1 local reverse time migration: salt flank imaging by ps waves xiang xiao and scott leaney 1 1...
TRANSCRIPT
![Page 1: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/1.jpg)
1
Local Reverse Time Migration: Salt Flank Imaging by PS
Waves
Xiang Xiao and Scott Leaney1
1Schlumberger
UTAM, Univ. of Utah
Feb. 8, 2008
![Page 2: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/2.jpg)
2
Outline
Motivation Theory Numerical Tests
Schlumberger VSP Data Set GOM VSP Data Set
Conclusions
Motivation Theory Numerical Tests Conclusions
![Page 3: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/3.jpg)
3
Outline
Motivation Theory Numerical Tests Conclusions
Motivation Theory Numerical Tests
Schlumberger VSP Data Set GOM VSP Data Set
Conclusions
![Page 4: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/4.jpg)
4
Standard P-to-S Migration
x
s
m(x) ~ s
~ ds G(x|s)
Forward source P
P
S
g
G(x|g)* D(g|s)dg
Backward data S
g
*
Converted wave VSP
D(g|s)
Motivation Theory Numerical Tests Conclusions
![Page 5: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/5.jpg)
5
Interferometric P-to-S Migration
x
s
P
P
S
D(g|g’) ~
s
~ ds*
g’
g
D(g’|s) D(g|s)
m(x) ~ g’
~ dg’dgg
D(g|g’)G(x|g) G(x|g’)* *
Virtual source gather
Motivation Theory Numerical Tests Conclusions
![Page 6: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/6.jpg)
6
Outline
Motivation Theory Numerical Tests
Motivation Theory Numerical Tests
Schlumberger VSP Data Set GOM VSP Data Set
Conclusions
Conclusions
![Page 7: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/7.jpg)
7
x
s
P
P
S
m(x) ~ s
~ dsg’
G(x|g’)* D(g’,s) dg’
Backward P
G(x|g)* D(g,s)dg
Backward S
g
g’
g
*
Local Reverse Time Migration Theory
Motivation Theory Numerical Tests Conclusions
![Page 8: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/8.jpg)
8
Benefits
• Target oriented!
Introduction Numerical Tests
– Only a local velocity model near the well is needed.
– Salt and overburden is avoided.
– Fast and easy to perform.
• Source statics are automatically accounted for.
• Immune to salt-related interbed cross-talk.
Theory Conclusions
![Page 9: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/9.jpg)
9
Outline
Introduction Numerical Tests Conclusion
Motivation Theory Numerical Tests
Schlumberger VSP Data Set GOM VSP Data Set
Conclusions
Theory
![Page 10: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/10.jpg)
10
Dep
th
(km
)
Offset (km)
10-12 12
0
Schlumberger 2D Isotropic Elastic Model
0
Introduction Numerical TestsTheory Conclusions
291 shots
287 receivers
![Page 11: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/11.jpg)
11
Dep
th
(km
)
10
0
Offset (km)-12 120
(a) Ray tracing direct P
(c) PPS events (d) Pp events
(b) PSS events
Dep
th
(km
)
10
0
Offset (km)-12 120
Aperture by Ray Tracing
Introduction Numerical TestsTheory Conclusions
![Page 12: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/12.jpg)
12
Direct PPPS
PSS
Dep
th
(km
)
Time (s)
8
0 6
VSP CSG X-component
VSP CSG Z-component4
Dep
th
(km
)
8
4
Two-component VSP Synthetic Data Set
Introduction Numerical Tests ConclusionTheory
![Page 13: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/13.jpg)
13
Dep
th
(km
)
8.5
6
Offset (km)0 1.8
(a) Standard Kirchhoff
(c) Interferometric migration (IM) (d) Local RTM
(b) Reduced-time migration (RM)
Dep
th
(km
)
8.5
6
Offset (km) 1.80
Introduction Numerical Tests ConclusionTheory
Comparison with Migration Methods
![Page 14: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/14.jpg)
14
Outline
Introduction Numerical Tests Conclusion
Motivation Theory Numerical Tests
Schlumberger VSP Data Set GOM VSP Data Set
Conclusions
Theory
![Page 15: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/15.jpg)
15
Dep
th
(m)
Offset (m)4878
0 1829
0
GOM VSP Well and Source LocationSource @150 m offset
Introduction Theory Numerical Tests Conclusions
2800 m
3200 m
Salt
82 receivers
![Page 16: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/16.jpg)
16
P-to-S ratio = 2.7
Velocity ProfileS WaveP Wave
Dep
th
(m)
0
45000 5000 0 5000
2800 m
3200 m
Salt
Incorrect velocity model
P-to-S ratio = 1.6
Introduction Theory Numerical Tests Conclusions
Velocity (m/s) Velocity (m/s)
![Page 17: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/17.jpg)
17
Z-Component VSP DataD
epth
(m
)
Traveltime (s)
2652
3887
1.2 3.0
Salt
Direct P
Reflected P
Reverberations
Introduction Theory Numerical Tests Conclusions
![Page 18: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/18.jpg)
18
X-Component VSP DataD
epth
(m
)
Traveltime (s)
2652
3887
1.2 3.0
Salt
Direct P
Reflected P
Reverberations Direct S
Introduction Theory Numerical Tests Conclusions
![Page 19: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/19.jpg)
19
Processing WorkflowOriginal Data
Rotate components
Pick desired events
Median filtering
Migration (KM, RM, IM, RTM)
Introduction Theory Numerical Tests Conclusions
![Page 20: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/20.jpg)
20
Raypath Coverage
2000
4200
0 200
Dep
th
(m)
Migration of PPS
Salt
Offset (m)Introduction Theory Numerical Tests Conclusions
39receivers
![Page 21: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/21.jpg)
21
Migration of PPS
Salt
RM IM
0 200 0 200
KM
2000
4200
0 200
Dep
th
(m)
Offset (m)
Introduction Numerical Tests ConclusionTheory
Offset (m) Offset (m)
![Page 22: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/22.jpg)
22
Migration of PPS
Salt
IM, sediment flood Local RTM
0 200 0 200
RM
2000
4200
0 200
Dep
th
(m)
Offset (m)
Introduction Numerical Tests ConclusionTheory
Offset (m) Offset (m)
![Page 23: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/23.jpg)
23
Conclusions
• Local RTM improves salt flank imaging.
Introduction Theory Numerical Tests Conclusions
• Imaging improvement is attained with a 1D velocity model for GOM data.
• Local RTM doesn’t suffer from the source statics and incorrect overburden and salt velocity model.
![Page 24: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/24.jpg)
24
Separation While Imaging
• Step 1: Elastic backward propagation of the whole wavefield;
• Step 2: P- and S- wavefield separation; Devaney and Oristaglio (1986)Dellinger and Etgen (1990)
• Step 3: Crosscorrelate the P- and S- waves;
![Page 25: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/25.jpg)
25
Thank you!
• Thank the sponsors of the 2005 UTAM consortium for their support.
![Page 26: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/26.jpg)
26
Dep
th
(m)
Offset (m)4878
0 200
0
Local RTM Image
Introduction Numerical Tests ConclusionTheory
IM
0 200Offset (m)
![Page 27: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/27.jpg)
27
Future works
Motivation Theory Numerical Tests Conclusions
![Page 28: 1 Local Reverse Time Migration: Salt Flank Imaging by PS Waves Xiang Xiao and Scott Leaney 1 1 Schlumberger UTAM, Univ. of Utah Feb. 8, 2008](https://reader035.vdocument.in/reader035/viewer/2022070412/5697bf841a28abf838c86c9f/html5/thumbnails/28.jpg)
28
Dep
th
(m)
Offset (m)4878
0 1829
0
Local RTM Image
Introduction Numerical Tests ConclusionTheory