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Migration Deconvolution for VSP and Surface Data

Migration Deconvolution for VSP and Surface Data. Jianhua Yu. Feb 3, 2005. Outline. Migration Deconvolution. Motivation. Examples. Summary. Outline. Migration Deconvolution. Examples. Motivation. Summary. Surface Seismic Migration and MD images. 5. WE Mig. Depth (km). MD. 10.

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Migration Deconvolution for VSP and Surface Data

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  1. Migration Deconvolution for VSP and Surface Data Jianhua Yu Feb 3, 2005

  2. Outline Migration Deconvolution Motivation Examples Summary

  3. Outline Migration Deconvolution Examples Motivation Summary

  4. Surface Seismic Migration and MD images 5 WE Mig. Depth (km) MD 10

  5. Irregular acquisition geometry 3D 2D well VSP Data:

  6. Develop migration deconvolution for VSP data Suppress migration noise and artifacts Improve spatial resolution Enhance illumination Objectives :

  7. Outline Migration Deconvolution Examples Motivation Summary

  8. -1 [ ] Reflectivity T T T T R R G G G G G G G G Migration image Migration Modeling -1 [ ] = m Migration: m = Migration deconvolution:

  9. T G G MD image -1 [ ] Migration Green’s Function Migration Deconvolution R = m

  10. Migrated data True Reflectivity FFT of Discrete Migration deconvolution

  11. Outline Migration deconvolution Examples Motivation VSP data Surface seismic data Summary

  12. Nsx=Nsy=21, dsx=dsy=150 m 12 geophone 1.75 km Ng=12, dgz=50 m (750 m – 1300m) 3 km 3 km

  13. VSP Geometry: source 21 x 21; geophone: 12 Migration MD Depth=1.75 km

  14. Nsx=Nsy=21, dsx=dsy=150 m 30 geophone 1.75 km Ng=30, dgz=50 m (100 m – 1500m) 3 km 3 km

  15. Migration MD Depth=1.75 km

  16. Outline Migration deconvolution Examples Motivation VSP data from salt model Surface seismic data Summary

  17. 16 km 320 shots 7 km 21 geophones 750 m 2D

  18. Well Depth (km) X (km) Velocity

  19. CRG 1 (z=7.0 km) CRG 21 (z=7.75 km) X (km) X (km) 0 15 0 15 0 Time (s) 10 (Courtesy of BP)

  20. Primary Migration Image 5 Depth (km) 12 0 15 X (km)

  21. MD X (km) 0 10 MIG X (km) 0 10 8 Depth (km) 10

  22. MD X (km) 4 10 MIG X (km) 4 10 8 Depth (km) 10

  23. Outline Migration deconvolution Examples Motivation vsp data Surface seismic data Summary

  24. L500 X X 0.0 Time (s) 4.5 Mig (Unocal) MD

  25. L500 X X 1.0 Time (s) 4.0 Mig (Unocal) MD

  26. X10 Y Y 1.0 Time (s) 5.0 Mig (Unocal) MD

  27. X10 Y Y 2.5 Time (s) 4.0 Mig (Unocal) MD

  28. MIG (Unocal) MD 1 Xline 500 1 Xline 500 2.4 Time (s) 4 Inline 171

  29. Mig MD Ycross x=50 0.5 Time 4.5 41 41 0 0 Y (kft) Y (kft)

  30. Mig MD Ycross x=50 0.5 Time 2.0 41 41 0 0 Y (kft) Y (kft)

  31. Mig MD Xcross Y=125 0.5 Time 4.5 12 12 0 0 X (kft) X (kft)

  32. Mig MD Xcross Y=125 2.5 Time 4.5 12 12 4 4 X (kft) X (kft)

  33. MIG (Unocal) MD 1 Inline 170 1 Inline 170 2.4 Time (s) 4 Xline 181

  34. MIG (Unocal) MD 1 Inline 170 1 Inline 170 2.4 Time (s) 4 Xline 281

  35. Z=3.0s 0 Y (kft) 41 0 X(kft) 12.75 X(kft) 12.75 Mig MD 0

  36. MD MIG (Unocal) Inline 1 170 1 Inline 170 1 Xline 550 3.4 s

  37. MD MIG (Unocal) Inline 1 170 1 Inline 170 1 Xline 550 3.6 s

  38. Outline Migration deconvolution Examples Motivation VSP data from salt model Surface seismic data Summary

  39. The cost depends acquisition geometry and filter length used Summary MD improves the resolution of VSP and surface migrated image partly

  40. Analytic MD operator Decimated acquisition geometry To reduce computational cost: Time MD and poststack MD is more stable. Summary

  41. Spectrum for Meandering Model MD Mig 0 Freq 120

  42. Spectrum for Unocal Data MD Mig 0 Freq 120

  43. BP, Unocal Brian Hornby, Hans Sugianto Acknowledgements UTAM Sponsors

  44. X10 Y Y 1.0 Time (s) 5.0 Mig (Unocal) MD

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