to the logging pipe The torpedo is a small stainless steel connector used for connecting two pieces of logging cable A good example is the connection between the cablehead pigtail and the logging cable The torpedo consists of two symmetrical halves which make a small enclosure for establishing conductor continuity between each cable Each piece of cable must contain a rope socket and exposed conductors for the torpedo connection to be complete A torpedo connection should not pass over a sheave Acquisition of log data is completed in the Minimum Configuration MAXIS Multitask Acquisition amp Imaging System located just port and forward of the helipad Presently the MCM contains two VAX processors and numerous control and power modules which communicate with the downhole tools during logging Real time displays of all log data may be viewed from here thus you will usually find the loggers here during logging operations The MCM is capable of communicating with all labs and workplaces on the ship and an intercom link exists with the winch shack A color plotter is available for producing log reprints Two views of the Minimum Configuratio
234. s several significant enhancements that were not available in the previous version Among these is a summary chart accessible from the Tool Selection page that lists all of the available logging tools and their principal scientific applications The Data Processing amp Analysis section has been augmented and contains updated sections on FMS GHMT processing New information on integration of log data with other data types such as core information and seismic profiles is now included The Glossary has also been significantly expanded We are always interested in your feedback as our goal is to make this document as helpful as possible to site proponents shipboard and shore based scientists and JOIDES panel members Please feel free to contact us anytime with comments suggestions or questions ODP Logging Services Data Data Acquisition Data Presentation index of amp MOSES amp mmm Pre Cruise Shipboard Post Cruise M Operations Hee Activities HOME e ACRONYMS GLOSSARY INDEX OF TOPICS CONTACT US Data Data Acquisition Data Presentation index of amp Processind cealstrings Pre Cruise Shipboard amp Post Cruise amp A 8 Planning Operations Analysis Activities Tons Pre Cruise Planning Interacting with the Logging Staff Scientist Selecting Logging Tools Estimating Logging Times Pre Cruise Meeting Data Data Acq
235. sator by comparing measurements of af ew et wc 8 oa Gevertoped Wy Smal yet ssgnilicant number use technologies developed for scientific research The recent history of advances in all of these technologies parallels advances in data transmission and computer capabilities which have led to remarkable increase in the quantity and speed of downhole data acquisition and processing Prensky 1994 Figure 3 shows how increases in data transmission have accompanied the introduction de in i a hydraulic heave eompensator that moves the wireline opposite to heave motion while log ging was first developed and used on the ODP drill ship Goldberg 1990 measured the effectiveness of this wire line heave compensator by comparing measurements of the acceleration of a downhole tool with the displace ment of the motion compensator on the ship The mea surements indicate that heave amplitudes reach about 35 3 REVIEWS OF GEOPHYSICS 2 5 m with vertical accelerations of up to 898 of seas with 3 4 m waves As the ship s dominant period was about 8 5 s the maximum downhole displacement and velocity due to heave were reduced to 1 5 m and 1 0 m s respectively using the wireline compensator Since typ ical logging speeds are 0 2 m s or less in high seas it is possible that a tool could move downward even when it is being pulled uphole on the wireline Muc
236. sheet retains focus over a shorter distance than the deep laterolog The Dual Laterolog has a response range of 0 2 to 40 000 ohm m whereas the DIT has a range of 0 2 to 2 000 ohm m The DLL is recommended for igneous environments e g oceanic basalts and gabbros because the resistivities can be higher than the upper limit of what the DIT can measure e g Hole 735B However in upper crustal environments seismic Layers 2A and 2B the resistivities are usually low enough that you can use the DIT This was the case in data from for example Legs 104 and 152 as well as Holes 395A and 504B The DLL is usually run in combination with the Natural Gamma Ray Spectrometry tool NGT but may be run with the Triple Combo or alone The depth of investigation of the laterolog depends on the resistivity of the rock and on the resistivity contrast between the zone invaded by the drilling fluid and the virgin uninvaded zone The vertical resolution of both LLd and LLs depends on the geometry defined by the focusing electrodes this is about 2 ft 61 cm Applications Porosity estimate Because of the inverse relationship between resistivity and porosity the dual laterolog can be used to compute the porosity of the rock from Archie s equation if the sediments rocks do not contain any clay or if the contribution of surface conduction to the signal is negligible Fracture Porosity Estimate This can be estimated from the separation bet
237. sing page of this manual which also describes the corrections that are applied to various log data types Shore based data distribution After the drilling leg is completed processed digital log data are placed on line by ODP Logging Services for use by the shipboard scientific party The data are considered proprietary for one year accessible only to shipboard scientists via a password security system implemented after the cruise One year after the conclusion of the cruise the password is lifted and data are accessible to all interested investigators For additional details see the on line data section of this manual ODP Logging Services also creates a CD ROM of log data that is distributed with each volume of the Initial Reports Details can be found on the log data CD ROM page Shore based Investigators Shore based investigators whose requests for log data have been approved by the shipboard scientific party may obtain log data during the one year data moratorium It is strongly suggested that such requests be submitted before the drilling leg in order to expedite the request approval process Shore based investigators who obtain either core or log data are subject to the same publishing restrictions and obligations as members of the shipboard scientific party A detailed discussion of the ODP publication policy can be found on the publications page of the Science Operator s web site http www odp tamu edu publicatio
238. sity o Hole size This is of particular importance as oversized holes cause an increase in the signal derived from the borehole fluids and a decrease in the signal from the formation The interpretation of geochemical logs should therefore always be undertaken in conjunction with caliper logs Because the aluminium activation clay tool has a low activation energy 2 MeV aluminium is measured in a much smaller volume of rock than those elements measured by the gamma spectroscopy tool As a result with increasing hole size the aluminium signal decreases rapidly and may reach background levels whereas the gamma spectroscopy tool elements can still be measured This problem is compounded by the oxide closure procedure which forces the major oxides to a constant sum usually 100 o Temperature Temperature effects can significantly reduce the efficiency of the Nal detector in the gamma ray spectrometry tool with higher temperatures resulting in a poor signal to noise ratio and decreased resolution Poor resolution will result in gamma ray peaks appearing in the wrong window and lead to incorrect identification of the element represented It is recommended that the GLT not be used in temperatures greater than 150 C The quality of the data can also be reduced during processing This can occur due to errors in the spectral inversion of the raw data inaccuracies in the oxide closure model caused by the presence of unmeasured elements and in
239. sity Tool CNT G which in the GLT is used solely as a carrier for Californium 252Cf source Californium is used instead of the conventional AmBe source because its spectrum has a lower energy 2 MeV instead of 4 5 MeV thus reducing the number of fast neutron reactions which would interfere with measurements taken by the tools below Next is the aluminium activation clay tool which 1 essentially a Natural Gamma Ray Tool with a modified spectrometer 7 windows instead of 5 to allow a more detailed analysis of the spectrum Finally a gamma ray spectrometry tool is located at the bottom of the string A boron exclusion sleeve surrounds the gamma ray spectrometry tool and increases the signal to noise ratio by shielding the path of fast neutrons from borehole fluid and reducing the number of capture reactions in the borehole itself thus counteracting the effects of chlorine and water present in the borehole The sleeve also reduces the interference of iron from the tool housing The natural gamma ray tool measures the abundance of K U and Th from the natural gamma radiation given out by these elements A sodium iodide detector is used for the measurement and this also provides a spectrum of the background radiation which is required for subsequent processing Data are collected as the tool string is pulled up the borehole so that natural gamma ray measurements are made before the formation is activated by the neutron and gamma
240. st be made collectively by the Logging Staff Scientist Operations Superintendent Rig Superintendent and the Schlumberger engineer A report must be filed by the Operations Superintendent and delivered to the Logging Staff Scientist In the event of loss involving a radioactive source the tool and hole must be abandoned with cement to safely entomb the sources There are four main types of tool sticking situations 1 The tool is either stuck in a bridge or stuck by cavings possibly beneath a bridge 2 The tool is not stuck but cannot be pulled up past a bridge The tool is stuck in the base of pipe 4 The tool is not stuck but cannot get into pipe Oo Strategies There are several available strategies for dealing with stuck tools 1 Pulling harder on the cable Pulling harder on the cable is recommended as the first course of action when a tool appears to be stuck Pulling may not exceed the combined cable weight plus weak point strength or 50 of cable strength whichever is less With this method situations 2 and 4 have a higher chance of recovery than 1 and 3 2 Adding pipe if using the CSES If the CSES is in the tool string stands of pipe may be added to break through a bridge or cuttings situations 1 and 2 Cable tension should be maintained when lowering pipe to prevent A cutting through or kinking a slack cable with the pipe or B sudden dropping of the tool when the tool is freed a 10 30 fr
241. stigation Eccentering Effects Depths of investigation for sonic devices depend on the formation type shear and compressional slowness the transmitter to receiver spacing wavelength of the wave considered and whether it is a head wave or a guided wave the source frequency and signal types Frequency determines the wavelength that drives the depth of investigation of the measurement Typical sonic wavelengths at different frequencies and slownesses are shown in the Additional Specifications table Low frequency penetrates deeper into the formation and helps read beyond altered zones Numerical simulations verified by measurements from scale models show that when eccentering is small compared to the borehole radius there is little change in the character of the dipole waveforms or in the STC processed slowness values Large eccentering on the order of 2 to 4 in in a 12 in borehole increases the flexural wave amplitude relative to the compressional For the DSI 2 tool the variation in the shear slowness estimate is 2 percent over the normal slowness range Log Presentation Output plot of DSI 2 data Specifications Temperature Rating 350 F 175 Pressure Rating 20 kpsi 13 8 kPa Tool Diameter 3 375 in 8 57 cm Minimum Tool Length 280 ft 85 m Sampling Interval 1 2 and 4 msec Max Logging Speed Stationary Vertical Resolution N A Additional Specifications Minimum Hole Size 5 5 in 13 9 cm Maximum H
242. t Finally new emerging technologies and experiments that promise significant advantages over current methods for downhole measurements in marine geology and geophysics are discussed use of logging is due to several causes including perma nent shipboard systems for routine operations vast im provements in downhole instrumentation technology and drilling methods and new measurements made on core samples that allow for one to one correlation with similar measurements made downhole There have been numerous published discussions of the scientific goals and overviews of DSDP and ODP that include elements of specific downhole measurement capabilities their successes and their failures For gen eral and historical background of the DSDP and ODP the interested reader is referred to Revelle 1981 and the proceedings of the International Conference on Scien tific Ocean Drilling COSOD 1987 oirn Oceano graphie Institutions for Deep Earth Sampling and Joint Occanographic fnstiraions fmc 1987 For more de tailed information on specific drilling locations the Ini tial Reports and Scientific Results of the ODP and DSDP offer summaries and various monographs of the American Geophysical Union present synthesis articles for sites around the globe For a more detailed discus sion of particular downhole measurements a number of smaller proceedings outline various specific applications eg M ontfington er al 1987 Hyndman 1991 Cell
243. t percent oxides The trace elements U Th and Gd are expressed in parts per million Post cruise processing also allows the expected errors on the GLT data to be calculated see figure GLT plot examples Specifications Temperature Rating 150 C 300 Pressure Rating 20 kpsi 13 8 kPa Tool Diameter 3 875 in 10 cm Tool Length 9 25 ft 2 82 m Sampling Interval 6 in 15 24 cm Max Logging Speed 600 ft hr Deployment Notes Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic INDEX OF TOPICS GLOSSARY ACRONYMS HOME High Temperature Operations Moderate to High Temperatures In moderate to high temperature environments i e a sheeted dike complex the measurement of borehole temperatures with either wireline or memory tools should precede any other logging operation in order to determine the temperature of the borehole fluids estimate the geothermal gradient and approximate the time of post drilling temperature rebound Schlumberger tools rated to 175 C can often be deployed with adequate hole cooling by circulating cold fluids for approximately 2 3 hours If temperatures rebound quickly however these tools are at risk and logs may only be recorded in cases where the side entry sub SES could be used After circulating for several hours a Schlumberger tool string should be lowered into the hole as quickly as possible and in combination with an Auxiliary Measurement Sonde
244. ted to read the enclosed review paper published in Reviews of Geophysics and reprinted by permission of the American Geophysical Union Gomme Feary is Wireline Caliper 1 in 10 20 Wireline Tranait Time Transa Timo by time of wireline Nate shale swelling fogging Disagreement caused by deteriorated hole condition at time of wireine fogging note wireline caliper indicating washout Taal length A 6 6 m Module Lenghts m Tool body 4 2 m Surface Panel PC based Data Acquisition System Wireline Telemetry System amp Accelerometer GRAM gt x GR 3 Gamma Ray Modules GR 2 E Schlumberger toolstring SELL III ao CGR LM SGE a units dee amem 200 200 ohm m 200 TIT 500 iij LL Led FERT 550 mill Wr TOG M Fo efi BOO B50 ggg Sagan Core Log Depth Matching Define Preliminary Core Log Depth Matching Parameters Stretch Compress Core Data Between 95 00 and 85 00 at 050 Intervals Slide LogUpDown Between 910 and intervals 0 15 Hole A P Correlation Depth Step m Hole Select Hol Invert Core Variable Ves 9 No e e s HoleD D Optimal _ Core Log SUSCEPTIBILITY SUMT _ Depth M
245. the EMEX voltage so that the response corresponds more closely to the conductivity of the formation Depth adjustment The natural gamma log SGR resulting from the BorEID speed correction is matched to the SGR log from the same pass after conventional log depth shifting The logs are checked for a good match and then the resulting depth shifts are applied to FMS images and their associated logs pad azimuth etc The resulting FMS images are then on a comparable depth scale to the conventional logs Image normalization Using the BorNor module of GeoFrame static and dynamic normalizations of the image are applied In the static normalization the resistivity range of the entire interval of data is computed and is partitioned into 256 color levels this image is good for examining large scale resistivity variations In the dynamic normalization the full range of color levels is assigned to resistivity range of short intervals e g 2m thus the color contrast is increased enhancing the fine details of the resistivity structure Data delivery Static images are output as GIF files and added to the on line database and the Initial Reports CD ROM In the future dynamic images will be treated in a similar manner The FMS data are also saved in DLIS format and archived GHMT Processing Once the GHMT logs have been depth shifted the magnetic polarity stratigraphy is determined as follows 1 The Earth s main field an
246. tial bridges cannot develop Even though the use of the CSES is not ordinarily planned for the Logging Scientist will estimate logging which incorporates its use If the CSES is planned for but not needed logging operations will take 4 12 hours less than planned at a site Estimation Assumptions 1 The spreadsheet calculations assume that the entire interval below the pipe depth is logged for all toolstring combinations 2 Logging rates as specified are constant for the duration of logging 3 Time estimation is not required for the rig up and rig down of the TAP tool Actual rig time required for this tool is negligible approximately 5 min 4 Fixed time estimates for operations such as retrieval speeds while tool is in drill pipe tool rig up and rig down may vary from leg to leg Contingencies Not Included in Estimations The logging times provided in the spreadsheet do not include three contingencies that commonly occur 1 Time required to punch through bridges or change to the sidewall entry sub if one starts logging without the CSES 2 For reentry holes in which it is not permissible to drop the bit at the bottom of the hole time to pull the drillstring take off the bit and reenter the hole 3 Time beyond 1 hour to drop the bit due to problems with the bit release tool or cable breakdown which occurs at about 10 of sites and requires 1 3 hours extra to deploy a backup tool or cut off faulty cable Safety
247. tic and the reflections in the seismic data The seismic can then be interpreted in terms of the actual formations and conversely you can find out how deep into the seismic the borehole penetrated Before being used in the IESX Synthetics application the data must be extended to the sea floor and bad data must be edited out We use the GeoFrame application WellEdit for this For example in the Hole 742A data the log density has some bad values due to hole washouts core based density measurements interpolated onto even spacing can be used instead In the Synthetics application a depth two way travel time relation is generated from the sonic velocity data or a checkshot survey An acoustic impedance log and reflection coefficients are calculated from the sonic and density logs Then a source wavelet extracted from the seismic survey data is convolved with the reflection coefficients to produce the synthetic seismogram The synthetic seismogram and the logs can be plotted on the seismic section in the Seis2DV application To make a hardcopy plot of the seismic section the plot can be exported in the seismic CGM graphics format and plotted For page size plots a screen dump is usually acceptable The project can be saved to tape for backup or for loading into another computer e g the Downhole Measurements Lab Unix workstation Data Processing Log Core Log Integration Log Seismic Overview Processing Splicer amp Sagan Integ
248. tio from core to log may be greater than 2 X 10 the ratio from log to seismic section may be 10 to 107 times larger In most integrated scientific applications there fore downhole measurements provide three comple mentary advantages 1 data are acquired under in situ gt ODP Logging 35 3 REVIEWS OF GEOPHYSICS rhe nnn 19 Eth Manual INDEX OF TOPICS GLOSSARY ACRONYMS HOME DOWN POLE MEASUREMENTS 317 Figure 1 Schematic diagram illustrating the diferent wales of meavurcment in after Worthington e at 1991 The span of mecaurements from core samples surveying B greater than 10 complicating the interpretation of data from samples to regional geology without intermediatc scale logging and borehole measurements conditions 2 data are acquired in continuous profiles measured throughout the interval with no missing scc tions and 3 data are sampled at a larger scale inter mediate between core and seismic measurements In most drilling environments continuous coring docs mot nesult in eontmuous core recovery fact core recovery by techniques other than piston coring is bless than 5095 on average amd this proportion is often dis turbed by the drilling process Ffyndrnan 1991 As result the true core depth becomes ambiguous Drilling disturbances within a recovered section can be cor rected however by correlation with c
249. to minimize the time spent by the logging tool beneath it One risk that can be somewhat avoided is bridge formation at the bottom of the bottom hole assembly BHA this results from ship heave which causes the BHA to pack down the soft sediments Move the pipe up 10 15m whenever possible e g during tool run up and down and during logging and then if a bridge forms lower the pipe 10 15m to punch through it Tool breakoff during circulation Pumping mud or circulating with high water pressure while the tool is in the BHA can break off the tool at the weak point e g Leg 114 The inside diameter of the BHA is only slightly larger than that of the logging tool so fluid flow is highly constricted between the two Rapid pressure buildup occurs blowing off the tool Solution Don t pump mud while the tool is in the BHA Either raise the tool into the larger diameter pipe above the BHA or less desirably lower the tool into open hole Occasionally it can be difficult getting the BHTV out the end of pipe and an extra push was needed from circulating sea water to get it out When using the CSES and moving the pipe up and down mud plugs form within the BHA or even higher in the pipe There is no choice but to run the tool down while circulating cautiously to try to punch out Breaking off the tool by pulling too hard The tool can be broken off the weak point by pulling too hard when it is stuck either on a bridge or entering pipe This c
250. tribute to the scientific goals of the leg Other points frequently included are o The particular advantages of wireline measurements and how they complement the other types of analysis that will be made o Past examples of applications and pertinent references o Information about who provides the logging services e g ODP Logging Services amp Schlumberger and the role that each plays Operations This section will provide operational details for the reader Some typical topics are as follows Hole is flushed with fluid Wiper trip is conducted Pipe pulled to logging depth e g 90m Tools assembled and lowered on 7 conductor cable WHC employed Details on data acquisition system and satellite transfer methods 0 09 O 0 0 Because the operations section is site specific it is possible to cover the general operational techniques in the introduction specific operational details in the site chapter and omit this as a separate section Logging Tools This section will introduce the tools and how they were combined during the leg Usually figures and tables are employed to present the information more coherently Typically a figure of the toolstrings employed on the leg and a table of the tools and their depth of investigation sample interval and vertical resolution are presented in this section In the text the names of the tools their acronyms and the measurements they make are introduced and the theory behind t
251. tric effect index is determined by comparing the counts from the far detector in the high energy region where only Compton scattering occurs with those in the low energy region where the count rates depend on both reactions The far detector is used because it has a greater depth of investigation The response of the short spacing detector which is mostly influenced by mudcake not present in ODP boreholes where a seawater based drilling fluid is used and borehole rugosity is used to correct the density measurement for these effects As with the case of the sonic tool the depth of investigation of the lithodensity tool cannot be easily quantified it is in the range of tens of centimeters depending on the density of the rock The vertical resolution is 16 in 38 cm Applications Porosity estimate If grain density is known porosity can be calculated from the density log Alternatively porosity and density logs can together be used to calculate grain density Seismic impedance calculation The product of velocity and density can be utilized as input to synthetic seismogram computations Lithology and rock chemistry definition In combination with the neutron log the density log allows for the definition of the lithology and of lithologic boundaries Because each element is characterized by a different photoelectric factor this can be used alone or in combination with other logs to determine the lithologic type Both density
252. ty 5 and 15 30 HLDS Bulk Density PEF 2 5 and 15 15 45 DIT E Resistivity 2 5 and 15 200 150 75 TLT Temperature 1 per second NGT Natural Gamma 15 45 GPIT Tool orientation 15 SDI Sonic Velocity 15 120 FMS Resistivity Image 0 25 0 5 NGT Natural Gamma 15 45 SUMS Susceptibility 5 and 15 35 FMS Total Field 5 and 15 45 WST Sonic Travel Time trademark of Schlumberger Table 2 Schlumberger tool and measurement acronyms Explanation Units Hostile Environment Natural Gamma Sonde Standard total Gamma Ray gAPI Computed Gamma Ray HSGR minus U contribution gAPI Formation Potassium fraction HFK HTHO HURA Thorium Uranium ppm ppm NGT APS HLDS DIT E GHMT SDT SGR CGR POTA THOR URAN APLC FPLC SIGF STOF RHOM PEFL LCAL DRH IDPH IMPH SFLU MAGS RMGS MAGC MAGB LTT1 4 DTLN Natural Gamma Ray Tool Standard total Gamma Ray Computed Gamma Ray SGR minus U contribution Potassium Thorium Uranium Accelerator Porosity Sonde Near Array Porosity Limestone Corrected Near Far Porosity Limestone Corrected Neutron capture cross section of the formation Tool Standoff computed distance from borehole wall High Temperature Litho Density Sonde Bulk density corrected Photoelectric effect Caliper measure of borehole diameter Bulk density correction Dual Induction Tool Deep Induction Phasor Processed Resistivity Medium Induction Phaso
253. ty Correction g cm3 PEF Photoelectric Factor barns e TNPH Thermal Neutron Porosity DCAL Differential Caliper in ROMT Max Rotational Density g cm DPOR Max Rotational Density Porosity p u HDIA Horizontal Diameter in VDIA Vertical Diameter in NTCK Neutron Detector Sample Depth Tick Mark DTCK Density Detector Sample Depth Tick Mark ROP Rate of Penetration ft hr or m hr TAB Time After Bit hr or min Deployment Notes Along with the LWD collars additional equipment such as jars must be included Responsibility for providing this equipment is discussed at the pre cruise meeting LWD deployment illustration LWD deployment photo trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index OD m OF TOPICS GLOSSARY ACRONYMS HOME gin While Drilling Compensated Density Neutron Tool LWD CDN Note the LWD CDN is no longer in use in the ODP logging program as it has been superseded by the LWD ADN This page is included to provide assistance to investigators working with CDN data Description The physics of the measurements made by the LWD CDN tool are similar to those of corresponding wireline services For the neutron porosity measurement fast neutrons are emitted from 7 5 curie americium beryllium source b The quantities of hydrogen in the formation in the form of water or oil filled porosity primarily control the
254. uisition Data Presentation index of 5 Processing amp Tocistrings i Shipboard amp Post Cruise amp Planning Operations Analysis Activities Tons Data Acquisition amp Shipboard Operations Data Acquisition amp Transfer Logging Operations Stuck Lost Tool Policy Shipboard Reports HOME ACRONYMS GLOSSARY INDEX OF TOPICS CONTACT US Data Data Acquisition Dota Presentation Index of amp Pr in amp T ncessing strings H Pre Cruise Shipboard amp Post Cruise amp a Planning Operations Analysis Activities Tools Data Processing amp Analysis Overview Log Processing Core Log Integration Log Seismic Integration IESX HOME ACRONYMS GLOSSARY INDEX OF TOPICS CONTACT US Data Data Acquisition Data Presentation index of amp E i Processing amp Tocistrings e H Pre Cruise Shipboard amp Post Cruise amp Lee Planning Operations Analysis Activities Data Presentation amp Post Cruise Analysis Post Cruise Meeting Data Distribution Online Data Log Data CD ROM HOME ACRONYMS GLOSSARY INDEX OF TOPICS CONTACT US Data Data Acquisitian Data Presentation index of amp E Processing amp Tootstrinds b p 5 Shipboard amp Post Cruise UWS SIS Middl luc Planning Operations Analysis Activities
255. unit as a fining upward sequence in mostly carbonatic sediments Similar saw tooth patterns in the resistivity response can also be observed in oceanic basalt units where they are related to porosity changes towards the top of each unit Applications Natural Gamma Ray Clay typing Potassium and thorium are the primary radioactive elements present in clays because the result is sometimes ambiguous it can help combining these curves or the ratios of the radioactive elements with the photoelectric effect from the lithodensity tool Mineralogy Carbonates usually display a low gamma ray signature an increase of potassium can be related to an algal origin or to the presence of glauconite while the presence of uranium is often associated with organic matter Ash layer detection Thorium is frequently found in ash layers The ratio of Th U can also help detect these ash layers Environmental Effects The CDR tool provides a set of corrections for different environmental effects These include corrections for adjacent formations borehole signal and invasion Differences in the temperature of drilling fluid compared to undisturbed formation temperatures can also generate environmental effects as conductivity in ionic fluids such as seawater is strongly temperature dependent Log Presentation Attenuation Resistivity ATR and Phase Shift Resistivity PSR are usually plotted in ohm m on a logarithmic scale along with gamma ray GR
256. up to 3 reference log curves The resulting core log timelines can be applied across equivalent mcd depths in different holes or just for individual cores Some specific example applications are o Compare multiple core data types in mbsf or mcd space to downhole log records log mbsf o Automatically or manually map core data back to log data to determine original stratigraphic depths o Accurately estimate the size and position of coring gaps as well as the accuracy of the composite section o After mapping core data into the logs the core data can be saved versus Estimated Log Depth eld as well as mcd and mbsf Data Processing Log Core Log Integration Log Seismic Overview Processing Splicer amp Sagan Integration IESX INDEX OF TOPICS GLOSSARY ACRONYMS HOME _ Log Seismic Integration IESX is used to display and interpret seismic surveys and to generate synthetic seismograms from sonic velocity and density data It is part of Schlumberger GeoQuest s GeoFrame software which has been used for several years by the ODP downhole logging groups to display and process ODP log data particularly FMS images We anticipate that it will become a very powerful interpretation tool able to integrate until now disparate data sets IESX is available at each of the ODP Logging Services offices an IESX Cookbook has been produced to guide new users in the use of this powerful but non intuitive software Currently IESX
257. ve of changes in fracture density porosity and in the material filling the pores In some cases compressional wave attenuation can also be computed from the full waveforms Log Presentation LWD Isonic output Specifications Drill collar nominal OD Drill collar IDs Drill collar joints Pony collar and saver sub joints Makeup length Measure point to tool bottom Total tool weight in air Maximum temperature Operating pressure Maximum flow rate Maximum tool curvature Rotating mode Sliding mode Bending strength ratio BSR Equivalent bending stiffness Pressure drop at maximum flow rate 6 75 in 4 75 in 2 38 in 5 5 in FH 5 5 in FH 22 08 ft without saver sub 13 5 ft 2100 Ibm 300 F 20 000 psi 800 gpm 30 psi at 11 ppg 4 100 ft 16 100 ft 2 0 23 ft of 6 5 in x 2 81 in Average inertia 85 in 4 Maximum bit size 9 875 in Maximum jarring load 330 000 Ibm 74 million L2 Ibm where L Maximum weight on bit distance betweeen stabilizers in feet Joint makeup 6 625 in FH 21 000 ft lbf Maximum rotary 16 000 ft Ibf Maximum torque pin yield 43 000 ft Ibf Deployment Notes The LWD Isonic is combinable with all other Logging While Drilling tools with no reduction in the drilling rate LWD deployment illustration LWD deployment photo trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index TEE INDEX ay
258. ween the deep and shallow measurements based on the observation that the former is sensitive to the presence of horizontal conductive features only while the latter responds to both horizontal and vertical conductive structures Environmental Effects For the LLd the borehole effect is small for hole diameters up to 16 in while the LLs provides good readings in holes not exceeding 12 in Corrections are available for holes up to 20 ft in diameter Log Presentation The LLd and LLs curves are usually displayed on a resistivity logarithmic scale along with the gamma ray log Output plot of DLL data Specifications Temperature Rating 350 175 Pressure Rating 20 kpsi 13 8 kPa Tool Diameter 3 625 in 9 21 cm Tool Length 30 6 ft 9 35 m Sampling Interval 6 in 15 24 cm Max Logging Speed 10 000 ft hr Vertical Resolution 2 ft 61 cm Depth of Investigation see discussion in Description section Output LLD Deep Laterolog ohm LLS Shallow Laterolog ohm Deployment Notes As noted above the DLL is usually run in combination with the Natural Gamma Ray Spectrometry tool NGT but may be run with the triple combo or alone Obviously combining the DLL with the Triple Combo will save an additional run Stuck lost tool information trademark of Schlumberger Triple Combo FMS Sonic Specialty Other Toolstring Index INDEX OF TOPICS GLOSSARY ACRONYMS HOME Estimating Logging Times I
259. y The principal advantage of these logs over the equivalent core measurements 15 that the logs record the in situ property whereas the cores are expanded and depressurized and can suffer from end effects and biscuiting Relation to the seismic section synthetic seismograms The Well Seismic Tool WST and air gun are used for checkshot surveys to obtain a depth traveltime relation and zero offset VSP experiments to obtain seismograms at the site The depth traveltime relation can also be derived from the sonic velocity log which together with the density log and seismic source wavelet combine to make a synthetic seismogram Thus reflectors on the seismic section can be identified with lithological or petrophysical changes in the borehole For almost every leg there is an extensive and extensively interpreted set of site survey seismic sections and so it is of great importance that the borehole information can be associated with seismic reflectors and mapped along the seismic lines Structure and fabric FMS data provide resistivity images of the borehole wall showing detailed structural faults fractures sedimentological turbidites beds bioturbation concretions clasts and igneous veins alteration and basalt pillows breccias and flows features Moreover the orientation of these features can be analyzed since the GPIT is on the same toolstring Under favorable circumstances a borehole televiewer or azimut
260. y that have con siderable water bound in their molecular structure Bro glia and Eilts 1990 Some neutron tools utilize a pulsed neutron acceleratar to bombard the nuclei of minerals in the formation The spectrum of gamma ray energies emitted by these interactions is recorded using crystal detector and provides a measure of the abundance of the major mineral forming elements such as Fe Si Ca and Al Merron et al 1993 The elemental abundances may be used to estimate mineral concentration when core materials can be combined te provide sufficient calibra tion Kerr et aL 1992 Myers 1992 Nuclear magnetic resonance NMR tools measure the H present in the formation and pore fluid by inducing proton movement around a pulsed magnetic feld Brown amd Carnson 1960 Jackson 1984 The time decay of the resonance signal is also directly related to the pore size distribution and can he used to indicate formation permeability Neutron measurements penetrate 0 51 0 m into the formation and the vertical resolution of the measure ment is approximately 0 4 m Borehole imaging tools Imaging tools deliver high resolution pictures of the wall of a borehole using pre cision measurements of either electrical conductivity optical variation or acoustic reflectivity These three imaging techniques are complementary since conductiv ity electrical color optical and reflectivity acoustic are controlled bw diferent physical and chemica

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