Three dimensional seismic prospecting method

Claim 1

A method of seismic prospecting comprising the steps of: (a) producing a plurality of seismic traces respectively corresponding to a plurality of seismic source-receiver pairs which define an areal array of source positions and receiver positions, wherein each source-receiver pair includes a source position and a receiver position and wherein any one seismic trace is produced by a seismic receiver located at the receiver position of the corresponding source-receiver pair in response to the reflection of at least one seismic wave transmitted into the subsurface of the earth by a seismic source located at the source position of the corresponding source-receiver pair; (b) selecting a fold number n 3 , where n 1 is an integer of a least 2; (c) selecting a common midpoint (CMP) of a set of source-receiver pairs which define at least a portion of said areal array, wherein the source position and receiver position of each source-receiver pair of said set has said CMP as the midpoint therebetween and wherein the number of source-receiver pairs in said set is greater than n 1 ; (d) segregating said areal array into n 2 angularly separated sections defined by at least one imaginary boundary passing through said CMP, where n 2 is an integer and 2≦n 2 ≦n 1 ; (e) segregating at least a portion of said areal array into n 3 shells defined by at least n 3 imaginary closed and nonintersecting boundaries which surround said CMP, such that the innermost shell is defined by the boundary closest to said CMP and such that each other shell is defined between adjacent shell boundaries, where n 3 is an integer and 2≦n 3 ≦n 1 ; (f) selecting n 1 source positions or n 1 receiver positions in said areal array which correspond to n 1 source-receiver pairs of said set of source-receiver pairs having said CMP as their midpoint, said selecting of source positions and receiver positions being performed such that each shell and each section includes at least one selected source position or receiver position therein to the extent that each said section or shell has at least one source position or receiver position therein which corresponds to a source-receiver pair of said set of source-receiver pairs having said CMP as their midpoint; (g) summing the seismic traces which respectively correspond to the n 1 source-receiver pairs of step (f) to yield a stacked trace.

Claim 2

A method of seismic prospecting comprising the steps of: (a) producing a plurality of seismic traces respectively corresponding to a plurality of seismic source-receiver pairs which define an areal array of source positions and receiver positions, wherein each source-receiver pair includes a source position and a receiver position and wherein any one seismic trace is produced by a seismic receiver located at the receiver position of the corresponding source-receiver pair in response to the reflection of at least one seismic wave transmitted into the subsurface of the earth by a seismic source located at the source position of the corresponding source-receiver pair; (b) selecting a fold number n 3 , where n 1 is an integer of a least 2; (c) selecting a common midpoint (CMP) of a set of source-receiver pairs which define at least a portion of said areal array, wherein the source position and receiver position of each source-receiver pair of said set has said CMP as the midpoint therebetween and wherein the number of source-receiver pairs in said set is greater than n 1 ; (d) segregating said areal array into n 2 angularly separated sections defined by at least one imaginary boundary passing through said CMP, where n 2 is an integer and 2≦n 2 ≦n 1 ; (e) segregating at least a portion of said areal array into n 3 shells defined by at least n 3 imaginary closed and nonintersecting boundaries which surround said CMP, such that the innermost shell is defined by the boundary closest to said CMP and such that each other shell is defined between adjacent shell boundaries, where n 3 is an integer and 2≦n 3 ≦n 1 ; (f) selecting n 1 source positions or n 1 receiver positions in said areal array which correspond to n 1 source-receiver pairs of said set of source-receiver pairs having said CMP as their midpoint, said selecting of source positions and receiver positions being performed such that each shell and each section includes at least one selected source position or receiver position therein to the extent that each said section or shell has at least one source position or receiver position therein which corresponds to a source-receiver pair of said set of source-receiver pairs having said CMP as their midpoint; (g) summing the seismic traces which respectively correspond to the n 1 source-receiver pairs of step (f) to yield a stacked trace.