1. Prestack Migration Deconvolution Jianxing Hu and Gerard T. Schuster University of Utah

2. Outline MotivationMotivation MethodologyMethodology Numerical TestsNumerical Tests ConclusionsConclusions

3. Comparison of Poststack MD Depth Slices 6 8 Y (km) Y (km) X (km) X (km)4 8 6 10 10 Kirchhoff Image Kirchhoff Image MD Image MD Image 6 8 Y (km) Y (km) X (km) X (km)4 8 6 10 10

4. Comparison of Prestack Migration and MD Images X (km) X (km) 4 6 8 10 10 1 4 Depth (km) Depth (km) X (km) X (km) 4 6 8 10 10 1 4 Depth (km) Depth (km) Prestack Kirchhoff Migration Image of Prestack Kirchhoff Migration Image of a North Sea Data Set a North Sea Data Set MD Image

5. Outline MotivationMotivation MethodologyMethodology Numerical TestsNumerical Tests ConclusionsConclusions

6. Modeling and Migration Seismic data Reflectivity Green’s Function Model Space Migrated Image Data Space Seismic Data Forward Modeling: Migration: Wavelet

7. Model Space Where: Denote as the migration Green’s Function Relation of Migrated Image and Reflectivity Distribution Relation of Migrated Image and Reflectivity Distribution Data Space

8. Reflectivity Modulated by Migration Green’s Function Model Space

9. Migration Deconvolution Model Space Model Space --- reference position of migration Green’s function

10. Lateral Velocity Variation Multi-Reference migration Green’s function Subdivide the migration image area and use multi- reference migration Green’s function to account for lateral velocity variation and far-field artifacts

11. Methodology Calculate migration Green’s function Recording geometry & migrated image dimension Velocity Model + Traveltime Table Migration Green’s function

12. Methodology Apply migration deconvolution filter to the stacked prestack migration image 5 Offset(km) 6 5 1 2 3 Depth (km) RTM Migration Image Deconvolved Image Deconvolved Image Pseudo-Convolution Offset(km) 6 5 1 2 3 Depth (km) RTM

13. Difference between Poststack MD and Prestack MD Zero-offset trace location & migrated image dimension Velocity Model Traveltime Table migration Poststack migration Green’s function Green’s function + migration Prestack migration Green’s function Green’s function Recording Geometry & migrated image dimension +

14. Outline MotivationMotivation MethodologyMethodology Numerical TestsNumerical Tests ConclusionsConclusions

15. Numerical Tests 3-D point scatterer model3-D point scatterer model 3-D meandering stream model3-D meandering stream model 2-D SEG/EAGE overthrust model2-D SEG/EAGE overthrust model 2-D Husky data set (Canadian Foothills)2-D Husky data set (Canadian Foothills) 3-D SEG/EAGE salt model3-D SEG/EAGE salt model 3-D West Texas data set3-D West Texas data set

16. 5 X 5 Sources; 21 X 21 Receivers (0, 0) (1km, 0) (1km, 1km) (0, 1km) Point scatterer Recording Geometry Wavelet frequency 50 Hz

17. Prestack KM vs. Prestack MD Y X Y X Y X Y X

18. Prestack KM vs. Poststack MD Y X Y X Y X Y X

19. Numerical Tests 3-D point scatterer model3-D point scatterer model 3-D meandering stream model3-D meandering stream model 2-D SEG/EAGE overthrust model2-D SEG/EAGE overthrust model 2-D Husky data set (Canadian Foothills)2-D Husky data set (Canadian Foothills) 3-D SEG/EAGE salt model3-D SEG/EAGE salt model 3-D West Texas data set3-D West Texas data set

20. (0, 0) (1 km, 0) (1 km,1 km) (0, 1 km) A river channel Recording Geometry 5 X 5 Sources; 21 X 21 Receivers Wavelet frequency 50 Hz

21. Meandering River Model 01000 X (m) 0 1000 Y (m)

22. Kirchhoff Migration Image 01000 X (m) 0 1000 Y (m)

23. MD Image 01000 X (m) 0 1000 Y (m)

24. Numerical Tests 3-D point scatterer model3-D point scatterer model 3-D meandering stream model3-D meandering stream model 2-D SEG/EAGE overthrust model2-D SEG/EAGE overthrust model 2-D Husky data set (Canadian Foothills)2-D Husky data set (Canadian Foothills) 3-D SEG/EAGE salt model3-D SEG/EAGE salt model 3-D West Texas data set3-D West Texas data set

25. Prestack Migration Image Prestack Migration Image Deconvolved Migration Image Deconvolved Migration Image 0 km 20 km 20 km 0 km 4 km 20 km 0 km 0 km 0 km 4 km X(km) Depth (km)

26. Zoom View of KM and MD Prestack KM Prestack MD 2 4 3 Depth (km) 37 X (km) 2 4 3 Depth (km) 37 X (km)

27. Numerical Tests 3-D point scatterer model3-D point scatterer model 3-D meandering stream model3-D meandering stream model 2-D SEG/EAGE overthrust model2-D SEG/EAGE overthrust model 2-D Husky data set (Canadian Foothills)2-D Husky data set (Canadian Foothills) 3-D SEG/EAGE salt model3-D SEG/EAGE salt model 3-D West Texas data set3-D West Texas data set

28. Husky Prestack Migration Image 4 6X(km)0 0 10 5 2 Depth (km)

29. Velocity Model for Husky Data 6X(km)0 0 10 5 2 Depth (km) 7000 3200 Velocity (m/s)

30. MD with 20 reference positions 6X(km)0 0 10 5 2 Depth (km) A

31. KM X(km) 95 1 3 Depth (km) MD X(km)95 1 3 Depth (km)

32. MD with 20 reference positions 6X(km)0 0 10 5 2 Depth (km) B

33. KM X(km) 1411 1 3 Depth (km) MD X(km)1411 1 3 Depth (km)

34. MD with 20 reference positions 6X(km)0 0 10 5 2 Depth (km) C

35. KM X(km)1410 2 5 Depth (km) MD X(km)1410 2 5 Depth (km)

36. Numerical Tests 3-D point scatterer model3-D point scatterer model 3-D meandering stream model3-D meandering stream model 2-D SEG/EAGE overthrust model2-D SEG/EAGE overthrust model 2-D Husky data set2-D Husky data set 3-D SEG/EAGE salt model3-D SEG/EAGE salt model 3-D West Texas data set3-D West Texas data set

37. KM Inline (97,Y) Section MD Inline (97,Y) Section 58 Y (km) 58 0 4 2 04 2 Depth (km)

38. KM Crossline (X,97) Section MD Crossline (X,97) Section 04 2 Depth (km) 118 X (km) 118 X (km) 04 2

39. Numerical Tests 3-D point scatterer model3-D point scatterer model 3-D meandering stream model3-D meandering stream model 2-D SEG/EAGE overthrust model2-D SEG/EAGE overthrust model 2-D Husky data set2-D Husky data set 3-D SEG/EAGE salt model3-D SEG/EAGE salt model 3-D West Texas data set3-D West Texas data set

40. KMMD03 X(kft)46 8 Depth (kft) 4 6 8 03 X(kft)

41. 46 8 Depth (kft) KMMD4 6 8 X(kft)2 4 2 4

42. Outline MotivationMotivation MethodologyMethodology Numerical TestsNumerical Tests ConclusionsConclusions

43. Conclusions Works well on 2-D land and 3-D synthetic marine prestack data More work is needed to remedy the problems in MD for 3-D land prestack data Standard post-migration processing procedure ?

44. Acknowledgement Thank 1999 UTAM sponsors for their financial supportThank 1999 UTAM sponsors for their financial support