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1. 3 3 D7 Sarine HOTOT cm 3 4 DB MOURNE MGS HOTPOT i cem 3 4 HOOT TUON rer raser E ren E ea 4 1 DLL cInettorab data STE cots oed nv satan ate alee nais adsense LIN DE M LUE 4 Ag Primary dala T P STESEE REDE 4 ANd PAU MIA Ata dosuet Du opido i qvasi En a od opus Ped ERE DEER std n RARE FEEL SES 4 2 TD CPU A CAA RP 4 9 4 2 Tutor Modei I sous e tdi e OD Ma enim Pa eS steiaceTewaadatetpaieecistamaeeicics 4 9 Mus eil E e 4 32 4E UEP IAL IMI OA CLS oeste t o Ret ordi Msc tdem EIL MIL LUE 4 45 Contents MEE 4 55 4 5 Interpretation eeeennnne temen Kw 45 1 General statement csccsecscssecsecssesssneensenenneenntnntassnnsnnsnne ne tee mimm 4 5 2 Preliminary hydrocarbon prospectivity assessment eene nene nennt 4 56 4 5 3 Significance of temperature maps 4 57 5 Reference to HOTPOT version 3 0 for WIndows itene ierann nE E iii ae 5 1 5 1 Windows menus and dialogues nnne 5 1 5 2 General information eerte nnne nnne nete enne trennen ener enne 5 1 5 3 Common dialogues eren nnne nnne nnne 5 2 5 3 1 The File Selector dialogue ennt 5 2 5 32 The File List dialogue seeseeennneeneenennenennenernnnennnennnnenetn nennen ennt 5 2 5 3 3 The Print dialogue nnnn een ennenenntne nnne 5 3 5 3 4 The Printer Setup dialogue eeesseereseresertnerererererreeorereritorensnsnererensrereetsernerereaersrene
2. BLO OO HtPot File Settings Calculate Display Help File Style REFERENCE COPY 92 13 Cs py wit D telik British Geological Survey International Division Bas n Thermal Modelling using HOTPOT HotPot Layer temperature X 162 6 Y 7 5 vja ost CACO LIRLLI LL TSLLS L etme x File Style Limits Tollerton Formation 220 0 over mature 152 0 154 0 dn mature Prepared for the Overseas Development Administration ODA Technical Report WC 93 04 Natural Environment British Geological Survey Council Keyworth Notts UK British Geological Survey Natural Environment Research Council Technical Report WC 93 04 International Geology Series Basin Thermal Modelling using HOTPOT version 3 0 W J Rowley R A Chadwick and D W Holliday Tectonics and Database Group Subject index Basin analysis computer modelling geothermal studies hydrocarbon maturity hydrocarbon prospectivity Bibliographic reference ROWLEY W J CHADWICK R A AND HOLLIDAY D W 1993 Basin Thermal Modelling using HOTPOT version 3 0 British Geological Survey Technical Report WC 93 04 This report was prepared for the Overseas Development Administration HOTPOT is a trademark of the British Geological Survey NERC Copyright 1993 Keyworth Nottingham British Geological Survey 1993 Contents Introduction ccceccssescsssceccscscsecsssecsseosscnessscserssoneeosecesessacssagonssoccsenacenssesoessas
3. These displays complete the backstripping and decompaction part of the program 4 18 HOTPOT Tutorial Layer density Tullerton Formation at 10 08Ma 3 EPIS hurt a Ard eee Coco LE PO GS Lo f Un Un Cn Cr WOT LLON OUN Gb UA QD CO QUGD COCOQ CO UGG CD W e m d 9 Y e v f 5 13 1 8 13 mean 2 38993 Figure 4 22 Adding annotation to displays HOTPOT has a facility to draw geographic features such as coastlines rivers etc on the grid maps This is called annotation The co ordinate data e g digitised coastline are stored in annotation files The format of annotation files is described in Appendix II 3 An example annotation file coast dat is supplied with the Tutorial data set Choose File menu from the HOTPOT Main Window menu bar Choose Annotation option A file list dialogue opens for you to select one or more annotation files Choose coast dat from Files list The full file path name c tutoriahcoast dat is copied into the Selected files list in the top half of the dialogue Fig 4 23 Choose Ok button The file list dialogue closes The selected annotation file is stored within the program Choose Display menu Options appropriate to the currently selected age or layer button will be enabled Choose a map display option e g The chosen data are displayed as a map in a grid display Layer thickness window Choose Style menu This drop down menu contains options w
4. Now all three layers of the model have been loaded and have their thermal properties defined The auxiliary data tables have been loaded You are ready to compute the basin history Carry out the instructions given in The thermal conductivity settings will be copied from the layers section 4 2 5 for decompacting the loaded to the layers created during backstripping model 4 3 7 Confirm that settings have been copied Select Tollerton Formation button under 20 Ma button Choose Settings menu Choose Conductivity option The Set Thermal Conductivity dialogue is opened for the Tollerton Fin at 20 Ma Note that the Depth variable radio button is already selected Choose Cancel button or press ESC Close the dialogue without making any changes key 4 3 8 Display of the backstripped data Carry out the instructions given in These displays should be the same as the ones for Model 1 as section 4 2 5 for display of the parameters affecting the decompaction calculation have not been backstripped data changed 4 3 9 Setting the age related thermal parameters for 0 Ma Now you need to set further thermal parameters in the program These parameters change during basin evolution so they are defined explicitly for each time calibration point Firstly the heatflow data will be input to HOTPOT In this Tutorial a heatflow map is available for the present day Fig 4 4 this needs to be anchored to the 0 00 Ma time calibration point Select
5. b Recompute the layer thicknesses using the new densities c Recompute the layer densities using the new thicknesses d Repeat b and c until the change in thicknesses is negligible this normally requires no more than about five iterations Decompaction with the top layer removed is now complete e Repeat a to d stripping off successive top layers until the entire sequence has been decompacted It is important to remember that the process of backstripping is a synthetic procedure designed to invert the real process of compaction In the real world sediments do not actually decompact as they are uplifted they tend to retain the porosities and thicknesses characteristic of their maximum depth of burial The basic backstripping procedure outlined above has to be modified to take this into account when eroded layers are present The compaction of layers beneath the eroded layers is determined by their maximum depth of burial this may have occurred during burial beneath the eroded material rather than beneath the present day overburden On encountering eroded layers within a succession HOTPOT computes and compares the relative thicknesses of eroded material and existing overburden If the thickness of eroded material is the greater the layers below are not decompacted Any eroded layers are restored at the appropriate times in the basin history In basins with long and complex geological histories there may have been more than one episod
6. 1760 1440 1600 1280 1440 1120 1280 960 1120 800 960 640 800 480 640 320 480 160 320 0 160 mean 604 582 164 0 166 0 Figure 4 44 4 38 Choose the gridding window File menu Choose Save option Type ruddinga into File box then choose Ok button or press RETURN key Choose Accept button Choose Settings menu Choose Conductivity option Select Depth variable radio button Choose Ok button Tollerton Formation HoTPotT Tutorial The file selector offers an automatically generated unique file name You replace this with a more meaningful name The file selector closes and HOTPOT saves the grid data into the file ruddinga hpg The grid is accepted and the gridding window closes The HOTPOT Main Window shows a Ruddington Fm layer button below the Keyworth Fm button The Ruddington Fm button has its name in white text to indicate that it is selected Opens the Set Thermal Conductivity dialogue for the Ruddington Fin Links the depth thermal conductivity table to the Ruddington Fin at 0 Ma present day Closes the dialogue and completes the setting In loading the data for this layer you may either enter the layer information yourself or use a file of layer information which we prepared for you Here you will experiment with the effects of differing search radii on the grids produced from the data set Choose File menu Choose Layer option To enter layer information you
7. 220 0 was 150 0 oil 100 0 under mature Figure 4 29 Choose grid display window File The grid display window closes and the HorPor Main Window menu then choose Close option is redisplayed Choose Display menu Choose Layer conductivity option A map of the computed thermal conductivity of decompacted Tollerton Fm at 10 Ma is shown in a grid display window Fig 4 30 The map can be printed by choosing File then Print Choose grid display window File menu then choose Close option By selecting the other layer buttons it is possible to obtain temperature maturity and thermal conductivity displays of all the layers available at any age as required These display options comprise the basic grid map output of a complete HOTPOT modelling session 4 2 13 Additional display options In addition to the grid map displays other display options are available within HoTPOT The most important of these involve the extraction of information about individual grid nodes giving local 1 D burial and thermal history plots aca Layer conductivity Tollertun Formation at 10 00Ma Ele Style Limits Age related display options Select 0 00 Ma button Choose Display menu Choose Loaded thickness option Move the cursor to any node on the grid and click the left mouse button to select the node HorTPoT Tutorial oa e e Qu eh et metres en anb en INO SOOO PO LO 4 ND GU Ja U 1 CO LO C2 GU da Ul ant ord m c NT INI NO NO
8. 12 light blue 13 light magenta 14 light cyan 15 white Any other entries in the colour palette will depend on factors outside the control of the HOTPOT program and are therefore unlikely to be consistent II 4 Grid data save files To illustrate the format here is an example grid data file for the small 4 rows x 4 columns 16 nodes grid shown in Figure II 1 Globals Titles Example Grid Grid cols 4 rows 4 Xmin 1000 Xmax 4000 Ymin 6000 Ymax 9000 Zmin 2 25 Zmax 3 5 Znull 9999 t G2 BO PO NO Co NO NO SO GU NO PO BU C9 uu NO SO ec 9000 Ymax 6000 Ymin 1000 4000 Xmin Xmax Figure II 1 11 6 HOTPOT data file formats These files are used to store grid data extracted from HOTPOT by selecting the Save option from either the Gridding Window or a Grid Display Window File menu The data from such a file may be read into a HOTPOT grid by selecting the Load option from the Gridding Window File menu The files may also be read by other computer programs such as data visualisation packages Grid data produced by other computer programs such as mapping and contouring packages may be translated to this format and then loaded directly into HOTPOT grids The recommended file type is HPG This file format has proved useful in a number of British Geological Survey computing applications that use gridded data The format includes features needed for some of these other applications
9. COINS 7 0 SN e 8 0 160 0 161 0 162 0 163 0 164 0 165 0 166 0 essa Area of anti masking contours 4 8 HotPot Tutorial 4 1 3 Optional data The area of interest Aol co ordinates and grid spacing can be input to HOTPOT by the user but for convenience are also stored in the file cMutoriaNutorial aoi Map annotation data in the form of a digitised coastline are stored in the file c tutorial coast dat 4 2 Tutorial Model 1 This is a basic model with no erosion and single value constant heatflow The modelling session is designed to provide you with an overview of the HOTPOT program and makes use of prepared data files wherever possible 4 2 Set the model title Start the HOTPOT program using the You should have the HOTPOT Main Window on the screen method described in Section 3 7 Choose Settings menu This drop down menu is used to set the model parameters Choose Title option This opens the Set Title dialogue Type Model 1 into the Title box then This sets the model title Fig 4 6 The HorPor Main Window is choose Ok button or press RETURN redisplayed with the new title shown on its caption bar key Figure 4 6 4 2 2 Define the area of interest Choose Settings menu Choose Area of interest option This opens the area of interest Aol dialogue The necessary data can be either entered directly from the keyboard or as in this Tutorial loaded from a previously saved file Choose Load button This ena
10. Formation Tollerton Formation Age 25 00Ma at base Lithology MDSLST Water depth 30 0m at end of deposition Isopach files e tutorial toller iso Basin history Period 0 00Ma Surface temperature 30 0 C Constant heatflow 80mW m Formation Keyworth Formation Thermal conductivities calculated from depths Formation Ruddington Formation Thermal conductivities calculated from depths Formation Tollerton Formation Thermal conductivities calculated from depths Period 10 00Ma Surface temperature 30 0 C Constant heatflow 80mw m Formation Ruddington Formation Thermal conductivities calculated from depths Formation Tollerton Formation Thermal conductivities calculated from depths Period 20 00Ma Surface temperature 30 0 C Constant heatflow 80mw m Formation Tollerton Formation Thermal conductivities calculated from depths Period 25 00Ma Surface temperature 30 0 C Constant heatflow 80mw m HOTPOT Tutorial 4 2 12 Display of thermal model results Display control is similar to that described for the backstripped sequence 4 2 6 The thermal results are all layer related To cnable the layer related options select the desired layer button for example Select Tollerton Fm button under The text label of the button changes to white to indicate selection 10 00 Ma button Choose Display menu In addition to the earlier options 4 2 6 Layer conductivity and Layer temperature are now enabled black text
11. IC 0 99 791 11 539 0 99 790 11 565 0 99 789 11 591 0 101 352 12 056 101 378 12 048 101 403 12 045 101 428 12 044 101 440 12 043 IC 500 99 994 11 646 0 99 999 11 672 0 100 010 11 701 0 100 018 11 727 0 100 027 11 754 0 wooooo All blank lines in the file are ignored their use is recommended to improve readability of the file All text on a line to the right of an exclamation point or a hash is treated as comment and ignored The use of comments is recommended as aides memoire to the data contained in the file e g its source and purpose The first line is a contour value record This begins with the pseudo comment C The contour value then follows on the same line For example in the extract the first contour value record is C 0 which indicates the start of the 0 zero contour and the second is C 500 which indicates the start of the 500 contour Following each contour value record are two or more records each containing three values The first value is the X co ordinate map easting or longitude the second is the Y co ordinate map northing or latitude and the last is the flag number The values are read in free format Each such record represents a digitised point on the contour The last point on the contour conventionally has the flag number 9 although this is not strictly necessary as the HOTPOT program does not use the flag number but recognises the end of a digitised contour by either encountering a
12. IV 6 UMU XNTZ Jeoy Notes on estimation of palaeoheatflow in extensional basins 20 40 60 80 100 time since extension Ma Figure IV 6 Heat flux at the base of the lithosphere as a function of time for various values of B IV 7
13. Local memory usage should not be excessive and should not cause problems The amount of global memory available is controlled by the Windows operating mode In modes other than 386 Enhanced Windows does not support virtual memory This will restrict the size of model which can be processed in these modes both in terms of number of layers and grid spacing within each layer In 386 Enhanced mode virtual memory is available and there should be no problem with number of layers Choose the Ok button to acknowledge the information 5 18 Reference to HOTPOT version 3 0 for Windows Help About HotPot May be chosen at any time Choosing this option displays a dialogue giving the version number and other information about the version of HOTPOT being used This dialogue is automatically displayed when the program 1s started Choose the Ok button to acknowledge the information 5 5 The Graph Display Window This type of window is used for displaying depth density data depth thermal conductivity data and 1 D basin history displays as in Figure 5 17 File Style Figure 5 17 A Graph Display Window is sizeable and moveable and may be minimized or maximized The graph displayed within the window may be zoomable or scrollable depending on the style setting These windows are owned by the HorPor Main Window and will always appear on top of the HOTPOT Main Window Any of these windows remaining open when either the New option is c
14. ee PNIS rta LE es Mr PA SA ok TEEN US oo a INI EEA ELIT EEL NISI PA PPC NLL LS i JR ae pu tate Na EE a Ro A oe Sa ERE bie he Oe ee E et a ee ey tee Ce ee ee eee eee eee eee ee ee ee re es 20 200 300 400 C Cermak amp Bodri 1986 Sekiguchi 1984 Somerton 1982 Ce es Figure 1 5 l 5 APPENDIX II HOTPOT data file formats General The HOTPOT program uses several types of data file 1 depth data table files 2 digitised contour files 3 annotation files 4 grid data save files All these files are ASCII text format Therefore they can be manipulated using standard text editors e g Windows Notepad or word processors e g Windows Write in non document mode They can also be printed out This appendix describes the format of these file types in order that users can prepare their own data for use with the program 11 1 Depth data table files The depth data table file format is used for storing digitised depth density curves and digitised depth thermal conductivity curves A depth data table is simply a list of depth values and corresponding observed data measurements for a specific lithology Several such tables may be incorporated into one file The recommended file types are DDT for depth density data and DKT for depth thermal conductivity data To illustrate the format here are some extracts from a depth density table file for u
15. either can be displayed by choosing it Choose Layer temperature option A map of the temperature of the base of the Tollerton Fm at 10 Ma is shown in a grid display window Fig 4 28 Note that nodes in the temperature grid are sct null where corresponding nodes in the thickness grid are zero i e temperatures are only displayed where the layer is present Compare figures 4 21 and 4 28 Cotten ad Layer temperature Totlerton Formation at 10 00Ma b eed amb amb et eed i e CoU JS UO COD UD C2 POCO Aa C 1 E E E E E EEE EEI DSS DODOSO d co Coe w amp C O1 OS CO UD eb anb cr cm mah oh cee cuoc na ocu MW 3 a 2 amd Figure 4 28 If you have a printer available on The temperature map is printed your computer Choose File menu from the grid display window then choose Print option In addition to the C temperature scale it is possible to display the temperature grid on a thermal maturity scale Choose Limits menu This drop down menu allows you to specify the limits of the colour scale used to draw the map HOTPOT Tutorial Choose Pseudo maturity option A map of the level of organic maturity is displayed in the window Fig 4 29 The map can be printed by choosing File then Print Note that this pseudo maturity scale is based solely on the temperature of the selected layer It is not a TTI type maturity scale Layer temperature Tottertun Formation at 10 00Ma Ele Style Limits SAE aniio
16. 0 160 0 161 0 162 0 163 0 164 0 Figure 4 1 Keyworth Formation Top Isopach map contours in metres Bottom Digitised isopach data file keyworth iso 10 0 9 0 ad 0000990 XXX x 9999990000000 2909 7 0 0 160 0 161 0 162 0 163 0 164 0 4 3 165 0 166 0 165 0 166 0 HOTPOT Tutorial 10 0 9 0 8 0 7 0 6 0 160 0 161 0 162 0 163 0 164 0 165 0 166 0 a eq ees Coastline Figure 4 2a Ruddington Formation Toy Original isopach map contours in metres Bottom Digitised original isopach data file ruddingo iso 10 0 oo aec nen a 9 0 NU OO eee goad 0 ocmoenonag 3307 d Ody xx 3 xxx st OO 0000000 99006 o 9 9 o ewe a 7 0 6 0 160 0 161 0 162 0 163 0 164 0 165 0 166 0 Area of anti masking contours 4 4 HOTPOT Tutorial 10 0 9 0 8 0 7 0 8 0 160 0 161 0 162 0 163 0 164 0 185 0 166 0 VV Ran CERAM ey Coastline Figure 4 2b Ruddington Formation Top Isopach map with additional control contours contour values in metres Bottom Digitised isopach data file ruddinga iso 10 0 m e A e A A m A 90000990000000000090000 ta 9006 oo o9 9 0 o ett Ske cO c boOcceDonog M n 90 a ya X LOOO SI P 0000000 206 7 0 8 0 160 0 161 0 162 0 163 0 164 0 165 0 166 0 Area of anti masking contours 4 5 HoTPoT Tutorial 10 0 9 0 8 0 7 0 6
17. 0 160 0 161 0 162 0 163 0 164 0 165 0 166 0 S Coastline Figure 4 3 Tollerton Formation Top Isopach map contour values in metres Bottom Digitised isopach data file toller iso 10 0 ye N J x 9 0 P 4 E d v o E d ta o t p o M i 9 a i E e wee M coo tee e c 3 Co 8 0 N t 5 9o 4 N C wor c x Ee FOER EUM A c c i e Da i nx e i MI e oy i A Cc 1 S i l 7 0 og 3 e d o 1 ua 6 0 Pr 160 0 161 0 162 0 163 0 164 0 165 0 166 0 ssesPeuss Area of anti masking contours 4 6 HoTPoT Tutorial 10 0 9 0 8 0 7 0 6 0 160 0 161 0 162 0 163 0 164 0 165 0 166 0 Figure 4 4 Present day heatflow map Top Heatflow contour map contour values in mW m Bottom digitised contour data file heatflow iso 10 0 x x xX xxx D OCocgogpCc Xxx x x xx x 247 o I000ppoo0 9 6 9 9 626 x v 4 6 0 7 7 0 x C c XX x x x y x x x x X X pic erm le PDPOODDbOD5boS ogcoc P 4 6 MAREA EAE RE DS SEE EDR 6 0 160 0 161 0 162 0 163 0 164 0 165 0 166 0 4 7 HOTPOT Tutorial 10 0 9 0 8 0 7 0 6 0 160 0 161 0 162 0 163 0 164 0 165 0 166 0 pind esate RENSES Coastline Figure 4 5 Bingham Member eroded topmost part of Ruddington Formation Top Isopach map contour values in metres Bottom digitised isopach data file bingham iso 10 0 9 0 8 0 0
18. A Print dialogue box will be displayed during this process The representation of the grid map on the printer depends on the selected printer and its configuration These can be changed either by choosing the Printer Setup option from this File menu or by using the Windows Control Panel described in Chapter 5 of the Microsoft Windows User s Guide Most dot matrix and laser printers will attempt some sort of grey scale representation of colour see Style menu Normal colours and Alternate colours options File Printer setup Choosing this option invokes a dialogue which allows printers to be selected and configured See description of Printer Setup dialogue under common dialogues section 5 3 4 When a Windows 3 printer driver is in use HOTPOT will by default print text reports using portrait page orientation and graphics using landscape page orientation If the page orientation is changed by choosing Printer setup from a HOTPOT Grid Display Window File menu only the orientation of graphics will be changed File Close Choosing this option closes the grid display window and returns to the HOTPOT main window The same effect can be achieved by double clicking the grid display window system menu button at the left end of the caption bar Style This is a drop down menu with the following options small Crosses grid cells shown as coloured small crosses Large Crosses grid cells shown as coloured large crosses Filled C
19. ALT initial letter keys together Point to and single click 3 4 Windows operating modes A comprehensive discussion of Windows operating modes is beyond the scope of this Manual The interested reader may refer to either Chapters 1 amp 13 of the Windows User s Guide for Windows 3 0 users or Chapter 1 of Getting started with Microsoft Windows and Chapter 14 of the Windows User s Guide for Windows 3 1 users for more information Briefly Windows has either two or three operating modes Real used mainly for compatibility with old Windows 2 0 applications and on small PC systems with 1Mb or less of RAM Windows 3 0 only Standard used where virtual memory is not required Windows 3 0 and 3 1 386 Enhanced used where virtual memory is required on PC systems which have an 80386SX 80386DX 804865 X 80486DX or 80486DX2 processor Windows 3 0 and 3 1 Although the HOTPOT software will work in any Windows mode it is designed for use with Windows in 386 Enhanced mode so that the Windows virtual memory manager is available This is SECTION 4 HOTPOT Tutorial 4 1 The tutorial data set 4 1 1 Primary data In the tutorial an imaginary sedimentary basin is modelled The basin fill comprises three stratigraphical units Isopach contour maps of these units are illustrated in Figures 4 1 4 2 and 4 3 The oldest unit the Tollerton Formation was deposited between 25 and 20 Ma ago and comprises the syn rift part of the b
20. Choose ruddinga lay from Files list Choose Ok button Choose the gridding window File menu Choose the Load option Choose ruddinga hpg from Files list Choose Yes button Choose Accept button Choose Settings menu Choose Conductivity option Select Depth variable radio button Choose Ok button Tollerton Formation Choose File menu Choose Layer option Choose Load button Choose toller lay from Files list HOTPOT Tutorial The layer information dialogue opens A file selector dialogue opens Layer information is loaded from file ruddinga lay The layer information dialogue is redisplayed with the information shown The gridding window opens A file selector dialogue opens This was the file saved when gridding the Ruddington Fin during Model 2 section 4 3 5 The file selector dialogue closes and HOTPOT loads information from the ruddinga hpg file It then opens the Grid Confirmation dialogue which shows both the name of the required grid and the name of the grid in the file you selected these should be the same and asks you to confirm that this is the grid you want to use HOTPOT loads the grid data into the layer grid and displays the grid map The grid is accepted and the gridding window closes The HorPor Main Window shows the Ruddington Fm button it is selected Links the depth thermal conductivity table to the Ruddington Fm at 0 Ma present day The layer information dialogue
21. IND RICO Za UT CD US C2 ta 4a Ul ON MOON b CO CO COO e E E E 5928555554 5 DON AaATTDONAaATNDOON d mean 1 8555 Figure 4 30 A map of the total sediment thickness at 0 Ma present day is displayed in a grid display window The X Y co ordinates and thickness value Z of that grid node are displayed at the right of the window menu bar Fig 4 31 Double click the left mouse button while keeping the cursor on the selected grid node Figure 4 31 The burial history curve total sediment thickness against time of the grid node is drawn in a graph display window Fig 4 32 This window now becomes the active window This corresponds to the burial history of the base of the bottom layer Tollerton Fm at the grid node The graph may be printed by choosing File then Print 4 27 HOTPOT Tutorial OOOO hoia Mose 6 Style 24 22 20 18 16 14 0 i mi THT Choose graph display window File menu then choose Close option Choose grid display window File menu then choose Close option Layer related display options Select Keyworth Fm button under 0 00 Ma button Choose Display menu Choose Layer thickness option Move the cursor to any node on the grid and select the node by clicking the left mouse button Double click the left mouse button while keeping the cursor on the selected grid node Loaded thickness 0 00 Ma Loaded thickness X 162 5 Y 7 5 0001 12 10 8 Figure 4 32 Th
22. PME Erebi CUTE NEUE Ce Atl propo oan rep LLLI is re n 73 7 nd EP so SELE tm APTIAN UNC gu he 3 Al Twt oec 7 ine 25 a ME X x an i ai i 3 a ut D pou CSS e T ET posteo S ee ENN a Figure IV 2 Examples of syn rift and post rift sequences a East African Rift System after McClay 1989 b East Canadian Shelf after Welsink et al 1989 IV 4 Notes on estimation of palaeoheatflow in extensional basins SI ee ee eee ee Pe ES tc N NEN LLL Lu od pt voto w e cC CLE 1000 C im r Baseoflithosphere Ti 1 2 TN NER ERES NNN DT TT Moho _ COOLING eta ro EEK ERE 1000 C SSS SS SS AS ee COOLING eh ieee a ce Dc ee Ee ge Re ee TL uen m ee mL AC eS HE dm umo AME MES m m CREER EA Figure IV 3 Uniform extensional thinning of the lithosphere giving syn rift subsidence S Thermal re equilibration cooling gives a further post rift subsidence Srp IV 5 a Notes on estimation of palaeoheatflow in extensional basins overlap overlap unconformity Figure IV 4 Syn rift and post rift subsidence phases giving a steer s head basin profile TIME SINCE RIFTING M Y 0 100 200 ST 1 B 1 25 2 x STR w 3 O B 166 a Ww a y 4 q 7 Bx 25 5 B 3 25 6 7 Figure IV 5 Predicted sediment starved subsidence curves for various values of B
23. The Windows interface provides the user with a flexible method of controlling these processes Contour maps depth isopach and heatflow data are a useful representation of spatially varying data for geologists but they are not readily manipulated by computer For computational efficiency spatially varying data are better represented in terms of values at the intersections nodes of regularly spaced grids For the spatial variation of different data types in an arca to be compared the grids used must have the same geographic limits and node spacing this is done by using a common area of interest specification The resultant overlaying gridded layers thus define the 3 D stratigraphical architecture and heatflow of the basin Each basin grid node has geographical x y co ordinates and several thickness and heatflow values corresponding to the layers through which it passes Fig 2 1 Thus each basin grid node holds the 1 D stratigraphy and burial history of that particular location Digitised contour maps input to HOTPOT are gridded using a distance weighted moving average algorithm described in Appendix III Nodes which lie outside of the basin i c where data are not defined have a NULL value 2 2 1 Decompaction by backstripping Layer by layer decompaction As stratigraphical sequence is laid down the sedimentary layers are progressively compacted by the weight of overlying strata Consequently present day preserved thicknesses
24. Y co ordinates increase a south to north Where longitude and latitude are used the origin is the intersection of the Greenwic Meridian 0 longitude with the Equator 0 latitude longitudes west of the Greenwich Meridian and latitudes south of the Equator are indicated by negative numbers II 3 Annotation files These files are used to store digitised line work which is to be plotted as overlays on displayed maps e g coastlines The recommended file type is DAT To illustrate the format here is an example of an annotation file an example of a digitised annotation file part of COAST DAT from the Tutorial data set 160 007 8 086 0 160 058 8 114 0 160 096 8 164 0 160 135 8 214 0 161 132 9 981 0 161 144 9 999 9 161 692 10 000 0 161 729 9 946 0 All blank lines in the file are ignored their use is recommended to improve readability of the file All text on a line to the right of an exclamation point or a hash is treated as comment and ignored The use of comments is recommended as aides memoire to the data contained in the file e g its source and purpose The file contains two or more records each comprising three numeric values The first value is the X co ordinate map easting or longitude the second is the Y co ordinate map northing or latitude and the last is the flag number The values are read in free format Each record represents a digitised point on an annotation line The last point on a line has t
25. are accomplished and the order in which they are done certain restrictions are imposed by the nature of the modelling process Briefly Basin modelling with HOTPOT The area of interest must be defined before layer information can be added because it is needed for the gridding process The decompaction calculation can only be performed when all layers have been defined and the density vs depth table has been loaded because both data sets are needed for the calculation Once the decompaction calculation has been performed the layer structure cannot be altered Thermal property values must be assigned to layers and time calibration points before the geothermal calculation can be performed because these data are needed for the calculation A thermal conductivity vs depth table must be loaded before the optional depth variable thermal conductivity values can be used in the geothermal calculation Heatflow data must be gridded and the grids attached to time calibration points before the optional gridded heatflow data can be used in the geothermal calculation The user interface is designed to control the order of events by enabling or disabling selectable activities according to the above rules The thermal parameters may be altered after the thermal calculation has been performed However this invalidates the results of the calculation so it must be performed again to bring the database up to date This is the key to the usage
26. are in general lower than original depositional thicknesses the greater the depth of burial the greater the discrepancy In order to compute the true subsidence history of the basin it is necessary to correct for this effect This is done by progressively decompacting the sediments by a procedure known as backstripping In HorPor backstripping is carried out on a node by node basis giving 1 D sediment decompaction at each grid node The backstripping method in HorPoT utilises the fact that as sediments are compacted their porosity and therefore density varies in a predictable manner with depth of burial The depth density relationship depends on lithology but if sufficient density data are available compaction curves can be generated for the basin of interest Alternatively the compaction curves supplied with HOTPOT can be used Appendix 1 The relationship between thickness and density for a given sedimentary layer is 2 3 Basin modelling with HOTPOT h P 7 Pw f pi mE P where t1 thickness at depth 1 pl density at depth 1 t thickness at depth 2 0 density at depth 2 p density of pore fluid 1 03 g cm Thus if the thickness and depth of a sedimentary layer are known its thickness at any other depth can be predicted Backstripping is an iterative process accomplished as follows a Strip off the top layer of the stratigraphical sequence move the remaining layers upwards and recompute their densities
27. button will close the dialogue without changing either the selected printer or its configuration 5 3 5 The Progress Reporting dialogue This dialogue is displayed when HOTPOT is carrying out a lengthy Decompacting data processing operation It is provided so that the user is aware of what data processing is being done and how near to completion it is Decompacting Figure 5 5 shows an example Ruddington Formation at 10 00Ma The text in the dialogue will describe the data processing operation being performed which data are being used and what percentage of the data have been processed For certain data processing operations the Cancel button in the dialogue may be chosen to cancel the data processing operation for Figure 5 5 example if the text messages indicate an error 5 4 The HOTPOT Main Window The HOTPOT Main Window is used to control the overall operation of the program The main window is moveable and sizeable and may be minimized or maximized Closing this window by choosing the Close option from its system menu exits the program closing all subsidiary windows and releasing all system resources used 5 4 Reference to HOTPOT version 3 0 for Windows ervewenemecdu ee we wawa wewaVevusewuwewewwee Talal tah didi wan arwwww y ru iirinn dekh abet r E E ied weeqevae M 0 si HotPet Model 1 i File Settings Calculate Display Help Figure 5 6 The HotPot model is displayed symbolically using colo
28. density does not vary with depth The depth density table for sea water is Water sea water 0 1 03 Other lithologies with effectively constant density such as anhydrite or salt may be defined in a similar manner 1I 2 Digitised contour files Digitised contour map data used with HOTPOT may include e isopachs digitised from time slice isopach maps e depth contours digitised from depth maps topographic or bathymetric contours digitised from geodetic or hydrographic maps heatflow contours digitised from heatflow maps HOTPOT will automatically recognise several file formats for this type of data the digitised isoline format used by many British Geological Survey computer programs the geographic data format used for maps produced by the CCOP WGRA Phases I and II e formats used by several commercial mapping programs used by CCOP Member Countries These formats are recognised by analysing the contents of a file rather than by making assumptions based on a file type suffix This means that HOTPOT will correctly interpret other file formats which are similar to the ones it has been programmed to recognise II 2 1 BGS isoline file format The standard file type is SO HOTPOT initially assumes this file format and file type when it asks the user to specify a list of digitised contour files H 2 HoTPot data file formats To illustrate the format here are some fragments of a ISO file an example of a digitised contour file
29. edited using the keyboard The Files list box shows files in the current directory Path matching the name in the File edit box The Directories list box shows a list of alternative directories The directory is the directory above the current directory in the file hierarchy any other directories are below the current directory The Drives list box shows a list of alternative disk drives The use of floppy disks or RAM disks with HOTPOT is not recommended Disk drives attached to a local area network server can be used Choosing the Ok button will action the selections in the dialogue If these form a valid file name that file will be used for the current operation and the dialogue will close Otherwise the fields of the dialogue will be updated with the selections and the dialogue will continue Choosing an item in a list box is the same as selecting that item then choosing the Ok button Choosing the Cancel button will close the dialogue and cancel the current operation of the program safely 9 3 2 The File List dialogue This is used whenever HOTPOT requires the user to select a list of one or more files so that data can be read from disk It is similar in operation to the multiple file selector dialogues used in other Windows applications Figure 5 2 shows an example of the HoTPor file list dialogue The dialogue caption in the top border will briefly explain what sort of files are required and what operation is being perform
30. i i t t l t t AZ fh k LAYER 1 t i t l l t t Z i t T Mat M k LAYER 2 Leem a AZ AZ thickness of n layer at i grid node Q k thermal conductivity of n layer at i grid node T Temperature at base of n layer at i grid node t Age at base of n layer at i grid node Q Heatflow through basin at i grid node Figure 2 1 Schematic cross section through a model sedimentary basin illustrating the layer and thermal parameters Data which relate directly to the stratigraphical layers and the thermal regime of the basin being modelled are referred to as primary data Data which may relate to a wider arca than the basin being modelled are referred to as auxiliary data 2 1 1 Primary data The primary data are sub divided into layer related and age related groups Layer related primary data These data define the structure and properties of each individual layer in the basin being modelled 2 Basin modelling with HoTPoT The data required for each layer are Notes a Either a digitised isopach contour map showing the thickness distribution of the layer b c d N e f 1 2 eee Nee r or a digitised depth contour map showing the depths to the base of the layer see Notes below These digitised contour data are stored in data files the various formats recognised by HOTPOT are described in Appendix II The average lithological compo
31. in a graph display window Fig 4 36 It may be printed by choosing File then Print Choose graph display window File The HorPor Main Window is redisplayed menu then choose Close option 0 mWjim K TOM MDSLST ENS tte RE VAL Figure 4 36 4 2 14 End modelling session Choose File menu Choose Exit option This closes the HOTPOT program Because a model is loaded into the program HOTPOT will open a dialogue Fig 4 37 asking you to confirm your intention to delete the model and exit HatPot Close Q Do you want to exit from the HotPot program Figure 4 37 Choose Yes button The model is deleted The HOTPOT program closes and the Windows desktop is redisplayed Take a coffee break You ve earned it HotPot Tutorial 4 3 Tutorial Model 2 This model shows the use of time and spatially variant heatflow The modelling session illustrates e how some of the modelling procedures can be reorganised to improve efficiency e how the area of interest specification is entered and saved for use in later modelling sessions e how the layer information is entered and saved for use in later modelling sessions e how gridding search radii are chosen e how the density of digitised data affects gridding and the need to include control contours and anti masking contours in the data sets prepared for use with HOTPOT e how model data grids can be saved for use in later modelling sessions Note that we refer to some of the
32. information shown This also includes a reference to the digitised isopach file toller iso Choose Ok button The gridding window opens The program is ready to grid the digitised Tollerton Fin isopach data Choose Grid button Type 0 19 into the Radius box then The program grids the isopach data with a search radius of 0 19 choose Ok button or press RETURN and shows a grid map Fig 4 16 Note the large area of zero key thickness nodes around the actual sedimentary fill Choose Accept button Tollertan Formation 990 x 1100 880 999 770 800 660 770 550 660 440 550 330 440 220 330 110 220 0 110 mean 171 153 Figure 4 16 4 14 HOTPOT Tutorial e 2 a 2 m 9 sg SE e ES a amp w Um E Cc E SE Es Cx to gt A ga 5 c tion The HoTPoT main window shows the Keyworth Formation Formation buttons displayed in a stratigraphic column Fig 4 17 loaded and are ready for decompac m v wT 2 z Ame Formation Figure 4 17 Before decompaction a table of density vs depth data must be loaded from an auxiliary data file 4 2 4 Load auxiliary depth density data Choose Depth Density option Choose File menu A file selector dialogue is displayed for you to select a depth density file The depth density information is loaded into the program and the HOTPOT Main Window is redisplayed Choose malay ddt from Files list 1pp
33. items File provides facilities for data output Style select display style settings Limits define displayed data range and scale Close closes the grid display window File This is a drop down menu with the following options Save save grid data in file Print print the displayed grid Printer setup select or configure printer File Save Choosing Save invokes a standard file selector dialogue This will offer an automatically generated file name of hpg type and will show a list of files of hpg type in the current directory The user may override the offered name by selecting from the file list or typing a new name If no file type is specified hpg will be used 5 22 Reference to HOTPOT version 3 0 for Windows The automatically generated name will be of the form hpxxxxaa hpg where xxxx is the four hexadecimal digit process identifier PID of the HOTPOT program in the current Windows session and aa is a pair of letters in the series aa for the first file ab for the second through to zz Such automatically generated filenames are unique in any one directory The maximum number of such files per directory per HOTPOT program run is 26 676 The data file created is ASCII text and may be transferred to other computer systems or programs The format is described in Appendix II 4 File Print Choosing this option causes the displayed data to be output to the selected printer via the Windows Print Manager
34. keyboard Unassigned null nodes have their value shown by the key word null nodes can be set to null by entering this key word Choose the Ok button to insert the edited value into the grid Choose the Cancel button to leave the existing value unchanged The File drop down menu has an additional item in the Gridding Window Load retrieve data from a saved grid file File Load Choosing this option allows a grid saved from the Gridding Window to be reloaded into the Gridding Window This avoids the need to regrid isopach data when repeating modelling sessions It is particularly useful when the preparation of a grid involves time consuming manual editing of grid nodes This function may also be used to load data gridded using other software such as mapping and contouring programs grid file format conversion will probably be required Appendix II 4 describes the HOTPOT grid file format Load invokes a standard file selector dialogue which will by Grid Contiemation default search for files of hpg type The grid title from the selected file will be displayed in a confirmation message box along with the title for the required grid Figure 5 25 Require Tollerton Formation Found Tollerton Formation Use thig grid Choose the Yes button to load the grid into the Gridding Window Choose the No button to return to the Gridding Window Figure 5 25 without loading the grid The grid loading operation will ver
35. necessary to insert some additional control contours these are interpolated between existing contour levels onto the original isopach map and then redigitise the map The Tutorial data set shows an example of this process see the description of gridding the Ruddington Formation in Model 2 section 4 3 5 Control contours are typically necessary in places such as basin margins where areas of strata having uniform thickness isopachs widely spaced are next to areas of rapidly changing stratal thickness isopachs closely spaced Where there are only a few isolated null nodes in an otherwise acceptable grid the Edit Grid Node dialogue section 5 7 may be used to set their values based on the Figure III 4 values of surrounding non null grid nodes Experience has shown that the visual inspection and comparison method as outlined above is more reliable than statistical assessment of goodness of gridding X III 2 APPENDIX IV Notes on estimation of palaeoheatflow in extensional basins IV 1 Basin subsidence and extension factors Evidence for crustal extension during basin development lies in the large normal faults which control basin evolution Fig IV 1 However the evolution of typical extensional sedimentary basins is rather more complex than would be expected from a simple crustal extension mechanism These basins characteristically show two distinct types of subsidence behaviour An initial extensional phase of rapid sub
36. new contour value record or the end of file II 2 2 Alternative contour file formats HoTPor interprets a digitised contour file according to the following rules e a line ina file containing a single numeric value is recognised as a contour value record e subsequent lines in the file containing two or more numeric values are treated as digitised points along that contour the first value being regarded as the X co ordinate and the second as the Y co ordinate e a contour is terminated when either a new contour value record or the end of file is found e non numeric data in the file are ignored This allows several digitised contour file formats to be recognised and interpreted correctly 1 3 HOTPOT data file formats The CCOP WGRA digitised contour format This format was devised for digitising the total sediment thickness and time slice isopach maps produced by CCOP Member Countries during the Phase I and II projects of the WGRA programme It should also be compatible with the line file format used by ARC INFO but note that ARC INFO line attributes may need translating to contour values depending upon how the line attributes have been encoded The normal file type is GEO The format is illustrated by the following extract from a GEO file 0 99 8586 11 8245 99 9018 11 8848 99 9487 11 9316 99 9877 11 9592 100 0000 11 9639 END 1 100 0000 10 4530 99 9823 10 4431 END 2 99 8361 11 4528 99 8905 11 3737 99 89
37. table to 0 00 M button the Ruddington Fm at 0 Ma Choose Settings menu Choose Conductivity option Select Depth variable radio button Choose Ok button Now repeat the procedure for the When this has been done the depth conductivity table from remaining 4 layers i e malay dkt is linked to all of the basin layers present day and Tollerton Fm at 0 00 Ma decompacted Ruddington Fm at 10 00 Ma Tollerton Fm at 10 00 Ma Tollerton Fm at 20 00 Ma HOTPOT Tutorial 4 2 9 Set age related thermal parameters You must now specify further thermal parameters to the program These parameters surface temperature and heatflow may change during basin evolution so they are defined explicitly for each time calibration point Select 0 00 Ma button The text on the button changes to white to indicate selection This means that thermal parameters set subsequently will apply to the 0 Ma present day time calibration point Choose Settings menu Choose Surface temperature The Set Surface Temperature dialogue opens for the selected option time calibration point 0 Ma Period 0 00 Ma Temperature Figure 4 26 Type 30 0 in Temperature box then This sets the surface temperature at 0 Ma to the assumed present choose Ok button or press RETURN day mean annual surface or seabed temperature In this key Tutorial the required value is 30 C Fig 4 26 Choose Settings menu Choose Heatflow option The Set Heatflow dialogue opens fo
38. years before present decimal fractions are permitted The difference between this age and the age of the base of the layer above will determine the duration of the period of erosion Isopachs isopach mode or Depths depth mode This is a group of controls for linking isopach or depth data files to the layer information Select one of the Units radio buttons to specify the units of measure m metres km kilometres or feet used for the isopach or depth values Choose the Data 5 8 Reference to HOTPOT version 3 0 for Windows Files button to display the a file list dialogue and select the digitised isopach or depth data files for this layer at least one file must be selected The formats which may be used for isopach or depth data files are described in Appendix II 2 Layer information entered in this dialogue ma be saved for later use by choosing the Save button Previously saved layer information may be recalled by choosing the Load button Both these actions will open a file selector dialogue for lay files which are used to store Layer Information dialogue entries The names of isopach or depth data files from the file list dialogue are also saved in the lay files When a lay file is loaded HOTPOT checks to ensure that all specified data file names are valid if any are not the whole list of data files is ignored Choosing the Ok button will complete the Layer Information dialogue and open a data gridding window for t
39. 0 00 Ma button Choose File menu Choose Heatflow option This displays a file list dialogue which allows you to select one or more files of digitised heatflow contour data for subsequent gridding Choose heatflow iso from the Files The full file path name cAMutoriaMeatflow iso is copied into the ist 00 Selected files list box in the upper part of the dialogue In this model you are only using one file however this dialogue allows multiple file selection unlike the normal file selector dialogue which only allows single file selection 4 42 Choose OK button Choose Grid button Type 0 26 into Radius box then choose OK button or press RETURN key 6 0 160 0 162 0 Choose Accept button Choose Settings menu Choose Heatflow option Choose Cancel button Choose Settings menu Choose Surface temperature option Type 30 0 into the Temperature box then choose OK button or press RETURN key HOTPOT Tutorial This closes the file list dialogue and opens the gridding window ready for you to grid the heatflow contour data Opens the search radius dialogue The program grids the heatflow data with a 0 26 search radius Fig 4 48 Experiment shows that this is the smallest value which generates no null nodes moreover the radius is acceptably small for the smoothly variable heatflow data You may of course save this grid for future use in the same way that you saved the layer isopac
40. 2 399 415 R 1 References McCLAY K R 1989 Physical models of structural styles during extension Memoir of the American Association of Petroleum Geologists 46 95 110 McKENZIE D P 1978 Some remarks on the development of sedimentary basins Earth and Planetary Science Letters 40 25 32 MICROSOFT 1990 Microsoft Windows User s Guide Microsoft Inc QUIGLEY T M amp MACKENZIE A S 1988 The temperature of oil and gas formation in the sub surface Nature London 333 549 552 ROWLEY W J 1990 Userguide to Version 1 of the 3 D sediment decompaction and geothermal modelling program DECOMP3D British Geological Survey Technical Report WC 90 21C SALVESON J O 1978 Variations in geology of rift basins a tectonic model Proceedings of the Rio Grande Rift Symposium Sante Fe Los Alamos Laboratory LA 7487 C 82 86 SCLATER J G amp CHRISTIE F A F 1980 Continental stretching an explanation of the post mid Cretaceous subsidence of the Central North Sea Basin Journal of Geophysical Research 85 3711 3739 SEKIGUCHI K 1984 A method for determining terrestrial heat flow in oil basinal areas Tectonophysics 103 67 79 SLEEP N H 1971 Thermal effects of the formations of Atlantic continental margins by continental breakup Geophysical Journal of the Royal Astronomical Society 24 325 350 SOMERTON W H 1992 Thermal properties and temperature related behaviour of rock fluid systems Developments in Petrol
41. 5 22 it has an empty map graticule showing the area of interest There are three buttons Accept Grid and Cancel The Accept button is initially disabled it is only enabled when a valid grid has been generated 5 25 Reference to HOTPOT version 3 0 for Windows Keyworth Formation Figure 5 22 The Accept Grid and Cancel buttons may be chosen by using the keyboard as well as by using the mouse The TAB and BACKTAB i e SHIFT TAB keys move the focus by one button at cach press The SPACEBAR is pressed to choose the button which has the focus Alternatively a button may be chosen by pressing its initial letter key e g A for Accept Additionally Cancel may be chosen by pressing the ESC key The provision of keyboard control allows the Windows Recorder program to be used more effectively to record and replay HOTPOT sessions e g for demonstrations or presentations Choosing the Cancel button cancels the command which initiated the MEES ET TTT gridding process closes the Gridding Window and returns control to the HOTPOT Main Window Keyworth Formation Choosing the Grid button opens a dialogue which shows the current value of the search radius Figure 5 23 Edit the value to that required then choose the Ok button to start the gridding process The Cancel button may be chosen to cancel the dialogue and return to the Gridding Window Figure 5 23 Gridding During the gridding process a Progress dialogue w
42. 61 11 3675 END Each segment of digitised contour begins with a contour value on a line by itself This is followed by one or more lines each with two values representing the X Y co ordinates of a digitised point on the contour A line containing the keyword END terminates the segment The contour values are specified in kilometres for isopachs The example shows segments of the Okm 1km and 2km contours ZCAP format This data format is produced from the Zycor ZCAP digitising software The format is illustrated by the following extract from a data file 0 1E 31 2000 106 116 48 033 105 776 48 270 105 268 48 355 104 840 48 679 104 443 49 334 104 291 49 906 104 206 50 445 104 138 50 873 0 1E 31 3000 108 278 49 809 108 060 49 897 107 953 50 323 108 271 50 975 Each line comprises two numeric values If the first value is 0 1E 31 i e 0 1 x 10 then the second value is interpreted as a contour value Otherwise the first value is the X co ordinate and the second the Y co ordinate of a digitised point on that contour 11 2 3 Co ordinate systems The X and Y co ordinates may be either map easting and northing or longitude and latitude Their 1 4 HOTPOT data file formats units are immaterial use kilometres metres or degrees as appropriate but must be consistent with the units used to specify the area of interest HOTPOT assumes the use of a regular co ordinate system i e X co ordinates increase from west to cast and
43. 89 Sclater amp Christie 1980 An alternative set of curves are supplied in the file danish dkt Fig 1 3 These are based on data from the continental shelf under the Danish sector of the North Sea Balling et al 1980 except for overpressured shale which is taken from the SE Asian data Auxiliary data MDSLST SST QPSHAIL Figure 1 2 m Wim K MDSLST SST OPSHAL Figure 1 3 l 2 Auxiliary data 1 3 Thermal conductivity Temperature relationship It is necessary to take into account the effects of temperature on thermal conductivity The prec se nature of this relationship is not well described but basically for a given rock type thermal conductivity decreases with increasing temperature see e g Houbolt amp Wells 1980 Wan Ismail 1984 Cermak amp Bodri 1986 HotTPot provides four options for specifying the thermal conductivity temperature relationship these are described in the following sub sections The required option is selected by choosing the Options item from the Calculate drop down menu of the HOTPOT main window see section 5 4 The Cermak amp Bodri 1986 option is automatically selected when the program is started Cermak amp Bodri 1986 k MEINE NN for T lt 300 C T 1 0 001A7 ky Kyo for T gt 300 C where AT T 20 C T temperature C kr thermal conductivity at temperature T ko thermal conductivity at 20 C k399 thermal conductivity at 300 C Sekig
44. A more complete evaluation therefore requires the prediction of palaeotemperatures which need to be considered in the light of the basin s tectonic and sedimentary history The main purpose of Hot1Por is the thermal modelling of sedimentary basins as an aid to hydrocarbon exploration However it should be emphasised that the program does have much wider applications in subsurface geological exploration and that there is a close genetic relationship between the generation of oil and gas coal rank and the origin of strata bound mineral deposits many of which contain small amounts of hydrocarbons 1 2 2 Generation of hydrocarbons Temperature and time are the key parameters which determine hydrocarbon generation from organic rich sediments Waples 1980 following Lopatin 1971 introduced a Time Temperature Index TTI which attempted to predict the combined effects of time and temperature vitrinite reflectance values on organic matter in the subsurface More recently the theoretical basis of the TTI has been questioned and use made instead of chemical kinetic models Wood 1988 Burnham amp sweeney 1989 Sweeney amp Burnham 1990 However in geologically young Cenozoic basins temperature is probably a more important factor than time Thus MacKenzie amp Quigley 1988 and Quigley amp MacKenzie 1988 have suggested that most oil has formed between 100 and 150 C and most gas between 150 and 220 C Most of the petroliferous basins
45. If you use a Windows based word processor you can use this technique to insert HOTPOT displays into report texts 4 2 7 Load auxiliary depth thermal conductivity data Before carrying out the thermal calculation a table of thermal conductivity vs depth data must be loaded from an auxiliary data file Choose File menu Choose Depth conductivity option A file selector dialogue opens for you to choose a depth thermal conductivity file 4 20 HoTPoT Tutorial Choose malay dkt from Files list The dialogue closes and the depth conductivity table is loaded into the program 4 2 8 Set the layer thermal conductivities You must now link the depth conductivity table to each layer at each time calibration point in turn Select Keyworth Fm button under The text on the button changes to white to indicate selection 0 00 Ma button Choose Settings menu Choose Conductivity option The Set Thermal Conductivity dialogue opens This allows you to choose either constant value or depth variable thermal conductivity for the selected layer wa Set Thermal Canductivity Keyworth Formation at 0 00Ma O Constant value oman Depth variable Figure 4 25 Select Depth variable radio button The depth conductivity table is linked to the Keyworth Fin at 0 Ma Fig 4 25 Choose Ok button The dialogue closes completing the setting Select Ruddington Fm button under The procedure is repeated to link the depth conductivity
46. RGENT AREA OF AREA OF AREA OF DIVERGENT PLATE MOVEMENTS CONVERGENT CONVERGENT PLATE MOVEMENTS PLATE PLATE MOVEMENTS DIVERGENT CONVERGENT CONVERGENT DIVERGENT AASIIETELES BASIN CYCLES BASIN CYCLES BASIN CYCLES INTERIOR MARGIN Zo MENOR OF ADIACENT TO My OF PLATE OFPUTE z near MARGIN wanc OF PLATE 2 2l n Ew Mn UN E TRENCH pons ri NIC OCEANIC OCEANIC SAG FRACTURE WRENCH j ASSOCIATE TRENCH RENCH FRACTURE SAG Figure 2 3 Global basin classification system after Kingston et al 1983 Appendix IV gives notes on how palacoheatflow may be predicted on a theoretical basis assuming uniform lithospheric extension Other methods of estimating palaeoheatflow may include vitrinite reflectance data spore coloration apatite fission track analysis etc Ultimately the means by which palaeoheatflow is estimated is up to the individual user OC F AN im pane oo ee mann o sari tap oe a CONTINENT meee wee ete oso ns ser ee ree aem 9 CUE AN trench pul trench pull suction sedinentary basin suction ROGERS Pras tension me tension x s wee 0o las fermes A i P A SURDUCHING Moho OCEANIC PLATE Or D E ES E base of lithosphere amp N extien Sion e f Figure 2 4 Schematic diagram to illustrate extension of the lithospheric plate after Bott 1982 2 4 HOTPOT program usage cycle Whilst the Windows user interface allows flexibility in the way that tasks
47. Setup This is a dialogue which allows printers to be selected and fw configured Printers All printers installed on the computer system including f ETIRI any attached to the network in the case of networked computers and configured for Windows use will be listed in the dialogue e g Figure 5 4 The currently selected printer is shown highlighted in the list An alternative may be selected from the list Choosing the Setup button in this dialogue will open the Figure 5 4 printer driver configuration dialogue for the selected printer This is part of the Windows printer driver software supplied by either Microsoft or the printer manufacturer Refer to the appropriate documentation for a description of printer configuration Only Windows 3 printer drivers may be configured in this way If the Setup button does not open a configuration dialogue this means that the printer driver is not Windows 3 compliant Windows 2 printer drivers which will work with Windows 3 must be configured from the Windows Control Panel program instead Choosing the Ok button will close the dialogue and effect any changes made to the printer selection or configuration Such changes apply only to the current instance of the HOTPOT program and may be limited to some of the window types used by HOTPOT see under File menu Printer setup option in each of the window type descriptions sections 5 4 5 5 and 5 6 for more information Choosing the Cancel
48. The effects of allowing in the modelling for the erosion of the topmost part of the Ruddington Formation i e the Bingham Member in Model 3 are shown in Figs 4 67 and 4 68 Both the Ruddington and Tollerton Formations were more deeply buried in the south than allowed for in Models 1 and 2 considered above These therefore underestimated the temperatures and organic maturities attained and the full extent of hydrocarbon generation prior to the post Ruddington Formation deformation and erosion 4 58 HoTPOT Tutorial 10 0 8 0 C Uer qaaturo 220 0 jas 150 0 oil 100 0 6 0 under mature 160 0 162 0 164 0 166 0 Figure 4 64a Tollerton Formation at 0 Ma Model 1 10 0 8 0 C over mature 220 0 gas 150 0 oil 100 0 6 0 under mature 150 0 162 0 154 0 165 0 Figure 4 64b Tollerton Formation at 0 Ma Model 2 4 59 HOTPOT Tutorial puer mature under mature Figure 4 65a Ruddington Formation at 0 Ma Model 1 b over matura 220 0 gas 150 0 oil 100 0 under mature Figure 4 65b Ruddington Formation at 0 Ma Model 2 HOTPOT Tutorial 10 0 8 0 C Pyer rnalurc 220 0 14s 150 0 j oil d e 100 0 5 0 under mature 160 0 162 0 164 0 166 0 Figure 4 66a Keyworth Formation at 0 Ma Modcl 1 10 0 uS ao fs r v i D No De te oe z s 8 0 D 2200 150 0 oil B nud 100 0 6 0 under mature 169 0 162 0 164 0 166 0 Figure 4 66b Keyworth Formation at 0 M
49. a Model 2 HOTPOT Tutorial eye pRa r under mature Figure 4 67 Ruddington Formation at 12 Ma Model 3 Vv over mature gt YAS oil 6 0 under mature 160 0 162 0 164 0 166 0 Figure 4 68 Tollerton Formation at 12 Ma Model 3 4 62 SECTION 5 Reference to HOTPOT version 3 0 for Windows 5 1 Windows menus and dialogues HOTPOT uses four types of windows for its displays e the HOTPOT Main Window e Graph Display Windows e Grid Display Windows e the Gridding Window Each window type has a menu bar containing drop down menus The following sections describe how these window types and their menus are used Several dialogues are used to obtain information from the user during program operations Some of these the File Selector dialogue the File List dialogue the Print dialogue the Printer Setup dialogue and the Progress Reporting dialogue are common to several operations and are described separately The other dialogues are described during the description of related menu items 5 2 General information The following Windows conventions have been used in the design of the HOTPOT user interface Any menu option shown in black text is enabled and can be chosen Any menu option shown in grey text is disabled and cannot be chosen Check marks Y are used in conjunction with some menu items V to indicate a currently selected option V to indicate to the user that an operation associated with the
50. a larger search radius If the search radius was too large then features especially small structures seen on the original map will have been smoothed and will not be seen be indistinct or begin to merge together on the grid display Fig 111 3 in this case the gridding operation needs to be repeated using a smaller search radius 1 1 Figure II 2 Gridding and the search radius The best value for the search radius is the one which is just large enough not to give any null nodes in areas of continuous data coverage Figure Ill 4 It is often found that large search radii give apparently satisfactory results compare figures III 3 and III 4 both seem acceptable and care is needed A good strategy is to first select a too small search radius then progressively increase it until no null nodes are seen then gradually reduce it until null nodes reappear and finally to increase it by one step again After the grid check map has been examined the user should respond by clicking the Accept button on the gridding window if the gridding is acceptable If it has been decided to repeat the gridding operation with a different search radius then the user should respond by Figure III 3 dicking the Grid button in this case the program will open the search radius dialogue ready to repeat the gridding operation If no value of the search radius can be found which gives a satisfactory result across the whole map area it may be
51. adius box A gridding search radius of 0 16 is chosen Fig 4 10 The choice of search radius is important and will be reviewed in detail in Model 2 keg Set Search Radios Keyworth Formation Radius Figure 4 10 Gridding vt Keyworth Formation ney a 0 16 gt cMutoriahkeyworth iso Figure 4 11 HotTPot Tutorial iddi in the top left of 3 RETURN Gridding starts and a progress dialogue opens in t vir the udin window This shows information about the data being gridded and the percentage completed Fig 4 11 When gridding is complete a grid map is shown in the gridding window Fig 4 12 Choose Accept button The grid is accepted the gridding window closed and the HorPor main window redisplayed Keyworth Formation mean 627 095 Figure 4 12 The HOTPOT Main Window now shows a rectangular cyan coloured Keyworth Formation button at the top left Fig 4 13 This indicates that the Keyworth Formation layer information and isopach grid have been stored for later use Figure 4 13 Load the Ruddington Formation data Choose File menu 4 12 en Choose Layer option Choose Load button Choose ruddinga lay from Files list Choose Ok button Choose Grid button Type 0 19 into Radius box then choose Ok button or press RETURN key Choose Accept button HOTPOT Tutorial The layer information dialogue opens A file selector dialogue opens Layer information is
52. and therefore not all parts of it are used by the current version of HoTPor To allow flexibility and compatibility the format is divided into named sections Programs writing data need only write the sections their target applications will want to read Programs reading data need only search for and then read the sections they require As a safeguard a program to read this file format must be coded so that it will detect when a section that it requires is wholly or partly missing and take appropriate action e g issue a warning to the user and prompt for the omitted data Section names can be easily identified as they end with an ellipsis The sections used by HOTPOT Version 3 0 are Globals This section is used to store any data about the data in the grid for example the values of variables used to calculate the grid The format of lines in this section is Key Word value where the Key Word identifies an item of data e g a variable name and the optional value indicates its setting This is the same format as that used in the Grid section HOTPOT Version 3 0 for Windows does not store any data in the Globals section The section title is however written into the file as a place holder for future use When HOTFOT Version 3 0 for Windows reads a grid file it ignores the contents of the Globals section Titles This section is used to store text strings which describe the grid and which are to be used as titles o
53. arked Y The initial style for cach Grid Display Window is Normal colours These style options apply to the current Grid Display Window only The Normal colours style is for displaying grids on a colour screen or colour printer The Alternate colours style is intended for displaying grids as smoothly gradational grey scale images on monochrome printers e g dot matrix or laser printers Style Annotate May be chosen when a list of annotation files has been specified The see under HOTPOT Main Window File Annotation section 5 4 for a description of how to specify annotation files The format of annotation files is described in Appendix II 3 Each time this option is chosen the annotation selection state is switched between on and off The on state is indicated by a checkmark V in the menu The annotate style option applies to the current Grid Display Window only When annotate is on Each time the grid data are displayed in the window or on the printer the display will be overlaid by the digitised map line work read from the annotation files This can slow the display considerably especially if there are several annotation files and or dense line work Limits This is a drop down menu with the following mutually exclusive options Individual scale set to this grid s limits Group scale set to limits of grid type group 5 24 Reference to HOTPOT version 3 0 for Windows User scale set to user supplied limits Pseudo maturi
54. asin fill with sediments restricted to local fault bounded basins Fig 4 3 Subsequent units form the post rift sequence and are unfaulted The Ruddington Formation Fig 4 2 was deposited between 20 and 10 Ma and the Keyworth Formation Fig 4 1 between 10 Ma and the present Layer information for the three units is summarised in Table 4 1 at Ruddington Formation 50 sandstone 20 Ma 10 m 50 limestone Table 4 1 Figures 4 1 4 2 and 4 3 also show the digitised contour data digitised with latitude and longitude increments of 0 05 derived from the isopach maps Note that the gridding algorithm within HOTPOT cannot deal with faults it is necessary to treat these features as steep gradients Fig 4 3 Tutorial Model 1 is a simple run of the program using data prepared in advance It is designed to give you an overview of the program s capabilities and features and to familiarise you with the program data displays and their use In Tutorial Models 2 and 3 you will do much of the data input yourself as you will do when you use your own data sets with HOTPOT In Model 2 you will compare two data sets for the Ruddington Formation You will find that the original Ruddington Formation isopach contours Fig 4 2a are too widely spaced to permit gridding with a reasonable search radius You will then use a second data set which has additional control contours These were constructed by interpolation between the ori
55. atflow is assumed to be constant then choose Ok button or press through the 10 to 25 Ma time points RETURN key Repeat the procedure for the remaining 2 time calibration points ie 20 00 Ma 25 00 Ma 4 3 11 Printing a model report Carry out the instructions given in Check that thermal parameter settings are in accordance with the section 4 2 10 for printing a model procedures carried out above If any are not repeat the report appropriate instructions 4 3 12 Thermal calculation The thermal parameters conductivity surface temperature and heatflow are now loaded and HOTPOT is able to perform the thermal calculation Choose Calculate menu Choose Geothermal option On completion of the thermal calculation the HOTPOT Main Window is redisplayed 4 44 HOTPOT Tutorial 4 3 13 Display of thermal model results Carry out the instructions given in The results are essentially the same as Model 1 except for the section 4 2 12 for displaying thermal thermal results at O Ma heatflow map replaces single value model results heatflow An example of this difference is given in Fig 4 49 which illustrates a grid node extraction of layer thermal history Compare with Fig 4 34 Note how the temperatures are the same at 25 20 and 10 Ma but different at the present day Detailed differences of the present day temperature grid maps are discussed in section 4 5 Loyer temperature X 2 182 5 Y 5 _ Figure 4 49 4 4 Tut
56. aximized The map displayed within the window may be zoomable or scrollable depending on the style setting it is initially zoomable These windows are owned by the HOTPOT Main Window and will always appear on top of the HoTPoT Main Window Any of these windows remaining open when either the New option is chosen from the HOTPOT main window File menu or the HOTPOT application is closed will automatically be closed The user may close a Grid Display Window by double clicking its system menu button The value of a node in the displayed grid may be obtained by identifying the node with the cursor and clicking the left mouse button The map co ordinates X easting or longitude and Y northing or latitude of the node and its data value Z will be displayed on the right of the menu bar Figure 5 20 Unassigned nodes yield Z null Figure 5 20 Grid nodes may be edited before the decompaction calculation is performed The use of the grid node editor is described along with the Gridding Window in section 5 7 After the decompaction calculation has been performed 1 D basin history data can be extracted and displayed Identify the node with the mouse pointer and double click the left mouse button Data will be extracted from the corresponding nodes in all grids of the same type and displayed against a geologic time scale in a Graph Display Window Figure 5 17 section 5 5 shows an example of this type of display The menu bar contains the following
57. ble to escape C VEL THERES He vil 100 0 under mature Figure 4 62 Tollerton Formation at 10 Ma Model 1 By the end of Ruddington Formation deposition at 10 Ma much of the Tollerton Formation was in the oil generating zone and in some deeper central areas some gas could have been generated Fig 4 62 from Model 1 Fig 4 63 also from Model 1 shows that the Ruddington Formation had reached temperatures in the oil generating zone however as its lithology indicates a lack of source potential it is unlikely that any oil actually formed Although the presence of suitable reservoir rocks in the Ruddington Formation can be anticipated the probable lack of closed structures suggests that most 4 57 HotPot Tutorial 160 0 162 0 154 0 166 0 C 220 0 a 150 0 oil 100 0 under mature s r mature 3 Figure 4 63 Ruddington Formation at 10 Ma Model 1 of the hydrocarbons generated continued to escape unless significant numbers of stratigraphical traps were present It is a reasonable expectation that sealed closed structural traps were formed during the post Ruddington Formation deformational event and that significant hydrocarbon entrapment began The present day temperature maps Figs 4 64 to 4 66 provide an qualitative estimate of the type and areal extent of hydrocarbon generation since the main structural traps were formed and the likely broad distribution of oil and gas in the sandstone res
58. bles previously saved Aol co ordinates and grid spacings to be loaded into HoTPot A file selector dialogue opens Choose from Directories list This is a list of current directories is the directory one level above the current directory in the hierarchy The lists in the Files and Directories list boxes will be updated 4 9 Choose tutorial from Directories list Choose tutorial aoi from Files list Choose Ok button HortPot Tutorial The selector switches the current Path to the cAMutorial directory and lists its files in the Files list box The file selector dialogue closes and the Aol co ordinates are loaded from file tutorial aoi and displayed in the boxes of the Aol dialogue Fig 4 7 The Ao dialogue closes and the area of interest specification is accepted You may notice next time you use the Settings drop down menu that the Area of interest option is check marked to indicate that it ts set Area of interest W E spacing W E nodes Figure 4 7 4 2 3 Load and grid the layer isopach data It is best to load the layer data in formation age order starting with the youngest Load the Keyworth Formation data Choose File menu Choose Layer option Choose Load button Choose keyworth lay from Files list This drop down menu is used to control data input and output operations The layer information dialogue opens The necessary lithological age and water depth data can be either e
59. boundary temperatures are shown in C Note that this display does not take into account any higher temperatures that may have existed earlier in the basin history To obtain a true picture of the basin maturity the user must examine and compare pseudo maturity scale temperature plots for all layers at all ages in the model The cover illustration of this report shows an example of a pseudo maturity display If the limits selection is changed the current and any subsequent grid display windows will use the new selection but any pre existing windows will retain the old selection If the Pseudo maturity option is selected when a non temperature grid is displayed the Individual option will be used instead 5 7 The Gridding Window This is a special type of Grid Display Window which is used during the data gridding process Only one Gridding Window can be open When it is in use all menu options which involve data gridding are disabled It is opened during the processing of the Layer Heatflow and Topography options in the HorPoT Main Window Files menu It is initially displayed as a full screen window and although it may be resized by the user it is recommended that it be used full size Unlike a Grid Display Window the Gridding Window has no Limits item in its menu bar no Close option in its File menu and it cannot be closed by double clicking the system menu button in the top left corner When the Gridding Window is opened Fig
60. caption on the HOTPOT main window A dialogue is displayed with the current title text shown in the Title edit box Fig 5 9 The user may select and edit this text using the keyboard Choose the Ok button to use the contents of the Title edit Figure 5 9 box as the new model title and Main Window caption Choose the Cancel button to retain the existing model title and caption Settings Depth mode May be chosen at any time prior to performing the decompaction calculation When Depth mode is selected this option will be check marked N in the menu This selects the depth mode of operation for HoTPor In this mode the data entered into the layer grids see File menu Layer are assumed to be depths to the bases of the layers The decompaction calculation then computes layer thicknesses from these A topographic surface must be defined before the decompaction calculation can be performed as it is needed to compute the thickness of the topmost layer Settings lsopach mode May be chosen at any time prior to performing the decompaction calculation When lsopach mode is selected this option will be check marked V in the menu lsopach mode is the default mode for HorTPor This selects the isopach mode of operation for HOTPOT In this mode the data entered into the layer grids see File menu Layer are assumed to be thicknesses of the layers A topographic surface need not be specified when working in isopach mode Setti
61. cycle 1 2 Qi 2 Enter layer data Decompact to reconstruct basin history Set thermal parameters Compute thermal model Display examine and review model data Modify thermal parameters and repeat from step 4 SECTION 3 Installing HOTPOT 3 1 System requirements Version 3 0 of the BGS basin modelling software HOTPOT is designed to be used on an IBM PC or PS 2 or compatible microcomputer with the following specification e either an 80386 or 80486 processor e atleast 2Mb of RAM e ahard disk with at least 5Mb free space e a3 5 inch 1 44Mb diskette required for software installation only e a VGA colour graphics display e a mouse and a keyboard e a maths coprocessor is not required but where available will provide a significant increase in program performance e MS DOS or PC DOS version 4 or above operating system e Microsoft Windows version 3 0 or above graphical user interface system 3 2 User requirements It is assumed that the user has a basic familiarity with the Windows user interface and its terminology and knows how to e manipulate displayed windows using the mouse pointer e manipulate dialogue boxes and their controls using the mouse pointer and keyboard e copy files using File Manager e install third party software using the Program Manager e start applications using either the Program Manager or the File Manager These topics are described by the first six chapters of the Microsoft Windows User s Gu
62. d which you will save for later use in Model 3 This drop down menu is used to control input and output of gridded data This is used to save a grid for use in a later modelling session to avoid repeating the gridding calculation A file selector dialogue opens Fig 4 42 The file selector will offer an automatically generated unique file name Fig 4 42a You replace this with a more meaningful name Fig 4 42b Replacement user supplied file name File Path cMutor al Eiles Directories Figure 4 42b The file selector closes and HOTPOT saves the grid data into the file keyworth hpg note that the file selector will add the hpg for you The grid is accepted and the gridding window closes The HorPor Main Window shows a Keyworth Fm layer button Note that the Keyworth Fm button has its name in white text to indicate that it is selected Choose Settings menu Choose Conductivity option Select Depth variable radio button Choose Ok button HOTPOT Tutorial Opens the Set Thermal Conductivity dialogue for the Keyworth Fm Links the depth thermal conductivity table to the Keyworth Fin at 0 Ma present day Closes the dialogue and completes the setting The Keyworth Formation now has all its data loaded into the model and has its thermal conductivity parameter set Ruddington Formation In loading the data for this layer you will use two files of layer information which we prepared for you T
63. data files the various formats recognised by HoTPoT are described in Appendix II Single values are entered via Windows dialogues b Surface or seabed temperatures expressed as single basin wide values Single values are entered via Windows dialogues 2 1 2 Auxiliary data In addition to the basin specific data HOTPOT requires auxiliary information to enable the backstripping decompaction and thermal conductivity computations to be carried out a Digitised density vs depth curves for the standard lithologies conventionally sandstone limestone silty mudstone and overpressured shale being used n2 t nm Basin modelling with HOTPOT b Digitised thermal conductivity vs depth data for the same standard lithologies These digitised curves are stored in data files the format is described in Appendix Il Ideally auxiliary data should be prepared by the user utilising information from the basin under study However if sufficient information is not available the data files provided for use in the HOTPOT tutorial may be used These are based upon typical basin sequences and are described in Appendix I 2 2 Data processing In HotPot the primary and auxiliary data are loaded into a model database internal to the program The decompaction and thermal calculation functions then operate on the database generating new entries within it Data may be extracted from the database for graphical display or for export to other programs
64. del 1 Fig 4 28 This is due to the compactional effects of the eroded layer which decrease stratigraphical thicknesses and increase thermal conductivities Figure 4 60 shows a grid node extraction of layer thermal histories compare this with Fig 4 34 Model 1 10 0 419 5 30 41 mean 119 171 6 0 160 0 162 0 164 0 165 0 Figure 4 58 HOTPOT Tutorial 19 0 C 144 4 153 2 135 6 144 4 126 8 135 6 118 0 126 8 109 2 118 0 8 0 100 4 109 2 91 62 100 4 82 8 91 6 74 0 82 8 65 2 8 74 0 56 4 65 2 47 6 e 56 4 38 8 e 47 6 30 0 38 8 6 0 mean 100 424 160 0 162 0 164 0 166 0 Figure 4 59 T 22 20 18 16 14 4 2 0 m CAMTIUIONMI FENA REER H T H 100 LEA a TR LL IN PASAT TL PINE dep H tes AN t Ed ME ae ol s at aa f we i e Do gt o j aus m e VS TE iv tn 5t DE IN DU ut 1 80 Figure 4 60 AL Tose ROE Bingham Member deddiagtan Formation 4 5 Interpretation 4 5 1 General statement The accuracy of the above modelling of the imaginary basin is constrained by the generalised nature of the isopach maps and by the practical necessity for demonstration purposes of grouping the strata into only three stratigraphical divisions It is probable that in a real basin the sequence would be divided into many more units with each isopach or structure contour map showing greater complexity and detail than those employed here leading to
65. dialogues will warn the user and the calculation will not be carried out Choosing this option performs the geothermal calculation During the calculation a Progress dialogue will be displayed This reports the progress of the calculation in terms of process layer and percentage completed The Cancel button in the progress dialogue is not enabled Note this calculation will be quite slow on a system which does not have a maths coprocessor installed Calculate Options May be chosen at any time Choosing this option opens a dialogue Figure 5 15 which allows the user to define the thermal conductivity vs temperature relationship The complex nature of this relationship is discussed in Appendix 1 3 5 15 Reference to HOTPOT version 3 0 for Windows Data from the table are displayed as a set of curves on a depth vs density scale in a Graph Display Window This is an independent subsidiary window to the HOTPOT Main Window The manipulation of Graph Display Windows is described in section 5 5 The window title will show the file name from which the table was loaded When this option is chosen after the decompaction calculation has been performed depth density curves for any proportional lithologies used calculated during decompaction will be shown Display Depth Conductivity May be chosen at any time after a depth thermal conductivity data table has been loaded Data from the table are displayed as a set of curves on a depth
66. e Bingham Member is restored as a normal layer which has been removed by backstripping in the 14 00 Ma column 4 4 7 Display of the backstripped data Display options for the results of backstripping are the same as those in Section 4 2 6 Examples of grid map displays are given in Figs 4 54 and 4 55 Fig 4 54 shows the loaded thickness grid at 12 Ma immediately prior to erosion Fig 4 55 shows the loaded thickness grid at 10 Ma immediately after erosion Note how the thicknesses in the southern part of the map are lower than those in 3640 3920 3360 3640 3080 3360 2800 3080 2520 2800 2240 2520 1960 2240 1680 1960 1400 1680 1120 1400 840 1120 560 840 280 560 0 280 mean 943 278 Figure 4 55 4 52 HOTPOT Tutorial Tutorial Model 1 Fig 4 20 due to the compaction effects of the eroded layer Thicknesses farther north where there was no crosion are identical to those on Fig 4 20 24 22 20 18 16 14 12 10 8 6 4 2 0 Figure 4 56 Results of grid node extractions at node 162 5 E 7 5 N are shown in Figs 4 56 and 4 57 Fig 4 56 shows the burial history of the base of the bottom layer i e Tollerton Formation and can be compared to Fig 4 32 Model 1 Fig 4 57 shows the burial histories of all four layers and can be compared to Fig 4 33 Note the period of erosion and uplift between 12 and 10 Ma Also note that the Bingham Member is shown only between start of deposition 14 Ma a
67. e file however this dialogue allows multiple file selection unlike the normal file selector dialogue which only allows single file selection This closes the file list dialogue and returns to the layer information dialogue Choose Save button Type kw in File box then choose Ok button or press RETURN key Choose Ok button Choose Grid button Type 0 16 into Radius box then choose Ok button or press RETURN key Choose the gridding window File menu Choose Save option Type keyworth into File box Mme atum eme me Am eue rly ee I n en ee en n tet etal File Path c tutorial Files Directories EN Figure 4 42a Choose Ok button or press RETURN key Choose Accept button Automatically generated unique file name ee HOTPot Tutorial A file selector dialogue opens The file selector closes The contents of the layer information dialogue including the name of the isopach data file keyworth iso are saved in the file kw lay for use in a later modelling session Note that the file selector will automatically add the lay file type for you The layer information dialogue remains open The file name is now shown under the caption bar of the dialogue The gridding window opens The search radius dialogue opens The program grids the isopach data with a search radius of 0 16 and displays a grid map as Fig 4 12 Model 1 This prepares an acceptable gri
68. e graph display window closes and the grid map is redisplayed It is then possible to display the burial histories of other grid nodes as required in the same manner The grid display window closes and the HOTPOT Main Window is redisplayed A map of the thickness of Keyworth Fin at 0 Ma present day is drawn in a grid display window The X Y co ordinates and the thickness Z value are given at the right of the menu bar The burial history of all three layers at the grid node ts drawn in a graph display window Fig 4 33 The graph may be printed by choosing File then Print options 4 28 Choose graph display window File menu then choose Close option Choose grid display window File menu then choose Close option Choose Display menu Choose Layer temperature option Move the cursor to any node on the grid and select the node by clicking the left mouse button e Style HOTPOT Tutorial Layer thickness X 162 5 Y 7 5 T Figure 4 33 The layer thickness map is redisplayed allowing other grid nodes to be selected and displayed in the same manner The HorPor Main Window is redisplayed A map of the temperature of the base of the Keyworth Fm at 0 Ma present day is displayed in a grid display window The X Y co ordinates and the temperature Z value are given at the right of the menu bar Layer temperature X 162 5 Y 7 5 Ma eyworth Formation Rudd
69. e of erosion It may also be desirable for stratigraphic reasons to represent erosional episodes by several eroded layers The algorithm which processes eroded layers operates recursively and can process models with multiple erosional episodes and with multiple layers in each episode An example of decompaction by backstripping is illustrated schematically in Fig 2 2 Note how the deeper sedimentary layers become more compacted than the shallower ones Note also the sediment loaded subsidence path which defines the subsidence history of the basement beneath the basin Thus decompaction of all the 1 D grid node stratigraphical sequences produces a pseudo 3 D basin decompaction Chronological calibration of the decompacted grid node sequences generates a pseudo 3 D burial history of the basin 2 4 Basin modelling with HOTPOT t 0Ma t 20 Ma t 40Ma t 50Ma m P o ee ee a ea m _ mme e mm _ _ _ ro A 2 scdiment loaded subsidence total sediment thickness backstripping process t 20Ma t 25 Ma 30Ma tz40Ma t 50Ma 0Ma s mme mm me mm me s sm me fe mm mp em 7 a a ms scdiment loaded subsidence total sediment thickness A Figure 2 2 Decompaction of schematic stratigraphical sequences with a no erosion b an erosional episode between 25 and 20 Ma Note how the layer thicknesses decrease with burial but do not increase again during erosiona
70. eave the dialogue contents unchanged The information entered into this dialogue may be saved for subsequent use by choosing the Save button Previously saved area of interest information may be reloaded by choosing the Load button Saved area of interest dialogue data is stored in an aoi file Both the Load and Save buttons will display file selector dialogues for aoi files Settings Top Age May be chosen at any time prior to performing the decompaction calculation A dialogue box is displayed with the current age of the top of the top layer shown in an edit box Fig 5 11 The user may select and edit this The age of the top of the top layer is given in Ma millions of years before present The default value is zero which is correct for basins where deposition is still in progress Figure 5 11 Choose the Ok button to use the new value Choose the Cancel button to retain the existing value Settings Surface temperature May be chosen at any time after the decompaction calculation has been performed and an age button Reference to HOTPOT version 3 0 for Windows Calculate This is a drop down menu with the following options Decompaction perform decompaction calculation Geothermal perform geothermal calculation Options select thermal conductivity vs temperature relationship Calculate Decompaction When using isopach mode this may be chosen at any time after a depth density data table has b
71. ed 5 2 Reference to HOTPOT version 3 0 for Windows The Path text File edit box and Files Directories BEEEEEEEEENE IU Tr UC 27 and Drives list boxes in the lower part of the Selected files dialogue perform the same functions as they do in cAccop data wgraliso1009 geo the File Selector dialogue cAccop datatwgralisot010 geo Choosing the Select button will action the selections in the Path text File edit box and Files Directories and Drives list boxes If these form a valid file name that file name will be copied to the Selected files list box in the upper part of the dialogue Otherwise the fields of the dialogue will be updated with the selections The dialogue will continue Choosing an item in one of these list i Directories boxes is the same as selecting the item then choosing the Select button iso1110 geo The Selected files list box in the upper part of the dialogue lists the full path names i e combined disk drive letter directories and filename for each file currently included in the file list Figure 5 2 Items in the Selected files list box may be selected hold down the CTRL key while making multiple selections and then removed from the list by choosing the Deselect button Choosing an item in this list box is the same as selecting the item then choosing the Deselect button This facility is provided in case incorrect names are inadvertently copied into the file list Choosing the Ok button will use t
72. een loaded and at least one layer has been added When using depth mode this may be chosen at any time after a depth density data table has been loaded at least one layer has been added and a topographic surface has been defined Choosing this option performs the decompaction calculation During the calculation a Progress dialogue will be displayed This reports the progress of the calculation in terms of process layer and percentage completed The Cancel button on the Progress dialogue is not enabled Note this calculation will be quite slow on a system which does not have a maths coprocessor installed When the decompaction calculation has been completed successfully the HoTPoT Main Window display will be updated to show a series of stratigraphic columns which reflect the historical development of the basin Each column will be headed by an age button colour coded yellow representing an age boundary within the model and will contain layer buttons colour coded cyan for those layers which had been deposited at that time Fig 5 6 The boundaries between layer buttons are drawn in black to indicate a normal boundary and magenta to indicate an erosional boundary Calculate Geothermal May be chosen at any time after the decompaction calculation has been performed and thermal properties surface temperature heatflow and thermal conductivity have been assigned to the model If it is chosen prior to assigning thermal properties message
73. ells grid cells shown as solid colour rectangles Zoomable display zoomed to fit window Scrollable display scrolls within window Reference to HOTPOT version 3 0 for Windows Normal colours colour scale for screen and colour printing Alternate colours colour scale for grey scale printing Annotate overlay map with line work The Small Crosses Large Crosses and Filled Cells styles are mutually exclusive The selected style will be check marked Y The initial style is Filled Cells It is recommended that Filled Cells style be used for printing on dot matrix ink jet laser or similar printers The crosses styles may be used for plotting on pen plotters Filled Celis centred on the grid node and the same size as a grid cell Large Crosses centred on the grid node and the same size as a grid cell Small Crosses centred on the grid node and half the size of a grid cell The Scrollable and Zoomable options are mutually exclusive The selected style will be check marked V The initial style is Zoomable These options are identical to those described for the Graph Display Window Refer to Style Zoomable and Style Scrollable under Graph Display Window section 5 5 If these style selections are changed the current and any subsequent Grid Display Windows will use the new selections but any pre existing windows will retain the old selections The Normal colours and Alternate colours styles are mutually exclusive The selected style will be check m
74. en HOTPOT will display a file selector dialogue for ddt depth density table files Use this dialogue to locate the correct disk drive directory and file Then choose the Ok button to load the data table from file into program memory An hourglass cursor will 5 6 Reference to HOTPOT version 3 0 for Windows be shown during this operation If depth density data are being displayed in a Graph Display Window section 5 5 when a new table is loaded the graphic display will be automatically updated This is a useful method for browsing through the available depth density table files File Depth Conductivity May be chosen at any time A depth conductivity table must be loaded in order to use depth varying thermal conductivity data when performing a thermal calculation When a depth conductivity data table is loaded a checkmark V is displayed next to this menu item When this menu option is chosen HOTPOT will display a file selector dialogue for dkt depth thermal conductivity table files Use this dialogue to locate the correct disk drive directory and file Then choose the Ok button to load the data table from file into program memory An hourglass cursor will be shown during this operation If depth conductivity data are being displayed in a Graph Display Window section 5 5 when a new table is loaded the graphic display will be automatically updated This is a useful method for browsing through the available depth conducti
75. ervoir rocks of the Ruddington Formation As the main source potential is confined to the Tollerton Formation the maps Fig 4 64 suggest that gas will probably form a major proportion of any reservoired hydrocarbons particularly in the central parts of the basin However there are also significant areas in the Tollerton Formation where if suitable kerogens were present oil could have been generated before migration and entrapment in the Ruddington Formation Comparison of the predicted temperatures derived from a single basin wide value for heatflow Figs 4 64a 4 65a 4 66a with those obtained using the heatflow map Figs 4 64b 4 65b 4 66b suggests that the former generally predict lower present day temperatures and hence lower current levels of maturity of organic matter Provided that the heatflow map is based on good data and can be employed with confidence then the temperature predictions based on its inclusion in the calculations are thought to provide the best possible estimates However it must always be remembered that the current heatflow distribution is probably influenced by groundwater convection and that the heatflow pattern may have been significantly different during earlier periods of basin history particularly prior to the post Ruddington Formation uplift and erosion The present heatflow pattern could be of relatively recent origin in which case the use of a single basin wide value may be more appropriate
76. es 2 4 5 3 5 The Progress Reporting dialoguo sese eene enne 5 4 54 The Horror Main Windows are tite ten bites era epi p vendor heat EREN 5 4 50 The Graph Display Window oi roin re UR paria tones oun das eb rne a 5 19 5 5 Ine Grid Display Wind Wi odo dre tha tines ono i pl enia eae ct ota La ade eae addis 5 21 37 H 1 18 GiGi Window su etti dt onte qeu Succ ones tient TERES vasa duos Son cal Prou REEL E 5 25 c dl M en K R 1 Glossary of selected terms ied sna dre Lom imi aeree Hase es e G 1 Appendix k Auxiliary dataset aa os rn l 1 BE DEMES DONS DAL E a a a a a I 1 1 2 Depth Thermal conductivity data eeessss sese tret I 1 1 3 Thermal conductivity Temperature relationship I 3 Appendix II HOTPOT data file formats ses e M RER SSD SELER aes II 1 IJ D pthedata table files auster tret tco E rede a petia II 1 D MES BUS contour MES cancers cus cept a Deed nat as ocnawdan fetes eat eastside eaduenvease tere H 2 11 2 1 BGS isoline file FORM res eit OR a ni H 2 11 2 2 Alternative file formats cccccsssececscsssssessesscsscssscssesecsesnssaceesseasarsescsossesesenseees H 3 23 Coordinate SY SECIS masenna A a 11 4 IE Ci m m H 5 C n ecin a a a AT 1 6 Appendix III Gridding and the search Padius sese stesse ir beri teca endet II1 1 Appendix IV Notes on estimation of palaeoheatflow in extensional basins 1 V 1 IV 1 Basin subsidence and extension
77. es in areas of continuous data cover Their use is illustrated in the Tutorial see sections 4 1 1 and 4 3 5 See also Appendix III Calculating the original thickness of a layer prior to its burial and compaction by younger overlying layers See also Backstripping Synonym for structure contour A specialised window which is used both to provide information to and request information from the user of a program with reference to a particular program procedure Double click Drop down list box Edit box Grid Grid node Gridding Hardware Heatflow Hotpot Isopach Isotherm List box Lithology Ma Masking Matunity Menu Menu bar Microsoft Windows Glossary of selected terms To press and release a mouse button twice in quick succession without moving the mouse A type of list box which normally shows only the selected item The list of alternatives is obtained by choosing the button at the right of the box A box in a dialogue in which text may be entered and or edited by the user System of regularly spaced observations or calculations over a mapped area A intersection between a N S grid line and an E W grid line of a map graticule at which a parameter e g thickness temperature etc is observed or calculated The computation of a grid from scattered data The computer and its associated peripheral equipment display screen printer etc The rate at which heat is lost from t
78. essure Palaeo Pseudo maturity Radio button Scattered data Scroll bars Sedimentary basin Select Software Stratigraphy Structure contour Text box Thermal conductivity WGRA Window Glossary of selected terms screen and manipulated by a user operated cursor Trademark of Microsoft Inc United Kingdom Overseas Development Administration A round button in a Windows dialogue which is marked with a e symbol when it is selected Option buttons are grouped and only one from a group of may be selected A situation commonly met in sedimentary basins where pressure of pore fluids in rocks is greater than would be normally expected Prefix meaning ancient or of past times from Greek e g palaeo temperatures temperatures in the past A HoTPOT display which presents present day temperature or palaeo temperature maps as organic maturity estimates Synonym for option button Irregularly spaced observations over a mapped area Strips drawn at the bottom and or right of a window when the data display size is larger than the window size They are used to select the portion of the data display to be shown in the window A depression in the earth s surface resulting from crustal subsidence and infilled by rocks formed largely by sedimentary processes To mark an item for use in a subsequent Microsoft Windows action Cf Choose A computer program or programs Cf Hardware The study of
79. eum Science 37 SWEENEY J J amp BURNHAM A K 1990 Evaluation of a simple model of vitrinite reflectance based on chemical kinetics Bulletin of the American Association of Petroleum Geologists 74 1559 1570 WAN ISMAIL WAN YUSOFF 1984 Heat flow study in Malay Basin Combined Proceedings of the Joint ASCOPE CCOP Workshops I and II CCOP TP 15 77 87 WAPLES D W 1980 Time and temperature in petroleum formation application of Lopatin s method to petroleum exploration Bulletin of the American Association of Petroleum Geologists 64 916 926 WELSINK H J SKRIVASTAVA S P amp TANKARD A J 1989 Basin architecture of the Newfoundland continental margin and its relationship to ocean crust fabric during extension Memoir of the American Association of Petroleum Geologists 46 197 214 WOOD D A 1988 Relationships between thermal maturity indices calculated using Arrhenius equation and Lopatin method implications for petroleum exploration Bulletin of the American Association of Petroleum Geologists 72 115 134 Algorithm Anti masking contours Backstripping Button Caption bar CCOP Cenozoic Check box Checkmark Choose Click Combo box Control contours Decompaction Depth contour Dialogue Glossary of selected terms A structured method of solving a problem forming the basis of a computer program Extra contours positioned around a data set to prevent the gridding procedure assigning nu
80. factors ad IV 1 IV52 Palacobca ULNA eo Ses stant adeat e ERR ND det iu tiet dct NE E EE IV 2 SECTION 1 Introduction 1 1 Background In 1989 at the request of the Technical Secretariat of the Committee for Co ordination of Joint Prospecting for Mineral Resources in Asian Offshore Areas CCOP and in collaboration with CCOP Member Countries the British Geological Survey BGS began an investigation of the thermal history of petroliferous basins within the CCOP Region The principal objective of the work was to develop for use by the Member Countries a system based on an IBM compatible personal computer PC for the prediction of subsurface present day and palaeotemperatures in sedimentary basins To illustrate the feasibility and usefulness of the study a pilot study using data from the Gulf of Thailand and Malay basins was undertaken The work was later extended to include other basins A preliminary version of the thermal modelling software DECOMP3D Rowley 1990 was distributed to the CCOP Technical Secretariat and to Member Countries in July 1990 This program formed the basis of the pilot study which established the feasibility of the project and demonstrated the value of the results that could be achieved The BGS sediment decompaction and geothermal modelling program was renamed HOTPOT and redeveloped as a Microsoft Windows application in 1991 2 The first usage of the new software was in a study of the North Sumatra Basin Modell
81. ginal contours digitised and appended to the original dataset Fig 4 2b This part of Model 2 illustrates a common problem that you may experience when you use your own data with HOTPOT and demonstrates its solution In parts of the backstripping process HOTPOT masks all layer grids down to the data area common to all the grids with null nodes generated elsewhere The sedimentary area of the Ruddington and Tollerton Formations is less than the sedimentary area of the Keyworth Formation In order that HOTPOT realises that areas outside the zero isopach contour represent a known absence of sediment 4 1 HOTPOT Tutorial rather than just an absence of data it is necessary to plot additional zero contours such that the contoured areas of all the layers fill the known area in this case the limits of the Keyworth Formation These zero value anti masking contours are spaced at about the same distance as the real contours and are digitised as part of the layer data file They are not illustrated in Figs 4 2 and 4 3 because their detailed shape is arbitrary but the area within which they occur is marked by the dashed line Model 1 assumes the simple case of constant heatflow through time Model 2 assumes a spatial variation of present day heatflow which is expressed as a heatflow contour mW m map Fig 4 4 This is digitised as above Model 3 of the Tutorial incorporates an episode of erosion The topmost subdivision of the Ruddingt
82. guration These can be changed either by choosing the Printer setup option from this File menu or by using the Windows Control Panel described in Chapter 5 of the Microsoft Windows User s Guide Most dot matrix and laser printers will attempt some sort of grey scale representation of colour File Printer setup Choosing this option invokes a dialogue which allows printers to be selected and configured See description of Printer Setup dialogue under common dialogues section 5 3 4 When a Windows 3 printer driver is in use HOTPOT will by default print text reports using portrait page orientation and graphics using landscape page orientation If the page orientation is changed by choosing Printer setup from a HOTPoT Graph Display Window File menu only the orientation of graphics will be changed File Close Choosing this option closes the graph display window and returns to the HOTPOT main window The same effect can be achieved by MOUCISEHORIRE the graph display window system menu button at the left end of the caption bar Style This is a drop down menu offering the following mutually exclusive options 5 20 Reference to HOTPOT version 3 0 for Windows Zoomable display zoomed to fit window Scrollable display scrolls within window When the window is maximized these styles yicld identical displays The selected style is check marked V Initially it is zoomable Style Zoomable When this style is chosen t
83. h grids mW im oth Uc oC uu NN O amp O ON OO da wona eo Uu wo an p a w e E on oco On ed CO LO LO t md d ot NSROU nOSL CN da Co cn PN us P 09 4 06 OU UON 45 68 51 39 9 45 6 mean 67 5251 164 0 166 0 Figure 4 48 The HorPor Main Window is redisplayed The gridded heatflow map is anchored to the 0 00 Ma time calibration point This can be tested as follows The Set Heatflow dialogue opens for 0 00 Ma with the Grid radio button already selected indicating that the heatflow grid is linked to 0 00 Ma and ready for use The Set Heatflow dialogue closes with no changes The 0 00 Ma Button is still selected enabling the surface temperature to be set The present day surface temperature is set to 30 C HOTPOT Tutorial 4 3 10 Setting the remaining age related thermal parameters It is most unlikely that the present day heatflow distribution will be applicable to earlier periods of basin evolution The earlier time calibration points will therefore be assigned single value heatflows as in Tutorial Model 1 Select 10 00 Ma button Choose Settings menu Choose Surface temperature option Type 30 0 into Temperature box For this tutorial model the surface temperature is assumed to be then choose Ok button or press constant through the 0 to 25 Ma time points RETURN key Choose Settings menu Choose Heatflow option Type 80 0 into Constant value box For this tutorial model the he
84. he HoTPOT Main Window contains the following items File loading saving and printing data Settings setting program and data parameters Calculate performing calculations on the model Display displaying data from the model Help obtaining information about program operation File This is a drop down menu with the following options New delete current model and start a new one Depth Density load depth density data Depth Conductivity load depth thermal conductivity data Topography add a topographic surface to the model Layer add a stratigraphic layer to the model Heatflow add heatflow map data to the model Annotation sclect a list of display annotation files Print print a description of the current model Printer setup select or configure printers Exit exit from the HOTPOT program File New May be chosen at any time If there is a model currently in HOTPOT a message dialogue will be displayed asking for confirmation before deleting the model Choose the Yes button to delete the model and reset the program ready to input a new model Choose the No button to resume working with the current model File Depth Density May be chosen at any time prior to performing the decompaction calculation A depth density table must be loaded in order to perform the decompaction calculation When a depth density data table is loaded a checkmark Y is displayed next to this menu item When this menu option is chos
85. he crust of the earth to the atmosphere Units mW m A traditional English dish of vegetables and optionally meat The ingredients are placed in layers in a basin and then cooked A line joining points of equal layer thickness A line joining points of equal temperature A box in a dialogue listing choices e g file names If there are many choices the list box may have a scroll bar on its right side Rock type or composition Millions of years before the present A grid to grid operation in which the values set in one grid are used to control the assignment or interpretation of values in a second grid HOTPOT uses two types of grid masking 1 during modelling calculations values in a layer grid are set null where values in the corresponding grid for the layer above are null 2 in displays density and temperature grid values are not shown where the corresponding thickness grid values are zero Measure of thermal alteration of organic matter in rocks indicative of their hydrocarbon generating potential thus rocks can be classified as undermature mature for oil mature for gas or overmature according to the degree of alteration of their organic matter A list of program commands or options A list of menu names displayed along the top of a window A Graphical User Interface for IBM PC type computers in which data programs etc are represented by stylised images on the computer display G 2 ODA Option button Overpr
86. he data in the isopach or depth files to be gridded The use of the data gridding window is described in section 5 7 If the data gridding operation is successful the data will be added to the model and a button bearing the Formation name will be shown on the HOTPOT Main Window Fig 5 6 The button will be coloured cyan for a normal layer or magenta for an eroded layer The layer buttons are shown as a stratigraphic column ordered by age with the youngest at the top Choosing the Cancel button will cancel the Layer operation and return to the HOTPOT Main Window File Heatflow May be chosen at any time after the decompaction calculation has been performed and an age button has been selected It is used to compute a heatflow grid from digitised heatflow map data The Heatflow Files file list dialogue is displayed for the user to select one or more data files containing digitised contours from a heatflow map The formats which may be used for digitised contour data files are described in Appendix II 2 Choosing the Ok button will close the dialogue and open the Gridding Window so that the user may grid the data The use of the data gridding window is described in section 5 7 The grid if successfully computed will be attached to the selected boundary age in the model Choosing the Cancel button will return the user to the Main Window without computing a heatflow grid File Annotation May be chosen at any time The Annotatio
87. he definition is complete 4 33 HOTPOT Tutorial Save hl O le Path cMutor al Eiles Directories EN Figure 4 39 4 3 3 Load auxiliary depth density data HoTPoT requires both depth density data and layer data in order to do the decompaction calculation However the order in which they are loaded is not important Carry out the instructions given in Section 4 2 4 4 3 4 Load auxiliary depth thermal conductivity data Loading the depth thermal conductivity data now will allow you to set the layer thermal conductivities before doing the decompaction calculation The settings will then be copied to the layers at 10 Ma and 20 Ma by the backstripping process which will save you setting them manually later Carry out the instructions given in Section 4 2 7 4 3 5 Load the layer data In this modelling session you will save all the grids that you calculate for use in Model 3 Saving grids enables you to re run modelling sessions quickly and easily As each layer is loaded you will set its thermal conductivity parameter this is an efficient working practice Keyworth Formation In Model 1 you used layer information which we had prepared and saved in files Here you will enter the layer information for the Keyworth Formation yourself and save it for use in Model 3 Saving layer information enables you to re run modelling sessions quickly and easily Chouse File menu Choose Layer option The layer i
88. he first demonstrates a common problem that you may encounter using your own data sets with HOTPOT The second shows a method for solving this problem Choose File menu Choose Layer option Choose Load button Choose ruddingo lay from Files list Choose Ok button Choose Grid button Type 0 19 intc Radius box then choose Ok button or press RETURN key Choose Cancel button The layer information dialogue opens A file selector dialogue opens Layer information is loaded from ruddingo lay The layer information dialogue is redisplayed with the information shown This includes a reference to the original digitised isopach file ruddingo iso The gridding window opens The program grids the isopach data with a search radius of 0 19 and displays a grid map Fig 4 43 There are large areas of null nodes particularly in the central and eastern parts of the basin This is because the contours in the original dataset were locally too widely spaced Fig 4 2a To grid the dataset without generating null nodes requires a search radius so large that unacceptable smoothing of the map occurs You may wish to try some other search radii to confirm this The grid must be discarded and additional control contours digitised before regridding The grid is discarded the gridding window closed and the HorPor Main Window redisplayed A revised Ruddington Formation dataset in which additional control contours augment the original da
89. he flag number 9 The example fragment of an annotation file shown above contains two lines The first ends at X 161 144 Y 9 999 and the second starts at X 161 692 Y 10 000 The notes on co ordinate systems given in IL 2 3 above apply here also Normally line work from annotation files is drawn in black at the standard line thickness However the flag numbers may be used to select other colours from the standard Windows colour palette and to change the line thickness The colour and thickness selection is set by the flag number of the first point on the line the example file could be edited to part of COAST DAT from the Tutorial data set modified to use different line colours and thicknesses 160 007 8 086 214 first line thickness 2 colour 14 160 058 8 114 0 160 096 8 164 O0 160 135 8 0 214 161 132 9 981 161 144 9 999 Oo C end of first line 1 5 HOTPOT data file formats 161 692 10 000 107 second line thickness 1 colour 7 161 729 9 946 0 The thickness number is a multiplier for the standard line thickness therefore thickness 1 is the same as the standard line thickness thickness 2 is twice the standard line thickness and so on The basic Windows colour palette contains 20 values HOTPOT sets the first 16 of these to 0 1 6 7 black dark red dark green dark yellow dark blue dark magenta dark cyan light grey 8 dark grey 9 light red 10 light green 11 light yellow
90. he graph is zoomed to fit the window size If the window size is changed the graph size changes also This is useful for making comparisons between entire graphs by displaying them side by side in separate windows Style Scrollable When this style is chosen the window is shown with scroll bars at the bottom and the right side The window shows a portion of the full size graph The portion shown is selected by moving the scroll bar sliders with the mouse The size of the portion is selected by sizing the window This style of display is useful for comparing details of graphs by displaying them side by side in separate windows and scrolling the windows so the details to be compared are in view 5 6 The Grid Display Window This type of window is used for displaying data grids thickness temperature etc as maps Figure 5 19 A hw MAAN At ALS ALAA NAA SS APP PAD PIPL APSARA IRR ARIA VASA AAA SAN AARS PAAR ON ARATRI ANA SNE NEEL ISA NARRA A Ae KAAS AR AP at UNS ha e tayer thickness Ruddington Formation at 10 00Ma gt BM ee File Style Limits ENE 3 Bs amp 2 2 2 1 1 1 1 1 4 2 0 9 7 5 3 1 9 7 5 3 1 OOOD DE 70 80 90 00 10 20 30 40 50 50 70 80 30 0 SOS SOh WUN Soo wa G9 IT CO m eth ett AOA PIAS G9 COCO OO LOADS c mean 733 299 Figure 5 19 5 21 Reference to HOTPOT version 3 0 for Windows A Grid Display Window is sizeable and moveable and may be minimized or m
91. he list of files in the Selected files list box to perform the current operation of the program and close the dialogue Choosing the Cancel button will close the dialogue and cancel the current operation of the program safely 5 3 3 The Print dialogue This dialogue is displayed when HoTDor is sending data to the EMEN Sr EN Windows Print Manager Fig 5 3 The Print Manager is used by Windows to control access to the system s printer and to queue documents to be printed The Print Manager is described in Chapter 6 HotPot North England of the Microsoft Windows User s Guide Sending to Print Manager The text in the dialogue box will describe the document being sent to the Print Manager The user may cancel the operation by clicking the Cancel button in the dialogue In this case the document will not be printed and the dialogue will be closed Figure 5 3 The dialogue will automatically close once the document has been sent to the Print Manager Control of the printing operation then passes to the Print Manager Any problem encountered as data is sent to the Print Manager or from the Print Manager to the printer will be reported by a message dialogue Acknowledge such a message by choosing its dialogue Ok button depending on the type of problem this may also cancel the print operation Reference to HOTPOT version 3 0 for Windows 5 3 4 The Printer Setup dialogue ce ott t n ce oc eo M M tcu Ap m a n p n ee Printer
92. hich control the style of display Currently selected options are checkinarked Choose Annotate option The map is redisplayed with a coastline overlay Fig 4 24 Note that this slows down the display speed This is why the Annotate option is not normally selected HOTPOT Tutorial Select Annotation Files NN Selected files cAtutorialicoast dat Path cMutor al Directories Figure 4 23 Choose Style menu Note that the Annotate option is checkmarked Choose Annotate option again The map is redisplayed without the coastline overlay e When annotation is on choosing Annotate switches it off e When annotation is off choosing Annotate switches it on This method of annotation is appropriate where geographic features need to be shown on the map in precise position The reduction in display speed means that it is gencrally only worthwhile using it for maps which you are printing You can also annotate maps by saving the HOTPOT screen displays into the Windows Clipboard starting a graphics program such as Windows Paintbrush and pasting the u display from the Clipboard into the graphics program All 8 6 es cia TT the facilities of the graphics program are then available to edit the picture Many of the illustrations in this report Figure 4 24 were prepared using this method The Microsoft Windows User s Guide describes how window displays are saved into the Clipboard and pasted from the Clipboard into Paintbrush
93. his invokes a dialogue which allows printers to be selected and configured 5ee description of Printer Setup dialogue under common dialogues section 5 3 4 When a Windows 3 printer driver is in use HOTPOT will by default print text reports using portrait page orientation and graphics using landscape page orientation If the page orientation is changed by choosing Printer setup from the HorPor Main Window File menu only the orientation of text reports will be changed File Exit May be chosen at any time This exits or quits the HOTPOT program and returns to the Windows desktop If a model is in use a dialogue will open prompting you to confirm your intention to delete the model and exit Choose the Yes button to exit Choose the NO button to resume work on the model See also Section 3 8 Quitting HOTPOT Settings This is a drop down menu with the following options Title main window caption text and model name Depth mode layer data entered as depths Isopach mode layer data entered as isopachs default Area of interest area of interest map and grid limits Top age age of top of top layer Surface temperature surface temperature at selected age 5 10 Reference to HOTPOT version 3 0 for Windows Heatflow heatflow at selected age Conductivity thermal conductivity of selected layer Settings Title May be chosen at any time TL T ENT C77 uT e This changes the model title shown in the
94. hosen from the HoTPor Main Window File menu or the HorPor application is closed will automatically be closed The user may close a Graph Display Window by double clicking its system menu button An estimate of the value of a point on the displayed graph may be obtained by identifying the point with the cursor and clicking the left mouse button The X and Y co ordinates of the point will be displayed on the right of the menu bar Figure 5 18 For depth density and depth thermal conductivity displays X corresponds to density or thermal conductivity and Y to depth For 1 D basin history displays X corresponds to geologic age and Y to the type of data shown Note that the value given is only an estimate due to the effects of screen resolution 5 19 Reference to HoTPot version 3 0 for Windows cAccop datalwessex ddt Pee Style X 2 4 3000 Figure 5 18 The menu bar contains the following items File provides facilities for data output Style controls the window scroll zoom system File This is a drop down menu containing the following items Print prints the displayed graph Printer setup select or configure printer Close closes the graph display window File Print Choosing this option causes the displayed data to be output to the selected printer via the Windows Print Manager A Print dialogue box will be displayed during this process The representation of the graph on the printer depends on the selected printer and its confi
95. ial but no certain inference can be drawn on likely kerogen type Potential sandstone or limestone reservoir rocks are absent or perhaps restricted to thin local basal and marginal clastic sediments As the Tollerton Formation was laid down at a time of syn extensional subsidence some closed structural traps could have formed during deposition but the potential for stratigraphical traps seems to be limited The Ruddington Formation comprises sandstone and limestone in equal proportions laid down in an average water depth of 10 m This suggests a shallow marine sequence with little source potential Both sandstones and limestones could provide suitable reservoirs The Ruddington Formation forms part of the post extension sequence and syn depositional faulting is stated to have largely ceased during deposition of this unit so few structural traps can have formed at this time However a sequence of alternating marine sandstones and limestones could provide the location for stratigraphical traps A period of uplift and crosion followed the deposition of the Ruddington Formation It is likely that structural traps were generated at this time particularly within the Ruddington Formation in which the main potential reservoirs occur but the lack of argillaceous rocks suggests that the reservoirs may not be well sealed The Keyworth Formation is a sandstone unit laid down close to sea level during the later stages of post extension subsidence The genera
96. ide part of the documentation supplied with the Windows software and should be familiar to anybody who has used applications such as Windows Write and Windows Paintbrush 3 3 Document conventions In this document the following printing styles are used for the stated purposes Bold Helvetica type Text or prompts in windows or dialogues SMALL CAPITALS TYPE Windows key sequences The following verbs are used with specific meaning in describing the operation of Windows Installing HOTPOT software to choose means to pick an item that begins an action to select means to mark an item for use in a future action This table shows how these terms relate to the Windows controls used in the HOTPOT program Keyboard Menu drop down from menu bar Press ALT initial letter keys together Point to and single click Point to and single click Press initial letter key Point to and single click Press ALT initial letter keys together Press RETURN for Ok button Press ESC for Cancel button Press ALT initial letter keys together Point to and single click Press ALT initial letter keys together Radio button and check box Fl Text in edit box Point to and doubie click Locate with up and down arrow keys then press RETURN Locate with up and down arrow keys then press SPACEBAR Point to and single click Press
97. ify the area of interest specification stored in the file against the area of interest required if they do not match a warning message dialogue will appear and the grid will not be loaded The Accept button in the Gridding Window will only be enabled if the grid is loaded successfully References BALDWIN B amp BUTLER C O 1985 Compaction curves Bulletin of the American Association of Petroleum Geologists 69 622 626 BALLING N KRISTIANSEN J I BREINER N POULSEN K D RASMUSSEN R amp SAXOV 5 1981 Geothermal measurements and subsurface temperature modelling in Denmark GeoSkrifter Aarhus Universitet 16 1 172 BOTT M H P 1982 Origin of lithospheric tension causing basin formation Philosophical Transactions of the Royal Society of London A305 319 324 BUCK W R MARTINEZ F STECKLER M S amp COCHRAN J R 1988 Thermal consequences of lithospheric extension pure and simple Tectonics 7 213 234 BURNHAM A K amp SWEENEY J J 1989 A chemical kinetic model of vitrinite maturation and reflectance Geochimica et Cosmochimica Acta 53 2649 2657 CERMAK V amp BODRI L 1986 Two dimensional temperature modelling along five East European geotraverses Journal of Geodynamics 5 135 163 CHADWICK R A HOLLIDAY DW amp ROWLEY W J 1992 HOTPoT Basin Thermal Modelling Workshop Manual British Geological Survey Technical Report WC 92 06C DEWEY J F 1982 Plate tectonics and the evo
98. ill be shown Figure 5 24 This tells the user which data file is open and the percentage of the file processed Note this Hus 0 16 calculation will be quite slow on a system which does not have a maths coprocessor installed If the user realises something is wrong e g the search radius is incorrect then the Cancel button in the Progress dialogue should be chosen to cancel the gridding process and return to the Gridding Window zur Keyworth Formation ID c Mutoriakeyworth iso Figure 5 24 When the gridding process has been completed successfully the grid will be displayed on the map 5 26 Reference to HOTPOT version 3 0 for Windows graticule and the Accept button will be enabled If the grid is satisfactory choose the Accept button to complete the gridding operation close the gridding window and return to the HOTPOT main window If the grid is not satisfactory choose the Grid button to repeat the gridding process with a different search radius The search radius and grid acceptability are discussed in Appendix III The grid node edit function is always available in the Gridding Window E Edit Grid Nod To use it identify the grid node with the cursor and double click the left mouse button The Edit Grid Node dialogue Figure 5 25 will be displayed This will show the selected grid node map co ordinates as a subtitle and the value of the grid node in the edit box The value may then be selected and edited using the
99. ing HOTPOT now has the necessary layer isopach and depth density data and is ready to begin the 4 2 5 Decompaction by backstr backstripping and decompaction process Choose Calculate menu This drop down menu contains the calculation options Choose Decompaction option based upon the m x a X S seE X SIA CES a ae Sx b n 0 V DO w gt tab SSE ES E WS SRE Sm 5 ce Mm em SELL Ss mm ra u Roe S A i t oo Bas lt Bee eek SS uk 95 B cu ec om Ls Ss t wo E e E A SO cu S ao 26 75 n a AR gt 2 5 wa OO S SC CON Se o ZS Q w e NE gt HZ 2 HH i RS a HERI c 9 Hag gt Be 9 S Fe c AA LE c E S x a c 2 E t e Uu c r 5 3 a e 10 50 done HotPot Tutorial Two types of buttons are used arranged as a series of stratigraphic columns to Hiusuate plea the stratigraphical evolution of the basin Fig 4 19 They show the Present day basin saga ee the decompacted sequences at stages in the basin history from 25 million years ago to the E i The yellow button at the top of each column shows the age of the column in millions of years i ore present Ma The cyan buttons show the layers present at each age This important display forms the basis of subsequent HOTPOT data processing options HutPot Model 1 wie File Settings Calculate Display Heip Tol
100. ing by Lemigas Indonesia through Dr Ir Mujito and the Institute of Marine Geology Qingdao China through Mr Li Shaoquan Mr Shuilin Zhao of the Institute of Geology Yangzhou China helped in testing and improving the program Thanks are due to colleagues at BGS for their help and advice during the project notably to Dr G A Kirby who reviewed the tutorial section of this report and Ms B Birch who helped with report production Special thanks go to Mr Ahmad Said and Petronas for their kind hospitality and logistical support of the 1992 Workshop The software development and the Workshop formed part of the ODA BGS Research and Development Programme Project numbers 91 23 and 92 13 funded by the United Kingdom Overseas Development Administration ODA SECTION 2 Basin modelling with HOTPOT This chapter will describe in general terms the principal features of the HOTPOT basin modelling software HOTPOT is a self contained 3 D sediment decompaction and thermal history modelling program The Microsoft Windows 3 Graphical User Interface is used to provide a flexible system for controlling the program 2 1 Data requirements HOTPOT requires that the basin to be modelled Fig 2 1 is described as a series of stratigraphical units or layers eroded layers can be incorporated into the basin model which lie within a specified thermal regime defined by heatflow and surface temperature Q t i grid node sample grid nodes lo To
101. ing studies of the Subei South Yellow Sea Basin of China were completed in early 1992 In response to requests from the CCOP Technical Secretariat and from Member Countries a Workshop was arranged in order to demonstrate in detail the application of the then current version of HOTPOT and to illustrate how its results might be interpreted and employed in hydrocarbon exploration The Workshop was held at the Petronas Training Centre at Bangi Malaysia from 25 to 28 February 1992 and was attended by representatives from CCOP Technical Secretariat China Indonesia Malaysia Thailand and Vietnam The first public release of the HOTPOT program Version 2 5 and user manual Chadwick et al 1992 was made at the Workshop Development of the HOTPOT program has continued throughout 1992 3 with the emphasis being on generalising the input data specifications to allow non CCOP specific data sets to be used and improving the user interface Feedback from users in the CCOP Technical Secretariat and CCOP Member Countries together with experience gained from BGS modelling studies of the Northumberland Solway Basin UK and the Bengal Basin Bangladesh has provided important information which enabled significant improvements to be made to some of the algorithms used in the program The resulting program HOTPOT Version 3 0 forms the second public release of the software 1 2 Economic significance of thermal modelling 1 2 1 General statement A re
102. ingtar Formation a E E Figure 4 34 4 29 HOTPOT Tutorial Double click the left mouse button The thermal history of all three layers at the grid node is drawn while keeping the cursor on the in a graph display window Fig 4 34 The graph may be printed selected grid node by choosing File then Print options Choose graph display window File The temperature grid map is redisplayed allowing other grid menu then choose Close option nodes to be selected and displayed in the same manner Choose grid display window File The HorPor Main Window is redisplayed menu then choose Close option You may display grid node extractions of other results sediment starved thicknesses layer densities layer conductivities etc in the same way as required Auxiliary data displays You may also display the contents of the auxiliary data files Choose Display menu Choose Depth density option The depth density relationship stored in the auxiliary data file malay ddt is drawn in a graph display window Fig 4 35 It may be printed by choosing File then Print Choose graph display window File The HorPor Main Window is redisplayed menu then choose Close option je i D c tutordaltmalay ddt NE Eile Style g cm SR E Lst AP OPSHAL Figure 4 35 Choose Display menu 4 30 HOTPOT Tutorial Choose Depth conductivity option The depth thermal conductivity relationship stored in the auxiliary data file malay dkt is drawn
103. instructions given for Model 1 rather than repeat them here 4 3 1 Set the model title Carry out the instructions given in The title is shown on the main window caption bar Section 4 2 1 but set the title to Model 2 instead of Model 1 4 3 2 Define the area of interest In Model 1 you used an area of interest definition which we had prepared and saved in a file Here you will enter the definition yourself and save it for use in Model 3 Saving an area of interest definition enables you to re run modelling sessions quickly and easily The geographical limits of the area of interest for the Tutorial data set are specified in latitude and longitude degrees When you use your own data you may use other units geographical co ordinate systems are discussed in Appendix II 2 3 Choose Settings menu Choose Area of interest option The area of interest dialogue opens The insertion point flashing cursor is in the North box Type 10 0 into North box Sets the northern limit of the area to be latitude 10 N Press TAB key Insertion point moves to South box Type 6 0 into South box Sets the southern limit of the area to be latitude 6 N Press TAB key e Insertion point moves to N S spacing box Type 0 1 into N S spacing box Sets the spacing between grid nodes in the north south direction i e the distance between adjacent grid rows to be 0 1 Press TAB key Type 160 0 into West box and press TAB key Type 166 0 into East box and pres
104. item has been performed successfully where no other visual confirmation would be available Buttons with their text shown in black are enabled and can be chosen Buttons with their text shown in grey are disabled and cannot be chosen An ellipsis a sequence of three periods is appended to the text label of any menu item or button which when chosen invokes a dialogue box All dialogues have a system menu button at the left end of their caption bars The system menu provides an alternative method for users to move and close the dialogue Choosing Close from a dialogue system menu is the same as choosing that dialogue s Cancel button 5 Reference to HOTPOT version 3 0 for Windows 5 3 Common dialogues 5 3 1 The File Selector dialogue This is used whenever HOTPOT requires the user to select a single file so that data File can be saved to disk or read from disk It i is similar in operation to the file selector Path clccop dats dialogues used by many Windows i Directories applications Figure 5 1 shows an example of the HOTPoT file selector dialogue The dialogue caption in the top border will briefly explain what sort of file is required and what operation is being performed Figure 5 1 The Path text shows the current directory The File edit box shows either a suggested file name or a wild card file specification used in conjunction with the Files list box Text in this edit box may be selected and then
105. l uplift Sediment starved thicknesses tectonic subsidence As a precursor to more sophisticated basin modelling techniques see Section 2 3 and Appendix IV HOTPOT computes sediment starved thicknesses also known as tectonic subsidence The effect of sediment loading is nullified at each grid node by using the sediment loading equation Ss Pm T P Pn Pw where S sediment starved thickness at grid node Basin modelling with HOTPOT S sediment loaded thickness at grid node pa density of mantle material 3 33 g cm p density of sea water 1 03 g cm p bulk density of sedimentary column at grid node This has the effect of normalising the thickness and density of the sedimentary sequence deposited at the end of each stratigraphical interval to an equivalent depth of sea water The depth of water during deposition is accounted for by simply adding it to the sediment starved thickness Sud ES Du h where S crustal subsidence corrected for water depth h water depth HorPor does not include a facility to take into account changes in global sea level which are at present very poorly quantified By applying these procedures HOTPoT produces sediment starved subsidence values at each grid node and thus sediment starved grids for the basin Output Backstripped output from the program is as follows a Colour shaded gridded maps depicting present day and palaeosediment thicknesses sediment
106. l lack of argillaceous rocks indicates that this unit can have no source potential The sandstones could have good reservoir characteristics but the lack of interbedded sealing shales and the limited tectonic deformation suggest that there are no closed sealed structures within this layer To summarise 1 Potential source rocks probably occur only in the Tollerton Formation 2 Structural traps with suitable reservoir rocks are largely restricted to the Ruddington Formation 3 The main potential for stratigraphical traps is in the Ruddington Formation 4 The main period of structural trap generation was at the end of deposition of the Ruddington Formation but some closed structures could have formed during the syn extension subsidence contemporary with the Tollerton Formation 4 56 HorDor Tutorial 8 0 E over mature 220 0 as 150 0 j oil 100 0 6 0 under mature 160 0 162 0 164 0 165 0 Figure 4 61 Tollerton Formation at 20 Ma Model 1 4 5 3 The significance of the temperature maps Figure 4 61 is a pseudo maturity map of the base of the Tollerton Formation at 20 Ma from Model 1 It suggests that any hydrocarbon source rocks particularly in the lower part of the Tollerton Formation could have begun to generate oil towards the close of syn extension subsidence at 20 Ma However because of the lack of suitable reservoir rocks and sealed structures at this time it must be assumed that most hydrocarbons formed were a
107. lanced crust as part of a lithospheric plate having a linear geothermal gradient and overlying an isothermal asthenosphcre Instantaneous thinning of the lithosphere occurs as a result of horizontal extension that causes its surface area to increase by a factor B Both crust and lithosphere are thinned by a factor 1 6 this thinning causing elevation of the lithospheric isotherms Fig IV 3 The crustal thinning causes an isostatically driven fault controlled subsidence S the syn extensional subsidence Owing to the buoyancy effect of the elevated isotherms S is less than the subsidence that would result from thinning only the crust Stora With time the elevated lithospheric isotherms relax back to their pre extension position allowing the crustal subsidence gradually to approach Sq514 This secondary post extensional subsidence Srp has the above mentioned characteristic of an exponentially decreasing rate with time Also it is of a regional nature characterised by an absence of normal faulting and may be accompanied by lithospheric flexure Sediments deposited during the phase of thermal relaxation subsidence commonly overlap the margins of the earlier faulted basin producing a characteristic steer s head profile Dewey 1982 illustrated in Figure IV 4 Thus The total subsidence S t at time t Ma after extension can be expressed S t 2 S S t IV 1 Notes on estimation of palaeoheatflow in extensional basins The total s
108. ll nodes and thus to control masking operations on other grids Their use is illustrated in the Tutorial see sections 4 1 1 and 4 3 5 See also Masking Reconstruction of the subsidence history of a point location by the sequential removal of successively older stratigraphical layers As each layer is removed the remaining layers are allowed to decompact according to some appropriate function A box in a dialogue or window which may be chosen or selected The strip displayed along the top edge of the window containing title text Shown highlighted traditionally in blue when the window is active Committee for Co ordination of Joint Prospecting for Mineral Resources in Asian Offshore Areas Technical Secretariat based in Bangkok Thailand The division of geological time extending from about 65 million years ago to the present day A square box in a dialogue which is marked with a x symbol when it is selected It is used to enable a program option A symbol used in a menu to indicate either a currently selected option or to provide visual confirmation that a procedure has been carried out To pick an item that begins an action within Microsoft Windows How this is done depends on the type of item and the method used Cf Select To press and release a mouse button Synonym for drop down list box Extra contours interpolated between existing widely spaced contours in order to prevent the gridding procedure assigning null nod
109. loaded from the file ruddinga lay The layer information dialogue is redisplayed with the information shown This also includes a reference to the digitised isopach file ruddinga iso The gridding window opens The program is ready to grid the digitised Ruddington Fm isopach data The program grids the isopach data with a search radius of 0 19 A grid map is shown Fig 4 14 The grid is accepted the gridding window closed and the HorPor main window redisplayed Ruddington Formation 2080 2240 1920 2080 1760 1920 1660 1760 1440 1600 1280 1440 1120 1280 960 1120 800 960 640 800 480 640 320 480 160 320 0a 160 mean 604 582 Figure 4 14 The HOTPOT main window display shows the Ruddington Formation button drawn below the Kcy worth Formation button in its correct stratigraphic position in the column Fig 4 15 Note that the Ruddington Formation button has its text shown in white while the Keyworth Formation button now has its in black The white text indicates the selected layer The last layer added is automatically selected Load the Tollerton Formation data Choose File menu HoTPoT Tutorial tud HutPat Madel t Elle Settings Calculate Display H ae DO are furddington MZ Figure 4 15 Choose Layer option Choose Load button Choose toller lay from Files list Layer information is loaded from file toller lay The layer information dialogue is redisplayed with the
110. lution of the British Isles Journal of the Geological Society London 139 371 412 EARLE M M JANKOWSKI E J amp VANN ER 1989 Structural and stratigraphic evolution of the Faeroe Shetland Channel and Northern Rockall Trough Memoir of the American Association of Petroleum Geologists 46 461 469 HOUBOLT J J U C amp WELLS P R A 1980 Estimation of heatflow in oil wells based on a relation between heat conductivity and sound velocity Geologie en Mijnbouw 59 215 224 ISSLER D R amp BEAUMONT C 1989 A finite element model of the subsidence and thermal evolution of extensional basins applications to the Labrador Continental Margin In NAESER N D Thermal history of sedimentary basins Springer Verlag New York 239 267 KINGSTON D R DISHROON C P amp WILLIAMS P A 1983 Global basin classification system Bulletin of the American Association of Petroleum Geologists 67 2175 2193 KLEMPERER S L amp WHITE N 1989 Coaxial stretching or lithospheric simple shear in the North Sea Evidence from deep seismic profiling and subsidence Memoir of the American Association of Petroleum Geologists 46 511 522 LOPATIN N V 1971 Temperature and geological time as factors in coalification In Russian Izvestiya Akademiya Nauk SSSR Seriya Geologicheskaya 3 95 106 MACKENZIE A S amp QUIGLEY T M 1988 Principles of geochemical prospect appraisal Bulletin of the American Association of Petroleum Geologists 7
111. more precise thermal models from the use of HOTPOT Similarly although the interpretation of the maps generated above can only be of a broad general nature they suffice to illustrate the main principles of how results from more detailed HoTDoT based modelling could be used in hydrocarbon exploration 4 55 HOTPOT Tutorial There is no single unique interpretation of the subsurface temperature maps as their meaning and value are dependent on the objectives of the user and the particular reasons for undertaking such modelling This report is concentrating on the use of thermal modelling in hydrocarbon exploration and therefore the layer temperature maps with maturity scales Figs 4 30 4 35 are the most relevant These indicate the present day and palaeo locations of the 100 150 and 220 isotherms which are taken as defining the oil gas and overmature zones As the basin modelled is stated to have formed in the last 25 Ma years this assumption is believed to valid The influence of time on the maturity of any organic matter in such a young basin can be assumed to have been negligible 4 5 2 Preliminary hydrocarbon prospectivity assessment Many of the preliminary data provided about the basin are of relevance in hydrocarbon prospectivity The following main conclusions can be drawn The Tollerton Formation is an almost totally argillaceous unit deposited in an average water depth of 30 m Therefore this unit could have good source potent
112. n 4 40 Type 0 19 into the Radius box then choose Ok button or press RETURN key 6 0 160 0 162 0 Choose the gridding window File menu Choose Save option Type toller into the File box then choose Ok button or press RETURN key Choose Accept button Choose Settings menu Choose Conductivity option Select Depth variable radio button Choose Ok button HOTPOT Tutorial The program grids the isopach data with a search radius of 0 19 and redisplays the grid map Fig 4 47 The search radius is now acceptably small There are no null nodes and separate features are distinct Note the large area of zero thickness nodes around the actual sedimentary fill this is due to zero value anti masking contours see 4 1 1 You will find more information about choosing gridding search radii in Appendix Ill This has prepared an acceptable grid which you will save for later use in Model 3 You should also now appreciate the convenience of being able to save grids for later use mean 171 163 164 0 166 0 Figure 4 47 The file selector closes and HOTPOT saves the grid data into the file toller hpg The grid is accepted and the gridding window closes The HorPor Main Window shows the Tollerton Fm layer button below the Ruddington Fm button it is selected Links the depth thermal conductivity table to the Tollerton Fm at 0 Ma present day 4 41 HOTPOT Tutorial 4 3 6 Decompaction by backstripping
113. n Files file list dialogue is displayed for the user to select a list of annotation files Annotation files are used n conjunction with the Annotate option in the Style menu of Grid Display Windows section 5 6 to overlay line work e g a coastline on displayed grid maps The format of annotation files is described in Appendix 11 3 Choosing the Ok button will close the dialogue and if the file list contains any files the Annotation menu option will be check marked Choosing the Cancel button will close the dialogue and leave any existing file list unchanged File Print May be chosen at any time 5 9 Reference to HOTPOT version 3 0 for Windows This produces a formatted report of the current state of the program and model The report is sent to the printer via the Windows Print Manager The printer and its configuration may be altered by choosing the Printer setup option from this menu A Print dialogue is displayed while this option is being processed The content of the report will depend on the status of HOTPOT Details will include as appropriate name of depth density table file name of depth thermal conductivity table file e area of interest specification e summary of stratigraphy layer information including names of isopach or depth data files e summary of basin history including thermal parameter settings and names of heatflow contour files File Printer setup May be chosen at any time T
114. nd completion of crosion 10 Ma on Fig 4 57 TL kon 24 0 See TED Payee glen Bingham Member 2000 Yussdinatun Farsrativn 4000 Figure 4 57 4 53 HOTPOT Tutorial 4 4 8 Setting age related thermal parameters Thermal computation can be carried out using either single value constant heatflow see Section 4 2 9 or spatially and time variant heatflow see Sections 4 3 9 and 4 3 10 as required When you set the age related parameters remember the two additional time calibration points at 12 Ma and 14 Ma in this model 4 4 9 Printing a model report Carry out the instructions given in Confirm that thermal parameter settings are as intended section 4 2 10 for printing a model report 4 4 10 Thermal calculation Choose Calculate menu Choose Geothermal option 4 4 11 Display of thermal model results Display options for the thermal results are similar to those described in section 4 2 12 and are not described in detail as you should by now be familiar with the technique Example grid maps from a single value constant heatflow thermal calculation as in Model 1 Section 4 2 6 are given in Figures 4 58 and 4 59 These show the temperatures at the base of the Tollerton Formation at 12 Ma Fig 4 58 and 10 Ma Fig 4 59 Note the fall in temperature in the southern part of the basin between 12 and 10 Ma Note also how the temperatures calculated here Fig 4 59 are lower than those obtained from Mo
115. nformation dialogue opens The insertion point flashing cursor is in the Formation name box Type Keyworth Formation in Formation name box Press TAB key Type SST in Lithology code box then press TAB key Type 10 in Age at base box then press TAB key Type 0 in Water depth box Select M radio button in lsopach Units group box Figure 4 40 Choose Data files button in Isopach box Choose keyworth iso from Files list Choose Ok button HoTPoT Tutorial This sets the name used to identify the formation Formation names may contain any printable characters and include spaces Insertion point moves to the Lithology code box This sets the lithology to be pure i e 100 sandstone The TAB moves the insertion point to the Age at base box This sets the age of the base of the layer to be 10 Ma The TAB moves the insertion point to the Water depth box The water depth was 0 metres when deposition of the layer finished The isopach data are in metres The dialogue should now look like Figure 4 40 o M RM Selectisopach Files Selected files Path cMutor al Directories Figure 4 41 This opens a file list dialogue for you to select one or more digitised isopach data files to be used for subsequent gridding The full file path name cAtutoriakeyworth iso is copied into the Selected files list box in the upper part of the dialogue Fig 4 41 In this model you are only using on
116. nformation is loaded from file kw lay which was saved when entering layer information for the Keyworth Fm during Model 2 section 4 3 5 The layer information dialogue is redisplayed with the information shown The gridding window opens This drop down menu is used to control input and output of gridded data This is used to load a grid saved during a previous modelling session A file selector dialogue opens This was the file saved when gridding the Keyworth Fin during Model 2 section 4 3 5 The file selector dialogue closes and HOTPOT loads information from the keyworth hpg file It then opens the Grid Confirmation dialogue which shows both the name of the required grid and the name of the grid in the file you selected these should be the same and asks you to confirm that this ts the grid you want to use Fig 4 50 4 46 HOTPOT Tutorial Grid Confirmation Require Keyworth Formation Found Keyworth Formation Use this grid Figure 4 50 Choose Yes button HorPor loads the grid data from the file into the layer grid and displays the grid map Choose Accept button The grid is accepted and the gridding window closes The HorPor Main Window shows the Keyworth Fm layer button it is selected Choose Settings menu Choose Conductivity option Select Depth variable radio button Links the depth thermal conductivity table to the Keyworth Fm at 0 Ma present day Choose Ok button Bingham Member You are no
117. ngs Area of Interest Must be chosen to define the arca of interest prior to choosing any menu option which invokes data gridding May be chosen at any time to show the current area of interest definition This will display a dialogue Fig 5 10 with edit boxes for entering the following information about the geographical area of interest North the northern map limit South the southern map limit N S spacing spacing between grid lines north to south Reference to HOTPOT version 3 0 for Windows West the western map limit East the eastern map limit W E spacing spacing between grid lines west to east These data must be in appropriate and consistent map grid units e g UTM metres Latitude and Longitude degrees see the note on co ordinate systems in Appendix II 2 3 Decimal fractions are permitted Choosing the Apply button will cause HOTPOT to verify information entered into the dialogue edit boxes and to calculate and display the numbers of grid nodes in the N S and W E directions This is particularly useful W E spacing when defining a new area of interest If WE nodes there are too many grid nodes maximum grid size is approximately 16129 nodes i e 127 x 127 nodes a Figure 5 10 warning message dialogue will be displayed in this case reduce the number of nodes by increasing the N S and W E spacing values and choose Apply again Choose the Ok button to complete the dialogue Choose the Cancel button to l
118. ntered will be interpreted with respect to the Units and Type selections Select the Digitised surface radio button if digitised contour data are available Then choose the Data Files button to open a file list dialogue and select the files containing the digitised contour 5 7 Reference to HOTPOT version 3 0 for Windows data The formats which may be used for digitised contour data files are described in Appendix II 2 Choose the Ok button to complete the dialogue If the digitised surface option was selected HOTPOT will open a Gridding Window for the data in the digitised contour files to be gridded Section 5 7 describes the data gridding window Otherwise a planar surface will be calculated Choose the Cancel button to close the dialogue without defining a topographic surface File Layer aa mmm A mm teh I Su arte May be chosen when an area of interest has been f Layer Information defined and prior to performing the decompaction c tutorlal bingham lay calculation The model must have at least one layer in order to perform the decompaction calculation ii e Lithology code SST 50 LST 50 Age at base i Ma Settings Choosing this item will display the Layer Information dialogue Figure 5 8 This dialogue has fields for entering the following information about Water depth m the layer Age eroded Formation name The geological formation name Eroded D 12 Ma which will be used to identify the layer Tex
119. ntered directly from the keyboard or as in this Tutorial loaded from a previously saved file This enables previously saved layer information to be loaded back into HOTPOT A file selector dialogue opens Layer information is loaded from file keyworth lay The layer information dialogue is redisplayed with the information shown Fig 4 8 cf Table 4 1 This information also includes a reference to the digitised isopach data file keyworth iso 4 10 HotPot Tutorial To confirm this file reference Choose A file list dialogue opens You should see the filename Data files button c tutorial keyworth iso in the Selected files list box at the top of the dialogue Fig 4 9 Layer information c utorial keyworth lay Age at base Ma Water depth gt m 1 Select isopach files Selected files cAtutoriallkeyworth iso Flle Path cMutorlal Directories ruddingo iso toller iso Figure 4 8 Figure 4 9 Choose Cancel button The file list dialogue closes without change The layer information dialogue is redisplayed Choose Ok button The layer information dialogue closes and the gridding window opens as a full screen window The program is ready to grid the digitised Keyworth Fm isopach data Choose Grid button The gridding search radius dialogue opens in the top left of the gridding window The search radius controls the resolution of the weighted mean type gridding algorithm used in HOTPOT Type 0 16 into R
120. o f surface or seabed temperature at time Q t heatflow at time t Az thickness of it time slice layer thermal conductivity of i time slicc layer HOTPOT utilises this summation in the computation of the thermal results giving output as follows a Colour shaded gridded maps depicting present day and palacotemperatures and layer thermal conductivities b 1 D grid node extractions depicting layer thermal histories 2 3 Prediction of palaeoheatflow As indicated above HOTPOT has the facility to incorporate time variable heatflow into the thermal calculation Present day heatflow values can be measured directly but estimation of palacoheatflow is more difficult requiring some knowledge of the mechanisms of basin formation Basin modelling with HOTPOT Sedimentary basins fall into many different categories depending upon their mode of development Fig 2 3 World wide however the large majority of hydrocarbon bearing basins can be classed as continental extensional basins These basins form in response to tensional forces resulting from destructive plate margin processes Fig 2 4 The basins can form both in continental interiors or close to the continental margin for example in a back arc environment UNKNOWN CYCLE OR BASIN BASINS FORMED ON CONTINENTAL CRUST BASINS COMPLETELY FORMED SEDIMENTS CAN OVERLAP ONTO OCEANIC CRUST ON OCEANIC CRUST ADIACENT TO CONTINENT CONTINENTAL BASINS OCEANIC BASINS AREA OF DIVE
121. of the CCOP Region are of Cenozoic age Therefore accurate estimation of present day and palaeo subsurface temperatures in particular the location of the 100 150 and 220 isotherms is assumed to be sufficient to predict adequately the time and place of hydrocarbon generation from known source rocks Such knowledge of the thermal history allied with information relating to source potential including kerogen type and to structural history is a necessary pre requisite in predicting the hydrocarbon prospectivity of any region 1 3 Acknowledgements It is a pleasure to record the co operation and the support of past and present members of the CCOP Technical Secretariat principally Dr G R Balce Prof Wang Daxiong Mr Sermsakadi Kulvanich Mr B Elishiwitz Prof He Qixiang Prof Weng Shijie Dr N Hanaoka Dr O Matsubayashi Mr I Miljeteig Mr S Maehle and Ms Petcharat Sarawisutra The constructive advice of Prot R Sinding Larsen Special Advisor from Norway to CCOP is also acknowledged The project could not have proceeded without the generous support of Member Countries and their representatives at the Working Group on Resources Assessment WGRA The Department of Introduction Mineral Resources Thailand through Mr Nares Sattayarak and the Exploration Department of Petronas Malaysia through Mr Ho Wan Kin provided data and valuable support to allow the pilot study to take place Further data were supplied in support of later modell
122. omplished if the present day heatflow the extension factor and the age of the basin are known simply by adding a constant value to the heatflow axis such that the predicted present day heatflow matches the observed heatflow Thus it is possible to predict palaeoheatflows in an extensional basin by assuming the McKenzie Model of uniform lithospheric extension The balance of evidence from heatflow studies Buck et al 1988 and deep seismic reflection profiling e g Klemperer amp White 1989 suggests that this model is widely applicable If local evidence unequivocally indicates non uniform lithospheric extension then other palaeoheatflow models must be employed The choice of model and estimation of palaeoheatflow is ultimately the responsibility of the user IV 2 WEST ORKNEY BASIN STACK SKERRY BASIN Notes on estimation of palaeoheatflow in extensional basins hee RR ON p Mri y i M eg I S ren d a i ls TR e n a vos pa jj AP M toe yi LED Y VISTA 0 0 6 0 1M1 8W H1d3Q U DEVONIAN L CARBONIFEROUS o Zz PEE 8 z gt OQ i TRE u O te a at d m NW European Figure IV 1 Extensional basin with large normal faults continental shelf after Earle et al 1989 Notes on estimation of palaeoheatflow in extensional basins SECONDS 0 0 1 0 A 2 0 3 0 4 0 SENE P PEN Twt se NE o eere We se pm m ae s 2
123. on Select 0 00 Ma or 20 00 Ma button HotTPot Tutorial HotPot Model 1 Loa ed thickness 10 00 Ma A mean 953 209 Figure 4 20 This drop down menu controls data output from the grid display The grid map is printed The representation of the colours will depend on the printer Colour printers should show the colours as seen on screen Black and white printers should produce a grey scale image Some printers may produce a better grey scale from the HOTPOT alternative colour palette To try this choose Style menu then choose Alternate colours option then repeat the print operation This closes the grid display window The HOTPOT Main Window is redisplayed The other available age related options Starved thickness and Bulk density can be displayed and printed as required Their grid display windows should be used as described for Loaded thickness above By selecting the other age buttons 0 or 20 Ma it is possible to display the other age related options as required in the manner described above for 10 Ma The layer related display options Select Tollerton Fm button in column under 10 00 Ma button The text on the button changes to white to indicate selection 4 17 Choose Display menu Choose Layer thickness Calculate Cee la aL ea a OO ae NS RN ARN RR a ODDO D EON If you have a printer available on your computer Choose grid display window File menu and then choose Prin
124. on Formation the Bingham Member was deposited from 14 to 12 Ma and then eroded between 12 and 10 Ma The eroded layer is expressed as an isopach contour map Fig 4 5 digitised as the above maps The information for the eroded layer is summarised in Table 4 2 50 sandstone 50 limestone Table 4 2 After installation section 3 6 the primary data should be stored on the disk as follows Keyworth Fm layer information seen c tutorial keyworth lay Keyworth Fm digitised isopachs sse c tutorial keyworth iso Ruddington Fm layer information original cc c tutoriahruddingo lay Ruddington Fm digitised isopachs original c tutorial ruddingo iso Ruddington Fm layer information additional CMutoriavuddinga lay Ruddington Fm digitised isopachs additional c tutorial ruddinga iso Tollerton Fm layer information seen c tutorialtoller lay Tollerton Fm digitised isopachs esee cMutoriaMoller iso Bingham Member digitised isopachs sees c tutoriaNbingham iso Faca thlow CORLOUES ansaan a cXutoriaMeatflow iso 4 1 2 Auxiliary data The following auxiliary data files are stored on the disk Depth Density date uei Gin e Rede to dete c tutorial malay dat Depth Thermal Conductivity data eese c tutorial malay dkt 4 2 HOTPOT Tutorial 10 0 9 0 sok 7 0 8
125. opens A file selector dialogue opens Layer information is loaded from file toller lay The layer information dialogue is redisplayed with the information shown Choose Ok button Choose gridding window File menu Choose the Load option Choose toller hpg from Files list Choose Yes button Choose Accept button Choose Settings menu Choose Conductivity option Select Depth variable radio button Choose Ok button HOTPOT Tutorial The gridding window opens A file selector dialogue opens HotPot loads information from the toller hpg file saved when gridding the Tollerton Fm during Model 2 section 4 3 5 and then opens the Grid Confirmation dialogue asking you to confirm that this is the grid you want to use HortPot loads the grid data into the layer grid and displays the grid map The grid is accepted and the gridding window closes The HotPot Main Window shows the Tollerton Fm layer button below the Ruddington Fm button it is selected Links the depth thermal conductivity table to the Tollerton Fm at 0 Ma present day 4 4 6 Decompaction by backstripping The HoTPoT Main Window shows the Keyworth Formation Bingham Member eroded Ruddington Formation and Tollerton Formation buttons in the stratigraphic column This indicates that all four model layers have been loaded and are ready for decompaction Carry out the instructions given in section 4 2 5 for decompacting the model The thermal conducti
126. orial Model 3 The third model shows how an eroded layer is incorporated into the model Single value constant heatflow is used for the thermal modelling as in Model 1 The modelling session illustrates e the re use of gridded data saved from previous modelling sessions Model 2 e the manual completion of a layer information dialogue for an eroded layer Note that we refer to some of the instructions given for Models 1 and 2 rather than repeat them herc 4 4 1 Set the model title Carry out the instructions given in The title is shown on the main window caption bar section 4 2 1 but set the title to Model 3 instead of Model 1 4 45 HOTPOT Tutorial 4 4 2 Define the area of interest Carry out the instructions given in Section 4 2 2 but use the file model aoi instead of tutorial aoi model aoi was the file saved when defining the area of interest during Model 2 section 4 3 2 4 4 3 Load auxiliary depth density data Carry out the instructions given in section 4 2 4 4 4 4 Load auxiliary depth thermal conductivity data Carry out the instructions given in section 4 2 7 4 4 5 Load the layer data Keyworth Formation Choose File menu Choose Layer option Choose Load button Choose kw lay from Files list Choose Ok button Choose the gridding window File menu Choose the Load option Choose keyworth hpg from Files list The layer information dialogue opens A file selector dialogue opens Layer i
127. print out if you have a printer available on your computer Choose File menu Choose Print option 4 2 11 Thermal calculation A report on the model parameters is printed Compare the data shown in this report to the data values given in the instructions above If any are incorrect you must repeat the relevant instructions The report text is reproduced here as Table 4 3 HOTPOT is now ready to carry out the thermal computation Choose Calculate menu Choose Geothermal option A progress dialogue shows information about the thermal modelling process This shows the name and age of each layer processed the type of calculation being performed and the percentage completed HorPor Tutorial Table 4 3 HotPot Model 1 Depth Density file c tutorial malay ddt Depth Thermal conductivity file c tutorial malay dkt Area of Interest file c tutorial tutorial aoi Western limit 160 Eastern limit 166 East West spacing 0 1 No East West nodes 61 Southern limit 6 Northern limit 10 North South spacing 0 1 No North South nodes 41 Age of top of top layer 0 00Ma Initial stratigraphy Formation Keyworth Formation Age 10 00Ma at base Lithology SST Water depth 0 0m at end of deposition Isopach files c tutorial keyworth iso Formation Ruddington Formation Age 20 00Ma at base Lithology SST 50 LST 50 Water depth 10 0m at end of deposition Isopach files c tutorial ruddinga iso
128. pth box The water depth was 10 metres when deposition of the layer finished The TAB moves the insertion point to the Eroded check box Pressing the SPACEBAR selects the Eroded check box so marking this layer as eroded The Age eroded box is automatically enabled and the insertion point moved into it This sets the age of the onset of erosion to 12 Ma Thus deposition of the Bingham Member lasted from 14 Ma to 12 Ma and the erosional episode lasted from 12 Ma to 10 Ma which is the age of the base of the overlying Keyworth Fin The isopach data are in metres Fig 4 51 shows the completed dialogue A file list dialogue opens for you to select digitised isopach data files for subsequent griddi ig The full file path name cAMutorialbingham iso is copied into the Selected files list box in the upper part of the dialogue The file list dialogue closes and the layer inforination dialogue is redisplayed A file selector dialogue opens Layer inform ation c tutorial bingham lay Formation name Age at base Ma Water depth m Age at top Eroded DX h2 Ma lsopach Units m O km Q teet Figure 4 51 4 48 Type bingham then choose Ok or press RETURN key Choose Ok button Choose Grid button Type 0 17 into Radius box then choose Ok button or press RETURN key Choose Accept button Choose Settings menu Choose Conductivity option Select Depth variable radio button Choose Ok but
129. r captions on displays of the grid data Each line is a separate title Only one title Example Grid is shown in the example data file above HoTPor Version 3 0 for Windows only stores one title in the Titles section This is the caption of the Grid Display Window or Gridding Window from which the grid was saved When HOTPOT Version 3 0 for Windows reads a grid file it only uses the first line of the Titles section ignoring any subsequent lines Grid This section is always present and is used to store the dimensions of the grid and then the data values at the grid nodes All applications using this file format use this section in the same way The grid dimensions are stored one per line The format of these lines is KeyWord value where the Key Word identifies a dimension and the value indicates its setting The keywords are cols the number of columns in the grid rows the number of rows in the grid I 7 Xmin Xmax Ymin Ymax Zmin Zmax Znull HOTPOT data file formats The number of nodes cols x rows the minimum x co ordinate value i e western limit of the grid the maximum x co ordinate value i e eastern limit of the grid X ax X nin The distance between columns is given by cols I the minimum y co ordinate value i e southern limit of the grid the maximum y co ordinate value i e northern limit of the grid ax max Y in The distance between rows is given by ro
130. r the selected time calibration point 0 Ma o c SetHeattiow Period 0 00 Ma Aom NREN Constant value min Figure 4 27 4 22 Type 80 0 in Constant value box then choose Ok button or press RETURN key Select 10 00 Ma button Choose Settings menu Choose Surface temperature option Type 30 0 in Temperature box then choose Ok button or press RETURN key Choose Settings menu Choose Heatflow option Type 80 0 in Constant value box then choose Ok button or press RETURN key Now repeat the procedure for the remaining two time calibration points i e 20 00 Ma 25 00 Ma HoTPot Tutorial This sets the heatflow at 0 Ma to the required value in this case to 80 mW m Note that the Constant value radio button is automatically selected as you enter the value Fig 4 27 This links the following thermal parameters to 10 Ma For this tutorial model assume that surface temperatures remained constant through time Though this need not be true in other cases For this tutorial model assume that heatflow remained constant through time Though this need not be true in other cases Set the thermal parameters for 20 Ma and for 25 Ma the onset of basin development The thermal parameters conductivity surface temperature and heatflow are now fully defined 4 2 10 Printing a model report It is advisable at this stage to check that the model parameters are correct by obtaining a summary
131. rself e fill in the dialogue boxes from the data given in Table 4 1 e specify toller iso as the isopach data file To use saved layer information e choose Load button choose toller lay from Files list Choose Ok button Choose Grid button The layer information dialogue opens In a similar manner to that described for the Keyworth Fin Layer information is loaded from file toller lay including a reference to the digitised isopach file toller iso The gridding window opens HOTPOT Tutorial Type 0 1 into the Radius box then The program grids the isopach data with a search radius of 0 1 choose Ok button or press RETURN and displays a grid map Fig 4 45 The search radius is too key small and null nodes white are seen between the bands of colour which follow the contours The search radius needs to be increased 6 0 mean 184 61 160 0 162 0 164 0 166 0 Figure 4 45 Choose Grid button Type 0 5 into the Radius box then The program grids the isopach data with a search radius of 0 5 choose Ok button or press RETURN and redisplays the grid map Fig 4 46 There are now no null key nodes white between the bands of colour which follow the contours However the two small basins within which the Tollerton Fm exists now appear to merge north east of map centre The search radius needs to be decreased 10 0 6 0 mean 138 293 160 0 162 0 164 0 166 0 Figure 4 46 Choose Grid butto
132. s TAB key Type 0 1 into W E spacing box Choose Apply button Pd North South idi N S spacing N S nodes HorPoT Tutorial Insertion point moves to West box Sets the western limit of the area of interest to be longitude 160 E Insertion point moves to East box Sets the eastern limit of the area of interest to be longitude 166 E Insertion point moves to W E spacing box Sets the spacing between grid nodes in the west east direction 1 e the distance between adjacent grid columns to be 0 1 The values entered in the boxes are verified The N S nodes and W E nodes boxes are updated with the numbers of grid nodes in the north south and west east directions respectively Fig 4 38 These numbers are calculated from the grid dimensions and spacings you entered Arca of interest unsaved W E spacing W E nodes Choose Save button Use Directories list box to find the c tutorial directory Type model into File box then choose OK button or press RETURN key Choose OK button Figure 4 38 Opens a file selector dialogue for you to save the area of interest definition Figure 4 39 The file selector closes and the Aol definition is saved into the file cMutorialmodel aoi note that the aoi file type is automatically added by the file selector The area of interest dialogue remains open The file name is now shown under the caption bar of the dialogue The area of interest dialogue closes and t
133. same units as grid spacing A good first estimate is the minimum of the grid spacing or the average separation of data points The search radius is set by clicking the Grid button in the Gridding Window section 5 7 This opens a dialogue which shows the existing search radius value in an edit box The user should edit the existing value or enter a new value then click the dialogue Ok button to initiate gridding When the grid has been calculated the program will display a grid check map of it in the Gridding Window On the map each grid node which has had a value assigned to it is shown as a coloured cell A scale on the right side of the map shows what the colours represent in terms of the data units e g thickness in metres for isopachs Grid nodes which are outside the search radii of all data points have no value assigned to them and are called null nodes Null nodes are not shown on the map The description of the Gridding Window in Section 5 7 of this Manual gives more information on the gridding window and its manipulation The grid map is used to assess the reliability of gridding and appropriateness of search radius It should be checked against the original isopach contour map If the search radius was too small then there will be null nodes appearing on the grid check as holes Fig II 2 within areas of continuous data coverage on the original map In this case the gridding operation needs to be repeated with
134. se with the HOTPOT package malay ddt density depth table for decompaction program based on well data from the Malay Basin Water sea water 0 1 03 Lst limestone 0 000 2 114 54 170 2 133 146 103 2 162 10000 00 2 710 15000 00 2 710 btiIidSlst mudstone siltstone 0 000 1 743 26 273 1 773 All blank lines in the file are ignored their use is recommended to improve readability of the file I 1 HOTPOT data file formats All text on a line to the right of an exclamation point or a hash is treated as comment and ignored The use of comments is recommended as aides memoire to the data contained in the file e g its source and purpose Each table within the file begins with a header line This comprises a one word lithology code followed by one or more SPACE and or TAB characters and then a description of the lithology For example in the second header in the extract the lithology code is LSt and the description 1s limestone Following the header line are one or more records each containing a pair of values The first value is the depth in metres below sea level and the second value is the corresponding density in grams per cubic centimetre The depths do not have to be in regular increments neither do they have to be in order The values are read in free format The end of a table is marked by either the header line for the next table or the end of file As a special case sea water is treated as a lithology whose
135. sidence accompanied by active normal faulting is followed by a secondary phase of more gradual regional unfaulted subsidence The first phase is commonly referred to as syn rift or syn extensional subsidence The second phase is known as post rift post extensional sag or thermal subsidence The two phases may be repeated several times during the evolution of the basin Examples of syn rift and post rift subsidence are given in Figure IV 2 An important property of the post rift phase of subsidence is the fact that the rate of subsidence decreases exponentially with time in a manner similar to the progressive subsidence of oceanic lithosphere as it moves away from a spreading ridge cooling as it ages Using this analogy Sleep 1971 proposed that sedimentary basins could be formed by a major thermal perturbation of the lithosphere which produced uplift erosion and upon cooling subsidence However in general no evidence exists for the required amounts of pre subsidence erosion and another explanation for the formation of the majority of basins is required Salveson 1978 proposed a qualitative model of lithospheric thinning which led to basin subsidence and ultimately to continental separation and the formation of passive continental margins McKenzie 1978 developed a quantitative model based upon the same concept of lithospheric extension which can explain the observed types of basin subsidence McKenzie s model assumes an isostatically ba
136. sition of the layer expressed as relative proportions of the standard lithologies conventionally sandstone limestone silty mudstone and overpressured shale but others may be used if the necessary auxiliary data are available This information is entered via a Windows dialogue Chronological calibration of the base of the layer This information is entered via a Windows dialogue If the layer has been eroded and is to be restored chronological calibration of the onset of erosion This information is entered via a Windows dialogue The water depth at the end of deposition of the layer This information is entered via a Windows dialogue An average thermal conductivity value for the layer where depth vs thermal conductivity auxiliary data are not available This information is entered via a Windows dialogue All normal layers must be defined by either depth or isopach thickness data the two types must not be mixed Any eroded layers in a model must be defined by isopach thickness data Where depth data are used a topographic or bathymetric surface either planar or gridded from digitised contour data must be defined in order to compute the thickness of the top layer Age related primary data The data pertinent to the ages of the layer boundaries are a Heatflow information expressed as either single basin wide values or digitised heatflow contour maps or a combination of both Digitised contour data are stored in
137. sseensees 1 1 1 1 Background eese enennnneennennnnnnnnen nennen nnne nennen 1 1 1 2 Economic significance of thermal modelling nnm 1 1 1 2 1 General statement eeereeee enne nennen ente nhna st ten annee teens tenait enin enne tnn nennen nenne ennt ntn 1 1 1 2 2 Generation of hydrocarbons eene nnne 1 2 1 3 Acknowledgemennts eese nennen nennen entente nnne tnnt nnne nnne tnnn nnn 12 Basin modelling with HOTPOT eene 2 1 2 1 Data requirements ener ennt ettet senere 2 1 2 1 1 Primary io M 2 1 2 12 Auxiliary dataserie e A e a ia Ner 2 2 22 D at POESI oisin eei tul vit N O N O Ap S 2 3 2 2 1 Decompaction by backstripping susende nende kedede 2 3 22 2 Thermal calculation ettet ttt ttt etate ttes btts 2 6 2 9 Preoicnon OF palaeoheatllOW i osea qeistalis rot Gaerne ed ushered veis ans ledet sens 2 7 24 HOTPOTDIORTaIm USALO CVCIQu ie nad ese ee necp tes Bn AS 2 8 Installing FIO TOP Sdocmieodtor tui ERU ome te dae te EUIS M OR etes EUR iue 3 1 JT DY SLOT regure nens odo ee e tenerla t edv eher abide eL a cine etc ede 92 DISC TOQquiremehs uot oiv adeo vd utr estbamteiv tates Da a o EC ASIE 3 1 0 9 DOCUMEN CONVENTION S arsen N be d tat M ves i c tH 3 1 54 Windows operating modes sina a AA een erts urd 3 2 2 5 Tustribabiom disk COMCIS racs arete iae s Tesi cec dece vn Po En do Ra Ure Ud 3 3 26 stala Gon e
138. starved thicknesses layer and bulk densities b 1 D grid node extractions depicting sediment loaded and sediment starved subsidence histories and layer burial histories 2 2 2 Thermal calculation Prior to the thermal calculation proper HorPor has the facility to merge the stratigraphical sequences with the auxiliary thermal conductivity vs depth data This allocates realistic thermal conductivities to the present day and decompacted stratigraphical layers at each grid node The thermal calculation assumes simple vertical conductive heat transfer in the basin with heat input from below Heat production within the basin sediments is assumed to be negligible i e heatflow at the bottom of the basin is equal to heatflow at the surface or seabed Thus at each grid node WT d where Q heatflow k thermal conductivity T temperature z depth Basin modelling with HOTPOT Therefore T z 1 at Q az To o K where T temperature at depth z T temperature at depth 0 surface or seabed Therefore T Q dz k For a basin with N layers i layer of thickness Az and thermal conductivity k the integral simplifies to the summation TA T Te O iz Incorporating time variable heatflow Q t the subsurface temperature at cach grid node varies with time and can be described by the expression L AZ Ty 0 Ty t Q t 9 ia K where T t temperature at base of Nth layer at time t T
139. stratified rocks especially their sequence composition and correlation A line joining points on the base of a stratigraphic unit that are of equal depth below a standard datum typically mean sea level MSL Synonym for edit box A measure of the ability of rocks to conduct heat Units mW m K CCOP Working Group on Resources Assessment A rectangular area on a computer display screen which is used by a program to communicate with its user G 3 APPENDIX I Auxiliary data I 1 Depth Density data The standard depth density compaction curves provided with HOTPOT are illustrated in Figure 1 1 and stored in file malay ddt The curves are based upon a detailed study of depth density data from Cenozoic sedimentary sequences in SE Asia The curves were further constrained at shallow lt 500m and great gt 3500m depths by published information Sclater amp Christie 1980 Baldwin amp Butler 1985 1 0 1 2 22 24 26 2 8 m NL LT cm ESS MA ER s E 2000 LST MDSLST 4000 L asT 6000 CEE CEE PE SE PE VAR Oe FA So es aaa a ara ll LLLL LLLA 14000 uu E 9 Figure I 1 I 2 Depth Thermal conductivity data The standard depth thermal conductivity curves provided with HOTPOT are illustrated in Figure 1 2 and stored in file malay dkt The curves are based upon data from Cenozoic sedimentary sequences in SE Asia with further constraints from published information Issler amp Beaumont 19
140. t in the edit box will scroll left when the right most limit of the box is reached Any printing characters may be used and spaces may be included in the name Lithology code The encoded lithological description which will be used to cross reference depth density and depth thermal conductivity tables The primary lithology codes used here must match those used in the tables The supplied tables use the following primary lithology codes SST for sandstone LST for limestone MDSLST for mudstone siltstone OPSHAL for overpressured shale Proportions of primary lithologies may be assigned in percent percentages must add up to 100 Primary lithologies are separated by spaces Text in the edit box will scroll left when the right most limit of the box is reached Examples are Figure 5 8 SST pure sandstone same as SST 100 SST 75 LST 25 calcareous sandstone MDSLST 20 LST 80 muddy silty limestone SST 85 OPSHAL 15 sandstone with overpressured shale Age at base The age of the base of the laver in Ma millions of years before present Decimal fractions are permitted Water depth The water depth in metres when deposition of the layer finished This value is used in the calculation of tectonic subsidence see Section 2 2 1 Eroded Select this check box if the isopach data represent a layer which has been eroded In this case the Age eroded edit box will be enabled Enter the age at which erosion commenced in Ma millions of
141. t option Choose grid display window File menu then choose Close option Choose Display menu Choose Layer density Choose grid display window File menu then choose Close option Display Help 66n6566650666666666606b656bo00000b000000Q0 0000000990009 000000000090OQ OSSA UU AAA A A HOTPOT Tutorial Two layer related options are shown enabled black text Layer thickness and Layer density Either can be chosen for display A map of decompacted Tollerton Fm isopachs at 10 Ma is shown in a Grid Display Window Fig 4 21 This window becomes the active window blue caption bar sf dhol iodide aa eee IO Grae eur Er od St a ee RECTE TC LE LE M a p IND Co Ja DX COLO NOG a DIG 3 Co IOI COO NG y ccoOcoooocoooooo u natcs55 Tzuu 7 c t OOOO OOOO OS Na Figure 4 21 The grid map is printed This closes the grid display window The HorPor Main Window is redisplayed A map of the decompacted density of Tollerton Fm at 10 Ma is displayed Fig 4 22 The map may be printed by choosing Print from the File menu as before Note that the zero thickness nodes are assigned null in the density grid i e densities are only displayed where the layer is present This closes the grid display window The HOTPOT Main Window 1s redisplayed By selecting the other layer buttons it is possible to obtain thickness and density displays of all the individual layers for each of the time calibration points as required
142. taset Fig 4 2b is stored in the file ruddinga iso Choose File menu Choose Layer option 4 37 Choose Load button 162 0 Choose ruddinga lay from Files list Choose Ok button Choose Grid button Type 0 19 into Radius box then choose Ok button or press RETURN key 10 0 8 0 6 0 160 0 162 0 HOTPOT Tutorial 1500 1650 1350 1500 1200 1350 1050 2 1200 900 1050 750 900 600 a 750 450 600 300 450 150 300 0 150 mean 596 011 164 0 166 0 Figure 4 43 Layer information is loaded from the file ruddinga lay The layer information dialogue is redisplayed with the information shown This includes a reference to the revised digitised isopach file ruddinga iso The gridding window opens The program grids the revised isopach data with a search radius of 0 19 and displays a grid map Fig 4 44 The search radius is acceptably small and experimentation shows this to be the smallest radius which yields no null grid nodes you may wish to experiment with other search radii As well as additional control contours within the zero isopach contour ruddinga iso contains zero value anti masking contours see 4 1 1 around the margins of the sedimentary fill This is seen as a greater area of zero nodes replacing null nodes compared to Fig 4 43 This prepares an acceptable grid which you will save for later use in Model 3 m 2080 2240 1920 2080 1760 1920 1600
143. terton Furimnation 7 Figure 4 19 4 2 6 Display of the backstripped data There are two types of display a displays related to an age button b displays related to a layer button The age related display options Select 10 00 Ma button The black text of the 10 00 Ma button is changed to white indicating that it is selected and hence options applicable to the 10 Ma time calibration point are activated Choose Display menu This menu lists all the display options Only those currently available are enabled i e shown in black text Display availability is controlled by the data that have been loaded the calculations that have been performed and the button selected in the main window Here the Depth Density option and the group of three age related display options are enabled Each can be displayed by choosing its menu option Choose Loaded thickness option A Grid Display Window opens overlapping the main window Fig 4 20 A map of total sediment thickness at 10 Ma is shown in this window This window is now the active window indicated by its blue caption bar You use it independently of the main window it may be moved resized maximized or minimized File If you have a printer available on your computer Choose the grid display window File menu and then choose Print option Choose grid display window File menu then choose Close option Choose Display menu then choose Starved thickness or Bulk density opti
144. ton HOTPOT Tutorial The file selector closes The contents of the layer information dialogue including the name of the isopach data file bingham iso are saved in the file bingham lay for use in a later modelling session The layer information dialogue remains open The layer information file name is now shoum below the dialogue caption bar Fig 4 51 The gridding window opens The search radius dialogue opens The program grids the eroded isopach data with a 0 17 search radius and displays the map Fig 4 52 Experiment indicates that this is the smallest radius which generates no null nodes Note the large area of zero nodes i e no erosion this is a necessary consequence of the anti masking zero contours Section 4 1 1 You may of course save this grid for future use in the same way that you saved the layer isopach grids during Model 2 m 754 812 696 754 638 696 580 638 522 580 454 522 40b 464 348 406 290 348 232 290 174 232 116 174 58 116 58 mean 158 767 164 0 166 0 Figure 4 52 The grid is accepted and the gridding window closes The HOTPOT Main Window shows the Bingham Member button colour coded magenta to distinguish it as an eroded layer It is selected white text Links the depth thermal conductivity table to the Bingham Member at 0 Ma present day 4 49 Ruddington Formation Choose File menu Choose Layer option Choose Load button
145. ty use 4 colour maturity scale The selected option will be check marked The initial limits setting is Individual The Pseudo maturity scale is only available for temperature grids individual limits are determined from the minimum and maximum values present in the grid being displayed They are useful for seeing detail in the variations in the data Group limits are determined from the minimum and maximum values present in all grids in the same display group e g all the temperature grids all the layer thickness grids etc They are useful for comparing grids e g the thicknesses of a layer at different stages of decompaction Set Display limits When the User limits option is chosen a dialogue is opened showing the current minimum and maximum value settings in edit boxes Fig 5 21 Edit these to the values required then choose the Ok button to display the data using the new limits Choose the Cancel button to retain the existing limits The User limits option is useful for emphasising features in the displayed data Note that any data values falling outside the user limits i e below minimum or above maximum will be shown in the minimum and maximum Figure 5 21 colour bands The Pseudo maturity scale shows four colour bands representing under mature zone oil generating zone gas generating zone and over mature zone The boundaries are determined solely from temperature i e a TTI type calculation is not used The
146. ubsidence Stora attained after complete relaxation of the lithospheric isotherms being Stora 5 Srp 2 The initial syn extensional subsidence S and the time dependent post extensional subsidence Srp can be predicted from the extension factor B using the criterion of local isostatic balance equations in McKenzie 1978 to produce standard subsidence history curves for various p factors Fig IV 5 N B Sj Spr and SroTaL are conventionally expressed as sediment starved subsidence values Thus the sediment starved output from HOTPOT can be used to estimate extension factors either for the basin as a whole using the grid map mean value or for parts of the basin using the grid node extractions IV 2 Palaeoheatflow It is possible to predict the palaeoheatflow from the basin extension factor equation in McKenzie 1978 Fig IV 6 illustrates a plot of heatflow against time at the base of the lithosphere for various extension factors Basically the curves show a pre extension sub lithospheric heatflow of Q rising to P Qm after extension and gradually decreasing with time thereafter Q was assumed by McKenzie to equal about 33 mW m7 The curves will only predict heatflow at the base of a sedimentary basin in the absence of lithospheric heat sources In reality crustal heat sources particularly in granitic terrains are very important Consequently the absolute values on the heatflow axis of Fig IV 6 need re calibration This can be acc
147. uchi 1984 k 366 kn iso 00068 1 84 o T4273 8 for T lt 300 C kr Kyo for T gt 300 C Somerton 1992 420 k k 0 001 AT amp 1 38 kyl 0018 T4273 1 28 Jg for T 300 C kr Koo for T gt 300 C I 3 Auxiliary data None With this option selected the thermal conductivity temperature relationship is disabled and thermal conductivity remains constant The results obtained will be unrealistic but provide a useful benchmark to assess the effects of the other options The three thermal conductivity temperature relationship options have a 300 C automatic cut off This is because radiative heat transfer becomes important above about 300 C with a consequent and poorly understood increase in effective thermal conductivity We strongly recommend that this cut off is retained The HOTPOT geothermal calculation options dialogue provides a facility to r override the cut off or modify the cut off temperature Figure 1 4 illustrates the three thermal conductivity temperature relationships showing how initial thermal conductivities k of 1 0 to 6 0 mW m K vary over the temperature range 20 to 400 C with no cut off temperature Figure I 5 shows these data with the 300 C cut off 20 200 300 400 C E T e eo ANTT Cermak amp Bodri 1 986 Sekiguchi 1984 PN Somerton 1 382 Figure I 4 Auxiliary data
148. ulation has been performed Display Bulk density May be chosen at any time after the decompaction calculation has been performed Reference to HOTPOT version 3 0 for Windows Display Layer thickness May be chosen at any time after the decompaction calculation has been performed Display Layer density May be chosen at any time after the decompaction calculation has been performed Display Heatflow May be chosen at any time after a heatflow grid has been loaded Display Layer conductivity May be chosen at any time after a geothermal calculation has been performed in which the selected layer has been set to use depth variable thermal conductivity Display Layer temperature May be chosen at any time after the geothermal calculation has been performed Help This is a drop down menu with the following options Memory usage provide information about memory usage About HotPot information about the HOTPOT program Help Memory usage May be chosen at any time EN WemoryAvallebilly Choosing this option displays an information message box Fig eo EGER KA bytes 5 16 showing the current memory usage by the program Values are given for Local Memory and Global Memory Commonly used information in the model database is stored in Local Memory Data grids are stored in Global Memory Global 7192256 bytes The amount of local memory available is not affected by the Figure 5 16 Windows operating mode
149. ur coded buttons arranged to simulate stratigraphic columns on the light grey window background Figure 5 6 The colour coding scheme is Before backstripping Cyan Normal laver Magenta Eroded laver Black boundary line Normal boundary After backstripping Yellow Stratigraphic column age Cyan Normal layer Black boundary line Normal boundary Magenta boundary line Erosional boundary When the stratigraphic column display exceeds the size of the window border scroll bars are switched on The buttons are used to select items from the model for setting parameters and for display in subsidiary windows The currently selected button is indicated by a white text label The layer and age buttons displayed in the main window may be selected by using the keyboard as well as bv using the mouse The TAB and BACKTAB i c SHIFT TAB keys move the focus by one button at each press The button having focus is indicated by a contrasting colour box drawn around its text label TAB moves the focus down the layer buttons of a column then to the age button of that column and then to the top layer button of the next oldest column BACKTAB moves the focus in the opposite direction The SPACEBAR is pressed to select the button having focus Keyboard control allows the Windows Recorder program to be used more effectively to record and replay HOTPOT sessions e g for demonstrations or presentations Reference to HOTPOT version 3 0 for Windows The menu bar of t
150. view of the importance of temperature in geological processes in general is beyond the scope of this report However it is thought useful at this preliminary stage briefly to consider the 1 1 Introduction l cessi dicting significance of temperature change with depth in sedimentary basins and the necessity of predicting such changes vil gas and coal reserves and also contain a wide variety of minerals of economic interest and significant amounts of Po a Sedimentary rocks are also currently used or are being considered for MOR SOE x uu pos d storage of a variety of materials including toxic and radioactive wastes C s ah g s compressed air Whether the requirement is for extraction or for storage or disposal accur prediction of present day subsurface temperatures 1s necessary Sedimentary basins are hosts to the world s The origin distribution and development of certain economic materials such as oil gas coal and many mineral deposits is in part dependent on temperature Hydrocarbons are generated by the action of heat on organic matter trapped and buried within sedimentary rocks The progressive development from peat through bituminous coal and semi anthracite to anthracite is in large part a function of temperature Many mineral deposits were formed from hot brines in the range 50 250 C The assessment of present day temperatures can at best only in part allow judgement on when and where such deposits might occur
151. vity settings will be copied from the layers loaded to the layers created during backstripping Figure 4 53 4 5 HOTPOT Tutorial 10 0 m 4030 4340 3720 4030 3410 3720 3100 3410 2790 3100 2480 2790 2170 2480 1860 2170 1550 1860 1240 1550 930 1240 620 930 310 620 0 310 6 0 mean 1097 46 160 0 162 0 164 0 166 0 Figure 4 54 On completion the HoTPOT Main Window should look similar to Fig 4 53 The main window display for this model is quite large and therefore may exceed the size of the main window In this case scroll bars will be displayed at the right and or bottom sides of the window These are used to move additional parts of the main window display into view as required The displayed buttons arranged as stratigraphic columns graphically illustrate the stratigraphical evolution of the basin They show the present day basin sequence and the decompacted sequences at stages in the basin history from 25 Ma to the present Note the extra two time calibration buttons 14 00 and 12 00 Ma which are required to define the period of erosion The eroded layer the Bingham Member is represented by a magenta coloured eroded boundary line between the Keyworth and Ruddington Formations in the present day 0 00 Ma stratigraphic column In the 10 00 Ma stratigraphic column it is indicated by a magenta coloured eroded surface line on top of the Ruddington Formation In the 12 00 Ma column th
152. vity table files File Topography May be chosen when an area of interest OOOO Topography Data has been defined and prior to performing the decompaction calculation Q Planar surface topographic surface must be defined in 4 order to perform the decompaction calculation in depth mode as it is required to calculate the thickness of the topmost layer When a topographic surface is defined a checkmark V is displayed next to this menu item Choosing this menu option displays the Figure 5 7 dialogue Fig 5 7 which controls the definition of the surface The group of radio buttons labelled Type give a choice of topographic or bathymetric specification Select Topography for a conventional topographic surface where heights above mean sea level MSL are represented by positive numbers and depths below MSL by negative numbers used with onshore data Select Bathymetry for a conventional bathymetric surface where depths below MSL are represented by positive numbers and heights above MSL by negative numbers used with offshore data The group of radio buttons labelled Units specify the units of measure for the data Select one of the available options which are metres m kilometres km feet and for bathymetric data only fathoms Select the Planar surface radio button to define a flat surface at a constant elevation with respect to MSL Then enter the elevation value into the Planar surface edit box The elevation value e
153. vs thermal conductivity scale in a Graph Display Window This is an independent subsidiary window to the HOTPOT Main Window The manipulation of Graph Display Windows is described in section 5 5 The window title will show the file name from which the table was loaded When this option is chosen after the geothermal calculation has been performed depth thermal conductivity curves for any proportional lithologies used calculated during geothermal modelling will be shown Map displays general information The Topography option can only be chosen when a topographic surface has been defined see File menu Topography option Before any of the other options can be chosen cither an age button or a layer button must be selected in the HorPor Main Window Only those map displays relevant to the model element corresponding to the selected button will be enabled in the menu The selected grid will be displayed in a Grid Display Window This is an independent subsidiary window to the HoTPoT Main Window The manipulation of Grid Display Windows is described in section 5 6 The window title will show the type of display the age and if appropriate layer name Display Topography This is only useful when a digitised topographic surface is being used Display Loaded thickness May be chosen at any time after the decompaction calculation has been performed Display Starved thickness May be chosen at any time after the decompaction calc
154. w ready to load the next layer the Bingham Member the eroded part of the Ruddington Formation of the model Choose File menu Choose Layer option The layer information dialogue opens The insertion point flashing cursor is in the Formation name box Type Bingham Member in This sets the name of the formation Formation name box Press TAB key Insertion point moves to the Lithology code box Type SST 50 LST 50 in This defines the lithology of this layer to be 50 sandstone and Lithology code box 50 limestone cf Ruddington Fm Note the space between the two component codes The component codes are given in the same order SST first LST second as for the Ruddington Fm This makes the decompaction and geothermal calculations more efficient as only one set of mixed lithology curves needs to be calculated for the two layers Always adopt a standard order for specifying the components of mixed lithologies Press TAB key The TAB moves the insertion point to the Age at base box 4 47 Type 14 in Age at base box then press TAB key Type 10 in Water depth box then press TAB key Press SPACEBAR Type 12 in Age eroded box Select m radio button in Isopach Units group box Choose Data Files button in the Isopach box Choose bingham iso from Files list Choose Ok button Choose Save button HoTPoT Tutorial This sets the age of the base of the layer to be 14 Ma The TAB moves the insertion point to the Water de
155. ws the minimum data node value in the grid the maximum data node value in the grid the value used to indicate unassigned data nodes null nodes in the grid HOTPOT conventionally uses the value 9999 for this purpose but other values can be specified The grid data node values follow These are stored in row major order as displayed on the grid map with one value per line The first value is at Xmin Ymin the south west corner and the last value is at Xmax Ymax the north east corner Figure H 1 shows how the nodes in the example grid file are arranged The last grid data node value is followed by a line containing the keyword End This marks the end of the file Its absence indicates an incomplete file 1 8 APPENDIX III Gridding and the search radius The gridding algorithm used in the HOTPOT program is a simple nearest neighbour type method It is however quite fast has minimal memory requirements and is suited to dealing with digitised contour data This algorithm handles faults as steep slopes Figure 11 1 The search radius R in Figure III 1 defines a circular area around a data point X4 Y 4 The value at any grid node located within this area is then adjusted to take into account the value of the data point The adjustment is distance weighted i e a grid node such as X Y near to a data point will be affected more than Mill one further away such as X Y The search radius is measured in the

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