1. Jianhua Yu University of Utah Robust Imaging for RVSP Data with Static Errors

2. Outline Problems in RVSP imaging How to eliminate the static errors in RVSP imaging Synthetic and real data examples Summary

3. Outline Problems in RVSP imaging How to eliminate the static errors in RVSP imaging Synthetic and real data examples Summary

4. Well Geophone ? RVSP Acquistion Geometry

5. Problems in RVSP imaging Don’t know initial time Have limitation to deviated well Don’t know source wavelet Static shift error may exist

6. Do not require source waveletDo not require source wavelet Image conditions:Image conditions: ( a) Primary reflection (solid line) (b) ghost reflection (solid line) Autocorrelogram Migration

7. Migration Formula: Migrated Image Autocorrelograms of seismic data

8. Outline Problems in RVSP imaging How to eliminate the static errors in RVSP imaging Synthetic and real data examples Summary

9. Primary Auto. Migration:

10. Outline Problems in RVSP imaging How to eliminate the static errors in RVSP imaging Synthetic and real data examples Summary

11. Depth (ft) 1750 250 RVSP and Geology Model 98 sources 25 geophones 625 ft Well

12. Time (s) 2.5 0 110.03 CRG 16 Depth (kft) CRG 2

13. Time (s) 2.5 0 110.03 CRG 2 Depth (kft) CRG 16

14. Time (s) 2.0 0 110.03 Autocorr. CRG 2 Depth (kft) Autocorr. CRG 16

15. Depth (ft) 1750 0 No static errors With static errors Primary Kichhoff Migration

16. Depth (ft) 1750 0 No static errors With static errors Primary Autocorr. Migration

17. Depth (ft) 1750 0 Kirchhoff Autocorr. Mig

18. Depth (ft) 1500 250 No static errors With static errors Ghost Kirchhoff Migration

19. Depth (ft) 1500 250 No static errors With static errors Ghost Autocorr. Migration

20. Depth (ft) 1500 250 Kirchhoff Autocorr Mig (Ghost)

21. Outline Problems in RVSP imaging How to eliminate the static errors in RVSP imaging Synthetic and real data examples Summary

22. Time (s) 0.35 0 0.03 11 CRG 6CRG 15 Depth (kft)

23. Time (s) 0.30 0 0.03 11 CRG 6: primaryCRG 15: primary Depth (kft)

24. Time (s) 0.30 0 0.03 11 Autocorr. CRG 6: primaryAutocorr. CRG 15: primary Depth (kft)

25. Time (s) 0.30 0 0.03 11 Autocorr. CRG 6: ghostAutocorr. CRG 15: ghost Depth (kft)

26. Depth (ft) 1200 150 Kirchhoff Mig. with Primary 120 ft

27. Depth (ft) 1000 0 Well Log and Kirchhoff Migration

28. Depth (ft) 1200 150 Autocorr. Mig. with Primary 120 ft

29. Depth (ft) 1000 0 Well Log and Primary Autocorr. Mig

30. Depth (ft) Kirchhoff Mig. Primary Auto. Mig. WellWellMigMig. 0 1000  Primary autocorrelogram migration gives better correlation with well log synthetic seismograms

31. Depth (ft) 1200 150 Auto mig. with P+G 120 ft

32. Depth (ft) 1000 0 Well Log and Mig without Separating Primary and Ghost

33. Depth (ft) 1200 150 Joint mig. with P+G 120 ft

34. Depth (ft) 1000 0 Well log and Joint Mig. with Primary and Ghost

35. Depth (ft) Mig. With P+G WellMig 0 1000 Joint Mig. With P+G WellMig

36. Outline Problems in RVSP imaging How to eliminate the static errors in RVSP imaging Synthetic and real data examples Summary

37. Summary Autocorrelogram imaging condition is capable of suppressing static shift errorsAutocorrelogram imaging condition is capable of suppressing static shift errors It can be used to image reflectivity with static error-polluted VSP and drill-bit data where no pilot signal is availableIt can be used to image reflectivity with static error-polluted VSP and drill-bit data where no pilot signal is available

38. Acknowledgments Thank 2002 sponsors of UTAM consortium for the financial supportThank 2002 sponsors of UTAM consortium for the financial support Thank Exxon for providing the real dataThank Exxon for providing the real data