Fatigue Analysis for Coiled Tubing FACT User Manual
Contents
1. Fill Color SS for life sections Border Color DS for life sections Language English O K Cancel a Show Constants P_i 1 895 hese constants will Q Factor 0 95 affect the model calculations Do not Nom 130 0 change without S_m 000000 0 A 5_p 1000 0 222. Maternal Density Ibs n cu 0 2833 Location weld at feet Factor Feel conecta Dota Reel Name Uned Core Diameter inches Reel Width Inches Outer Diameter inches Sieg ate COCCO i No O es The option frames are as follows Units Selects the units system to be used for entering the data The units system will apply to the whole form During the entry of the data the user may change to the other units system by clicking on the Convert Units To and select one of the available options This will convert all data entered thus far to the newly selected units system e Convert Units To Use this to convert the entered data from one units system to another You may use this as many times as you wish but bear in mind that some round off errors may occur String with Cable Capillaries By default this option is set to NO If however the string does have a cable or capillaries then you may use this option and select the YES option By selecting the YES option the fifth data frame will appear Note that the cable capillaries existence will not affect the fatigue analysis but have been included here to allow for compatibility with TAS data files Thus when using the same string in TAS for fluid or force analysis computations the string will have the appropriate data relating to the cable capillaries The Data Frames are as follows Coiled Tubing String Data You may select coiled tubing from the database create a true
3. tapered section or enter data directly into the grid The length of each coiled tubing segment must be entered manually To add more rows in the grid point the mouse to the grid and right click then select INSERT ROW Ideally you should insert sufficient rows in the grid before starting to enter data applicable to tapered strings Ideally the user should enter the string data as supplied by the manufacturer i e enter the strip number in the component name column and name the string by its number The minimum yield stress of each element of the coiled tubing string must be selected from the list available in the MIN YIELD column Note that when creating a tapered string care must be taken to ensure that the data is entered in the correct order The correct order is to start the top row in the grid with the free end of the coiled tubing string Welds Data This data is optional If the coiled tubing string has no welds then simply ignore this frame If however there are welds then they should be entered here even if they were 12 manufacturer s welds Most manufacturers of coiled tubing claim that the stress concentration is removed from the welds done at the factory by a process of stress relief annealing However it is recommended that you keep track of these welds by specifying a weld factor of 0 95 or higher up to a maximum of unity meaning that 95 of the stress concentration is relieved If you wish to change the manufacturer s
4. The factor RA has a value of 0 53 for QT 700 and 0 57 for QT 800 or equivalent Welds The effect of welds is to induce stress concentration locally Depending on the type of weld used a weld factor F will reflect the effect Typical values for weld factor are 0 7 for smoothly dressed butt welded section 0 5 for poorly dressed butt welded section and 0 31 for undressed butt welded section Corrosion Two types of corrosion may be encountered in coiled tubing applications acid corrosion and corrosion due to sour gases The two corrosion effects are different in nature The acid will corrode the material of the coiled tubing and reduce the wall thickness while the sour gas molecules will embed themselves in between the material molecules thus inducing stress concentration A corrosion factor F is normally used to account for either effect Typical values for the corrosion factor are 0 66 for 15 HCl acid and 0 5 for HS gas Reliability of Empirical Data A reliability factor Fr is also introduced to reflect the confidence in the test data The reliability factor is a function of the reliability level O and is given as 1 nO 15 1 F 11 47 1003 13 Note that using 50 reliability will appear to be the best fit of the sample data as it does represent the average number of cycles that can be sustained before a failure occurs In reality though this will mean that 50 of the coiled tubing will survive the predi
5. become known we have to make some assumptions to account for the loss of wall thickness Clearly the wall loss will reduce the coiled tubing cross sectional area thus increasing the stresses due to the same load being applied A number of corrosion factors have been suggested and are basically representative of reduction of wall thickness 1 e are always less than 100 in FACT less than 1 Similarly stress concentration factors are assumed for welds and HS gas and these basically mean that the stresses are increased because even before loading locally concentrated stresses exist Again stress concentration factors are less than 100 in FACT less than 1 Finally when a corrosive fluid is pumped through the coiled tubing the wall loss will take place through the entire length and not just the parts that moved out of the reel However FACT will only subject the coiled tubing to stresses if 1t has moved during the job Thus to account for the wall loss due to internal corrosion the whole length of the coiled tubing is cycled once in and out of the well towards the end of the job When the PULL OUT button in FACT is clicked Theoretical Background The stress strain relationship given by Hooke s law dictates that the coiled tubing must not exceed the minimum yield stress to remain within the elastic range of the curve Since the slope of the curve is given by the Young modulus E the following condition for the strain e must be satis
6. cbse nian tanae E a E a E se ualeatandatearchast 18 SPOON ri ie Fe A O O 18 DACAB ASE seca EE E E E T E EEE T A E ET EE E E E E E AET 20 Corrosion and Weld FICO a to ici 20 Cooled A ON 20 Fanou C yelesi a a a e A ei shict ca enecedeti E a e aE at 21 in a r r a a Eaa earar r e erao a raaraa aai 22 Overview Fatigue Analysis for Coiled Tubing FACT version 1 xx is the latest of the coiled tubing fatigue module produced by MEDCO This program performs fatigue analysis and tri axial stress computations of coiled tubing in real time in post job mode and or using manual data entry The fatigue analysis takes into account the geometry of the coiled tubing material properties and the equipment used In addition corrosion stress concentrations and statistical reliability of the empirical data are also considered FACT keeps track of the coiled tubing fatigue history per job and gives the user the option of reviewing the fatigue history at any moment of time In keeping an accurate account of the fatigue history this program is a vital tool for managing the coiled tubing strings without the risk of failure Coiled tubing goes through several plastic deformation cycles through it s usage in and out of wells The first deformation cycle takes place as the coiled tubing leaves the reel where the coiled tubing is deformed from being bent to being straight Next are two cycles of deformation while going through the gooseneck straight to bent and ben
7. weld factor in the database then see Corrosion and Weld Factors section Reel Geometry Data You must enter the dimensions of the reel Otherwise the program will report many errors during the fatigue computations You may wish to specify a name of the reel different to that of the string Material Properties With the exception of the minimum yield stress the remaining material properties are set to default values 30 000 Kpsi Young Modulus and 0 2833 bs in material density You may change any of these by typing the appropriate value Cable Capillaries Data As mentioned above this group of data is not used in the fatigue analysis However the same files created using this program are compatible with the Tubing Analysis System TAS Thus when using fluid circulation or force and stress analysis in TAS this data will be pertinent They are therefore included here for completeness 13 Entering Job Events Data When using FACT in AUTOMATIC MODE there will be no need for the user to enter data into the program The user simply has to ensure that the appropriate fields are assigned see FACT Modes of Operation Automatic and Manual On the other hand if the user wishes to use the program in post job analysis then the data can be entered either manually from a tally book record or directly from database files produced by the data acquisition system or software To enter the data manually there are again two options The
8. CT have exactly the same names as those in the database file then FACT will automatically assign them to the appropriate fields else the user should do this manually by clicking on the field name in AVAILABLE FIELDS and clicking on the appropriate assign button to match it to the required parameter in FACT When using FACT in real time the program will read data from the specified database file being produced in real time by some data acquisition system program such as DART If FACT is started after the creation of the real time database file then FACT will read 100 records at a time or to the end of file approximately every 5 seconds If the user does not wish to have real time or post job automatic data entry then the CANCEL button will remove this window and the program will entered in manual mode While in manual mode the user can still switch to automatic mode by selecting the menu option MODE gt AUTOMATIC Manual Mode In manual mode the user simply enters the job events and click the COMPUTE button or press the ENTER key on the keyboard and the computations are performed The events should be entered as they occur on the job FACT requires information regarding depth and tube pressure as well as information regarding corrosion gooseneck radius distance between reel and gooseneck coiled tubing geometry welds and reel geometry to compute fatigue In addition wellhead pressure and string weight are needed to compute tri axial stre
9. IMPORT OLD FORMAT function to import the strings reels The OPEN EXPORTED function is described in more detail in the SYSTEM MAINTENANCE section FACT Modes of Operation Automatic and Manual There are two modes of operation for FACT automatic and manual The automatic mode gets the data from a database file being created by a data acquisition system software in real time such as DART In this mode any changes that take place will activate the calculations of the coiled tubing fatigue All changes will be considered as actual depth changes or job events The DART program announces to WINDOWS the database file being used When FACT starts it searches for the current or last database file created by DART this information is available to all WINDOWS applications through the system registry FACT will then prompt the user to use the data in the most recent database file created by DART if applicable 1 e if DART does not exist then this procedure will be ignored Alternatively if the user wishes to use another database file then the browse button can be used to locate the file Getting External Database File Data l x Database Name C downloadstsapescorD1 01 Usversion 15045 mm Available Fields Depth Browse 2 Flow Rate Depth button 3 Flow Total iS Tube Pressure Pump Pressure Well Head Pressure Well Head Pressure Weight gt weight Cancel Assign button 10 If the parameters required in FA
10. OLS gt SPOOL CT Cutting CT E spooling Spool off a 20 C and back No another reel as spooling From length 5 feet To length 2151 feet opool to reel 17727 end reel core diameter inches nd reel width inches Weld BH LES moothie dressed butt weld Cancel 19 DataBase Corrosion and Weld Factors The corrosion and weld factors are stored in a database file called FACT mdb This file is compatible with Microsoft Access It is strongly recommended that any editing of this file be done from within FACT To edit either of the tables select TOOLS gt DATABASE gt CORROSION FACTORS or gt WELD FACTORS The supplied database includes corrosion and weld factors suggested in the literature and are not in any way considered comprehensive Coiled Tubing This database is provided to aid the user when entering data while creating a new coiled tubing string The database includes most known coiled tubing sizes The user may edit this database as required by going to TOOLS gt DATABASE gt COILED TUBING 20 Fatigue Cycles This option computes the number of cycles that a section of coiled tubing can go through before fatigue failure would occur A cycle is defined as a complete run in and out of the hole This option is used to get some idea of the effects of changing equipment size material properties and internal pressure To access this option select TOOLS gt FATIGUE CYCLES w Fatigue Cycles to Fail
11. al 1993 As can be seen within the elastic range the number of cycles would be in the order of 10 and more while in the plastic range the number of cycles is reduced significantly An equation of the form S aN bN P will sufficiently describe the upper bound curve of figure 4 The term aN represents the elastic range while the term bN represents the plastic range Since the coiled tubing is being used in the plastic range the first term of the equation can be neglected Hence we can rewrite the equation as S bN 6 The power index has a value of 2 Using empirical median life in cycles Nm and median fatigue strength Sm found by tests we can write an expression for the fatigue damage A caused by a stress cycle as _ S S A x 100 The value given in the literature for Sm is 1000 and for Nm is 130 As we have seen before the coiled tubing goes through 2 cycles of plastic deformation on the reel and further 4 on the gooseneck Each of these cycles induces axial stress which can be calculated as follows e Over the gooseneck the axial stress Sag 18 d E Sag 2R 8 Where R is the gooseneck radius e Over the reel the axial stress Sar 1S d E Sar m Dg m Where Dp is the reel diameter Effects of Pressure Internal coiled tubing pressure induces further hoop circumferential and radial stresses The additional stresses due to the internal pressure will adversely affect the coil
12. cted number of cycles while the other 50 are likely to fail before reaching the predicted number of cycles To increase the reliability of the predictions we need to consider a much higher reliability factor probably in the order of 95 Equation 7 can now be modified to include all the above factors l SIS Y x E x 100 A m 14 Using FACT Upon starting FACT the user is prompted to enter some job related parameters The job parameters required are the gooseneck radius the distance between the reel and the gooseneck the distance between the gooseneck to the stripper the bottom hole assembly length the coiled tubing string and the reel geometry data Job Related Data Gooseneck Radius Gooseneck Radius Gooseneck Radius inches Cancel Distance between Reel to Gooseneck Reel to Gooseneck Distance Distance of Reel to Gooseneck feet Distance of Gooseneck to Stripper Distance of Gooseneck to Stripper Gooseneck to Stripper feet Cancel Bottom hole Assembly Length BHA Length BHA Length feet Cancel a y Coiled Tubing String Reel RRF Strings Empty Reels String 0893 la la Cancel Import Old Format Open Exported The default values will be the same as last used and the default units are those selected in TOOLS gt OPTIONS If you have been using previous versions of the FATIGUE module such as TAS FATIGUE ANALYSIS or CTFATIGUE then use the
13. ed tubing life because they will increase the overall stress 1 e moving upwards on the Y axis of figure 4 Note however if no axial stress were present no movement of coiled tubing taking place simultaneously then the stresses due to the internal pressure will only be within the elastic range thus having an insignificant effect on the coiled tubing life The additional stress component due to the internal pressure can be computed as 2d P S d _ d 10 The total stress is computed using an empirical formula and is given as S S S e 11 Where m is a constant determined empirically Equation 11 is applicable to both cases of the stress over the gooseneck and the reel where S is the axial stress Effects of Weight The coiled tubing parts being held by the chain blocks support the weight of the coiled tubing in the well This part of the coiled tubing is not being subjected to any bending thus the stresses are only due to the weight of the coiled tubing and any additional stresses due to pressure However since in practice these stresses are always kept below the minimum yield stress the cycling in this section will not affect the coiled tubing life significantly Other Effects Material Strength Higher strength coiled tubing will be able to sustain more fatigue cycles This effect is included in a strength factor Fm which is a function of the reduction in area RA in fractions pe ind RA ds In 0 47 re 19
14. er date simply select the BROWSE button jm Coiled Tubing Fatigue Life History DD MM ATTY Life On 28 1 2 2004 12 07 33 Validate n Current From To Consumed Date feet feet Life Factor 2041222004 12 07 33 1 00 2041222004 12 07 33 1 00 2041222004 12 07 33 1 00 2041222004 12 07 33 1 00 2041222004 12 07 33 1 00 2041222004 12 07 33 1 00 2041222004 12 07 33 i 1 00 2041222004 12 07 33 1 00 2041222004 12 07 33 1 001 Total Footage 46363 Job 2871272004 12 03 40 28225 Job 26 72 2004 12 06 36 18137 5999240875 16 System Maintenance To export import a string reel data use the facility in FILE gt SYSTEM MAINTENANCE Y coiled Tubing Fatigue version 1 24 File Data Mode Tools Graph Window Help oe 3 Le 9 gt Biles Save Converted computed values ooo oca e US bee hey System Maintenance PF Export String F Import String Undo Exported String T Corrosion water Delete Current String a H25 Soure Gas present Delete Unused Reel COMPUTE PULL OUT This facility is particularly useful when you have several copies of FACT and one of them is being used as an administrator system keeping records of all coiled tubing strings reels in the company w Exporting String Strings string 125 C Program Files FALTADO c Please press OF to continue otherwise press exit Cancel OF When another user using another copy of FACT needs to work on a particular coiled tubing
15. fied to remain within the elastic range Figure 1 Hooke s law for the stress strain relationship If we were to substitute the values of the minimum yield stress and the Young modulus of elasticity for coiled tubing QT 700 say then we obtain a maximum strain of 7 3x10 E 30 x 10 psi a 70 000 psi CT outer diameter d Radius of Curvature R Figure 2 Geometry of coiled tubing when subjected to bending Effect of Equipment Size In figure 2 if we assume the radius of curvature over which the coiled tubing is being bent to be R and the coiled tubing outer diameter to be d then the length of the non deformed coiled tubing is given by d L 2x R 5 While the length of the outer side of the coiled tubing is given by L AL 27 R d Therefore the strain can be calculated as R fag D 2 6 20 Thus if we were to keep a 2 QT 800 coiled tubing typical for coiled tubing used in drilling applications within the elastic range at all times the radius of curvature must be greater than 31 2 ft This implies that the gooseneck must have a radius of 32 ft and the reel must have a core diameter of 63 ft Clearly such dimensions are not acceptable because of the costs involved in building such equipment and the difficulties of transporting them As a result the coiled tubing equipment is built with reasonable sizes which unfortunately dictates that the coiled tubing will suffer plastic deforma
16. first option would be to enter the data in the DEPTH and TUBE PRESSURE fields in the program s main form then pressing the ENTER key on the keyboard or using the COMPUTE button If corrosion effects are to be included then select the corrosive material from the list Y FACT 1 32 String String 101 on Reel Working Reel 101 Coiled Tubing History gt Fie Data M Tools Input Data Depth 3019 Tube Pressure 2 WH Pressure Weight Corrosion water H25 Sour Gas Canaan COMPUTE PULL OUT Add Ovality PS The second alternative for entering data manually is to select DATA gt EVENTS DATA and enter the job events in the table again selecting the appropriate corrosion factor where applicable w Job Events Graph Window Help r Converted computed values Converting to feet divide by yw Converting to psi divide byl lw Converting to psi divide by ip y Converting to lbs divide by Loo 0 00 0 00 0 20 0 00 0 20 0 00 13 80 15 00 1016 50 393 40 6015 50 Corrosion Factor J Direction Current Fatique Life Consumption 81 70 Water 694 60 Water 00 40 Water 694 60 Water 717 90 Water 280 20 Water 198 40 Water 554 50 Water 566 10 Water 1657 60 Water 1645 90 Water eee DO Ja Ee Pulling Out 1 696 COMPUTE FATIGUE 14 Ek A x Hea E a al e Job related information Gooseneck Radius 72 inches y Reel to Gooseneck Distance 130 feet Gooseneck to Strippe
17. hese can be accessed through the menu option TOOLS gt CUT CT Cutting and Dispose CT FACT allows the cutting and disposal of pieces of the coiled tubing The cutting is not restricted to the free end of the coiled tubing However if a cut is to take place in the middle of the string then the program will automatically prompt the user to add a weld Spooling Spool off spoolto C and back o another reel q spooling From length lo feet To length 75 feet opool to reel nd reel core diameter inches nd reel width inches Weld type No weld O K Cancel Spool and Cut If for example there is a need to remove a damaged portion by spooling the string to some empty reel or wooden spool then spooling back on the original reel then this can be achieved by selecting the Spool off and back on option Cutting CT spooling Spool off pal i and back another reel aes spooling From length 2200 feet To length 2350 feet Spool to reel y end reel core diameter 72 inches nd reel width 70 inches Weld type 5 moothly dressed bukt weld O K Cancel Spool to another reel This option is used for moving a portion or the whole length of a string from one reel to another with or without an existing string To use this option at least one coiled tubing string must be loaded while 18 the second may just be an empty reel or a reel with an existing string To load more than one reel use the menu option TO
18. pa E COC Co Modelling Engineering amp Development Company Limited Fatigue Analysis for Coiled Tubing FACT Version 1 xx O ch de 7 Convertingto pa divida by 1 w Reel to Gooseneck Distance 30 feel Converting to pa divide by ersliviy Citan op x Converting to bs divide by 1 gt os Curmulstive foctage E84 TriAvial Stress User Manual Courtenay House Monument Way East Woking Surrey GU21 SLY U K Tel 44 1483 750600 Fax 44 1483 762233 Email support medcotas com Home Page http www medcotas com Table of Contents O A 3 TheoreticaliBackoroUndao id iaa 4 ENector Equip IZ cio 4 BIlects OF Axial SUESSOn Faur uc Li Csaire EE AELE 5 AO A 7 A o E 7 A A A 7 Materai Tem Aie A 7 VVC A 7 MP ESEN 7 Rehabil or Empuical Data cms sitos 8 UA cacao oo orton cdas coo RO nu sOvaNAS 9 ln NA 9 GOO e Neck Rad US rasp ias 9 Distance between Ree 1o GOOSENC estado 9 Distance of Gooseneck to Sippel tal td 9 Bottom hole Assembly Len Ct dad A AAA AA A KEN inte ai 9 Coiled Tubing Stine REC rt A eel 10 FACT Modes of Operation Automatic and Manual oooooooonnnncnnnnnnnnnnnnnnnnnononononannnnnnnnnnnnnnnnonononnnnns 10 Converting to APLEpS HSK UASD A EEA EPEE 11 Creatina New SITIO iii 12 Entero Job Events Dalai O Ade III TUN 14 REVIEWS Sirine OS 16 System bic AAA a ed atta 17 Manipulating Coiled Tubing SEM lacio 18 CNG Oat DE OSS CU ss sis sais gases Wena tied estan eadeuaten amet antadt 18 SOOM iia MG Uos e e
19. r 32 feet Cummulative footage 46363 feet Tridxial Stress 162 psi Corrosion H25 Present If on the other hand the job events data were available from a data acquisition system or software program then this data can be imported directly into the JOB EVENTS table shown above To do this the data must be in a database format and the user can select the FILE gt IMPORT DATA FILE The same field assignments form will appear to ask the user to assign the appropriate fields to the parameters needed for the computations w Job Events Mer 26 12 2004 12 06 36 Open Job Events H25 Present Export Fluid Type H25 Present Import Data File eg DART data 21 70 Water 694 60 Water 200 40 Water 0 00 694 60 Water 0 20 717 90 Water 0 00 200 20 Water 19 80 198 40 Water 15 00 554 50 Water 1016 90 566 10 Water 993 40 1657 60 Water 6015 80 1645 90 Water COMPUTE FATIGUE Once the data has been successfully imported the COMPUTE button can then be clicked to compute the fatigue damage 15 Reviewing String History At any time the user can review the string history and if necessary revert back to an earlier date This is true as long as the string has not been deleted from the database To review the string history select DATA gt LIFE CONSUMPTION DATA and a table of the string history data will appear The Life Consumption data will be reflective of the current status of the coiled tubing To revert to an earli
20. sses The gooseneck radius the distance between the reel to gooseneck distance of gooseneck to stripper and BHA length are information required only once for any one job Similarly the coiled tubing string geometry and history the welds and the reel geometry are only required once Converting to API English units FACT does all the computations using API English units These are feet for depth and psi for pressure Thus if non API English units are being used in both operation modes the appropriate conversion factors should be selected or entered FACT by default assumes a conversion factor of 1 or whatever the user previously used Conversion factors for meters to feet kPa to psi and MPa to psi are included in the lists When finishing a job the user should select the PULL OUT button to finish then SAVE to save the history of the string 11 Creating New String To create a new string select FILE gt NEW a blank data form will appear There are three options frames and five data frames within the form Initially however you will only see four data frames as the last one is dependent on the Cable Capillaries option Edit input CT Data ES f API English API Metric gt Cotes Fang Siang Data String Marne Untitled Click here to select LT Curnmulative Component Outer Dia Wall Thick Min Yield Length Mame inches inches pel peit Date Young Modulus K pal 30000 Click here to select weld
21. string reel the string reel can be exported from the administrator copy onto a separate file which can be named anything with or without an extension then copied across to the user s computer or workspace The file can then be directly accessed using FILE gt OPEN and then selecting OPEN EXPORTED The string reel can then be used to update the coiled tubing history real time or manual Finally when finished the string reel can be imported back into the administrator s copy w Importing exported String a ES Of x Strings string 001 C Program Files FACT strO01 Please press OK to continue othermize press exit Cancel OF To revert back to the original string reel data as it were on the administrator s records use the UNDO EXPORTED STRING If data related to a coiled tubing string is no longer needed then the string can also be cleared to simplify the system maintenance Load the string then go to FILE gt SYSTEM MAINTENANCE gt DELETE CURRENT STRING Similarly if a reel is no longer in use then the data related to the reel can be removed by going to FILE gt SYSTEM MAINTENANCE gt DELETE UNUSED REEL Note though that this option will only apply to an empty reel Thus the string associated with the reel must be removed first 17 Manipulating Coiled Tubing Strings Several functions exist in FACT enabling the user keep track of various tasks that can be implemented on the coiled tubing string T
22. t to straight These cycles are experienced both ways i e when going into the well and when pulling out of the well Thus the total number of cycles of plastic deformation will be six During a coiled tubing job the coiled tubing is further cycled by the operators when performing a pull test for example But some of these may work part of the coiled tubing over the gooseneck only and other parts that may have left the reel would go back on the reel but do not reach the gooseneck Thus to have an accurate record of the cycles knowledge of the distance between the reel and the gooseneck is required The above is only concerned with plastic deformation of the coiled tubing due to axial loading and unloading The axial forces impose axial stresses that are in excess of the material minimum yield stress However our concern is the total stress and not just the axial stress Thus internal pressure corrosion and stress concentration due to welds and or presence of HS sour gas all become pertinent A special technique is utilized to account for each of these effects The internal pressure will change the hoop and radial stresses and these can be simply calculated and thus the total stress computed accordingly Corrosion and stress concentrations are more difficult to account for Corrosion will normally reduce the wall thickness of the coiled tubing however we do not have an exact measure of how much wall thickness is lost and until such measures
23. tion Effects of Axial Stress on Fatigue Life As a result the coiled tubing is subjected to stresses higher than the minimum yield stress when travelling from the reel to the gooseneck and from the gooseneck into the injector as shown in figure 3 During this journey the coiled tubing is subjected to 3 plastic deformation cycles and on the journey out of the well a further 3 plastic deformation cycles are experienced Bending events 2 and 5 Bending events 3 and 4 Bending A Figure 3 Plastic deformation cycles of coiled tubing during running in and pulling out of a well Figure 4 shows the effects of stresses on the number of cycles that could be attained before fatigue failure ensues The figure shows two curves intersecting at the point corresponding to the normalised minimum yield stress on the Y axis To use this figure the normalised stress should be determined first then go across horizontally until intersecting with the upper of the two curves Sas J aworsky I Alexander Coiled Tubing Operations and Services Part 3 Tube Technology and Capabilities World Oilm Feb 1992 Avakov V A Foster J C and Smith E J Coiled Tubing Life Prediction OTC 7325 25 Annual OTC Houston May 1993 1 E 04 1 E 03 1 E 02 1 E 01 NT 1 E 00 1 E 01 1 E 02 1 E 03 1 E 04 1 E 05 1 E 06 1 E 07 Stress Range S Fatigue Life Cycles N Figure 4 Low cycle S N Line Avakov et
24. ure Cie Conver Li To f API English API Metric API English Select colled tubing 1 5 0 095 CT Outer Diameter oo inches Wall Thickness 09 Inches Reel Diameter 2000 Inches Gooseneck Radius 72 00 Inches Select Minimum eld 70000 pal internal Pressure Range From fo To 5000 00 psi DRAW CHART 21 Program Options Several options may be changed through the menu option TOOLS gt OPTIONS These options are mainly to give the program the look and feel that best suits the user This option is protected by a password FACT to prevent un authorised access In addition there are some constants that are used in the fatigue computations The constants are used in the equations mentioned in the Theoretical Background section of this manual As these can have a dramatic effect on the calculations it is strongly recommended that no changes be made to the constants without consulting with MEDCO first To see the current constants settings the Program Options window must be vertically stretched then click the SHOW CONSTANTS button Again this is deliberately hidden to prevent un authorised access The equivalent parameters in the equations of the Theoretical Background section are as follows e P_i min equation 11 Q_ Factor is the reliability factor N_m used in equation 7 S_m used in equation 7 S_p used in equation 11 w Program Options Ez Owner Company Medco Default Units AFI English
Download Pdf Manuals
Related Search