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Reverse Time Migration. 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. Liberty Park Lake. Rolls of Toilet Paper. Time. Find Location of Rock.
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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
Liberty Park Lake Rolls of Toilet Paper Time
Find Location of Rock Rolls of Toilet Paper Time
Find Location of Rock Rolls of Toilet Paper Time
Find Location of Rock Rolls of Toilet Paper Time
Find Location of Rock Rolls of Toilet Paper Time
Find Location of Rock Rolls of Toilet Paper Time
Find Location of Rock Rolls of Toilet Paper Time
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
1-way time ZO Modeling 5 0 Reverse Order Traces in Time
Reverse Time Migration (Go Backwards in Time) 1-way time 0 -5 T=0 Focuses at Hand Grenades
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
Reverse Time Migration (Reverse Traces Go Forward in Time) 1-way time 0 -5 T=0 Focuses at Hand Grenades
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
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
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
3D Synthetic Data 3D SEG/EAGE Salt Model X 3.5 Km Z 2.0 Km Y 3.5 Km 4
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
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
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
Numerical Examples • GOM Data • Prism Synthetic Example
GOM RTM ?
Numerical Examples • GOM Data • Prism Synthetic Example
Prism Wave Migration One Way Migration of Prestack Data RTM of Prestack Data Courtesy TLE: Farmer et al. (2006)
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.
? ? Solution • Claim: Image both Primaries and Multiples • Methods: RTM A D
? ? Piecemeal Methods 2-Way Mirror Wave Migration: • Assume Knowledge of Important Mirror • Reverse Time Migration A D