Digital reflection searching and section plotting

Claim 3

The method recited in claim 1 wherein said generating step includes: adding the amplitudes of said values of said adjacent traces.

Claim 4

The new use of an automatic digital computer and automatic plotting means to produce a seismic section from seismic data including a plurality of traces represented by digital values at periodic sampling times on each trace and representing the occurrence times of seismic energy from a plurality of spaced sources and reflected from subsurface interfaces comprising: converting said seismic data in said digital computer to a first physical representation of the occurrence time of energy reflected from a particular subsurface interface and a second physical representation of the attitude of said particular subsurface interface, said converting including: searching along search lines across adjacent related traces at each sampling time on one of said traces, said search lines occurring at different attitudes corresponding with the arrival times of reflections from said subsurface interfaces, adding the amplitudes of the digital values of said adjacent traces along each of said search lines, and for each occurrence time, selecting the maximum sum obtained from said adding operation, the attitude of the search line producing said maximum sum being said second physical representation indicating the arrival time versus distance of said particular subsurface interface, plotting on said automatic plotting means said particular subsurface interface at the attitude represented by said second physical representation and the occurrence time represented by said first physical representation.

Claim 5

The new use of an automatic digital computer and automatic plotting means to produce a seismic section from seismic data including a plurality of traces represented by digital values at periodic sampling times on each trace and representing the occurrence times of seismic energy from a plurality of spaced sources and reflected from subsurface interfaces comprising: converting said seismic data in said digital computer to a first physical representation of the occurrence time of energy reflected from a particular subsurface interface and a second physical representation of the attitude of said particular subsurface interface, said converting including: searching along search lines across adjacent related traces at each sampling time on one of said traces, said search lines occurring at different attitudes corresponding with the arrival times of reflections from said subsurface interfaces, adding the amplitudes of the digital values of said adjacent traces along each of said search lines, and for each occurrence time, selecting the maximum sum obtained from said adding operation, the attitude of the search line producing said maximum sum being said second physical representation indicating the arrival time versus distance of said particular subsurface interface, plotting on said automatic plotting means said particular subsurface interface at the attitude represented by said second physical representation and the occurrence time represented by said first physical representation.

Claim 6

In seismic exploration wherein seismic data represent the occurrence times of seismic energy from a plurality of spaced sources and reflected from subsurface interfaces, the method of operating a system including automatic digital computing apparatus and automatic plotting means, said digital computing apparatus including: an input unit for transforming said data to electric signals in a form which can be utilized by said computer, a storage unit for storing said electric signals, an arithmetic unit for operating upon said electric signals, and an output unit for transforming said electric signals into a form which can be utilized by said automatic plotting means, said method comprising: transferring to said storage unit digital samples representing the traces of a plurality of digitized seismograms, summing in said arithmetic unit the amplitudes of digital samples of adjacent related traces occurring along search lines of various attitudes, for each occurrence time, storing in said storage unit the maximum sum obtained from said summing operation as indicative of the amplitude of a reflection on said seismograms, storing in said storage unit the attitude of the search line producing the maximum sum as indicative of the arrival time versus distance of the particular reflecting interface producing said reflection, storing in said storage unit the occurrence time of the search line producing the maximum sum as indicative of the depth of said particular reflecting interface, transferring the stored values indicative of depth and arrival time versus distance to said arithmetic unit to migrate them to values representing actual depth and horizontal displacement with respect to said sources, applying said values of arrival time versus distance, actual depth and actual horizontal displacement to said output unit for conversion to electric signals representing said dip, actual depth and actual horizontal displacement, applying said last-named electric signals to said automatic plotting means, and plotting said particular reflecting interface at the values of actual depth and actual horizontal displacement and with an attitude corresponding with the value of said arrival time versus distance.

Claim 7

In seismic exploration wherein seismic data represent the occurrence times of seismic energy from a plurality of spaced sources and reflected from subsurface interfaces, the method of operating a system including automatic digital computing apparatus and automatic plotting means, said digital computing apparatus including: an input unit for transforming said data to electric signals in a form which can be utilized by said computer, a storage unit for storing said electric signals, an arithmetic unit for operating upon said electric signals, and an output unit for transforming said electric signals into a form which can be utilized by said automatic plotting means, said method comprising: transferring to said storage unit digital samples representing the traces of a plurality of digitized seismograms, summing in said arithmetic unit the amplitudes of digital samples of adjacent related traces occurring along search lines of various attitudes, for each occurrence time, storing in said storage unit the maximum sum obtained from said summing operation as indicative of the amplitude of a reflection on said seismograms, storing in said storage unit the attitude of the search line producing the maximum sum as indicative of the arrival time versus distance of the particular reflecting interface producing said reflection, storing in said storage unit the occurrence time of the search line producing the maximum sum as indicative of the depth of said particular reflecting interface, transferring the stored values indicative of depth and arrival time versus distance to said arithmetic unit to migrate them to values representing actual depth and horizontal displacement with respect to said sources, applying said values of arrival time versus distance, actual depth and actual horizontal displacement to said output unit for conversion to electric signals representing said dip, actual depth and actual horizontal displacement, applying said last-named electric signals to said automatic plotting means, and plotting said particular reflecting interface at the values of actual depth and actual horizontal displacement and with an attitude corresponding with the value of said arrival time versus distance.

Claim 8

The method recited in claim 4 further including: applying said maximum sum to said arithmetic unit to divide said maximum sum by the number of traces included therein to determine maximum mean amplitude, and storing said maximum mean amplitude in said storage unit as an indication of the grade of reflections included in said sum.

Claim 9

The method recited in claim 4 further including: applying said maximum sum to said arithmetic unit to compare said maximum sum with a threshold level indicating that reflections exist across said seismograms at the stored occurrence time on said traces and at the attitude of said search line producing said maximum sum.

Claim 10

The method recited in claim 4 wherein multiple reflections are removed from said seismic data further comprising: adding in said digital computing apparatus physical representations of occurrence times to obtain all combinations of the sums of said occurrence times, adding in said digital computing apparatus physical representations of attitudes to obtain all combinations of the sums of said attitudes, comparing in said digital computing apparatus each physical representation of said occurrence times and each physical representation of said attitudes with each sum of occurrence times and each sum of attitudes respectively to determine correspondence, and rejecting in said digital computing apparatus physical representations of said occurrence times and attitudes which produce correspondence as being indicative of multiple reflections.

Claim 11

The method recited in claim 4 further including: generating from said seismic data a plurality of physical representations of actual occurrence times for energy from successive ones of said spaced sources, generating from said seismic data a plurality of physical representations predictive of the occurrence times for energy from succeeding sources, comparing, for each succeeding source, said physical representations of actual occurrence times with said physical representations predictive of occurrence times, and interconnecting the plot of said particular subsurface interface between the occurrence time for energy from a particular source and the occurrence time for energy from the next succeeding source if said comparing step indicates agreement between predicted and actual occurrence time.

Claim 12

The new use of an automatic digital computer and automatic plotting means to produce a migrated seismic section from seismic data including a plurality of traces represented by digital values at periodic sampling times on each trace and representing the occurrence times of seismic energy from a plurality of spaced sources and reflected from subsurface interfaces comprising: adjusting the amplitude of each trace in said digital computer so that the rms level of each trace is equal for all traces, converting said seismic data in said digital computer to a first physical representation of the occurrence time of energy reflected from a particular subsurface interface and a second physical representation of the attitude of said particular subsurface interface, migrating in said digital computer said first physical representation of occurrence time and said second physical representation of attitude to values representating actual depth and horizontal displacement with respect to said sources, and plotting said particular subsurface interface at the attitude and actual depth and horizontal displacement of said particular subsurface interface.

Claim 13

The new use of an automatic digital computer and automatic plotting means to produce a migrated seismic section from seismic data including a plurality of traces represented by digital values at periodic sampling times on each trace and representing the occurrence times of seismic energy from a plurality of spaced sources and reflected from subsurface interfaces comprising: adjusting the amplitude of each trace in said digital computer so that the rms level of each trace is equal for all traces, converting said seismic data in said digital computer to a first physical representation of the occurrence time of energy reflected from a particular subsurface interface and a second physical representation of the attitude of said particular subsurface interface, migrating in said digital computer said first physical representation of occurrence time and said second physical representation of attitude to values representating actual depth and horizontal displacement with respect to said sources, and plotting said particular subsurface interface at the attitude and actual depth and horizontal displacement of said particular subsurface interface.

Claim 14

The new use recited in claim 9 wherein multiple reflections are removed from said seismic data,said new use further comprising: adding in said digital computer physical representations of occurrence times to obtain all combinations of the sums of said occurrence times, adding in said digital computer physical representations of attitudes to obtain all combinations of the sums of said attitudes, comparing in said digital computer each physical representation of said occurrence times and each physical representation of said attitudes with each sum of occurrence times and each sum of attitudes respectively to determine correspondence, and rejecting in said digital computer physical representations of said occurrence times and attitudes which produce correspondence as being indicative of multiple reflections.

Claim 15

The new use recited in claim 9 further including: generating from said seismic data a plurality of physical representations of actual occurrence times for energy from successive ones of said spaced sources, generating from said seismic data a plurality of physical representations predictive of the occurence times for energy from succeeding sources, comparing, for each succeeding source, said physical representations of actual occurrence times with said physical representations predictive of occurrence times, and interconnecting the plot of said particular subsurface interface between the occurrence time for energy from a particular source and the occurrence time for energy from the next succeeding source if said comparing step indicates continuity.

Claim 16

The new use of apparatus for seismic exploration wherein seismic data represents the occurrence times of seismic energy from a plurality of spaced sources and reflected from subsurface interfaces, and wherein a migrated seismic depth section is produced from a seismic time section having lines of continuity through reflections from particular subsurface interfaces, said apparatus comprising: a curve following means, automatic digital computing means, and automatic plotting apparatus, said new use comprising: following with said curve following means each line of continuity to generate at successive increments along said lines of continuity first signals representative of the occurrence times of reflected energy from particular interfaces and horizontal distances across said seismic time section, applying said first signals to said digital computing means so that said digital computing means is responsive to said first signals for generating second signals representative of attitude, actual depth, and horizontal displacement with respect to said sources of successive points on the particular subsurface interfaces represented by said lines of continuity, applying said second signals to said automatic plotting apparatus, said automatic plotting apparatus being responsive to said second signals for plotting said interfaces to produce said migrated seismic depth section.

Claim 17

The new use of apparatus for seismic exploration wherein seismic data represents the occurrence times of seismic energy from a plurality of spaced sources and reflected from subsurface interfaces, and wherein a migrated seismic depth section is produced from a seismic time section having lines of continuity through reflections from particular subsurface interfaces, said apparatus comprising: a curve following means, automatic digital computing means, and automatic plotting apparatus, said new use comprising: following with said curve following means each line of continuity to generate at successive increments along said lines of continuity first signals representative of the occurrence times of reflected energy from particular interfaces and horizontal distances across said seismic time section, applying said first signals to said digital computing means so that said digital computing means is responsive to said first signals for generating second signals representative of attitude, actual depth, and horizontal displacement with respect to said sources of successive points on the particular subsurface interfaces represented by said lines of continuity, applying said second signals to said automatic plotting apparatus, said automatic plotting apparatus being responsive to said second signals for plotting said interfaces to produce said migrated seismic depth section.

Claim 24

Apparatus for producing a migrated seismic section from seismic data including a plurality of traces represented by values at periodic sampling times on each trace and representing the occurrence times of seismic energy from a plurality of spaced sources and reflected from subsurface interfaces comprising: means for searching along search lines across adjacent traces at each sampling time on one of said traces, said search lines occurring at different attitudes corresponding with the arrival times of reflections from said subsurface interfaces, means for generating a function of said values of said adjacent traces along each of said search lines, means for selecting the maximum of said function obtained from said generating operation, the attitudes of said search lines producing said maximum being second physical representation indicating the arrival time versus distance of said particular subsurface interface, means for migrating said first physical representation of occurrence time and said second physical representation of attitude to values representing actual depth and horizontal displacement with respect to said source, and a plotter for plotting said particular subsurface interface at the attitude and actual depth and horizontal displacement of said particular subsurface interface.

Claim 25

Apparatus for producing a migrated seismic section from seismic data including a plurality of traces represented by values at periodic sampling times on each trace and representing the occurrence times of seismic energy from a plurality of spaced sources and reflected from subsurface interfaces comprising: means for searching along search lines across adjacent traces at each sampling time on one of said traces, said search lines occurring at different attitudes corresponding with the arrival times of reflections from said subsurface interfaces, means for generating a function of said values of said adjacent traces along each of said search lines, means for selecting the maximum of said function obtained from said generating operation, the attitudes of said search lines producing said maximum being second physical representation indicating the arrival time versus distance of said particular subsurface interface, means for migrating said first physical representation of occurrence time and said second physical representation of attitude to values representing actual depth and horizontal displacement with respect to said source, and a plotter for plotting said particular subsurface interface at the attitude and actual depth and horizontal displacement of said particular subsurface interface.

Claim 28

Apparatus for producing a migrated seismic section from seismic data including a plurality of traces represented by digital values at periodic sampling times on each trace and representing the occurrence times of seismic energy from a plurality of spaced sources and reflected from subsurface interfaces comprising: means for adjusting the amplitude of each trace so that the rms level of each trace is equal for all traces, means for converting said seismic data to a first physical representation of the occurrence time of energy reflected from a particular subsurface interface and a second physical representation of the attitude of said particular subsurface interface, means for migrating said first physical representation of occurrence time and said second physical representation of attitude to values representing actual depth and horizontal displacement with respect to said sources, and means for plotting said particular subsurface interface at the attitude and actual depth and horizontal displacement of said particular subsurface interface.

Claim 29

Apparatus for producing a migrated seismic section from seismic data including a plurality of traces represented by digital values at periodic sampling times on each trace and representing the occurrence times of seismic energy from a plurality of spaced sources and reflected from subsurface interfaces comprising: means for adjusting the amplitude of each trace so that the rms level of each trace is equal for all traces, means for converting said seismic data to a first physical representation of the occurrence time of energy reflected from a particular subsurface interface and a second physical representation of the attitude of said particular subsurface interface, means for migrating said first physical representation of occurrence time and said second physical representation of attitude to values representing actual depth and horizontal displacement with respect to said sources, and means for plotting said particular subsurface interface at the attitude and actual depth and horizontal displacement of said particular subsurface interface.