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Jianhua Yu University of Utah

Robust Imaging for RVSP Data with Static Errors. Jianhua Yu University of Utah. Problems in RVSP imaging. How to eliminate the static errors in RVSP imaging. Synthetic and real data examples. Summary. Outline. Problems in RVSP imaging. Outline.

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Jianhua Yu University of Utah

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

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

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

  4. Geophone Well RVSP Acquistion Geometry ?

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

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

  7. Migrated Image Autocorrelograms of seismic data Migration Formula:

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

  9. Primary Auto. Migration:

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

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

  12. 0.03 Depth (kft) 1 0.03 Depth (kft) 1 0 CRG 16 CRG 2 Time (s) 2.5

  13. 0.03 Depth (kft) 1 0.03 Depth (kft) 1 0 CRG 16 CRG 2 Time (s) 2.5

  14. 0.03 Depth (kft) 1 0.03 Depth (kft) 1 0 Time (s) Autocorr. CRG 16 Autocorr. CRG 2 2.0

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

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

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

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

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

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

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

  22. Depth (kft) Depth (kft) 1 0.03 1 0.03 0 CRG 6 CRG 15 Time (s) 0.35

  23. Depth (kft) Depth (kft) 1 0.03 1 0.03 0 CRG 6: primary CRG 15: primary Time (s) 0.30

  24. Depth (kft) Depth (kft) 1 0.03 1 0.03 0 Time (s) Autocorr. CRG 6: primary Autocorr. CRG 15: primary 0.30

  25. Depth (kft) Depth (kft) 1 0.03 1 0.03 0 Time (s) Autocorr. CRG 6: ghost Autocorr. CRG 15: ghost 0.30

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

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

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

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

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

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

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

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

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

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

  36. Outline Problemsin RVSP imaging How to eliminate the static errors in RVSP imaging Synthetic andreal data examples Summary

  37. Summary • Autocorrelogram 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 available

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

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