First Arrival Traveltim First Arrival Traveltim nd Waveform Inversion o nd Waveform Inversion o Refraction Data Refraction Data Jianming Sheng and Gerard T. Jianming Sheng and Gerard T. Schuster Schuster University of Utah University of Utah October, 2002 October, 2002
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First Arrival Traveltime and Waveform Inversion of Refraction Data
First Arrival Traveltime and Waveform Inversion of Refraction Data. Jianming Sheng and Gerard T. Schuster University of Utah October, 2002. Outline. Motivation First arrival traveltime and waveform inversion Numerical examples Summary. Motivation. Given:. Traveltime and waveform - PowerPoint PPT Presentation
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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
OutlineOutline• MotivationMotivation• First arrival traveltime and waveform First arrival traveltime and waveform
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
• Step 3:Step 3:
First arrival traveltime First arrival traveltime tomography tomography
Suggested by Suggested by Konstantin OsypovKonstantin Osypov
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
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.
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.)
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
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 .
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.)
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.)
Wavelet ExtractedWavelet Extracted00
0.10.1
Tim
e (s
ec.)
Tim
e (s
ec.)
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
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 .)
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
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
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
Predicted CSGPredicted CSG
11 120120Geophone #Geophone #
00
0.20.2
Tim
e (s
ec.)
Tim
e (s
ec.)
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.)
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
ProblemsSeismic attenuationSeismic attenuation
Surface wave noiseSurface wave noise
Source wavelet inversion Source wavelet inversion & objective function & objective function
OutlineOutline• MotivationMotivation• First arrival traveltime and waveform First arrival traveltime and waveform
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.
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.