Patent US4979150A successfully refreshed from Google Patents.
US4979150A
Expired / Lapsed
US
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System for attenuation of water-column reverberations
Assignee: Westerngeco LLC
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Filing: 1989-08-25
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Granted: 1990-12-18
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Expires: 2009-08-25
Abstract
Abstract A marine seismic reflection prospecting system reduces coherent noise by applying a scale factor to the output of a pressure transducer and a particle velocity transducer positioned substantially adjacent one another in the water. The transducers can be positioned at a point in the water above the bottom and, thereby, eliminate downgoing components of reverberation, or they can be positioned on the water's bottom and, thereby, eliminate both upgoing and downgoing components of the reverberation. The scale factor, which derives from the acoustical impedance of the water or water-bottom material, can be determined both deterministically and statistically. The former involves measuring and comparing the responses of the pressure and velocity transducers to a pressure wave induced in the water. The latter involves comparing the magnitude of the pressure signal autocorrelation to the pressure and velocity signal crosscorrelation at selected lag values or, alternatively, comparing the magnitude of the pressure signal autocorrelation to the velocity signal autocorrelation at selected lag values.
Inventors
- 👤 Frederick J. Barr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 01:05
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/28; G01V1/36; G01V1/364; G01V1/38; G01V1/3808; G01V2210/00; G01V2210/50; G01V2210/56
Claims Analysis
Total Claims: 43
Claim 1
Independent Claim
145 words
An improved seismic reflection method for geophysical prospecting in water covered areas, comprising the steps of A. generating a seismic wave for reflection from earth strata, B. detecting water pressure at a first position in the water resulting from said seismic wave and generating a signal representative thereof, C. detecting water velocity at a position substantially near said first position resulting from said seismic wave and generating a signal representative thereof, and D. generating an enhanced seismic reflection signal by multiplying at least one of said water pressure-representative signal and the water velocity-representative signal by a scale factor dependent upon an acoustical impedance of a substance through which said seismic wave travels, and by summing said scaled water velocity-representative and water pressure-representative signals, and enhanced seismic reflection signal being substantially free of at least downwardly-propagating components of reverberation of said seismic wave within the water.
Claim 2
Dependent Claim
145 words
An improved seismic reflection method for geophysical prospecting in water covered areas, comprising the steps of A. generating a seismic wave for reflection from earth strata, B. detecting water pressure at a first position in the water resulting from said seismic wave and generating a signal representative thereof, C. detecting water velocity at a position substantially near said first position resulting from said seismic wave and generating a signal representative thereof, and D. generating an enhanced seismic reflection signal by multiplying at least one of said water pressure-representative signal and the water velocity-representative signal by a scale factor dependent upon an acoustical impedance of a substance through which said seismic wave travels, and by summing said scaled water velocity-representative and water pressure-representative signals, and enhanced seismic reflection signal being substantially free of at least downwardly-propagating components of reverberation of said seismic wave within the water.
Claim 3
Dependent Claim
65 words
A method according to claim 1, wherein said enhanced seismic reflection signal-generating step includes the steps of A. scaling said water velocity-representative and water pressure-representative signals by multiplying at least a selected one of them by a scale factor dependent upon an acoustical impedance of the water, and B. summing said scaled water velocity-representative and water pressure-representative signals to produce said enhanced seismic reflection signal.
Claim 4
Dependent Claim
56 words
A method according to claim 2, wherein said scaling step includes the step of multiplying said at least one selected signal by a value dependent upon ρ'α'/Dir.sub.corr where ρ' is a density of the water, α' is a velocity of propagation of the seismic wave in the water, and Dir corr is a directivity correction factor.
Claim 5
Dependent Claim
56 words
A method according to claim 3, wherein said scaling step includes the step of multiplying said at least one selected signal by a value dependent upon (ρ'α'/Dir.sub.coor)*(G.sub.p G.sub.v) where G p is a transduction constant associated with the water pressure detecting step, and G v is a transduction constant associated with the water velocity detecting step.
Claim 6
Dependent Claim
27 words
A method according to claim 3, wherein said scaling step includes the step of determining said directivity correction factor, Dir corr , to be equal to one.
Claim 7
Dependent Claim
46 words
A method according to claim 3, wherein said scaling step includes the step of determining said directivity correction factor Dir corr , to be equal to cos(γ p '), whee γ p ' is an angle of propagation from vertical of the seismic wave in water.
Claim 8
Dependent Claim
65 words
A method according to claim 4, wherein said scaling step includes the step of generating said directivity correction factor, Dir corr , to be equal to cos (γ p ') for γ p ' less than a selected critical angle, and to otherwise be equal to 1, where γ p ' is an angle of propagation from vertical of the seismic wave in the water.
Claim 9
Dependent Claim
57 words
A method according to claim 7, wherein said scaling step includes the step of determining said critical angle to be substantially equal to arcsin(α'/α), where α' is the velocity of propagation of the seismic wave in the water and α is a velocity of propagation of the seismic wave in an earth material at said water's bottom.
Claim 10
Dependent Claim
22 words
A method according to claim 2, wherein said scaling step includes the step of multiplying said water velocity-representative signal by (G.sub.p /G.sub.v)*ρ'α'
Claim 11
Dependent Claim
38 words
A method according to claim 1, comprising the step of positioning a pressure detector and a velocity detector substantially near water's bottom for detecting said water pressure and said water velocity and for generating signals representative thereof, respectively.
Claim 12
Dependent Claim
92 words
A method according to claim 10, wherein said enhanced seismic reflection signal-generating step includes the steps of A. scaling said water velocity-representative and water pressure-representative signals by multiplying at least a selected one of them by a scale factor dependent upon an acoustical impedance of a solid earth material at said water's bottom, B. summing said scaled water velocity-representative and water pressure-representative signals to produce said enhanced seismic reflection signal, said enhanced seismic reflection signal being substantially free of downwardly-propagating and upwardly-propagating components of reverberation of said seismic wave within the water.
Claim 13
Dependent Claim
61 words
A method according to claim 11, wherein said scaling step includes the further step of multiplying said at least one selected signal by a value dependent upon ρα/Dir.sub.corr where ρ is a density of said solid earth material, α is a velocity of propagation of the seismic wave in said solid earth material, and Dir corr is a directivity correction factor.
Claim 14
Dependent Claim
56 words
A method according to claim 12, wherein said scaling step includes the step of multiplying said at least one selected signal by a value dependent upon (ρα/Dir.sub.corr)*(G.sub.p /G.sub.v) where G p is a transduction constant associated with the water pressure detecting step, and G v is a transduction constant associated with the water velocity detecting step.
Claim 15
Dependent Claim
64 words
A method according to claim 13, wherein said scaling step includes the step of generating said directivity correction factor, Dir corr , to be equal to cos(γ p ') for γ p ' less than a selected critical angle, and to otherwise be equal to 1, where γ p ' is an angle of propagation from vertical of the seismic wave in the water.
Claim 16
Dependent Claim
58 words
A method according to claim 14, wherein said scaling step includes the step of determining said critical angle to be substantially equal to arcsin(α'/α), where α', is the velocity of propagation of the seismic wave in the water and α is a velocity of propagation of the seismic wave in said solid earth material at said water's bottom.
Claim 17
Dependent Claim
27 words
A method according to claim 12, wherein said scaling step includes the step of determining said directivity correction factor, Dir corr , to be equal to one.
Claim 18
Dependent Claim
23 words
A method according to claim 12, wherein said scale factor-determining step includes the step of dividing said ratio-dependent scale factor by (G.sub.p /G.sub.v)*ρα.
Claim 19
Dependent Claim
22 words
A method according to claim 11, wherein said scaling step includes the step of multiplying said water velocity-representative signal by (G.sub.p /G.sub.v)*ρα.
Claim 20
Dependent Claim
15 words
A method according to claim 11, including the step of determining said scale factor statistically.
Claim 21
Dependent Claim
79 words
A method according to claim 19, wherein said scale factor-determining step includes the steps of A. computing an autocorrelation of said water pressure-representative signal at a selected lag value and generating a signal representative thereof, B. computing an autocorrelation of said water particle velocity-representative signal at a selected lag value and generating a signal representative thereof, C. determining said scale factor as dependent on a ratio of said water pressure autocorrelation-representative signal to said water particle velocity autocorrelation-representative signal.
Claim 22
Dependent Claim
40 words
A method according to claim 20 wherein said scale factor-determining step includes the step of determining said scale factor as dependent on a ratio of said water pressure autocorrelation-representative signal to said water particle velocity autocorrelation-representative signal at zero lag.
Claim 23
Dependent Claim
54 words
A method according to claim 20 wherein said scale factor-determining step includes the step of determining said scale factor as dependent on a ratio of said water pressure autocorrelation-representative signal to said water particle velocity autocorrelation-representative signal at selected lags corresponding to a time of two-way travel of said seismic wave through said water.
Claim 24
Dependent Claim
24 words
A method according to claim 22, wherein said scale factor-determining step includes the step of taking the square root of said ratio-dependent scale factor.
Claim 25
Dependent Claim
78 words
A method according to claim 19, wherein said scale factor-determining step includes the steps of: A. computing an autocorrelation of said water pressure-representative signal and generating a signal representative thereof, B. computing a crosscorrelation of said water pressure-representative signal and said water velocity-representative signal and generating a signal representative thereof, and C. determining said scale factor as dependent on a ratio of said autocorrelation-representative signal at a Selected lag value and said crosscorrelation-representative signal a selected lag value.
Claim 26
Dependent Claim
50 words
A method according to claim 24 wherein said scale factor-determining step includes the step of determining said scale factor as dependent on a ratio of said autocorrelation-representative signal and said crosscorrelation-representative signal, both at selected legs corresponding to a time of two-way travel of said seismic wave through said water.
Claim 27
Dependent Claim
15 words
A method according to claim 11, including the step of determining said scale factor deterministically.
Claim 28
Dependent Claim
112 words
A method according to claim 26, where said scale factor determining step includes the steps of A. generating a pressure wave from a position above the position of said pressure and velocity detectors, B. detecting, with said water pressure detector, water pressure during a selected arrival of said pressure wave and generating a signal representative thereof, C. detecting, with said velocity detector, a signal representative of water velocity during a selected arrival of said pressure wave and generating a signal representative thereof, and D. determining said scale factor as dependent on a ratio of the absolute values of the magnitudes of the pressure wave velocity-representative signal and the pressure wave pressure-representative signal.
Claim 29
Dependent Claim
29 words
A method according to claim 27, wherein said pressure wave-generating step includes the step of generating said pressure wave from a position directly over said pressure and velocity detectors.
Claim 30
Dependent Claim
52 words
A method according to claim 28, wherein A. said pressure wave pressure detecting step includes the step of detecting water pressure during a first arrival of said pressure wave, and B. said pressure wave velocity detecting step includes the step of detecting water velocity during a first arrival of said pressure wave.
Claim 31
Dependent Claim
53 words
A method according to claim 11, including the step determining said scale factor by iteratively performing said scaling and summing steps with one or more candidate scale factors, stacking the resultant enhanced seismic reflection signals and determining said scale factor to be a candidate factor which minimizes the effect of water column reverberations.
Claim 32
Dependent Claim
237 words
An improved seismic reflection method for geophysical prospecting in water covered areas, said method being free of filter means including a deconvolution operation for changing the frequency content of any one of pressure-detecting and velocity-detecting elements, said method comprising the steps of A. generating a seismic wave for reflection from earth strata, B. positioning a pressure detector and a velocity detector substantially near water's bottom for detecting said water pressure and said water velocity and for generating signals representative thereof, C. detecting water velocity at a position substantially near the position of said pressure detector resulting from said seismic wave and generating a signal representative thereof, and D. generating an enhanced seismic reflection signal as a selected linear combination of said water pressure representative signal and the water velocity-representative signal, said enhanced seismic reflection signal being substantially free of at least downwardly-propagating components of reverberation of said seismic wave within the water, said enhanced seismic reflection signal-generating step includes the steps of i. scaling said water velocity-representative and water pressure-representative signals by multiplying at least a selected one of them by a scale factor dependent upon an acoustical impedance of a solid earth material at said water's bottom, ii. summing said scaled water velocity-representative and water pressure-representative signals to produce said enhanced seismic reflection signal, said enhanced seismic reflection signal being substantially free of downwardly-propagating and upwardly-propagating components of reverberation of said seismic wave within the water.
Claim 33
Dependent Claim
237 words
An improved seismic reflection method for geophysical prospecting in water covered areas, said method being free of filter means including a deconvolution operation for changing the frequency content of any one of pressure-detecting and velocity-detecting elements, said method comprising the steps of A. generating a seismic wave for reflection from earth strata, B. positioning a pressure detector and a velocity detector substantially near water's bottom for detecting said water pressure and said water velocity and for generating signals representative thereof, C. detecting water velocity at a position substantially near the position of said pressure detector resulting from said seismic wave and generating a signal representative thereof, and D. generating an enhanced seismic reflection signal as a selected linear combination of said water pressure representative signal and the water velocity-representative signal, said enhanced seismic reflection signal being substantially free of at least downwardly-propagating components of reverberation of said seismic wave within the water, said enhanced seismic reflection signal-generating step includes the steps of i. scaling said water velocity-representative and water pressure-representative signals by multiplying at least a selected one of them by a scale factor dependent upon an acoustical impedance of a solid earth material at said water's bottom, ii. summing said scaled water velocity-representative and water pressure-representative signals to produce said enhanced seismic reflection signal, said enhanced seismic reflection signal being substantially free of downwardly-propagating and upwardly-propagating components of reverberation of said seismic wave within the water.
Claim 34
Dependent Claim
15 words
A method according to claim 31, including the step of determining said scale factor statistically.
Claim 35
Dependent Claim
70 words
A method according to claim 32, wherein said scale factor-determining step includes the steps of: A. computing an autocorrelation of said water pressure-representative signal and generating a signal representative thereof, B. computing a autocorrelation of said water pressure-representative signal and said water velocity-representative signal and generating a signal representative thereof, and C. determining said scale factor as dependent on a ratio of said autocorrelation-representative signals at a selected leg value.
Claim 36
Dependent Claim
15 words
A method according to claim 31, including the step of determining said scale factor deterministically.
Claim 37
Dependent Claim
112 words
A method according to claim 34, wherein said scale factor determining step includes the steps of A. generating a pressure wave from a position above the position of said pressure and velocity detectors, B. detecting, with said water pressure detector, water pressure during a selected arrival of said pressure wave and generating a signal representative thereof, C. detecting, with said velocity detector, a signal representative of water velocity during a selected arrival of said pressure wave and generating a signal representative thereof, and D. determining said scale factor as dependent on a ratio of the absolute values of the magnitudes of the pressure wave velocity-representative signal and the pressure wave pressure-representative signal.
Claim 38
Dependent Claim
252 words
An improved system for seismic reflection prospecting in water covered areas, said system being free of filter means including a deconvolution operation for changing the frequency content of any one of pressure-detecting an velocity-detecting elements, said system comprising A. means for generating a seismic wave for reflection from earth strata, B. Pressure detection means disposed substantially near a bottom of said water for detecting a pressure associated with a resultant seismic wave and for generating signals representative thereof, C. particle velocity detection means disposed at a position substantially near said pressure detection means for detecting a particle velocity associated with said resultant seismic wave and generating a signal representative thereof, and D. enhanced seismic reflection means coupled with said pressure detection means and said particle velocity means for generating an enhanced seismic reflection signal as a selected linear combination of said water pressure-representative signal and the water velocity-representative signal, said enhanced seismic reflection signal being substantially free of at least downwardly-propagating components of reverberation of said seismic wave within the water, said enhanced seismic reflection means including i. means for multiplying at least a selected one of said pressure-representative and water velocity-representative signals by a scale factor dependent upon an acoustical impedance of a solid earth material at said water's bottom, ii. means for summing said scaled water velocity-representative and water pressure-representative signals to produce said enhanced seismic reflection signal, said enhanced seismic reflection signal being substantially free of downwardly-propagating and upwardly-propagating components of reverberation of said seismic wave within the water.
Claim 39
Dependent Claim
252 words
An improved system for seismic reflection prospecting in water covered areas, said system being free of filter means including a deconvolution operation for changing the frequency content of any one of pressure-detecting an velocity-detecting elements, said system comprising A. means for generating a seismic wave for reflection from earth strata, B. Pressure detection means disposed substantially near a bottom of said water for detecting a pressure associated with a resultant seismic wave and for generating signals representative thereof, C. particle velocity detection means disposed at a position substantially near said pressure detection means for detecting a particle velocity associated with said resultant seismic wave and generating a signal representative thereof, and D. enhanced seismic reflection means coupled with said pressure detection means and said particle velocity means for generating an enhanced seismic reflection signal as a selected linear combination of said water pressure-representative signal and the water velocity-representative signal, said enhanced seismic reflection signal being substantially free of at least downwardly-propagating components of reverberation of said seismic wave within the water, said enhanced seismic reflection means including i. means for multiplying at least a selected one of said pressure-representative and water velocity-representative signals by a scale factor dependent upon an acoustical impedance of a solid earth material at said water's bottom, ii. means for summing said scaled water velocity-representative and water pressure-representative signals to produce said enhanced seismic reflection signal, said enhanced seismic reflection signal being substantially free of downwardly-propagating and upwardly-propagating components of reverberation of said seismic wave within the water.
Claim 40
Dependent Claim
14 words
A system according to claim 36, comprising means for determining said scale factor statistically.
Claim 41
Dependent Claim
79 words
A system according to claim 37, wherein said scale factor-determining means includes: A. means for computing an autocorrelation of said water pressure-representative signal at a selected lag value and generating a signal representative thereof, B. means for computing an autocorrelation of said water velocity-representative signal at a selected lag value and generating a signal representative thereof, and C. means for determining said scale factor as dependent on a ratio of said pressure autocorrelation-representative signal to said velocity autocorrelation-representative signal.
Claim 42
Dependent Claim
14 words
A system according to claim 36, including means for determining said scale factor deterministically.
Claim 43
Dependent Claim
116 words
A system according to claim 39, where said scale factor-determining means includes A. means for generating a pressure wave from a position above the position of said pressure and velocity detectors, B. means for detecting, with said water pressure detector, water pressure during a selected arrival of said pressure wave and generating a signal representative thereof, C. means for detecting, with said velocity detector, a signal representative of water velocity during a selected arrival of said pressure wave and generating a signal representative thereof, and D. means for determining said scale factor as dependent on a ratio of the absolute values of the magnitudes of the pressure wave velocity-representative signal and the pressure wave pressure-representative signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-12-17 | 1994-06-18 | 1994-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-17 | 1998-06-18 | 1998-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-17 | 2002-06-18 | 2002-12-18 | $7700.00 | Window Closed / Lapsed |