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MS thesis. Salt Flank Delineation by Interferometric Imaging of Transmitted P-to-S Waves. Xiang Xiao Advisor: Gerard T. Schuster Committee: Michael Zhdanov Bob Smith Cari Jonson Univ. of Utah Nov. 15. Outline. Motivation Theory - PowerPoint PPT Presentation
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Salt Flank Delineation by Interferometric Imaging of Transmitted P-to-S Waves
Xiang Xiao
Advisor: Gerard T. SchusterCommittee: Michael Zhdanov Bob Smith Cari Jonson
Univ. of UtahNov. 15
MS thesis
Outline
I. Motivation
II. Theory
III. Numerical Tests
IV. Field Data Examples
V. Conclusion
Outline
I. Motivation
II. Theory
III. Numerical Tests
IV. Field Data Examples
V. Conclusion
I. Motivation
• Goal:– Salt Flank Imaging with Migration of Transmitted P-to-S Waves;
• Method:
– Standard Migration (KM);
– Reduced-time Migration (RM), Sheley and Schuster, 2003;
– Interferometric Migration (IM), and Interferometric Redatuming (IR), Schuster, 2004;
Outline
I. Motivation
II. Theory
III. Numerical Tests
IV. Field Data Examples
V. Conclusion
Goal: Image Interface by PS Transmitted WavesGoal: Image Interface by PS Transmitted Waves
MM
gg
Uninteresting PartUninteresting Part of Mediumof Medium
ss
TimeTime
PP
d(M|d(M|ss))
d(g|s)d(g|s)PPPP
PPSS
X
eei wi w ((tt + t+ t))––
ww,s,,s,MMm(x) =m(x) = d(M|d(M|ss)) sxsx xxMM
Standard Kirchhoff Migration:
Goal: Image Interface by PS Transmitted WavesGoal: Image Interface by PS Transmitted Waves
MM
gg
Uninteresting PartUninteresting Part of Mediumof Medium
ss
TimeTime
PP
d(M|d(M|ss))
d(g|s)d(g|s)PPPP
PPSS
XReduced-time migration:
eei wi w ((tt + t + t+ t + t))––
ww,s,,s,MMm(x) =m(x) = d(M|d(M|ss)) sxsx xxMM errorerror
~( ~( t t + t )- + t )- ( ( t t + t )+ t )sxsx xgxg
pickpickpickpick
sxsx xgxg
errorerrortt sxsx xxMM=( =( t t + + tt )- )- ( ( t t + + tt ) )pickpickpickpick
sxsx xxMM
Goal: Image Interface by PS Transmitted WavesGoal: Image Interface by PS Transmitted Waves
MM
gg
Uninteresting PartUninteresting Part of Mediumof Medium
ss
TimeTime
PP
d(M|d(M|ss))
d(g|s)d(g|s)PPPP
PPSS
d(M|d(M|ss)) d(g|s)*d(g|s)*((gg,,MM) =) =
~ e ~ e eei wi w t + t + i wi w tt -i w-i w t - t - i wi w tt
PPSS PPPP
== e ei wi w ((t t –– tt))
Interferometric migration:
MM
gg
Uninteresting PartUninteresting Part of Mediumof Medium
ss
TimeTime
PP
d(M|d(M|ss))
d(g|s)d(g|s)PPPP
PPSS
Goal: Image Interface by PS Transmitted WavesGoal: Image Interface by PS Transmitted Waves
ss
d(M|d(M|ss)) d(g|s)*d(g|s)*((gg,,MM) = ) =
MM
gg
Uninteresting PartUninteresting Part of Mediumof Medium
ss
TimeTime
PP
d(M|d(M|ss))
d(g|s)d(g|s)PPPP
PPSS
Goal: Image Interface by PS Transmitted WavesGoal: Image Interface by PS Transmitted Waves
ss
d(M|d(M|ss)) d(g|s)*d(g|s)*((gg,,MM) = ) =
MM
gg
Uninteresting PartUninteresting Part of Mediumof Medium
ss
TimeTime
PP
d(M|d(M|ss))
d(g|s)d(g|s)PPPP
PPSS
ss
d(M|d(M|ss)) d(g|s)*d(g|s)*((gg,,MM) = ) =
Goal: Image Interface by PS Transmitted WavesGoal: Image Interface by PS Transmitted Waves
Unique Specular Point Snell’s Law OKUnique Specular Point Snell’s Law OK
eei wi w ((t t –– tt))––
w,g,w,g,MM
((gg,,MM) ) m(x) =m(x) = xxMM xgxg
Datuming
MigrationX
Interferometric PS DatumingInterferometric PS Datuming
g,g,MM
((gg,,MM) ) m(x) =m(x) = eei wi w ((t t –– tt))––
xx xx
Eliminates src/rec statics and Eliminates src/rec statics and uninteresting parts of the medium.uninteresting parts of the medium.
Move surface src to interesting inter.Move surface src to interesting inter.
Outline
I. Motivation
II. Theory
III. Numerical Tests
IV. Field Data Examples
V. Conclusion
III. Numerical Tests
I. Rugose Lower Salt Boundary
II. Elastic Salt Model
Salt Velocity ModelSalt S-wave Velocity ModelSalt P-wave Velocity Model
Dep
th
(m)
X (m)X (m) m/s m/s
III. Numerical test
P-to-S ratios = 30.5
0
12000 1200
4400
20000 1200
2540
1170
VSP Gathers
Time (s)
PS Waves Shot @ (0,0)
Time (s)
P Wave Shot @ (0,0)
Dep
th
(m)
III. Numerical test
Interferometric PS DatumingInterferometric PS Datuming
g,g,MM
((gg,,MM) ) m(x) =m(x) = eei wi w ((t t –– tt))––
xx xx
Eliminates src/rec statics and Eliminates src/rec statics and uninteresting parts of the medium.uninteresting parts of the medium.
Move surface src to interesting inter.Move surface src to interesting inter.
Synthetic vs. Redatuming Data
Time (s)
S-P Data from IR
Time (s)
Synthetic S-P SWI Data
Dep
th
(m)
III. Numerical test
KM vs. IM with Correct Velocity Model
IMKM
Dep
th
(m)
X (m)X (m)
III. Numerical test
0
12000 1200
963
13130 1200
7E4
-8E4
KM, RM vs. IM
Constant Static Shift in Data
Each Trace Advances 8 ms
III. Numerical test
KMD
epth
(m
)
X (m)
0
1200
0 1200
400
-700
Incorrectly imagedBoundary is shifted
III. Numerical test
RMD
epth
(m
)
X (m)
0
1200
0 1200
850
-950
Correctly imaged
Poor focused
III. Numerical test
IMD
epth
(m
)
X (m)
0
1200
0 1200
7E4
-8E4
Correctly imaged
Strong focused!Small cover of PS ray
Additionally imaged
III. Numerical test
ComparisonD
epth
(m
)
X (m)
0
1200
0 1200
KMRM
IM
III. Numerical test
Incorrect Migration Model
KM, RM vs. IM
90% Velocity Above Salt
III. Numerical test
KMD
epth
(m
)
X (m)
0
1200
0 1200
850
-1000
Correct place
Incorrectly imaged
III. Numerical test
RMD
epth
(m
)
X (m)
0
1200
0 1200
850
-1000
Incorrectly imaged,Should image as black boundary
Correctly imaged
III. Numerical test
Elliptical artifacts
IMD
epth
(m
)
X (m)
0
1200
0 1200
4E4
-6E4
Correctly imaged
Correctly imaged!
III. Numerical test
Elliptical artifacts are removed
Comparison
KMRM
IM
Dep
th
(m)
X (m)
0
1200
0 1200
III. Numerical test
II. Elastic Salt Model
P-wave velocity model0
Dep
th (
m)
11000
0 16000X (m)
Velocity (m/s)
4500
1500
Gas target lower boundary
a) P-wave velocity model b) S-wave velocity model0
Dep
th (
m)
110000 16000X (m)
0 16000X (m)
0
Dep
th (
m)
11000
0
12
c) CRG 1 X-component d) CRG 1 Z-component
Shot number
Tim
e (s
)
0 319Shot number
0 319
0
12
Tim
e (s
)
a) Ray tracing: direct P b) Ray tracing: PPS events0
Dep
th (
km)
110 16X (km) 0 16X (km)
0
Dep
th (
km)
11
c) Ray tracing: PSS events0
Dep
th (
km)
110 16X (km)
a) PP Standard Migration b) PS Standard Migration0
Dep
th (
m)
11000
5000
8000
0 16000X (m)
c) Zoom View of PS KM d) Zoom View of PS IM
X (m)
0 16000X (m)
0
Dep
th (
m)
11000
Dep
th (
m)
6900 8700
5000
8000
X (m)
Dep
th (
m)
6900 8700
PS IM
PS interferometric migration
X (m)
Dep
th (
m)
0 8000 16000
0
3000
6000
9000
Correctly imaged!
Outline
I. Motivation
II. Theory
III. Numerical Tests
IV. Field Data Examples
V. Conclusion
IV. Field Data
D
epth
(m
)
Offset (m)4878
0 1829
0
Well and Source Location
Source @150 m offset
P-to-S ratios = 2.7
Velocity ProfileS WaveP Wave
Dep
th
(m)
Velocity (m/s)
0
45000 5000 0 5000
2800 m
3200 m
Salt
IV. Field Data
Incorrect velocity model
P-to-S ratios = 1.6
150 Z ComponentD
epth
(m
)
Traveltime (s)
2652
3887
1.2 3.0
Salt
Direct P
Reflect P
Alias (Reverberation)
IV. Field Data
150 X ComponentD
epth
(m
)
Traveltime (s)
2652
3887
1.2 3.0
Salt
Direct P
Reflect P
Alias (Reverberation) Direct S
IV. Field Data
Processing Flow ChartOriginal Data
Reoriented
Pick desired events
Flatten, median filter, unflatten
Migration (KM, RM, IM)
Dep
th
(m)
Traveltime (s)
2652
3887
1.2 3.0
IV. Field Data
150 X Before Rotation
Dep
th
(m)
Traveltime (s)
2652
3887
1.2 3.0
IV. Field Data
150 X After RotationP wave energy was maximized
Dep
th
(m)
Traveltime (s)
2652
3887
1.2 3.0
III. Field Data
150 X PSS EventsTransmitted at upper boundary
150 X PPS EventsD
epth
(m
)
Traveltime (s)
2652
3887
1.2 3.0
III. Field Data
Transmitted at lower boundary
Migration of PSS
IV. Field Data
Ray Path Coverage
2000
4200
0 200
Dep
th
(m) SAL
T
Offset (m)
Migration of PSS
IV. Field Data
SALT
150 offset RM 150 offset IM
0 200 0 200Offset (m)
150 offset KM
2000
4200
0 200
Dep
th
(m)
Ray Path Coverage
2000
4200
0 200
Dep
th
(m)
Migration of PPS
IV. Field Data
SALT
Offset (m)
IV. Field Data
Migration of PPS
SALT
150 offset RM 150 offset IM
0 200 0 200
150 offset KM
2000
4200
0 200
Dep
th
(m)
Offset (m)
Outline
I. Motivation
II. Theory
III. Numerical Tests
IV. Field Data Examples
V. Conclusion
IV. Conclusion
• Advantage of PS transmission migration– it is capable of illuminating the boundary of
salt flanks above the receivers (and nearly vertical boundaries if they exist).
IV. Conclusion• Benefits of IM:
– Remove influence of static shifts and/or migration velocity errors;
– Eliminated source statics by correlation;
– Accurately image the salt boundary above the receivers;
• Drawbacks of IM:– Migration artifacts due to violation of stationary phase approximation;
– Extra summations and computation time;
– Small range of incidence angle than true SWI data;
– Worse spatial resolution than KM;
– Does not require knowledge of the overburden velocity;
V. Future Work
• Pp/Ps reflection interferometric migration• Anisotropy migration
– Try different VTI FD synthetic walkaway VSP data set;– Apply it to a real data set;
• Preprocessing:– Reorientation, separation, filtering, statics correction
• Postprocessing:– Deconvolution
• Potential application– Kirchhoff multi arrival migration– Subsalt imaging– Interferometric tomography
Thanks to
• Jerry Schuster and my committee members: Dr. Michael Zhdanov, Dr. Bob smith, Dr. Cari Johnson for their advice and constructive criticism;
• Scott Leaney and Hornby Brian for their help on modeling;
Thanks to
• UTAM friends:– Jianhua Yu for his help on Linux programming;
– Jianming Sheng and Min Zhou for their experiences on interferometric imaging;
– Zhiyong Jiang and Ruiqing He for their help on classes;
– Travis Crosby and all UTAM students for their cheerful attitude; All UTAM sponsors for their support;
• Family– My parents, brother and sister;
• Friends– Liyun Ma, Huajian Yao, Zhaoyu Luo and Meiping Tong,
who encouraged me to continue on with my research.
Questions?
