First Arrival Traveltime and Waveform Inversion of Refraction Data
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Transcript of First Arrival Traveltime and Waveform Inversion of Refraction Data
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First Arrival Traveltime and First Arrival Traveltime and Waveform Inversion of Waveform Inversion of
Refraction DataRefraction Data
Jianming Sheng and Gerard T. SchusterJianming Sheng and Gerard T. Schuster
University of UtahUniversity of UtahOctober, 2002October, 2002
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OutlineOutline• MotivationMotivation• First arrival traveltime and waveform First arrival traveltime and waveform
inversioninversion• Numerical examplesNumerical examples• SummarySummary
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MotivationMotivationTraveltime and waveform Traveltime and waveform of CDP refraction dataof CDP refraction data
Given:Given:
Goal:Goal: High resolution tomogram High resolution tomogram
Problem:Problem: Can waveform tomography Can waveform tomography provide better resolution than provide better resolution than
ray-based tomography?ray-based tomography?
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Ray-based Tomography vs. Ray-based Tomography vs. Full Waveform InversionFull Waveform Inversion
Ray-based Ray-based tomographytomography
Efficient and robustEfficient and robust Resolution limited by Resolution limited by high-freq. assumptionhigh-freq. assumption
Full Full waveform waveform tomographytomography
No high-freq. limitationNo high-freq. limitation Slow convergence andSlow convergence andlocal minima problemlocal minima problem
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First-arrival Traveltime andFirst-arrival Traveltime andWaveform InversionWaveform Inversion
Ray-basedRay-basedtraveltime traveltime tomographytomography
Efficient and robustEfficient and robust
First-arrival First-arrival waveform waveform inversioninversion
No high-freq. limitationNo high-freq. limitation
Better convergence andBetter convergence andmild nonlinearmild nonlinear
Initial modelInitial model
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OutlineOutline• MotivationMotivation• First arrival traveltime and waveform First arrival traveltime and waveform
inversioninversion• Numerical examplesNumerical examples• SummarySummary
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First Arrival Traveltime and First Arrival Traveltime and Waveform InversionWaveform Inversion
• Step 1:Step 1: Preprocessing the raw data: Preprocessing the raw data: band-pass, 3D to 2D band-pass, 3D to 2D transform, trace normalizationtransform, trace normalization
• Step 2:Step 2: Picking first-arrival Picking first-arrival traveltimes and muting out traveltimes and muting out other waves except first other waves except first arrivalsarrivals
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• Step 3:Step 3:
First arrival traveltime First arrival traveltime tomography tomography
Minimizes traveltime residualMinimizes traveltime residual
Initial modelInitial model
2 preobs
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• Step 4:Step 4: First arrival First arrival waveform inversionwaveform inversion
ObservedObservedPredictedPredicted
, , 2,
obs pres g s g
s g
D DMisfit Misfit functionfunction
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Multigrid TomographyMultigrid Tomography• Traveltime tomography:Traveltime tomography:
Dynamic smoothing schemeDynamic smoothing scheme(to attack local minima problem)(to attack local minima problem)
(Nemeth, T., Normark, E. and Qin, F., 1992)(Nemeth, T., Normark, E. and Qin, F., 1992)
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OutlineOutline• MotivationMotivation• First arrival traveltime and waveform First arrival traveltime and waveform
inversioninversion• Numerical examplesNumerical examples• SummarySummary
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Numerical ExamplesNumerical Examples
• Synthetic data I: Three-layerSynthetic data I: Three-layer
• Synthetic data II: WesternGeco (Blind Synthetic data II: WesternGeco (Blind
test)test)
• Redmond mine survey dataRedmond mine survey data
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Synthetic Model ISynthetic Model I00
2020
4040
6060
Dep
th (m
)D
epth
(m)
00 200200100100Distance (m)Distance (m)
25002500
19581958
14161416
873873
331331(m/s)(m/s)
Source Freq. 60 HzSource Freq. 60 HzAvg. Velocity 2400 m/sAvg. Velocity 2400 m/s
Source Wavelength 40 mSource Wavelength 40 m
Suggested by Suggested by Konstantin OsypovKonstantin Osypov
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00
2020
4040
6060
Dep
th (m
)D
epth
(m)
00 200200100100Distance (m)Distance (m)
25002500
19581958
14161416
873873
331331(m/s)(m/s)
40 m40 m
Synthetic Model ISynthetic Model I
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Synthetic Data ISynthetic Data I• Synthetic data set was calculated Synthetic data set was calculated
by 2-D FD acoustic wave equation by 2-D FD acoustic wave equation solversolver
• Twenty-one shots and 51 traces Twenty-one shots and 51 traces per shot were used. per shot were used. • Computational grid dimension was Computational grid dimension was 401*121.401*121.
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Synthetic Shot Gather Synthetic Shot Gather 0.00.0
0.10.1
Tim
e (s
ec.)
Tim
e (s
ec.)
-80-80 120120Offset (m)Offset (m)
Air WaveAir Wave
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Traveltime TomogramTraveltime Tomogram 00
2020
4040
6060
Dep
th (m
)D
epth
(m)
00 200200100100Distance (m)Distance (m)
25002500
19581958
14161416
873873
331331(m/s)(m/s)
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Synthetic Model ISynthetic Model I00
2020
4040
6060
Dep
th (m
)D
epth
(m)
00 200200100100Distance (m)Distance (m)
25002500
19581958
14161416
873873
331331(m/s)(m/s)
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Traveltime ResidualTraveltime Residual
11 3030IterationsIterations
2.02.0
1.01.0
0.00.0
Tra
vel ti
me
Res
idu a
l (s e
c .)
Tra
vel ti
me
Res
idua
l (s e
c .)
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Waveform TomogramWaveform Tomogram00
2020
4040
6060
Dep
th (m
)D
epth
(m)
00 200200100100Distance (m)Distance (m)
25002500
19581958
14161416
873873
331331(m/s)(m/s)
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Synthetic Model ISynthetic Model I00
2020
4040
6060
Dep
th (m
)D
epth
(m)
00 200200100100Distance (m)Distance (m)
25002500
19581958
14161416
873873
331331(m/s)(m/s)
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Waveform ResidualWaveform Residual
11 3030IterationsIterations
12,00012,000
00
8,0008,000
4,0004,000
Wa v
e for
m R
esid
u al
Wa v
e for
m R
esid
ual
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Numerical ExamplesNumerical Examples
• Synthetic data I: Three-layerSynthetic data I: Three-layer
• Synthetic data II: WesternGeco (Blind Synthetic data II: WesternGeco (Blind
test)test)
• Redmond mine survey dataRedmond mine survey data
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True Velocity ModelTrue Velocity Model
0.00.0
1.01.0
Dep
th (k
m)
Dep
th (k
m)
0.00.0 2626Horizontal distance (km)Horizontal distance (km)
1000 m/s1000 m/s
2050~2500 m/s2050~2500 m/s
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True Density ModelTrue Density Model0.00.0 2626Horizontal distance (km)Horizontal distance (km)
0.00.0
1.01.0
Dep
th (k
m)
Dep
th (k
m)
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Recorded CSG # 150Recorded CSG # 150-3000-3000 30003000Offset (m)Offset (m)
0.00.0
2.02.0
Tim
e (s
ec.)
Tim
e (s
ec.)
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Guessed Density ModelGuessed Density Model
10001000 50005000Velocity (m/s)Velocity (m/s)
34003400
14001400
Den
sity
(kg/
mD
ensi
ty (k
g/m
33 ))
0.5
21001981.2v
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Source WaveletSource Wavelet400400
Am
plitu
deA
mpl
itude 00
-600-6000.00.0 0.250.25Time (sec.)Time (sec.)
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Waveform MatchingWaveform MatchingA
mpl
itude
Am
plitu
de
0.00.0 0.20.2Time (sec.)Time (sec.)
OffsetOffset(m)(m)-50-50
2525
5050
00
-25-25
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Traveltime TomogramTraveltime Tomogram
27122712
22842284
18561856
14281428
10001000
m/sm/s0.00.0 2626Horizontal distance (km)Horizontal distance (km)0.00.0
1.01.0
Dep
th (k
m)
Dep
th (k
m)
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Traveltime TomogramTraveltime Tomogram
24092409
20572057
17051705
13521352
10001000
m/sm/s5.05.0 8.758.75Horizontal distance (km)Horizontal distance (km)0.00.0
0.40.4
Dep
th (k
m)
Dep
th (k
m)
0.10.1
0.20.2
0.30.3
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Waveform TomogramWaveform Tomogram
27002700
22752275
18501850
14251425
10001000
m/sm/s5.05.0 8.758.75Horizontal distance (km)Horizontal distance (km)0.00.0
0.40.4
Dep
th (k
m)
Dep
th (k
m)
0.10.1
0.20.2
0.30.3
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Migration sectionMigration section5.05.0 8.758.75Horizontal distance (km)Horizontal distance (km)
0.00.0
0.40.4
Dep
th (k
m)
Dep
th (k
m)
0.10.1
0.20.2
0.30.3
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Predicted CSG #150Predicted CSG #150
0.00.0
2.02.0
Tim
e (s
ec.)
Tim
e (s
ec.)
-3000-3000 30003000Offset (m)Offset (m)
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Recorded CSG # 150Recorded CSG # 150-3000-3000 30003000Offset (m)Offset (m)
0.00.0
2.02.0
Tim
e (s
ec.)
Tim
e (s
ec.)
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Numerical ExamplesNumerical Examples
• Synthetic data I: Three-layerSynthetic data I: Three-layer
• Synthetic data II: WesternGeco (Blind Synthetic data II: WesternGeco (Blind
test)test)
• Redmond mine survey dataRedmond mine survey data
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Salt Diapir DataSalt Diapir Data • Thirty-one shots and 120 traces Thirty-one shots and 120 traces total 3188 traveltimes picked. total 3188 traveltimes picked. Shot interval: 20 m Shot interval: 20 m geophone interval 5 mgeophone interval 5 m
• Source frequency 40 Hz. Source frequency 40 Hz.
• Record length 1 sec. Record length 1 sec. sample interval 0.5 millisecond . sample interval 0.5 millisecond .
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CSG for Field Data CSG for Field Data After PreprocessingAfter Preprocessing
11 120120Geophone #Geophone #
00
0.20.2
Tim
e (s
ec.)
Tim
e (s
ec.)
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CSG for Field Data CSG for Field Data After MutingAfter Muting
11 120120Geophone #Geophone #
00
0.20.2
Tim
e (s
ec.)
Tim
e (s
ec.)
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Wavelet ExtractedWavelet Extracted00
0.10.1
Tim
e (s
ec.)
Tim
e (s
ec.)
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Traveltime TomogramTraveltime Tomogram00
130130
Dep
th (m
)D
epth
( m)
00 590590Distance (m)Distance (m)
55005500
45004500
35003500
25002500
15001500
500500
(m/s)(m/s)
TunnelTunnel
20 m20 m
55 m55 m
SALTSALT
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Traveltime ResidualTraveltime Residual
11 3030IterationsIterations
2.02.0
1.01.0
0.00.0
Tra
vel ti
me
Res
idu a
l (s e
c .)
Tra
vel ti
me
Res
idua
l (s e
c .)
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00
130130
Dep
th (m
)D
ept h
(m)
Waveform TomogramWaveform Tomogram
00 590590Distance (m)Distance (m)
55005500
45004500
35003500
25002500
15001500
500500
(m/s)(m/s)
TunnelTunnel55 m55 m
20 m20 m
SALTSALT
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Traveltime TomogramTraveltime Tomogram00
130130
Dep
th (m
)D
epth
( m)
00 590590Distance (m)Distance (m)
55005500
45004500
35003500
25002500
15001500
500500
(m/s)(m/s)
TunnelTunnel
20 m20 m
55 m55 m
SALTSALT
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Waveform ResidualWaveform Residual
11 3030IterationsIterations
6,0006,000
00
4,0004,000
2,0002,000
Wa v
e for
m R
esid
u al
Wa v
e for
m R
esid
ual
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Predicted CSGPredicted CSG
11 120120Geophone #Geophone #
00
0.20.2
Tim
e (s
ec.)
Tim
e (s
ec.)
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CSG for Salt Data CSG for Salt Data After MutingAfter Muting
11 120120Geophone #Geophone #
00
0.20.2
Tim
e (s
ec.)
Tim
e (s
ec.)
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22
Log
10 A
mpl
itude
Log
10 A
mpl
itude
00
-2-2
-4-400 400400Offset (m)Offset (m)
Logarithmic Amplitude Vs. OffsetLogarithmic Amplitude Vs. Offset
SyntheticSynthetic
ObservedObserved
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ProblemsSeismic attenuationSeismic attenuation
Surface wave noiseSurface wave noise
Source wavelet inversion Source wavelet inversion & objective function & objective function
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OutlineOutline• MotivationMotivation• First arrival traveltime and waveform First arrival traveltime and waveform
inversioninversion• Numerical examplesNumerical examples• SummarySummary
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SummarySummary• Synthetic results show that the Synthetic results show that the
waveform tomogram is much more waveform tomogram is much more resolved;resolved;
• The preliminary results for the field data The preliminary results for the field data are not as good as expected, and further are not as good as expected, and further work is needed.work is needed.
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AcknowledgmentAcknowledgmentI thank the sponsors of the 2002 University I thank the sponsors of the 2002 University of Utah Tomography and Modeling of Utah Tomography and Modeling /Migration (UTAM) Consortium for their /Migration (UTAM) Consortium for their financial support . I thank Konstantin financial support . I thank Konstantin Osypov for providing the data set.Osypov for providing the data set.