1. MD + AVO Inversion Jianhua Yu, University of Utah Jianxing Hu GXT

2. Outline Motivation Methodology Numerical Tests Conclusions

3. Seismic Trace G S Layer 2 Layer 1 Incorrect Contribution Actual reflection point Amplitude Preserved Prestack Migration + AVO Inversion Migration Ellipse

4. Influences on CRG Image Migration noise How to deal with above problems? Footprints due to the coarse acquisition geometry

5. Motivation Increase CRG spatial resolutionIncrease CRG spatial resolution Reduce prestack migration noise and artifactsReduce prestack migration noise and artifacts Improve AVO attribute inversionImprove AVO attribute inversion MD:

6. Outline Motivation Methodology Numerical Tests Conclusions

7. m’ = L d T Prestack Migration but d = L m Migrated Section Data L m Migration Image m’ = True Reflectivity Model m

8. T m = (L L ) m’ Migration Deconvolution Reflectivity Deblurring operator Migrated Imaage or CRG

9. Processing Steps: Preprocessing : Filtering, amplitude balancing, and demultiple Prestack migration to generate the migrated common offset (CO) sections Velocity analysis and velocity estimate for migration in time domain

10. Apply MD to common offset sections Normal AVO parameter Inversion Apply MD to AVO section Processing Steps:

11. Outline Motivation Methodology Numerical Tests Conclusions

12. Outline Motivation Methodology Numerical Tests Conclusions Synthetic data Field marine data

13. Time (s) 0 2.5 1515 0 CDP 150 X(km) CO (45-55) Section MDMig

14. Time (s) 0.5 2.5 1212 0.5 2.5 CDP 150 X(km) Closeup of COG (45-55) Section MDMig

15. Time (s) 0.6 1.8 1 1 0.6 1.8 X(km) Closeup of One CDP Gather MD Mig

16. Frequency (Hz) 0.0 60 100110100110 0.0 60 CDP 150 Trace No. Spectrums of Mig and MD Images MDMig

17. Outline Motivation Methodology Numerical Tests Conclusions Synthetic data Field data I

18. Time (s) 1.0 3.0 0.262.01.53.5 1.0 3.0 CDP 150 Offset (km)Velocity (km/s) CDP 150

19. Offset (km) -6.0 -3.5 200800 Shot Number -6.0 -3.5 RMS Amplitudes Raw data After preprocessed

20. Time (s) 0.0 3.0 0.262.0 Offset (km) 0.262.0 Offset (km) 0.262.0 Offset (km) Raw dataDemultipleMultiples

21. Time (s) 0.0 3.0 0.262.00.262.0 0.0 3.0 Offset (km) raw dataDemultiple

22. Time (s) 0.0 3.0 0.262.00.262.0 0.0 3.0 Offset (km) AVO AVO ? raw dataDemultiple

23. Velocity (km/s) 5 1 03 Time (s) Comparison of Estimated RMS Velocity and Well Sonic Data Well Vint Well Vrms Estimated Vrms

24. Time (s) 0 3.5 7 20 X (km) MD Result in Time Domain Mig+MDMig 12.1 13.6 - - 3.6 - +2.3 Before MD After MD Zone of interest

25. B -0.4 0.4 A Crossplot of A and B before MD Near Well A Time interval: 1900-2900 ms

26. B -0.4 0.4 A Crossplot of A and B after MD Near Well A Time interval: 1900-2900 ms

27. B -0.4 0.4 A Crossplot of A and B Based on Well log from Well 1 ( from C.-S. Yin, M.L. Batzle, and C. C. Mosher) Depth: 1900-3100 m

28. B -0.4 0.4 A Well Data -0.40.4 A -0.40.4 A After MDBefore MD

29. Outline Motivation Methodology Numerical Tests Conclusions Synthetic data Field data II

30. Amplitude within Geometry Map 1 Receiver Number 177 Shot Number 1800 0.03 0.005

31. Velocity Scanning of CMP Gathers CDP 4600 CDP 4750 8 Time (s) 0 CDP 4850 CDP 5000CDP 5500CDP 6000

32. Time (s) Offset (km) CRG before and After MD Before MD After MD 0.5 1.3 Before MDAfter MD Multiple

33. Time (s) 0 2.0 015 X (km) AVO Parameter: A*B Before MD

34. Time (s) 0 2.0 015 X (km) AVO Parameter: A*B After MD

35. Outline Motivation Methodology Numerical Tests Conclusions

36. Conclusions Improves stratigraphyic resolution Help to identify lithology anomaly in AVO attribute sections Attenuate migration noise and artifacts artifacts

37. Conclusions Amplitude fidelity is still explored when designing MD operator

38. Acknowledgments Thank ChevronTxaco and WesternGeco for providing the data setsThank ChevronTxaco and WesternGeco for providing the data sets Thank UTAM sponsors for their financial supportThank UTAM sponsors for their financial support Thank Alan Leeds for his constructive comments and suggestions.Thank Alan Leeds for his constructive comments and suggestions.