Anti-aliasing of spatial frequencies by geophone and source placement

Claim 2

In a method of seismic geophysical prospecting, which includes generating seismic waves by seismic energy sources horizontally spaced along a line of survey, and detecting subsequent reflections of the generated seismic waves from subsurface strata, by a plurality of groups of geophones horizontally spaced along said line of survey adjacent the surface of the earth, each group of geophones producing a seismic trace to be displayed with other traces, side-by-side, to form a seismic record, in which method the prior art attempted to suppress broad bands of undesired, higher spatial frequencies, to minimize the interfering effects of spatial frequencies above the desired pass band, the improvement of more effectively suppressing only those particular spatial frequencies that would ''''alias'''' back into said desired pass band, which comprises positioning at least one of the two kinds of seismic elements, consisting of geophones and seismic sources, so that their respective group-responSe-versus-spatial-frequency functions suppress the aliasing frequencies, by performing the following steps: a. placing a plurality of individual geophones within each of said geophone groups at horizontal positions, denoted in terms of the horizontal coordinate, g, along said line of survey, said positions being the convolved positions from within two uniformly spaced component arrays, the first array having m geophone positions and the second array having n geophone positions, where m and n are integers, and the individual, uniform, geophone-to-geophone spacings in said first component array and said second component array, are respectively, Delta g/m and Delta g/n, where Delta g is the distance between successive geophone group centers along said line of survey, b. placing individual sources at a plurality of horizontal positions denoted in terms of the horizontal coordinate s, along said line of survey, the distance between individual sources, Delta s, being equal to Delta g, c. energizing at least one of said sources, and d. adding the traces from at least one set of three neighboring geophone groups that have received waves caused by a common source, using binomial weighting, the central trace being given a weight twice that of each of the two adjacent traces so that the effective geophone group-response-versus-spatial-frequency function is substantially zero at the half-integral multiples of 1/ Delta g.

Claim 3

In a method of seismic geophysical prospecting, which includes generating seismic waves by seismic energy sources horizontally spaced along a line of survey, and detecting subsequent reflections of the generated seismic waves from subsurface strata, by a plurality of groups of geophones horizontally spaced along said line of survey adjacent the surface of the earth, each group of geophones producing a seismic trace to be displayed with other traces, side-by-side, to form a seismic record, in which method the prior art attempted to suppress broad bands of undesired, higher spatial frequencies, to minimize the interfering effects of spatial frequencies above the desired pass band, the improvement of more effectively suppressing only those particular spatial frequencies that would ''''alias'''' back into said desired pass band, which comprises positioning at least one of the two kinds of seismic elements, consisting of geophones and seismic sources, so that their respective group-responSe-versus-spatial-frequency functions suppress the aliasing frequencies, by performing the following steps: a. placing a plurality of individual geophones within each of said geophone groups at horizontal positions, denoted in terms of the horizontal coordinate, g, along said line of survey, said positions being the convolved positions from within two uniformly spaced component arrays, the first array having m geophone positions and the second array having n geophone positions, where m and n are integers, and the individual, uniform, geophone-to-geophone spacings in said first component array and said second component array, are respectively, Delta g/m and Delta g/n, where Delta g is the distance between successive geophone group centers along said line of survey, b. placing individual sources at a plurality of horizontal positions denoted in terms of the horizontal coordinate s, along said line of survey, the distance between individual sources, Delta s, being equal to Delta g, c. energizing at least one of said sources, and d. adding the traces from at least one set of three neighboring geophone groups that have received waves caused by a common source, using binomial weighting, the central trace being given a weight twice that of each of the two adjacent traces so that the effective geophone group-response-versus-spatial-frequency function is substantially zero at the half-integral multiples of 1/ Delta g.

Claim 4

In a method of seismic geophysical prospecting, which includes generating seismic waves by seismic energy sources horizontally spaced along a line of survey, and detecting subsequent reflections of the generated seismic waves from subsurface strata, by a plurality of groups of geophones horizontally spaced along said line of survey adjacent the surface of the earth, each group of geophones producing a seismic trace to be displayed with other traces, side-by-side, to form a seismic record, in which method the prior art attempted to suppress broad bands of undesired, higher spatial frequencies, to minimize the interfering effects of spatial frequencies above the desired pass band, the improvement of more effectively suppressing only those particular spatial frequencies that would ''''alias'''' back into said desired pass band, which comprises positioning at least one of the two kinds of seismic elements, consisting of geophones and seismic sources, so that their respective group-responSe-versus-spatial-frequency functions suppress the aliasing frequencies, by performing the following steps: a. placing a plurality of individual geophones within each of said geophone groups at horizontal positions, denoted in terms of the horizontal coordinate, g, along said line of survey, said positions being the convolved positions from within two uniformly spaced component arrays, the first array having m geophone positions and the second array having n geophone positions, where m and n are integers, and the individual, uniform, geophone-to-geophone spacings in said first component array and said second component array, are respectively, Delta g/m and Delta g/n, where Delta g is the distance between successive geophone group centers along said line of survey, b. placing individual sources at a plurality of horizontal positions denoted in terms of the horizontal coordinate s, along said line of survey, the distance between individual sources, Delta s, being equal to Delta g, c. energizing at least one of said sources, and d. adding the traces from at least one set of three neighboring geophone groups that have received waves caused by a common source, using binomial weighting, the central trace being given a weight twice that of each of the two adjacent traces so that the effective geophone group-response-versus-spatial-frequency function is substantially zero at the half-integral multiples of 1/ Delta g.

Claim 5

In a method of seismic geophysical prospecting, which includes generating seismic waves by seismic energy sources horizontally spaced along a line of survey, and detecting subsequent reflections of the generated seismic waves from subsurface strata, by a plurality of groups of geophones horizontally spaced along said line of survey adjacent the surface of the earth, each group of geophones producing a seismic trace to be displayed with other traces, side-by-side, to form a seismic record, in which method the prior art attempted to suppress broad bands of undesired, higher spacial frequencies, to minimize the interfering effects of spatial frequencies above the desired pass band, the improvement of more effectively suppressing only those particular spatial frequencies that would ''''alias'''' back into said desired pass band, which comprises positioning at least one of the two kinds of seismic elements, consisting of geophones and seismic sources, so that their respective group-response-versus-spatial-frequency functions suppress the aliasing frequencies, by performing the following steps: a. placing a plurality of individual sources within each of a set of source groups at horizontal positions, denoted in terms of the horizontal coordinate, s, along said line of survey, said positions within each group being the convolved positions from within two uniformly spaced component arrays, the first array having p source positions and the second array having q source positions, where p and q are integers, and the individual, uniform, source-to-source spacings in said first component array and said second component array, are respectively, Delta s/p and Delta s/q, where Delta s is the distance between successive source group centers along said line of survey, b. placing a plurality of individual geophones within each of said geophone groups at horizontal positions, denoted in terms of the horizontal coordinate, g, along said line of survey, said positions being the convolved positions from within two uniformly spaced component arrays, the first array having m geophone positions and the second array having n geophone positions, where m and n are integers, and the individual, uniform, geophone-to-geophone spacings in said first component array and said second component array, are respectively, Delta g/m and Delta g/n, where Delta g is the distance between successive geophone group centers along said line of survey, and Delta g Delta s, c. energizing separately and sequentially at least three neighboring ones of said source groups, d. adding the traces from at least one set of three neighboring geophone groups that have received waves caused by a common source group, using binomial weighting, the central trace being given a weight twice that of each of the two adjacent traces, and e. adding at least one set of three traces that have been received by one geophone group from the actuation of three neighboring source groups, using binomial weighting, the central trace being given a weight twice that of each of the two adjacent traces so that both the effective source-group-response-versus-spatial-frequency function and the effective geophone-group-response-versus-spatial-frequency function are substantially zero at the half-integral multiples of 1/ Delta s 1/ Delta g.

Claim 6

In a method of seismic geophysical prospecting, which includes generating seismic waves by seismic energy sources horizontally spaced along a line of survey, and detecting subsequent reflections of the generated seismic waves from subsurface strata, by a plurality of groups of geophones horizontally spaced along said line of survey adjacent the surface of the earth, each group of geophones producing a seismic trace to be displayed with other traces, side-by-side, to form a seismic record, in which method the prior art attempted to suppress broad bands of undesired, higher spacial frequencies, to minimize the interfering effects of spatial frequencies above the desired pass band, the improvement of more effectively suppressing only those particular spatial frequencies that would ''''alias'''' back into said desired pass band, which comprises positioning at least one of the two kinds of seismic elements, consisting of geophones and seismic sources, so that their respective group-response-versus-spatial-frequency functions suppress the aliasing frequencies, by performing the following steps: a. placing a plurality of individual sources within each of a set of source groups at horizontal positions, denoted in terms of the horizontal coordinate, s, along said line of survey, said positions within each group being the convolved positions from within two uniformly spaced component arrays, the first array having p source positions and the second array having q source positions, where p and q are integers, and the individual, uniform, source-to-source spacings in said first component array and said second component array, are respectively, Delta s/p and Delta s/q, where Delta s is the distance between successive source group centers along said line of survey, b. placing a plurality of individual geophones within each of said geophone groups at horizontal positions, denoted in terms of the horizontal coordinate, g, along said line of survey, said positions being the convolved positions from within two uniformly spaced component arrays, the first array having m geophone positions and the second array having n geophone positions, where m and n are integers, and the individual, uniform, geophone-to-geophone spacings in said first component array and said second component array, are respectively, Delta g/m and Delta g/n, where Delta g is the distance between successive geophone group centers along said line of survey, and Delta g Delta s, c. energizing separately and sequentially at least three neighboring ones of said source groups, d. adding the traces from at least one set of three neighboring geophone groups that have received waves caused by a common source group, using binomial weighting, the central trace being given a weight twice that of each of the two adjacent traces, and e. adding at least one set of three traces that have been received by one geophone group from the actuation of three neighboring source groups, using binomial weighting, the central trace being given a weight twice that of each of the two adjacent traces so that both the effective source-group-response-versus-spatial-frequency function and the effective geophone-group-response-versus-spatial-frequency function are substantially zero at the half-integral multiples of 1/ Delta s 1/ Delta g.

Claim 7

In a method of seismic geophysical prospecting, which includes generating seismic waves by seismic energy sources horizontally spaced along a line of survey, and detecting subsequent reflections of the generated seismic waves from subsurface strata, by a plurality of groups of geophones horizontally spaced along said line of survey adjacent the surface of the earth, each group of geophones producing a seismic trace to be displayed with other traces, side-by-side, to form a seismic record, in which method the prior art attempted to suppress broad bands of undesired, higher spatial frequencies, to minimize the interfering effects of spatial frequencies above the desired pass band, the improvement of more effectively suppressing only those particular spatial frequencies that would ''''alias'''' back into said desired pass band, which comprises positioning at least one of two kinds of seismic elements, consisting of geophones and seismic sources, so that their respective group-response-versus-spatial-frequency functions suppress the aliasing frequencies, by performing the following steps: a. positioning pluralities of one of said kinds of seismic elements in groups along said line of survey so that the horizontal interval between the centers of adjacent groups is Delta e, b. positioning the individual elements of said one kind of seismic element within its respective group so that the respective group-response-versus-spatial-frequency function becomes substantially zero at the early, integral multiples of 1/ Delta e, c. mixing seismic traces from near neighboring groups of said one kind of seismic element and a common single group of said other kinds of seismic elements, so that the effective said respective group-response-versus-spatial-frequency function becomes substantially zero also at the odd, half-integral multiples of 1/ Delta e.

Claim 8

In a method of seismic geophysical prospecting, which includes generating seismic waves by seismic energy sources horizontally spaced along a line of survey, and detecting subsequent reflections of the generated seismic waves from subsurface strata, by a plurality of groups of geophones horizontally spaced along said line of survey adjacent the surface of the earth, each group of geophones producing a seismic trace to be displayed with other traces, side-by-side, to form a seismic record, in which method the prior art attempted to suppress broad bands of undesired, higher spatial frequencies, to minimize the interfering effects of spatial frequencies above the desired pass band, the improvement of more effectively suppressing only those particular spatial frequencies that would ''''alias'''' back into said desired pass band, which comprises positioning at least one of two kinds of seismic elements, consisting of geophones and seismic sources, so that their respective group-response-versus-spatial-frequency functions suppress the aliasing frequencies, by performing the following steps: a. positioning pluralities of one of said kinds of seismic elements in groups along said line of survey so that the horizontal interval between the centers of adjacent groups is Delta e, b. positioning the individual elements of said one kind of seismic element within its respective group so that the respective group-response-versus-spatial-frequency function becomes substantially zero at the early, integral multiples of 1/ Delta e, c. mixing seismic traces from near neighboring groups of said one kind of seismic element and a common single group of said other kinds of seismic elements, so that the effective said respective group-response-versus-spatial-frequency function becomes substantially zero also at the odd, half-integral multiples of 1/ Delta e.

Claim 9

The method of claim 3 in which said one of said kinds of seismic elements is a geophone and said other of said kinds of seismic elements is a source.

Claim 10

The method of claim 3 in which said one of said kinds of seismic elements is a source and the other of said kinds of seismic elements is a geophone.

Claim 11

In a method of seismic geophysical prospecting, which includes generating seismic waves by seismic energy sources horizontally spaced along a line of survey, and detecting subsequent reflections of the generated seismic waves from subsurface strata, by a plurality of groups of geophones horizontally spaced along said line of survey adjacent the surface of the earth, each group of geophones producing a seismic trace to be displayed with other traces, side-by-side, to form a seismic record, in which method the prior art attempted to suppress broad bands of undesired, higher spatial frequencies, to minimize the interfering effects of spatial frequencies above the desired pass band, the improvement of more effectively suppressing only those particular spatial frequencies that would ''''alias'''' back into said desired pass band, which comprises positioning at least one of two kinds of seismic elements, consisting of geophones aNd seismic sources, so that their respective group-response-versus-spatial-frequency functions suppress the aliasing frequencies, by performing the following steps: a. positioning pluralities of one of said kinds of seismic elements in groups along said line of survey so that the horizontal interval between the centers of adjacent groups is Delta e, b. positioning the individual elements of said one kind of seismic element within its respective group so that the respective group-response-versus-spatial-frequency function becomes substantially zero at all the early half-integral multiples of 1/ Delta e.

Claim 12

In a method of seismic geophysical prospecting, which includes generating seismic waves by seismic energy sources horizontally spaced along a line of survey, and detecting subsequent reflections of the generated seismic waves from subsurface strata, by a plurality of groups of geophones horizontally spaced along said line of survey adjacent the surface of the earth, each group of geophones producing a seismic trace to be displayed with other traces, side-by-side, to form a seismic record, in which method the prior art attempted to suppress broad bands of undesired, higher spatial frequencies, to minimize the interfering effects of spatial frequencies above the desired pass band, the improvement of more effectively suppressing only those particular spatial frequencies that would ''''alias'''' back into said desired pass band, which comprises positioning at least one of two kinds of seismic elements, consisting of geophones aNd seismic sources, so that their respective group-response-versus-spatial-frequency functions suppress the aliasing frequencies, by performing the following steps: a. positioning pluralities of one of said kinds of seismic elements in groups along said line of survey so that the horizontal interval between the centers of adjacent groups is Delta e, b. positioning the individual elements of said one kind of seismic element within its respective group so that the respective group-response-versus-spatial-frequency function becomes substantially zero at all the early half-integral multiples of 1/ Delta e.

Claim 13

The method of claim 6 in which said one of said kinds of seismic elements is a geophone.

Claim 14

The method of claim 6 in which said one of said kinds of seismic elements is a source.

Claim 15

The method of claim 4 with the additional step of positioning pluralities of sources in groups along said line of survey, the individual sources within the source groups being positioned so that the source group-response-versus-spatial-frequency function becomes substantially zero at the early integral multiples of 1/ Delta s, the reciprocal of the source group interval.

Claim 16

The method of claim 4 with the additional step of mixing seismic traces from adjacent source groups and a common geophone group in a binomial mix, so that the effective source group-response-versus-spatial-frequency function becomes substantially zero at the odd, half-integral multiples of 1/ Delta s, the reciprocal of the source group interval.

Claim 17

The method of claim 7 with the additional step of positioning pluralities of sources in groups along said line of survey, the individual sources within the source groups being positioned so that the source group-response-versus-spatial-frequency function becomes substantially zero at the early integral multiples of 1/ Delta s, the reciprocal of the source group interval.

Claim 18

The method of claim 7 with the additional step of mixing seismic traces from adjacent source groups and a common geophone group in a binomial mix, so that the effective source group-response-versus-spatial-frequency function becomes substantially zero at the odd, half-integral multiples of 1/ Delta s, the reciprocal of the source group interval.

Claim 19

The method of claim 5 with additional step of positioning pluralities of geophones in groups along said line of survey, the individual geophones within the geophone groups being positioned so that the geophone group-response-versus-spatial-frequency function becomes substantially zero at the early integral multiples of 1/ Delta g, the reciprocal of the geophone group interval.

Claim 20

The method of claim 5 with the additional step of mixing seismic traces from adjacent geophone groups and a common source group in a binomial mix, so that the effective geophone group-response-versus-spatial-frequency function becomes substantially zero at the odd, half-integral multiples of 1/ Delta g, the reciprocal of the geophone group interval.

Claim 21

The method of claim 8 with the additional step of positioning pluralities of geophones in groups along said line of survey, the individual geophones within the geophone groups being positioned so that the geophone group-response-versus-spatial-frequency function becomes substantially zero at the early integral multiples of 1/ Delta g, the reciprocal of the geophone group interval.