Migration Deconvolution

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
ZO Modeling
5
0
Reverse Order Traces in Time
12
Reverse Time Migration (Go Backwards in Time)
0
-5
T0 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)
0
-5
T0 Focuses at Hand Grenades
15
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
Forward Modeling
for it11nt p2 2p1 - p0
cns.del2(p1) p2(xs,zs) p2(xs,zs)
RICKER(it) Add bodypoint src term
p0p1p1p2 end
18
Recall Forward Modeling






ò
dLm d(x) G(xx)m(x)dx
Forward reconstruction of half circles
19
Migration Adjoint of Data
Note t lt ts
20
Migration Adjoint of Data
Note t lt ts
21
Migration Adjoint of Data
Note t lt ts
22
Migration Adjoint of Data
Note t lt ts
23
Migration Adjoint of Data
Note t lt ts
Backward reconstruction of half circles
24
Migration Adjoint of Data
Let ts -ts
Note t lt ts
Note t gt ts
Forward prop. Of reverse time data
25
Advantages of
m(xdx) d(x) G(xxdx)
x
Kirchhoff Mig. vs Full Trace
Migration
1. Low-Fold Stack vs Superstack
2. Poor Resolution vs Superresolution
26
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

27
Numerical Examples
28
3D Synthetic Data
3D SEG/EAGE Salt Model
X 3.5 Km
Z 2.0 Km
Y 3.5 Km
4
29
3D Synthetic Data
W
E
Kirchhoff Migration
0
Depth (Km)
Redatum KM
2.0
3.5
Offset (km)
0
3.5
Offset (km)
0
5
Cross line 160
30
3D Synthetic Data
Kirchhoff Migration
W
E
0
Redatum KM
Depth (Km)
2.0
Offset (km)
3.5
Offset (km)
0
3.5
0
6
Cross line 180
31
3D Synthetic Data
Kirchhoff Migration
W
E
0
Redatum KM
Depth (Km)
2.0
Offset (km)
3.5
Offset (km)
0
3.5
0
7
Cross line 200
32
Numerical Examples

• GOM Data

• Prism Synthetic Example

33
GOM Kirchhoff
?
34
GOM RTM
?
35
?
36
Numerical Examples

• GOM Data

• Prism Synthetic Example

37
Prism Wave Migration
One Way Migration of Prestack Data
RTM of Prestack Data
Courtesy TLE Farmer et al. (2006)
38
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.
39
Solution

• Claim Image both Primaries and Multiples

• Methods RTM

A
D
40
Piecemeal Methods
2-Way Mirror Wave Migration

• Assume Knowledge of Important Mirror

• Reverse Time Migration

A
D