Comparing Seismic Imaging Methods (Pre & Post Stack ...
Transcript of Comparing Seismic Imaging Methods (Pre & Post Stack ...
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Comparing Seismic Imaging Methods (Pre & Post Stack)Methods (Pre & Post Stack)
Student: Tianci Cui Supervisor: Gary F. Margrave
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OutlineOutline1 Introduction2 Channel model3 Marmousi model4 Conclusions
Outline
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1 Introduction• Migration of seismic data can move dipping events to their
correct positions, collapse diffractions and increase spatialresolutionresolution.
• In pre-stack migration, seismic data is adjusted beforestacking sequence occurs.g q
• Post-stack migration operates on the stacked section which isassumed to be zero-offset section.
1 Introduction
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2 Channel Model
2 Channel model
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Pre-stack Migration
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Pre-stack Migration
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Post-stack Migration
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Comparisonp
• Pre and post migration both image three interfaces well.• Pre and post migration both image the channel similarly.
2 Channel model
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3 Marmousi Model
3 Marmousi model
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Pre-stack Migration Imaging Condition
source receiver
Imaging Condition
DDown-going field
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Cross Correlation Imaging ConditionPre-stack MigrationCross-Correlation Imaging Condition
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Stabilized Deconvolution Imaging Condition μ=0 0001Pre-stack MigrationStabilized Deconvolution Imaging Condition, μ=0.0001
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Pre-stack MigrationStabilized Deconvolution Imaging ConditionStabilized Deconvolution Imaging Condition
μ=0.0001 μ=0.01
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Post-stack Migration
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Comparison
• Migration image has a higher resolution under deconvolutionimaging condition than cross-correlation imaging condition.imaging condition than cross correlation imaging condition.
• Pre-stack migration images better than post-stack migration.
3 Marmousi model
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Comparison of Calculation Time
Calculation Time Channel Model
(Kirchhoff time migration)
Marmousi Model
(PSPI depth migration) Post stack Migration 33 (s) 318 (s)Post-stack Migration 33 (s) 318 (s)
Pre-stack Migration 23.5*40=940 (s) 440*41=18040 (s)
• In both models, post-stack migration spends much less timethan the corresponding pre-stack migration.
3 Marmousi model
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4 Conclusions i l d l i h di l l l i i i• For a simple model without dips or lateral velocity variations,
post-stack migration and pre-stack migration have similarimaging results.g g
• For a complex model with large dips and strong lateral velocityvariations, pre-stack migration images better than post-stack
i ti th dmigration method.• Muting migrated data correctly can improve imaging quality.• Post-stack migration is much faster than the corresponding pre-Post stack migration is much faster than the corresponding pre
stack migration.
4 Conclusions
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Acknowledgement
P f M• Professor Margrave• CREWES staff and students
CREWES• CREWES sponsors
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Questions & Comments