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US 5,892,732 AGranted
Method and apparatus for seismic signal processing and exploration
AssigneeAmoco Corporation
InventorAdam Gersztenkorn
Life of this patent
Estimating the term…
Abstract
A method and apparatus for the exploration of hydrocarbons comprising the steps of: obtaining a set of seismic signal traces distributed over a predetermined three-dimensional volume of the earth; dividing the three-dimensional volume into a plurality of analysis cells having portions of at least two seismic traces located therein; computing outer products of the seismic traces within each cell; forming the covariance matrix for each cell from these outer products; computing the dominant eigenvalue and the sum of the eigenvalues of the covariance matrix of each cell and computing a seismic attribute from the ratio of the dominant eigenvalue to the sum of the eigenvalues of the covariance matrix of each cell; and forming map of the seismic attributes of selected groups of cells.
Claims48
A method for the exploration of hydrocarbons, comprising the steps of:
- a) obtaining a set of seismic traces distributed over a pre-determined three-dimensional volume of the earth;
- b) dividing said three-dimensional volume into a plurality of vertically stacked and generally spaced apart horizontal time layers and arranging said time layers into a plurality of cells that extend laterally and vertically, each of said time layers having portions of at least two seismic traces located therein that define a data vector;
- c) calculating in each of said time layers of said cells the outer-product of said data vector;
- d) combining said outer products to obtain a covariance matrix for each of said cells;
- e) computing in each of said cells a measure of the coherency of said seismic traces, wherein said measure of coherency is at least a function of the largest eigenvalue of said covariance matrix and at least a partial sum of the diagonal elements of said covariance matrix;
- and
- f) forming a seismic attribute map from a plurality of said measures of coherency of said seismic traces.
4 more elements
A method for the exploration of hydrocarbons, comprising the steps of:
- a) obtaining a set of seismic traces distributed over a pre-determined three-dimensional volume of the earth;
- b) dividing said three-dimensional volume into a plurality of vertically stacked and generally spaced apart horizontal time layers and arranging at least one of said time layers into a plurality of cells, each of said cells having portions of at least two seismic traces located therein that define a data vector;
- c) calculating in said cells the outer-product of said data vectors;
- d) combining said outer products to obtain a covariance matrix for said cells;
- e) computing in each of said cells a measure of the coherency of said seismic traces by:
- computing the largest eigenvalue of said covariance matrix,
- computing a sum of at least two of the eigenvalues of said covariance matrix, and
- computing the ratio of said largest eigenvalue to said sum of eigenvalues of said covariance matrix;
- and
- f) forming a seismic attribute map from a plurality of said measures of coherency of said seismic traces of said cells of said at least one time layer.
7 more elements
A method of locating subterranean features, faults, and contours, comprising the steps of:
- a) acquiring 3-D seismic data covering a pre-determined volume of the earth, said data comprising seismic traces characterized by time, position and amplitude;
- b) dividing at least a portion of said volume into at least one array of relatively small, adjacent, overlapping, three-dimensional analysis cubes, wherein each of said analysis cubes contains at least three laterally separated seismic traces, and dividing each analysis cube into a plurality of sample intervals such that each sample interval defines a plurality of one by three data vectors;
- c) computing a seismic attribute for each said cube that is a function of the dominant eigenvalue of a covariance matrix formed from outer products of said data vectors, and that is a function of a sum of the diagonal elements of said covariance matrix;
- and
- d) storing said seismic attributes of said analysis cubes for display in the form of a two-dimensional map of subterranean features.
2 more elements
A method of locating subterranean features, faults, and contours, comprising the steps of:
- a) acquiring 3-D seismic data covering a pre-determined volume of the earth, said data comprising seismic traces characterized by time, position and amplitude;
- b) dividing at least a Portion of said volume into at least one array of relatively small, adjacent, overlapping, three-dimensional analysis cells, wherein each of said analysis cells contains at least three laterally separated seismic traces, and dividing each analysis cell into a plurality of sample intervals such that each sample interval defines a plurality of one by three data vectors:
- c) computing for each cell a seismic attribute that is a function of the ratio of at least the dominant eigenvalue of a covariance matrix formed from outer products of said data vectors to a sum of at least two of the eigenvalues of said covariance matrix of said cell;
- and
- d) storing said seismic attributes of said analysis cells for display in the form of at least a two-dimensional map of subterranean features.
2 more elements
In seismic exploration wherein 3-D seismic data comprising reflected seismic energy is recorded as a function of time to produce a series of seismic traces, and wherein a computer is used that is adapted to process such seismic traces, an article of manufacture comprising:
- a medium that is readable by a computer and that carries instructions for said computer to perform a process comprising the steps of:
- (a) accessing 3-D seismic data over a predetermined volume, said data comprising seismic signal vectors characterized by time, position and amplitude;
- and
- (b) ascertaining the similarity of nearby regions of said 3-D seismic data of said volume by:
- (1) dividing at least a portion of said data into an array of relatively small, adjacent, overlapping, three-dimensional analysis cubes, wherein each of said analysis cubes contains at least two data vectors;
- and
- (2) computing a seismic attribute for each cube that is a function of the principal eigenvalue of a covariance matrix that is formed from a sum of outer products of said vectors of said cube and that is a function of a sum of the diagonal elements of said covariance matrix.
4 more elements
In seismic exploration wherein 3-D seismic data comprising reflected seismic energy is recorded as a function of time to produce a series of seismic traces, and wherein a computer is used that is adapted to process such seismic traces, an article of manufacture comprising:
- a medium that is readable by a computer and that carries instructions for said computer to perform a process comprising the steps of:
- (a) accessing 3-D seismic data over a predetermined volume, said data comprising seismic signal vectors characterized at least by time, position and amplitude;
- and
- (b) ascertaining the similarity of nearby regions of said 3-D seismic data of said volume by:
- (1) dividing at least a portion of said data into an array of relatively small, adjacent, overlapping, three-dimensional analysis cells, wherein each of said analysis cells contains at least two data vectors;
- and
- (2) computing a seismic attribute for each cell that is representative of the ratio of the principal eigenvalue to a sum of eigenvalues of a covariance matrix formed from outer products of said data vectors of said cell.
4 more elements
In seismic exploration wherein 3-D seismic data comprising reflected seismic energy is recorded as a function of time to produce a series of seismic traces, and wherein a computer is used that is adapted to process such seismic traces, an article of manufacture comprising:
- a medium that is readable by a computer and that carries instructions for said computer to perform a process comprising the steps of:
- (a) accessing 3-D seismic data over a predetermined volume, said data comprising seismic signal vectors characterized by time, position and amplitude;
- and
- (b) ascertaining the similarity of nearby regions of said 3-D seismic data of said volume by:
- (1) dividing at least a portion of said data into an array of relatively small, adjacent, overlapping, three-dimensional analysis cells, wherein each of said analysis cells contains at least two data vectors;
- and
- (2) computing a seismic attribute for each cell that is representative of the ratio of the principal eigenvalue to a sum of the diagonal elements of a covariance matrix formed from outer products of said data vectors of said cell.
4 more elements
In seismic exploration wherein reflected seismic energy is recorded as a function of time to produce a series of seismic traces, a method comprising the steps of:
- (a) determining the outer-product of two data vectors formed from at least two seismic traces;
- (b) forming a covariance matrix by adding said outer-products of step (a);
- (c) computing a seismic attribute that is an independent function of at least the principal eigenvalue of said covariance matrix of step (b);
- (d) repeating steps (a) through (c) across at least a part of at least one time window;
- and
- (e) forming a map of said seismic attributes over said time window.
3 more elements
In seismic exploration wherein reflected seismic energy is recorded as a function of time to produce a series of seismic traces, a method comprising the steps of:
- (a) determining the outer-product of two data vectors formed from at least two seismic traces;
- (b) forming a covariance matrix by adding said outer-products of step (a);
- (c) computing a seismic attribute that is a function of at least the ratio of a principal eigenvalue to at least a partial sum of the eigenvalues of said covariance matrix;
- (d) repeating steps (a) through (c) across at least a part of at least one time window;
- and
- (e) forming a map of said seismic attributes over said time window.
3 more elements
In seismic exploration wherein reflected seismic energy is recorded as a function of time to produce a series of seismic traces, a method comprising the steps of:
- (a) determining the outer-product of two data vectors formed from at least two seismic traces;
- (b) forming a covariance matrix by adding said outer-products of step (a);
- (c) computing a seismic attribute that is a function of at least the ratio of a principal eigenvalue to at least a partial sum of the diagonal elements of said covariance matrix;
- (d) repeating steps (a) through (c) across at least a part of at least one time window;
- and
- (e) forming a map of said seismic attributes over said time window.
3 more elements
In seismic exploration wherein reflected seismic energy is recorded as a function of time to produce a series of seismic traces, a method comprising the steps of:
- (a) determining the outer-product of two data vectors formed from at least two seismic traces by performing at least the following steps:
- (1) accessing 3-D seismic data over a predetermined volume of the earth, said 3-D seismic data seismic traces characterized at least by time, position and amplitude;
- and
- (2) dividing a portion of said volume into at least one time window comprising an array of relatively small, overlapping, three-dimensional analysis cells that contain said at least two seismic traces;
- (b) forming a covariance matrix by adding said outer-products of step (a);
- (c) computing a seismic attribute that is a function of at least the principal eigenvalue of said covariance matrix of step (b);
- (d) repeating steps (a) through (c) across at least a part of at least one time window;
- and
- (e) forming a map of said seismic attributes over said time window.
6 more elements
A method of seismic exploration, comprising the steps of:
- a) reading a 3-D seismic data set comprising seismic signal traces distributed over a volume of the earth;
- b) selecting at least one horizon slice from said volume and forming thereon cells that are arranged into laterally extending rows and columns, each of said cells comprising at least three seismic traces extending generally therethrough;
- c) computing for each of said cells:
- (1) the outer-product of data vectors defined by a plurality of time intervals on each side of the center said cell;
- (2) a covariance matrix from said outer products of step (1);
- (3) the largest eigenvalue of said covariance matrix;
- (4) the numerical trace of said covariance matrix;
- and
- (5) a linear function of said largest eigenvalue and said numerical trace;
- and
- d) examining said first order function of said cells along said at least one horizon slice.
8 more elements
A method of seismic exploration, comprising the steps of:
- a) reading a 3-D seismic data set comprising seismic signal traces distributed over a volume of the earth;
- and forming thereon cells that are arranged into laterally extending rows and columns, each of said cells comprising at least portions of at least three seismic traces extending generally therethrough;
- b) selecting at least one plane passing through said volume;
- c) computing for each of said cells:
- (1) the outer-product of data vectors defined by said portions of said seismic traces;
- (2) a covariance matrix from said outer products of step (1);
- and
- (3) at least the largest eigenvalue of said covariance matrix;
- and
- d) displaying a representation of at least said largest eigenvalues of said cells across said at least one plane passing through said volume.
7 more elements
In seismic exploration wherein reflected seismic energy is recorded as a function of time to produce a series of seismic traces, a method comprising the steps of:
- (a) arranging 3-D seismic data into relatively small, overlapping, three-dimensional analysis cubes that contain a plurality of seismic traces;
- (b) determining the outer-product of the data vectors defined by said analysis cubes;
- (c) forming a covariance matrix for each cube by adding said outer-products of step (b);
- (d) computing a seismic attribute that is a function of the ratio of the principal eigenvalue of each covariance matrix to the numerical trace of that covariance matrix;
- and
- (e) arranging said seismic attributes for being displayed as a map.
3 more elements
A device, comprising:
- computer readable means carrying instructions for a process comprising the steps of:
- (1) reading into memory 3-D seismic data that covers a pre-determined volume of the earth;
- (2) digitally sorting said 3-D seismic data into an array of relatively small three-dimensional cells wherein each of said cells contains at least a portion of at least three seismic traces;
- (3) calculating in each said cells a coherency value from a linear function of the largest of the eigenvalues of a covariance matrix that is formed from a plurality of outer products of said at least three traces;
- and
- (4) storing said coherency values of said cells for displaying same in the form of two-dimensional map of subterranean features represented by said coherency values.
3 more elements
A method of locating subterranean features, faults, and contours, comprising the steps of:
- a) obtaining seismic data covering a pre-determined volume of the earth;
- b) dividing said volume into an array of relatively small three-dimensional cells wherein each of said cells is characterized by at least two seismic data vectors located therein;
- c) computing a covariance matrix from the outer products of said data vectors
- d) mapping a representation of a linear function of the eigenvalues of said covariance matrix.
1 more element
A method of locating subterranean features, faults, and contours, comprising the steps of:
- a) obtaining seismic data covering a pre-determined volume of the earth;
- b) dividing said volume into an array of relatively small three-dimensional cells wherein each of said cells is characterized by at least two seismic data vectors located therein;
- c) computing a covariance matrix from said data vectors of said cells, wherein the elements of said covariance matrix are formed from adding a plurality of outer products;
- and
- d) mapping a linear function of the eigenvalues of said covariance matrix.
2 more elements
A method of prospecting for hydrocarbon deposits, comprising the steps of:
- a) obtaining a seismic attribute map of coherency values of 3-D seismic data for a pre-determined three-dimensional volume of the earth, said map being generated by using a computer and a program for said computer that instructs said computer to perform the following steps:
- (1) reading said data and sorting said volume into an array of relatively small three-dimensional cells, wherein each of said cells has at least two seismic data vectors located therein;
- and
- (2) calculating in each of said cells a coherency value for said seismic traces that is a linear function of the largest of the eigenvalues of a covariance matrix formed from outer products of said data vectors and that is a function of the numerical trace of said covariance matrix;
- and
- (b) using said map to identify subsurface structural and sedimentological features commonly associated with the entrapment and storage of hydrocarbons.
3 more elements
A method of prospecting for hydrocarbon deposits, comprising the steps of:
- a) obtaining a seismic attribute map of coherency values of 3-D seismic data for a pre-determined three-dimensional volume of the earth, said map being generated by using a computer and a program for said computer that instructs said computer to perform the following steps:
- (1) reading said data and sorting said volume into an array of relatively small three-dimensional cells, wherein each of said cells has at least two seismic data vectors located therein;
- and
- (2) calculating in each of said cells a coherency value for said seismic traces that is a function of the eigenvalues of a covariance matrix formed from outer products of said data vectors;
- and
- (b) using said map to identify:
- subsurface structural and sedimentological features commonly associated with the entrapment and storage of hydrocarbons, and drilling hazards.
4 more elements
A computer workstation for use in the exploration of oil and gas, comprising:
- a digital computer,
- a memory,
- means for converting numerical values that are representatives of seismic data and that are read into said memory into a visual display, and
- a medium readable by the computer and containing a representation of a coherency cube, said coherency cube comprising measurements of the coherency of 3D seismic data, each of said measurements being a linear and an independent function of the eigenvalues of a covariance matrix formed from adding at least two outer products of at least two seismic data vectors.
1 more element
Dependencies are inferred from the claim text.