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Reverse Time Migration

Explore reverse time migration techniques, modeling, and numerical examples in both backward and forward time directions. Learn about synthetic data, salt models, and the benefits of RTM over Kirchhoff migration. Discover the claim to image both primaries and multiples using RTM.

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Reverse Time Migration

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  1. Reverse Time Migration

  2. Outline • Finding a Rock Splash at Liberty Park • ZO Reverse Time Migration (backwd in time) • ZO Reverse Time Migration (forwd in time) • ZO Reverse Time Migration Code • Examples

  3. Liberty Park Lake Rolls of Toilet Paper Time

  4. Find Location of Rock Rolls of Toilet Paper Time

  5. Find Location of Rock Rolls of Toilet Paper Time

  6. Find Location of Rock Rolls of Toilet Paper Time

  7. Find Location of Rock Rolls of Toilet Paper Time

  8. Find Location of Rock Rolls of Toilet Paper Time

  9. Find Location of Rock Rolls of Toilet Paper Time

  10. Outline • Finding a Rock Splash at Liberty Park • ZO Reverse Time Migration (backwd in time) • ZO Reverse Time Migration (forwd in time) • ZO Reverse Time Migration Code • Examples

  11. 1-way time ZO Modeling 5 0 Reverse Order Traces in Time

  12. Reverse Time Migration (Go Backwards in Time) 1-way time 0 -5 T=0 Focuses at Hand Grenades

  13. Outline • Finding a Rock Splash at Liberty Park • ZO Reverse Time Migration (backwd in time) • ZO Reverse Time Migration (forwd in time) • ZO Reverse Time Migration Code • Examples

  14. Reverse Time Migration (Reverse Traces Go Forward in Time) 1-way time 0 -5 T=0 Focuses at Hand Grenades

  15. 1-way time 1-way time 0 0 -5 Poststack RTM 1. Reverse Time Order of Traces 5 2. Reversed Traces are Wavelets of loudspeakers

  16. Outline • Finding a Rock Splash at Liberty Park • ZO Reverse Time Migration (backwd in time) • ZO Reverse Time Migration (forwd in time) • ZO Reverse Time Migration Code • Examples

  17. Reverse Time Modeling for it=nt:-1:1 p2 = 2*p1 - p0 + cns.*del2(p1); p2(1:nx,2) = p2(1:nx,2) + data(1:nx,it); % Add bodypoint src term p0=p1;p1=p2; end Forward Modeling for it=1:1:nt p2 = 2*p1 - p0 + cns.*del2(p1); p2(xs,zs) = p2(xs,zs) + RICKER(it); % Add bodypoint src term p0=p1;p1=p2; end

  18. Numerical Examples

  19. 3D Synthetic Data 3D SEG/EAGE Salt Model X 3.5 Km Z 2.0 Km Y 3.5 Km 4

  20. 3D Synthetic Data W E Kirchhoff Migration 0 Depth (Km) Redatum + KM 2.0 0 Offset (km) 3.5 0 Offset (km) 3.5 5 Cross line 160

  21. 3D Synthetic Data Kirchhoff Migration W E 0 Redatum + KM Depth (Km) 2.0 Offset (km) 0 Offset (km) 3.5 0 3.5 6 Cross line 180

  22. 3D Synthetic Data Kirchhoff Migration W E 0 Redatum + KM Depth (Km) 2.0 Offset (km) 0 Offset (km) 3.5 0 3.5 7 Cross line 200

  23. Numerical Examples • GOM Data • Prism Synthetic Example

  24. GOM Kirchhoff ?

  25. GOM RTM ?

  26. ?

  27. Numerical Examples • GOM Data • Prism Synthetic Example

  28. Prism Wave Migration One Way Migration of Prestack Data RTM of Prestack Data Courtesy TLE: Farmer et al. (2006)

  29. Summary 1. RTM much more expensive than Kirchhoff Mig. 2. If V(x,y,z) accurate then all multiples Included so better S/N ration and better Resolution. 3. If V(x,y,z) not accurate then smooth velocity Model seems to work better. Free surface multiples included. 4. RTM worth it for salt models, not layered V(x,y,z). 5. RTM is State of art for GOM and Salt Structures.

  30. ? ? Solution • Claim: Image both Primaries and Multiples • Methods: RTM A D

  31. ? ? Piecemeal Methods 2-Way Mirror Wave Migration: • Assume Knowledge of Important Mirror • Reverse Time Migration A D

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