EP0066423A1
Expired / Lapsed
EP
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Method of determining the signatures of arrays of marine seismic sources, and of accumulating data for use in such methods
Assignee: Britoil Ltd
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Filing: 1982-05-20
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Granted: —
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Expires: 2002-05-20
Abstract
Abstract In order to determine the signature of an array of n seismic sources 21 to 27, for instance marine seismic sources in the form of air guns, the array is actuated and the emitted pressure wave is measured at n independent points whose positions will respect to the array are known by hydrophones 31 to 37. The measurements are processed to produce n equivalent signatures of the n sources taking into account the interactions therebetween. The signature of the array is then determined merely by superposing the n equivalent signatures.
Inventors
- 👤 Antoni Marjan Ziolkowski
- 👤 Leslie Hatton
- 👤 Gregory Ernest Parkes
- 👤 Tor-Arvid Haugland
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 15:48
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/003; G01V1/006; G01V13/00
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
71 words
A method of determing the signature of an array of n seismic sources, comprising actuating the array of seismic sources, measuring the emitted pressure wave at n independent points whose positions are known with respect to the array, processing the measurements so as to produce n ecuivalent signatures of the n sources taking into account the interactions therebetween, and providing the signature of the array by superposing the n equivalent signatures.
Claim 2
Independent Claim
71 words
A method of determing the signature of an array of n seismic sources, comprising actuating the array of seismic sources, measuring the emitted pressure wave at n independent points whose positions are known with respect to the array, processing the measurements so as to produce n ecuivalent signatures of the n sources taking into account the interactions therebetween, and providing the signature of the array by superposing the n equivalent signatures.
Claim 3
Dependent Claim
25 words
A method according to claim 1, characterized in that an array of n marine seismic sources is provided as the array of n seismic sources.
Claim 4
Dependent Claim
23 words
A method according to claim 2, characterized in that an . air gun (10,11,21-27) is provided as each of the marine seismic sources.
Claim 5
Dependent Claim
24 words
A method according to claim 2 or 3, characterized in that n hydrophones (12, 13, 31-37) are used to measure the emitted pressure waves.
Claim 6
Dependent Claim
54 words
A method according to claim 4 when dependent on claim 3, characterized in that each hydrophone (12, 13, 31-37) is disposed adjacent a respective one of the air guns (10, 11, 21-27, respectively) but spaced therefrom by a distance such that the hydrophone does not penetrate the air bubble produced by the air gun.
Claim 7
Dependent Claim
104 words
A method according to claim 4 or 5, characterized in that the processing of the measurements comprises forming n simultaneous equations: i = 1,2,..., n where h i (t) is the signal provided by the ith hydrophone, s i is the sensitivity of the i th hydrophone, a ij is the distance between the i th hydrophone and the j th seismic source, c is the speed of sound in water, t is time, and P ' j (t) is the equivalent signature of the j th seismic source, and solving the n simultaneous equations for P' j (t) where j = 1,2,..., n.
Claim 8
Dependent Claim
94 words
A method according to claim 6, characterized in that the n simultaneous equations are formed as: where q' j (t) is the equivalent signature of a virtual seismic source corresponding to the j th seismic source and formed by reflection at the sea surface, b ij is the distance from the i th hydrophone to the j th virtual source, q' j = R . P' j (t), R is the coefficient of reflection of the sea surface, and the amplitude of the pressure wave at the sea surface does not exceed atmospheric pressure.
Claim 9
Dependent Claim
50 words
A method according to claim 6 or 7, characterized in that the signature P (t) of the array at a predetermined point is provided by superposing the n equivalent signatures according to the equation: where r j . is the distance from the j th source to the predetermined point.
Claim 10
Dependent Claim
35 words
A method according to claim 2 or 3, characterized in that the amplitude of the pressure wave at the sea surface exceeds atmospheric pressure and 2 n hydrophones are used to measure the pressure wave.
Claim 11
Dependent Claim
151 words
A method according to claim 9, characterized in that the processing of the measurements comprises forming 2 n simultaneous equations: i = 1,2, ..., 2n where h i . (t) is the signal provided by the i th hydrophone, s i is the sensitivity of the i th hydrophone, a ij is the distance between the i th hydrophone and the j th seismic source, c is the speed of sound in water, t is time, P' j (t) for j = 1,2...., n is the equivalent signature of the j th seismic source, and P' j (t) for j = n + 1, ... ,2 n is the equivalent signature of an virtual seismic source corresponding to the (j - n ) th seismic source and formed by reflection in the sea surface, and solving the 2n simultaneous equations for P' j (t) where j = 1,2, ... , 2n.
Claim 12
Dependent Claim
60 words
A method according to claim 10, characterized in that the signature P (t) of the array at a predetermined point is provided by superposing the 2n equivalent signatures of the seismic sources and the virtual seismic sources according to the equation: where r j is the distance from the j th seismic source or virtual source to the predetermined point.
Claim 13
Dependent Claim
21 words
An array of seismic sources whose signature has been determined by a method according to any one of the preceding claims.
Claim 14
Dependent Claim
24 words
Use of an array of seismic sources whose signature has been determined by a method according to any one of claims 1 to 11.
Claim 15
Dependent Claim
14 words
Data collected by use of an array of seismic sources according to claim 13.
References Cited (Backward Citations)
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