1. Imaging Sand Distribution From Acoustic Impedance Suphan Buri Basin, Central Thailand. Imaging Sand Distribution From Acoustic Impedance Suphan Buri Basin, Central Thailand. Dept. Petroleum Geoscience, Universiti Brunei Darussalam. PTT Exploration and Production PCL., Bangkok, Thailand. Ronghe, S., and Surarat, K. 12 1 2

2. CONTENTS Study objectives Location and geology Wireline analysis Well to seismic correlation Seismic attribute analysis Inverse modeling Results and interpretation Conclusions Acknowledgements

3. STUDY OBJECTIVES To determine the potential of wireline and seismic as a discriminator of formation lithology / fluid. To apply the seismic inversion to image depositional succession

4. STUDY LOCATION Phitsanulok Basin Sing Buri Basin Kamphaeng Saen Basin Ayuthaya Basin Sala Daeng Basin THAILAND BANGKOK Three Pagodas Fault Zone Mae Ping Fault Zone 30 km N Adapted from O’Leary and Hill (1989) STUDY AREA Suphan Buri Basin

5. Oligocene Miocene Pliocene - Recent Lower Mid Upper AgeUnit U A B C D E C1 C2 Pre Tertiary C3 C4 D7 D1 D6 D5 D4 D3 D2 1000 - U 1500 - 2000 - 500 - m Alluvial - Fluvial Depositional system Fluvio- lacustrine Lacustrine Early basin fill Alluvial - lacustrine Lithology Sands, gravels, siltstone & mudstone, fluvial origin Fluvio-lacustrine sandstone, siltstone interbedded with mudstone. Fluvial channel sandstone and conglomeratic sandstone. Intercalated sandstone, siltstone & mudstone. Lacustrine system with fluvial influence. Mudstone with minor siltstone. Conglomerate, sandstone interbedded with siltstone and minor mudstone. Basement complex: clastics, carbonate rocks or metasediments. Petroleum system Reservoirs Source and Reservoirs Source and Reservoirs Source Depth Schematic stratigraphic sequence, Suphan Buri Basin Adapted from Intharawijitr (1993)

6. Time (ms) 1 Km N Horizon D3 UT1-3 UT1-7 UT1-3/D1 UT1-7/D2 560 630 700 770 840 910 980 1059 Time structure map Area = 37 sq. km. TWT STRUCTURAL MAP

7. GR AI Well UT1-7Well UT1-3 m TVD m TVD Sub-unit D1 Sub-unit D2 Sub-unit D3 Sub-unit D5 Sub-unit D6 Sub-unit D4 OWC Wireline cross-plots Below OWC Wireline cross-plots Above OWC

8. CONTENTS Study objectives Location and geology Wireline analysis Well to seismic correlation Seismic attribute analysis Inverse modeling Results and interpretation Conclusions Acknowledgements

9. GRAI Shaly-sand Sand Shale Wireline cross-plot: Below OWC Low High Impedance (g/cc * m/s) Gamma ray (API) UT1- 3

10. GRLLD Wireline cross-plot: Below OWC Gamma ray (API) Resistivity (ohm / m) UT1- 3

11. Shaly-sand Sand Shale GRAI Wireline cross-plot: Above OWC Low High Impedance (g/cc * m/s) Gamma ray (API) UT1- 7

12. GRLLD Wireline cross-plot: Above OWC Gamma ray (API) Resistivity (ohm / m) UT1- 7

13. Wavelet Synthetic Seismic Synthetic Impedance (g/cc*m/s) WELL TO SEISMIC CORRELATION

14. CONTENTS Study objectives Location and geology Wireline analysis Well to seismic correlation Seismic attribute analysis Inverse modeling Results and interpretation Conclusions Acknowledgements

15. SEISMIC ATTRIBUTE ANALYSIS OWC -126 126

16. SEISMIC ATTRIBUTE ANALYSIS Low High OWC

17. GR AI Well UT1-7Well UT1-3 m TVD m TVD Sub-unit D1 Sub-unit D2 Sub-unit D3 Sub-unit D5 Sub-unit D6 Sub-unit D4 OWC Wireline cross-plots Below OWC Wireline cross-plots Above OWC

18. CONTENTS Study objectives Location and geology Wireline analysis Well to seismic correlation Seismic attribute analysis Inverse modeling Results and interpretation Conclusions Acknowledgements

19. INVERSE MODELLING FLOWCHART Final AI result Trace merge Impedance (mid frequency) Impedance (low frequency) CSSIAI model Solid earth model AI Constraints AI Interpolation WAVELETS SEISMIC LOGS TOPS HORIZONS FAULTS

20. AI log ConstraintsTrend IMPEDANCE TREND AND CONSTRAINTS Well SK-1

21. INVERSE MODELING RESULT Low High

22. 20m 12m 18m INVERSE MODELING RESULT

23. Impedance (g/cc * m/s) 10000 10500 11000 11500 12000 12500 13000 13500 SAND Sub-unit D6 Maximum impedance distribution 1 Km N UT1-3 UT1-7 UT1-3/D1 UT1-7/D2 Sub-unit D5 Maximum impedance distribution 1 Km N Impedance (g/cc * m/s) 13500 10000 12000 12500 13000 10500 11500 11000 9500 SAND UT1-3 UT1-7 UT1-3/D1 UT1-7/D2

24. Impedance (g/cc * m/s) 9500 9000 10000 10500 11000 11500 12000 12500 13000 SAND Sub-unit D4 Maximum impedance distribution 1 Km N UT1-3 UT1-7 UT1-3/D1 UT1-7/D2 Sub-unit D3 Maximum impedance distribution 1 Km N Impedance (g/cc * m/s) 12500 13000 12000 11500 11000 10500 10000 9500 9000 SAND UT1-3 UT1-7 UT1-3/D1 UT1-7/D2

25. Generalized rift structure and sedimentation patterns DELTAIC / FLUVIAL Sandstone + mudstone Fan in footwall transfer zone ALLUVIAL FAN / FAN DELTA Conglomerate + sandstone (Modified from Leeder and Gawthorpe 1987)

26. 1 Km N FS DL Sub-unit D6 Impedance Interpretation FS FC FS DL Sub-unit D5 Impedance Interpretation 1 Km N LEGEND FS DL Shale Sand Transport direction Fan / slump Delta lobe Feeder canyon FC

27. BF C DL FS Sub-unit D4 Impedance Interpretation 1 Km N LEGEND FS DL Shale Sand Transport direction Fan / slump Delta lobe Channel Basinfloor fan C BF C DL FS FC Sub-unit D3 Impedance Interpretation 1 Km N

28. Axial delta lobe Basinfloor fans Axial channel Maximum displacement Remnant relay ramp Maximum displacement Minimum displ. Fault linkage Feeder canyons N 1.5 0 Km Fan or slump SUMMARY GEOLOGICAL MODEL OF THE STUDY AREA

29. CONCLUSIONS (1) Wireline impedance and seismic attributes responded primarily to lithology. Inverse modeling resulted in good comparison between wireline impedance and adjacent derived impedance traces, and enabled vertical sand resolution of about 12 m. Maximum impedance extractions imaged two styles of sand distribution: axial and boundary fault induced deposits.

30. CONCLUSIONS (2) Axial deposits (delta lobes, channels and basinfloor fans) prograded from south to north downdip into the basin. Boundary fault induced deposits (fans / slumps and feeder canyons) showed two component pathways: Fans / slumps were transported perpendicular to the fault. Feeder canyons transported sediment downslope to the NE. The basin architecture and sedimentation patterns agree with published general models of rift geology.

31. ACKNOWLEDGEMENTS PTT Exploration and Production Public Co. Ltd. for data & permission to present the results. Jason Geosystems and Landmark Graphic Corp. for software donation to the Department of Petroleum Geoscience, UBD. Jason Geosystems for technical support and review of this study.

32. PRESENTATION OVERVIEW Acoustic impedance is used to map the locations and shapes of sand bodies deposited within a producing fluvio- lacustrine interval of a continental half graben basin.