Data acquisition and prestack migration based on seismic visibility analysis
First Claim
1. A seismic survey method that comprises:
- determining visibility values of a target event as a function of seismic source and receiver positions, wherein said determining the visibility values of a target event includes;
finding, for each of multiple simulated shots, a reflection wavefield from the target event in a seismic model;
calculating, for each of multiple receiver positions, a contribution signal from each reflection wavefield; and
converting each contribution signal into a source-receiver visibility value that indicates an energy intensity of a respective contribution signal;
acquiring seismic data using a source-receiver geometry selected at least in part to include source and receiver positions associated with visibility values above a threshold; and
imaging the target event based on the acquired seismic data.
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Abstract
Seismic visibility analysis of selected subsurface structures is employed to determine surface locations offering high visibility of target events. These locations can then be used as a basis for acquiring additional seismic survey data and/or selecting existing traces for re-migration with more sophisticated migration methods. With either usage, the newly migrated data is expected to offer enhanced images of the target event. In some embodiments, the visibility determination includes using a wave equation based propagator to find, for each of multiple simulated shots, a reflection wavefield from the target event in a seismic model; and to calculate, for each of multiple receiver positions, a contribution signal from each reflection wavefield. The visibility determination further includes converting each contribution signal into a source-receiver visibility value. Because data acquisition and/or re-migration is limited to the selected region, the imaging effort for the target event is significantly reduced.
43 Citations
18 Claims
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1. A seismic survey method that comprises:
determining visibility values of a target event as a function of seismic source and receiver positions, wherein said determining the visibility values of a target event includes; finding, for each of multiple simulated shots, a reflection wavefield from the target event in a seismic model; calculating, for each of multiple receiver positions, a contribution signal from each reflection wavefield; and converting each contribution signal into a source-receiver visibility value that indicates an energy intensity of a respective contribution signal; acquiring seismic data using a source-receiver geometry selected at least in part to include source and receiver positions associated with visibility values above a threshold; and imaging the target event based on the acquired seismic data. - View Dependent Claims (2, 3, 4, 5)
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6. A seismic migration method that comprises:
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determining visibility values of a target event at the source and receiver positions of traces in an existing seismic survey, wherein said determining the visibility values of a target event includes; finding, for each of multiple simulated shots, a reflection wavefield from said target event in a seismic model; calculating, for each of multiple receiver positions, a contribution signal from each reflection wavefield; and converting each contribution signal into a source-receiver visibility value that indicates an energy intensity of a respective contribution signal; re-migrating traces associated with visibility values above a threshold to generate an image of the target event; and displaying the image of the target event on a user interface. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A visibility analysis system that comprises:
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a memory that stores visibility analysis software; and at least one processor coupled to the memory to execute the visibility analysis software, wherein the software configures the at least one processor to; determine, for each of multiple shots, a reflection wavefield from at least one target event in a seismic model; calculate, for each of multiple receiver positions, a contribution signal from each reflection wavefield; convert each contribution signal into a source-receiver visibility value that indicates an energy intensity of a respective contribution signal; process seismic data acquired using a source-receiver geometry selected at least in part to include source and receiver positions associated with source-receiver visibility values above a threshold to generate an image of the at least one target event, or re-migrate traces associated with source-receiver visibility values above a threshold to generate an image of the at least one target event; and display an image of the target event on a user interface. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification