Seismic Attenuation Modeling from Pre-Migration CIP Ratio Analysis
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Solution Overview
Problem
Conventional seismic imaging methods for subsurface reservoirs face challenges in accurately estimating attenuation (Q) models, leading to costly and time-consuming processes that are sensitive to wavelet stretch and migration-induced amplitude distortions, which affect the precision of hydrocarbon reservoir identification and project planning.
Innovation Solution
A method for estimating attenuation (Q) models through pre-migration seismic data processing, involving the calculation of pre-migration attenuated travel time, time derivative, and multiple migrations to generate weighted common image point gathers, thereby avoiding the need for tomography and its associated complexities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional tomographic methods are used to build velocity and attenuation models, then the models can be generated, but the process is costly in terms of manpower and project time and suffers from wavelet stretch and migration-induced amplitude distortions
Solution Approach 1:
The patent performs attenuation estimation on pre-migration data before the migration process, rather than after. This preliminary action on pre-stack data avoids the wavelet stretch and amplitude distortions that occur during migration, eliminating the need for time-consuming post-migration correction steps and manual picking operations.
Solution Approach 2:
The patent extracts attenuation information (1/Q) directly from pre-migration seismic data using spectral ratio analysis, separating the attenuation estimation process from the conventional tomographic workflow. This extraction approach eliminates dependency on depth-domain picking and manual intervention, reducing both time and cost.
2Measurement precision
If depth domain picking is used for attenuation analysis, then attenuation models can be built, but the process suffers from wavelet stretch and migration-induced amplitude distortions that reduce precision
Solution Approach 1:
The patent performs attenuation estimation on pre-migration data before the migration process, rather than after. This preliminary action on pre-stack data avoids the wavelet stretch and amplitude distortions that occur during migration, eliminating the need for time-consuming post-migration correction steps and manual picking operations.
Solution Approach 2:
The patent replaces manual depth-domain picking with an automated spectral ratio analysis method applied to pre-migration data. This substitution eliminates the need for human intervention in picking attenuation values and avoids the complexities associated with depth-domain processing and migration-induced distortions.
3Measurement precision
If conventional tomographic methods are used for building Q models, then attenuation models can be generated, but the process is costly in terms of manpower
Solution Approach 1:
The patent implements an automated workflow where the computer system performs spectral ratio analysis, attenuation estimation, and migration operations without manual picking or intervention. The system self-services by automatically processing pre-migration data through the complete attenuation estimation pipeline, eliminating the need for manual manpower in attenuation analysis.
Solution Approach 2:
The patent extracts attenuation information (1/Q) directly from pre-migration seismic data using spectral ratio analysis, separating the attenuation estimation process from the conventional tomographic workflow. This extraction approach eliminates dependency on depth-domain picking and manual intervention, reducing both time and cost.
Data Source
Figure 1A~1B
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AI summary
A method is described for seismic imaging improved by an estimation of attenuation including receiving a pre-migration seismic dataset D(s,r;t) representative of a subsurface volume of interest wherein s indicates source location, r indicates receiver location, and t is the recorded travel time; calculating a pre-migration attenuated travel time t*(s,r;t); computing a time derivative of the pre-migration attenuated travel time wherein 1/Q(s,r;t) = ∂t*(s,r;t)/∂t; performing a first migration on D(s,r;t) to generate common image point (CIP) gathers G(x,h) wherein x is subsurface image point and h is angle or offset; performing a second migration on D(s,r;t) * 1/Q(s,r;t) to generate weighted common image point (CIP) gathers G 1/Q (x,h); and calculating a conditioned ratio of the weighted CIP gathers G 1/Q (x,h) over the CIP gathers G(x,h) to get CIP gathers of 1/Q(x,h) is disclosed.