3-dimensional migration of irregular grids of 2-dimensional seismic data
First Claim
1. A method for deriving a three-dimensional seismic image from two-dimensional seismic data arranged according to a plurality of shot lines in a survey area, comprising the steps of:
- representing said seismic data in a representation which corresponds to the spatial relationship of the shot lines in the survey area;
for each portion of said seismic data corresponding to each of said shot lines, performing a two-dimensional migration thereof to generate migrated seismic data in the form of a plurality of migrated traces corresponding to each shot line;
selecting a plurality of image points in said representation, said image points corresponding to points in said survey area;
for each of said selected image points, performing the substeps of;
selecting the migrated trace for each of said plurality of migrated shot lines that is closest to the image point in said representation; and
for each selected migrated trace, performing a migration with respect to the image point; and
forming a migrated three-dimensional image using the results of said migrations of said selected migrated traces with respect to said image points.
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Abstract
A method and apparatus for deriving a three-dimensional seismic image from an irregular grid of two-dimensional seismic data is provided. The two-dimensional seismic data incldue a plurality of shot lines. For each of the shot lines, a two-dimensional migration is performed therealong (22) to create a plurality of migrated shot lines. For each of a plurality of three-dimensional image points, the following substeps are performed. A migrated trace (X) is selected from each of the migrated shot lines that is closest to the image point (I). A further migration (30) is performed on each selected migrated trace (28) with respect to the image point (I). A three-dimensional migrated image (30) comprising the image points is thereby obtained. The invention allows the use of historical, irregular two-dimensional grids of seismic data to be efficiently used for the three-dimensional imaging of subsurface features.
26 Citations
20 Claims
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1. A method for deriving a three-dimensional seismic image from two-dimensional seismic data arranged according to a plurality of shot lines in a survey area, comprising the steps of:
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representing said seismic data in a representation which corresponds to the spatial relationship of the shot lines in the survey area; for each portion of said seismic data corresponding to each of said shot lines, performing a two-dimensional migration thereof to generate migrated seismic data in the form of a plurality of migrated traces corresponding to each shot line; selecting a plurality of image points in said representation, said image points corresponding to points in said survey area; for each of said selected image points, performing the substeps of; selecting the migrated trace for each of said plurality of migrated shot lines that is closest to the image point in said representation; and for each selected migrated trace, performing a migration with respect to the image point; and forming a migrated three-dimensional image using the results of said migrations of said selected migrated traces with respect to said image points. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for producing a migrated three-dimensional seismic image from two-dimensional seismic data from a plurality of shot lines in a seismic survey area, comprising the steps of:
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creating a representation of the survey area according to the position and the orientation of each of the shot lines relative to one another; for the portion of the seismic data corresponding to each shot line, performing a two-dimensional migration to produce a plurality of migrated shot lines; selecting a plurality of image points in said representation; for each image point, performing the following substeps; for each migrated shot line, selecting a migrated trace therein in such a manner that a line drawn in said representation from the selected image point to the selected trace is perpendicular to the migrated shot line; performing a two-dimensional migration of each selected trace with respect to the image point; and summing the migrated selected traces to form an output trace corresponding to the image point. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A computer for creating three-dimensional representations of stored two-dimensional seismic data, taken from a plurality of shot lines in a survey area, said computer programmed to perform the steps of:
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representing said seismic data in a representation which corresponds to the spatial relationship of the shot lines in the survey area; for each portion of said seismic data corresponding to each of said shot lines, performing a two-dimensional migration thereof to generate migrated seismic data in the form of a plurality of migrated traces corresponding to each shot line; selecting a plurality of image points in said representation, said image points corresponding to points in said survey area; for each of said selected image points, performing the substeps of; selecting the migrated trace for each of said plurality of migrated shot lines that is closest to the image point in said representation; and for each selected migrated trace, performing a migration with respect to the image point; and storing, for each of said image points, the results of said migrations of said selected migrated traces performed therewith, to form a migrated three-dimensional image of the survey area. - View Dependent Claims (19, 20)
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Specification