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2001 Sponsors

2001 Sponsors. Aramco Amerada Hess BP-AMOCO Chevron Conoco Japan Nat. Oil Co. Inst. Mex. Pet. INCO Marathon Phillips Sisimage Texaco Veritas. Salient 2001 Research Achievements. 1. Wave-Beam Migration. Wave- Beam. Phase-Shift. Ray-Beam Kirchhoff. Migration Accuracy vs $$$.

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2001 Sponsors

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  1. 2001 Sponsors • Aramco • Amerada Hess • BP-AMOCO • Chevron • Conoco • Japan Nat. Oil Co. • Inst. Mex. Pet. • INCO • Marathon • Phillips • Sisimage • Texaco • Veritas

  2. Salient 2001 Research Achievements 1. Wave-Beam Migration

  3. Wave-Beam Phase-Shift Ray-Beam Kirchhoff Migration Accuracy vs $$$ Full-Wave No Approx. Multiples Anti-aliasing Accuracy Expense

  4. Slant Stack Fresnel Zone Smear Reflection along Wavepath Smear Reflection along Wavepath S R Image Point

  5. Wavefront FD Standard FD 0 1.5 km 0 4.5 km

  6. Cost Ratio of Standard /Wavefront 45 5 Cost Ratio 500 3000 # Gridpts along side

  7. Model 0 1.5 km 1.5 km/s 2.2 km/s 1.8 km/s Prestack Migration Image 0 1.5 km 0 4.5 km

  8. Eikonal Traveltime Field 0 Depth (kft) 3 0 Distance (kft) 5 Wave-Equation Traveltime Field 0 Depth (kft) 3 Distance (kft) 5 0

  9. Model 0 Depth (km) 3 5 0 Distance (km) Wave Equation Traveltimes Kirchhoff 5 Depth (kft) 11 0 5 Distance (km) 0 Distance (km) 5

  10. Wavefront Reverse Time Migration 1. Order Mag. Cheaper than 3-D RT 2. Fewer Artifacts 3. Optimal Accuracy Open Questions 1. More Storage 2. Resorting Overhead 3. Large scale tests?

  11. Salient 2001 Research Achievements 1. Wave-Beam Migration 2. Multiple Removal POIC

  12. Multiple Removal by Primary-Only Imaging Condition Hongchuan Sun

  13.  S R   R S Forward Modeling Primary Multiple S S R R Depth Depth Distance Distance

  14.  S R Migration with POIC S R The rays intersect at point P, and the traveltime SP +RP =obs P Depth Distance

  15. The rays never intersect; or the traveltime SP +RP =obs   R S Multiple Removal S R Depth P Distance

  16. SEG/EAGE 2-D Salt Data 0 Depth (kft) Model KM Image POIC Image 11 0 Depth (kft) 11 0 Depth (kft) 11 Distance (kft) 51 0

  17. 15 15 15 Distance (kft) Distance (kft) Distance (kft) 51 51 51 Offsets Used: 0 ~ 14000 ft Model 5 Depth (kft) 11 KM Image POIC Image 5 Depth (kft) 11

  18. KM Image Model POIC Image 0 Depth (kft) 11 Distance (kft) Distance (kft) Distance (kft) 17 17 17 0 0 0 Offsets Used: 0 ~ 14000 ft

  19. Offsets Used: 1600 ~ 14000 ft KM Image Model POIC Image 0 Depth (kft) 11 Distance (kft) Distance (kft) Distance (kft) 17 17 17 0 0 0

  20. Conclusions • POIC effectively remove surface • related multiples • POIC performs much better when • near-offset data are not used • POIC should be applicable to • interbed multiple removal

  21. Salient 2001 Research Achievements 1. Wave-Beam Migration 2. Multiple Removal POIC 3. Sparse Fequency Migration

  22. Fourier Finite Difference Migration with Sparse Frequencies Jianhua Yu Department of Geology & Geophysics University of Utah

  23. Objective  Improve computational efficiency of wave-equation extrapolation  Hi-quality Image

  24. Frequency Domain Migration o 70 Fourier Finite Difference Method 1/4 Sparser Frequency Domain Sampling

  25. Comparison of 3D Impulse Response X (km) 0 4 0 FD algorithm Depth (km) 2.4 0 Main energy wider angle FFD Depth (km) 2.4

  26. 2D Impulse Response (Velocity contrast, i.e., V/Vmin = 3.0) X (km) X (km) 0 4 0 4 0 Depth (km) 2.4 Standard wider angle FFD Main energy wider angle FFD

  27. Comparison of FFD and Main Energy FFD Migration X (km) 0 4 0 FFD algorithm Depth (km) 2.4 0 Main energy FFD (computational time saving about 38 %) Depth (km) 2.4

  28. 3D SEG/EAGE Zero Offset Imaging Result X (km) X (km) 4 0 4 0 0 0 Depth (km) 2.0 0 Y (km) 8 Y (km) 0 Depth (km) 8 2.0

  29. Efficient forward extrapolation Wider angle FFD operator Less numerical anisotropy in 3D by applying high order implicit FD algorithm Coding Complexity Fewer Frequencies Reduced Quality Strengths: Weaknesses:

  30. Salient 2001 Research Achievements 1. Wave-Beam Migration 2. Multiple Removal POIC 3. Sparse Fequency Migration 4. AVO Migration Decon

  31. Prestack Migration Decon for AVO Analysis Jianhua Yu Department of Geology & Geophysics University of Utah

  32. Lr d = L r but Migration Section = Blured Image of r T m = L d -1 r = ( L L ) m T Reflectivity Migrated Section Reason: Solution: Deconvolve the point scatterer response from the migrated image Migrated Section Data

  33. Objective of PMD AVO Suppress unwanted interference  Increase estimation accuracy of AVO parameters  Enhance resolution of AVO sections

  34. X(km) 1.0 2.0 0.5 Time (s) 2.0 After PMD Zoom View of AVO parameter Section Before and After PMD X(km) 1.0 2.0 0.5 Time (s) 2.0 Before PMD

  35. Migration CRG Before and After PMD Trace Trace 1 60 1 60 0.6 0.6 Time (s) Time (s) 1.8 1.8 Before PMD After PMD

  36. Comparison of Amplitude & Angle Estimation Before and After PMD 1st layer 2rd layer 3rd layer 1 Amplitude 0 0 60 0 Angle 60 0 Angle 60 Angle +: Before PMD *: After PMD Solid line: Theoretical value

  37. Summary & Future • MD reduces artifacts • MD improves resolution & AVO • MD field data case by Feb.

  38. Salient 2001 Research Achievements 1. Wave-Beam Migration 2. Multiple Removal POIC 3. Sparse Fequency Migration 4. AVO Migration Decon 5. Joint Autocorrelation Imaging

  39. Joint Imaging Using Both Primary and Multiple for IVSP Data Jianhua Yu Department of Geology & Geophysics University of Utah

  40. Problems for Deviated and Horizontal well No Source Wavelet & Initiation Time  Not Easy to Get Pilot Signal in  Hard to Separate Primary and Ghost Static Shift at Source and Receiver

  41. Auto. Imaging using Primary and Ghost

  42. Geological Model X (m) 0 4 0 V1 V2 Depth (m) V3 V4 V5 V6 3

  43. Shot Gather and Autocorrelogram Traces Traces 1 200 1 200 0 0 Time (s) Time (s) 4 4

  44. X (km) 1.6 2.1 Joint Migration Eliminate Interferences using Joint Imaging in Time Domain X (km) 1.6 2.1 0 Time (s) 2.2 Standard Migration

  45. X (km) 1.6 2.1 Joint Imaging Eliminate Interferences using Joint Imaging in Depth Domain X (km) 1.6 2.1 0 Depth (km) 2.8 Conventional Imaging

  46. Kirchhoff and Auto. Migration with Statics Error at Source and Receiver X (km) X (km) 1.6 2.0 1.6 2.0 0 Depth (km) 2.8 Kirchhoff joint migrationg Auto. joint migrationg

  47. Works for deviated and horizontal well Eliminating static shift errors Don’t require pilot signal & wavelet initial time Avoiding separating primary and ghost waves for horizontal well data SUMMARY Joint Migration method:

  48. Salient 2001 Research Achievements 1. Wave-Beam Migration 2. Multiple Removal POIC 3. Sparse Fequency Migration 4. AVO Migration Decon 5. Joint Autocorrelation Imaging 6. Xwell Statics & Tomography

  49. INCO Project Report M. Zhou Geology and Geophysics Department University of Utah

  50. Objective Invert velocity & geometry jointly

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