1. Migrating elastic data
Aaron Stanton

2. Outline The seismic imaging problem Why not direct inversion?
Migrating scalar wavefields
Downward continuation
Imaging condition
Migrating vector wavefields
Wavefield decomposition
Wavefield recomposition

3. The forward problem

4. The forward problem

5. The forward problem

6. The forward problem

7. The forward problem

8. The forward problem
model
data

9. model data ? The inverse problem
Non-linear, underdetermined (grid sizes are very tiny), and data sets are massive (tera bytes and even peta-bytes).

10. Linearize!

11. Model

12. Model perturbation

13. Born Scattering

14. Born Scattering

15. Born Scattering

16. Migration

17. Migration
image = up/down

18. Downward continuation

19. Now for vector wavefields!

20. Vector data

21. Vector data

22. Vector data
If we assume isotropy we can use Helmholtz decomposition

23. Helmholtz decomposition

24. Helmholtz decomposition
Etgen, 1988

25. Helmholtz recomposition
Etgen, 1988

26. Synthetic data example
Marmousi 2

27. vp

28. vs

29. Shot gathers

30. LS Migration: mpp
25˚ incidence angle

31. Migration: mps
25˚ incidence angle

32. Synthetic data example
Anticline model

33. Simulated OBC Acquisition★
osx = 100m ; dsx = 100m ; nsx = 69 ; sz = 10m ;
dgx = 8m ; gz = 550m ; recording aperture = 6608m

34. X-Component

35. Z-Component

36. Mpp
Constant Incidence angle of 10˚

37. Mpp
x = 1600m

38. Mps
Constant Incidence angle of 10˚

39. Mps
x = 1600m

40. Conclusions Migration of scalar wavefields consists of
downward continuation
imaging condition
Migration of vector wavefields consists of
wavefield separation
wavefield recombination