moveout correction and migration of surface-related resonant multiples bowen guo*,1, yunsong huang 2...
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Moveout Correction and Migration of Surface-related Resonant Multiples
Bowen Guo*,1, Yunsong Huang2 and Gerard Schuster1
1King Abdullah University of Science and Technology2CGG
Outline
Conclusions and future work
Introduction and motivation
Theory and workflow
Numerical results
Introduction What is a surface-related resonant
multiple ?Free surface
Reflector
Raypaths overlap
Raypaths overlap
Introduction Why migrate resonant multiples ? Super-resolution
Case 1: migrate primary reflections
Where did this come from ?
๐ก๐
๐ง๐1
๐ง๐1=๐ฃ๐ก๐ /2
๐ก๐+T
๐ง๐2
๐ง๐2=๐ฃ (๐กยฟยฟ๐+๐ )/2ยฟ
โ
t
๐ /๐๐ฃ
Motivation Why migrate resonant multiples ? Super-resolution
Where did this come from ?
๐ง๐1๐ง๐ 2
๐ก๐
+T
๐ง๐1=๐ฃ๐ก๐/4๐ง๐ 2=๐ฃ (๐ก ยฟยฟ๐+๐ )/4 ยฟ
โ
Case 2: migrate resonant multiples
t
โ
๐ฃ๐ง๐1๐ง๐2๐ /๐
Super-resolution by migrating resonant multiples
Problem Only received by near-offset traces low SNR
Motivation
Freesurface
Reflector
Freesurface
Reflector
Multiple Image
Primary Image
Z (km
)
X (km)
X (km)Schuster and Huang (2014)
0.69
0.8533.5 36.533.5 36.5
Problem: Low SNR
t (s)
X (km)
1.5
6.0
0 30
COG offset=107 m
Solution: Step 1: CMP moveout correction. Step 2: Stacking to improve SNR.
t
offset
CMPt
offset
CMP
Pre-resonant multiples
Resonant multiples
Before stackingAfterstacking
Resonant multiple
Primary reflection
Motivation
Introduction and motivation
Theory
Numerical results
Conclusions and future work
Outline
Theory: Pre-resonant Multiples
Free surface
Reflector 1
Reflector 2
Multiples from dissimilar interface
Pre-resonant multiples from similar interface
Free surface
Reflector
๐ผ
h
Resonant multiples
Theory: Moveout Correction
Moveout correction based on moveout formla
Free surface
Reflector
๐ผ
Pre-resonant multiples ๐0๐
Valid for homogeneous velocity model
Theory: Moveout Correction
Free surface
Reflector
๐ผ
๐ ๐๐โฒ๐
Moveout correction based on Fermatโs principle
๐ ๐๐ โฒ
๐๐โฒ๐๐
Indentify for different offsets Stack into zero-offsets
๐ ๐๐๐ =min
๐โฒ(๐ ๐๐โฒ
๐ +๐ ๐โฒ๐๐ )
Valid for heterogeneous velocity model
Theory: Migration of Resonant Multiples Migration of post-stack resonant multiples
๐ฅ
2๐๐ฅ๐ 2๐๐ฅ๐ด
Free surface
๐ ๐ด
m() =c(, ) d( , t-2-2)
Primary Reflection Migration Image
Horizontal distanceD
epth
Resonant Multiple Migration Image
Horizontal distance
Dep
th
Work Flow
CMP
Moveout Correction for Non-zero Offset Traces
Stack into zero-offset
Migration of post-stack resonant multiples
t
x
ZOG
t
x
Post-stack ZOG
z
x
Image
t
offset
CMP
0
t
offset
CMP
0
Introduction and motivation
Theory
Numerical results
Conclusions and future work
Outline
Synthetic Result: Point Scatterers
Data generated by Kirchhoff modeling and migrated by Kirchhoff migration
Z (k
m)
x (km) x (km)
0.64
2.0811.6 12.4 11.6 12.4
Primary Image Resonance Image
Field Data Example
X (km)0 30
t (s)
1.5
6.0
COG = 107 m
Resonant multiple
Primary reflection
Zoom in
Field Data: Zoom-in of COG
X (km)0 30
t (s)
3.3
6.0
Dissimilar multiplesBefore After
h
1
CMP0.0
6.00.1 5.0
t (s)
5.0(km) h
2
0.0
6.00.1 h
t (s)
5.0 5.0(km)
h
CMP
3
0.0
6.00.1 h
t (s)
5.0 5.0(km) h
Top of Salt
Z (k
m)
X (km)2.0
0 30
Primary Reflection Image0.0
Multiple Image
X (km)0 30
Post-stack Multiple Image
Field Data: Migration Image
Higher-resolution top of the salt
False reflectors from dissimilar multiples
Field Data 2: Sonar Data
Processsed 120 kHz data
0
80
1600 370 x (m)
t (m
s)
Primary reflection
Resonant multiple
Processsed 200 kHz data
0 370 x (m)
Primary reflection
Migration Image of the Sea BottomImage from 120 kHz Primary Reflections
0
60
0 270 x (m)
Z (m
)
Image from 120 kHz Resonant Multiples0
60
Z (m
)
Image from 200 kHz Primary Reflections
Image from 120 kHz Resonant Multiples
Introduction and motivation
Theory
Numerical results
Conclusions and future work
Outline
Conclusions Resonant multiples give super-resolution
Pre-resonant multiples resonant multiples
Alignment and stacking improve SNR
0.0
6.00.1 5.0
t (s)
h (km)
CMP0.0
6.00.1 5.0
t (s)
h (km)
CMP
Limitations and Future Research
Multiples suffer more from attenuation than primaries
Inaccurate moveout correction blur the stacked resonant multiples
Multiples from dissimilar reflectors cause artifacts
Acknowledgement
We would like to thank King Abdullah University of Science and Technology for their support
Thank you for your attention