Tomostatic Waveform Tomography Tomostatic Waveform Tomography for Mapleton, Utah datafor Mapleton, Utah data

Jianming Sheng, and Maike Buddensiek Jianming Sheng, and Maike Buddensiek

University of UtahUniversity of Utah

Feb. 5, 2004Feb. 5, 2004

OutlineOutline

Data PreprocessingsData Preprocessings

SummarySummary

MotivationMotivation

Waveform TomogramWaveform Tomogram

First-break + First-peak First-break + First-peak

00

4545

Dep

th (

m)

Dep

th (

m)

25002500

500500

m/sm/s00 8080Distances (m)Distances (m)

MotivationsMotivations

• Produce better seismic image by Produce better seismic image by fitting waveformsfitting waveforms

ObservedObserved

PredictedPredicted

Recorded CSG # 49Recorded CSG # 49

00

0.150.15

Tim

e (s

ec.)

Tim

e (s

ec.)

2020 160160Geophone #Geophone #

168 shots168 shots168 receiver168 receiver

Interval: 5mInterval: 5m

dt: 0.5 msdt: 0.5 mslength: 1slength: 1s

OutlineOutline

SummarySummary

MotivationMotivation

Waveform TomogramWaveform Tomogram

Data PreprocessingsData Preprocessings

Data PreprocessingsData Preprocessings

• Instrument caused amplitude anomaliesInstrument caused amplitude anomalies

Amplitude Vs. TraveltimeAmplitude Vs. Traveltime

Dashed: FittedDashed: FittedSolid: ObservedSolid: Observed

4040

2020

Log

-Am

pli

tud

eL

og-A

mp

litu

de

00 0.090.09Traveltime (sec.)Traveltime (sec.)

Data PreprocessingsData Preprocessings

• Instrument caused amplitude anomaliesInstrument caused amplitude anomalies• Earth attenuationEarth attenuation

Frequency Spectrum Vs. OffsetFrequency Spectrum Vs. OffsetF

req

uen

cy (

Hz)

Fre

qu

ency

(H

z)

0.00.0

Offset (m)Offset (m) 606000100100

Attenuation CompensationAttenuation Compensation

Liao and McMechan (1997)Liao and McMechan (1997)

22 sr sf f t

Q

Centroid frequencyCentroid frequency

Spectrum Spectrum variancevariance

Attenuation factorAttenuation factor

Frequency vs. TraveltimeFrequency vs. Traveltime

8585

4040

Fre

qu

ency

(H

z)F

req

uen

cy (

Hz)

00 0.10.1Traveltime (sec.)Traveltime (sec.)

Q=24.0013Q=24.0013

Data PreprocessingsData Preprocessings

• Instrument caused amplitude anomaliesInstrument caused amplitude anomalies• Earth attenuationEarth attenuation

• Transform data to 2D formatTransform data to 2D format

i

multiplymultiply to spectrumto spectrum

multiplymultiply t for the geometrical spreadingfor the geometrical spreading

Preprocessed CSG # 49Preprocessed CSG # 49

00

0.150.15

Tim

e (s

ec.)

Tim

e (s

ec.)

2020 160160Geophone #Geophone #

Frequency Spectrum Vs. OffsetFrequency Spectrum Vs. OffsetF

req

uen

cy (

Hz)

Fre

qu

ency

(H

z)

0.00.0

Offset (m)Offset (m) 606000100100

Frequency Spectrum Vs. OffsetFrequency Spectrum Vs. OffsetF

req

uen

cy (

Hz)

Fre

qu

ency

(H

z)

0.00.0

Offset (m)Offset (m) 606000100100

OutlineOutline

SummarySummary

MotivationMotivation

Waveform TomogramWaveform Tomogram

Data PreprocessingsData Preprocessings

Misfit FunctionMisfit Function

2

0

2

00mmWddddme

s g

calsg

obssg

calsg

obssg

ConvolutionConvolution Selected receiverSelected receiver

Frazer and Sun, 1998Frazer and Sun, 1998

Waveform Tomogram Waveform Tomogram

00

4545

Dep

th (

m)

Dep

th (

m)

25002500

500500

m/sm/s00 8080Distances (m)Distances (m)

First-break + First-peak First-break + First-peak

00

4545

Dep

th (

m)

Dep

th (

m)

25002500

500500

m/sm/s00 8080Distances (m)Distances (m)

OutlineOutline

SummarySummary

MotivationMotivation

Waveform TomogramWaveform Tomogram

Data PreprocessingsData Preprocessings

SummarySummary• The waveform tomogram does not show The waveform tomogram does not show much improvement compared to the first-much improvement compared to the first- break and first-peak tomogram.break and first-peak tomogram.

• Elastic modeling code is needed.Elastic modeling code is needed.

AcknowledgmentAcknowledgment

I thank the sponsors of the 2003 UTAM I thank the sponsors of the 2003 UTAM Consortium for their financial support . Consortium for their financial support .