1. Midyear Overview of Year 2001 UTAM Results T. Crosby, Y. Liu, G. Schuster, D. Sheley, J. Sheng, H. Sun, J. Yu and M. Zhou J. Yu and M. Zhou

2. 2001 Sponsors AramcoAramco Amerada HessAmerada Hess BP-AMOCOBP-AMOCO ChevronChevron ConocoConoco Japan Nat. Oil Co.Japan Nat. Oil Co. Inst. Mex. Pet.Inst. Mex. Pet. INCOINCO MarathonMarathon PhillipsPhillips SisimageSisimage TexacoTexaco VeritasVeritas

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

4. Expense Accuracy Full-Wave Ray-BeamKirchhoff Phase-Shift Migration Accuracy vs $$$ Wave-Beam No Approx. MultiplesAnti-aliasing

5. SR ImagePoint Fresnel Zone Smear Reflection along Wavepath Slant Stack Smear Reflection along Wavepath

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

7. Cost Ratio of Standard /Wavefront # Gridpts along side 500 3000 455 Cost Ratio

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

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

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

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

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

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

14. Forward Modeling Distance Depth S R PrimaryMultipleSR Distance Depth S RR S

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

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

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

18. Depth (kft) 5 11 Distance (kft) 1551 KM ImagePOIC Image Model Depth (kft) 5 11 Distance (kft) 1551 1551 Offsets Used: 0 ~ 14000 ft

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

20. Distance (kft) Depth (kft) 0 11 0 17 Distance (kft) 0 17 0 17 KM ImageModelPOIC Image Offsets Used: 1600 ~ 14000 ft

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

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

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

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

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

26. Comparison of 3D Impulse Response X (km) 04 Depth (km) 0 2.4 FD algorithm Main energy wider angle FFD Depth (km) 0 2.4

27. 2D Impulse Response X (km) 04 Depth (km) 0 2.4 Standard wider angle FFD X (km) 04 Main energy wider angle FFD (Velocity contrast, i.e., V/Vmin = 3.0)

28. Comparison of FFD and Main Energy FFD Migration X (km) 04 Depth (km) 0 2.4 FFD algorithm Main energy FFD (computational time saving about 38 %) Depth (km) 0 2.4

29. 3D SEG/EAGE Zero Offset Imaging Result X (km) 04 Depth (km) 0 2.0 0 2.0 Y (km) 08 4 0 0 8 X (km) Y (km)

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

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

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

33. Solution: Deconvolve the point scatterer response from the migrated image T r = ( L L ) m Reflectivity Migrated Section Section Reason: m = L d TMigratedSectionData but d = L r L rL rL rL r Migration Section = Blured Image of r

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

35. Zoom View of AVO parameter Section Before and After PMD X(km) 1.02.0 Time (s) 0.5 2.0 Before PMD Time (s) After PMD 0.5 2.0X(km)1.02.0

36. Migration CRG Before and After PMD Trace Trace 160160 Time (s) 0.6 1.8 Before PMD After PMD 0.6 1.8

37. Comparison of Amplitude & Angle Estimation Before and After PMD 2rd layer Amplitude 1 0 1st layer 3rd layer +: Before PMD *: After PMD Solid line: Theoretical value Angle 0600 0

38. Summary & Future MD reduces artifactsMD reduces artifacts MD improves resolution & AVOMD improves resolution & AVO MD field data case by Feb.MD field data case by Feb.

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

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

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

42. Auto. Imaging using Primary and Ghost

43. Geological Model 0 Depth (m) 3 40 X (m) V1 V2 V4 V3 V5 V6

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

45. 1.6 2.1 0 2.2 Time (s) X (km) Standard Migration 1.6 2.1 X (km) Joint Migration Eliminate Interferences using Joint Imaging in Time Domain

46. Eliminate Interferences using Joint Imaging in Depth Domain Depth (km) 2.8 0 1.62.1 X (km) Conventional Imaging X (km) 1.62.1 Joint Imaging

47. Kirchhoff and Auto. Migration with Statics Error at Source and Receiver Depth (km) 2.8 0 1.62.0 X (km) Kirchhoff joint migrationg 1.62.0 X (km) Auto. joint migrationg

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

49. 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

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

51. Objective Invert velocity & geometry jointly

52. Normalized Traveltime Residuals vs. Velocity & Geometry Changes 500 m V=5.0km/sec Velocity (km/sec) Horizontal shift (m) Vertical Shift (m) Rotation (degree) 2.57.5 5.0 0.0 1.0 0.5 0.0250 -2500.0250 -250 0.030 -30

53. Problems 1) Geometry is coupled with velocity 2) Joint inversion is ill-posed

54. a) Synthetic Model b) Standard Inversion with 10 m shot shift c) Joint Inversion for the shot shift ( all shots have the same shift ) d) Joint Inversion + a priori information for individual shot locations Depth (m) 200 0 100 080080 -10 200 0 100 0 80 -10 Offset (m) 80-10 10 Km/s2.5 5.0 4.5 3.0 Km/s2.5 5.0 4.5 3.0 Geometry Error: synthetic example I

55. a) Synthetic Model c) Standard Inversion with +10 m shot shifts Depth (m) 300 0 100 080 -10 200 0 100 0 80 -10 Offset (m) 80-10 10 Geometry Error: synthetic example II 200 0 100-10300Km/s2.0 3.2 2.8 2.4 Km/s 2.0 3.2 2.8 2.4 b) Standard Inversion without shot shift d) Joint Inversion for the shot shift

56. a) Synthetic Model c) Joint Inversion + a priori information for the shot shift d) Joint Inversion + a priori information for individual shot locations Depth (m) 300 0 100 080 -10 200 0 100 0 80 -10 Offset (m) 80-10 10 Geometry Error: synthetic example II 200 0 100-10300Km/s2.0 3.2 2.8 2.4 Km/s 2.0 3.2 2.8 2.4 b) Standard Inversion without shot shift

57. Conclusions works for simple model works for simple model needs additional information needs additional information Joint inversion