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US4486864A Expired / Lapsed US ⏱️ 0.0 years remaining

Method for marine seismic exploration

Assignee: Shell USA Inc
•
Filing: 1981-07-20
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Granted: 1984-12-04
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Expires: 2001-07-20
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Abstract

Abstract A method for marine seismic exploration, comprising the steps of first discharging simultaneously a set number of seismic sources having a known volume V 1 , resulting in several seismic waves with substantially identical form which after reflection by a same series of reflection points are detected by hydrophones as a sum signal of the individual emitted source waves having a frequency range f 1 . The sum signal is subsequently filtered by means of a suitable filter operation having a frequency range f 1 , resulting in a sum signal having substantially equal phase of the individual components in the frequency range f 1 , next discharging simultaneously a set number of seismic sources having a known volume V 2 , different from volume V 1 , resulting in several seismic waves with substantially identical form which after reflection are detected by hydrophones as a sum signal of the individual emitted source waves having a frequency range f 2 . The sum signal is filtered by means of a suitable filter operation having a frequency range f 2 , to obtain substantially equal phase of the individual components in the frequency range f 2 , then repeating the abovementioned procedure of discharging simultaneously seismic sources having a known volume, detecting the several seismic waves after reflection and filtering the sum signals in a suitable way with seismic sources having mutually different volumes V 3 , V 4 -V n respectively. Finally, "stacking" the obtained signals, which results in a final "stacked" sum signal having a frequency range f 1 -f n .

Inventors

  • 👤 Leo Ongkiehong
  • 👤 Willem Huizer

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-03 16:27
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/003; G01V1/006; G01V1/38; G01V1/3808

Claims Analysis

Total Claims: 11
Claim 1
Independent Claim 191 words
A method for marine seismic exploration in which a seismic source array comprising a plurality of seismic sources is used, said method comprising: discharging simultaneously a preset number of seismic sources, each having a known volume V 1 , said sources producing seismic waves having substantially identical form and a frequency range f 1 ; detecting said seismic waves after they have been reflected by a series of reflection points and providing a sum signal; filtering said sum signal using a filter having a frequency range f 1 to provide a signal having substantially equal phase of the individual components in the frequency range f 1 ; repeating the above steps using a preset number of seismic sources, each having a known volume V 2 different than V 1 to produce seismic waves substantially identical form and a frequency range f 2 ; repeating the above steps using seismic sources having volumes V 3 , V 4 -V n and frequency ranges f 3 , f 4 -f n ; and, stacking the filtered sum signals to produce a final sum signal having a frequency range f 1 -f n .
Claim 2
Independent Claim 191 words
A method for marine seismic exploration in which a seismic source array comprising a plurality of seismic sources is used, said method comprising: discharging simultaneously a preset number of seismic sources, each having a known volume V 1 , said sources producing seismic waves having substantially identical form and a frequency range f 1 ; detecting said seismic waves after they have been reflected by a series of reflection points and providing a sum signal; filtering said sum signal using a filter having a frequency range f 1 to provide a signal having substantially equal phase of the individual components in the frequency range f 1 ; repeating the above steps using a preset number of seismic sources, each having a known volume V 2 different than V 1 to produce seismic waves substantially identical form and a frequency range f 2 ; repeating the above steps using seismic sources having volumes V 3 , V 4 -V n and frequency ranges f 3 , f 4 -f n ; and, stacking the filtered sum signals to produce a final sum signal having a frequency range f 1 -f n .
Claim 3
Dependent Claim 13 words
The method of claim 1, wherein the seismic sources consist of air guns.
Claim 4
Dependent Claim 28 words
The method of claim 2, wherein the air guns of the air gun array are divided in groups, each group consisting of air guns having a same volume.
Claim 5
Dependent Claim 14 words
The method of claim 2, wherein air guns having an adjustable volume are used.
Claim 6
Independent Claim 24 words
The method of claims 2, 3 or 4, wherein the number of air guns being discharged simultaneously during the operation is always the same.
Claim 7
Independent Claim 22 words
The method of claims 2, 3 or 4, wherein the number of air guns being discharged simultaneously during the operation is variable.
Claim 8
Independent Claim 22 words
The method of claims 1, 2, 3 or 4, wherein the filtering operation takes place by means of a band pass filter.
Claim 9
Dependent Claim 38 words
The method of claim 1, wherein the filtering operation provides substantially equal phase of the individual components of a sum signal having a determined frequency range by means of zero-phasing of the individual sum signals prior to "stacking".
Claim 10
Dependent Claim 22 words
The method as claimed in claim 8, wherein a cross-correlation of the detected signal with the undistorted measured source signal takes place.
Claim 11
Dependent Claim 21 words
The method as claimed in claim 8, wherein a cross-correlation of the detected signal with a computer-simulated source signal takes place.

References Cited (Backward Citations)

US3284763A Cited
US3351899A Cited
US3413596A Cited
US3437170A Cited
US3602878A Cited
US4208732A Cited
US4004267A Cited
US4146870A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1987-12-04 1988-06-04 1988-12-04 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1991-12-04 1992-06-04 1992-12-04 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1995-12-04 1996-06-04 1996-12-04 $7700.00 Window Closed / Lapsed

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