Patent US5524100A successfully refreshed from Google Patents.
US5524100A
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Method for deriving water bottom reflectivity in dual sensor seismic surveys
Assignee: Westerngeco LLC
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Filing: 1995-03-07
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Granted: 1996-06-04
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Expires: 2015-03-07
Abstract
Abstract Pressure and velocity seismic signals are combined, the combined signal is transformed into the frequency domain and multiplied by the inverse Backus operator or the combined signal is convolved with the inverse Backus operator, and an optimization algorithm is utilized to solve for water bottom reflectivity. Pressure and velocity seismic signals are combined, and the combined signal is multiplied by the inverse Backus operator containing the water bottom reflectivity to eliminate first order peg leg multiples.
Inventors
- 👤 Josef Paffenholz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:12
CPC Classifications
G; G01; G01H; G01H15/00; G01V; G01V1/00; G01V1/38; G01V1/3808
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
166 words
A method for determining water bottom reflectivity in dual sensor seismic surveys, comprising the steps of: detecting water pressure at a first position in a water layer and generating a pressure signal correlative to said detected pressure; detecting water velocity at a position substantially near said first position in said water layer and generating a velocity signal correlative to said detected velocity; combining said pressure and velocity signals to generate a combined signal containing only upwardly-travelling energy; transforming said combined signal from the time domain to the frequency domain, generating a transformed signal; selecting a value R for said water bottom reflectivity; calculating an inverse Backus operator (1+RZ) 2 in the frequency domain for said value R of said water bottom reflectivity, where Z is the Z-transform of the two-way travel time delay operator in said water layer; multiplying said transformed signal by said inverse Backus operator, generating a filtered signal; and applying an optimization algorithm to said filtered signal to determine said water bottom reflectivity.
Claim 2
Independent Claim
166 words
A method for determining water bottom reflectivity in dual sensor seismic surveys, comprising the steps of: detecting water pressure at a first position in a water layer and generating a pressure signal correlative to said detected pressure; detecting water velocity at a position substantially near said first position in said water layer and generating a velocity signal correlative to said detected velocity; combining said pressure and velocity signals to generate a combined signal containing only upwardly-travelling energy; transforming said combined signal from the time domain to the frequency domain, generating a transformed signal; selecting a value R for said water bottom reflectivity; calculating an inverse Backus operator (1+RZ) 2 in the frequency domain for said value R of said water bottom reflectivity, where Z is the Z-transform of the two-way travel time delay operator in said water layer; multiplying said transformed signal by said inverse Backus operator, generating a filtered signal; and applying an optimization algorithm to said filtered signal to determine said water bottom reflectivity.
Claim 3
Dependent Claim
32 words
The method of claim 1, further comprising the steps of: repeating all previous steps for a plurality of pairs of said pressure and velocity signals; and averaging said determined water bottom reflectivities.
Claim 4
Dependent Claim
69 words
The method of claim 1, wherein said optimization algorithm comprises the steps of: squaring the amplitudes of the frequency spectrum of said filtered signal, generating a squared signal; summing said squared signals, generating a power; repeating said selecting, calculating, multiplying, squaring and summing steps, using different values for said water bottom reflectivity; and determining the value for said water bottom reflectivity which yields the lowest value for said power.
Claim 5
Dependent Claim
17 words
The method of claim 3, wherein said determining lowest value step is accomplished using the Levenberg-Marquardt method.
Claim 6
Dependent Claim
75 words
The method of claim 3, wherein said determining lowest value step comprises the following steps: selecting an initial value and a final value defining a range of values for said water bottom reflectivity; selecting an increment value; and selecting said different values for said water bottom reflectivity in said repeating step as all values between said initial value and said final value which are an integral number of said increment values from said initial value.
Claim 7
Dependent Claim
16 words
The method of claim 3, wherein the summing step is performed in a restricted frequency band.
Claim 8
Dependent Claim
17 words
The method of claim 6, wherein said frequency band is the range from 15 to 80 Hertz.
Claim 9
Dependent Claim
45 words
The method of claim 3, further comprising the steps of: repeating all previous steps at a plurality of said pressure and velocity detecting positions; and summing said powers from said pressure and velocity detecting positions to generate said power for said determining lowest value step.
Claim 10
Dependent Claim
52 words
The method of claim 3, further comprising the steps of: repeating all previous steps at a restricted offset range of said pressure and velocity detecting positions; and summing said powers from said restricted offset range of said pressure and velocity detecting positions to generate said power for said determining lowest value step.
Claim 11
Dependent Claim
39 words
The method of claim 1, further comprising the steps of: applying a time window to said pressure signal, generating the pressure signal for combining; and applying said time window to said velocity signal, generating the velocity signal for combining.
Claim 12
Dependent Claim
41 words
The method of claim 10, further comprising the steps of: determining an occurrence time for first break of said pressure signal; determining an occurrence time for first break of said velocity signal; and placing said time window after said occurrence times.
Claim 13
Dependent Claim
21 words
The method of claim 11, wherein said time window is the range from 0.8 to 2.5 seconds after said occurrence times.
Claim 14
Independent Claim
147 words
A method for determining water bottom reflectivity in dual sensor seismic surveys, comprising the steps of: detecting water pressure at a first position in a water layer and generating a pressure signal correlative to said detected pressure; detecting water velocity at a position substantially near said first position in said water layer and generating a velocity signal correlative to said detected velocity; combining said pressure and velocity signals to generate a combined signal containing only upwardly-travelling energy; selecting a value R for said water bottom reflectivity; calculating an inverse Backus operator (1+RZ) 2 in the time domain for said value R of said water bottom reflectivity, where Z is the two-way travel time delay operator in said water layer; convolving said combined signal with said inverse Backus operator, generating a filtered signal; and applying an optimization algorithm to said filtered signal to determine said water bottom reflectivity.
Claim 15
Independent Claim
147 words
A method for determining water bottom reflectivity in dual sensor seismic surveys, comprising the steps of: detecting water pressure at a first position in a water layer and generating a pressure signal correlative to said detected pressure; detecting water velocity at a position substantially near said first position in said water layer and generating a velocity signal correlative to said detected velocity; combining said pressure and velocity signals to generate a combined signal containing only upwardly-travelling energy; selecting a value R for said water bottom reflectivity; calculating an inverse Backus operator (1+RZ) 2 in the time domain for said value R of said water bottom reflectivity, where Z is the two-way travel time delay operator in said water layer; convolving said combined signal with said inverse Backus operator, generating a filtered signal; and applying an optimization algorithm to said filtered signal to determine said water bottom reflectivity.
Claim 16
Dependent Claim
32 words
The method of claim 13, further comprising the steps of: repeating all previous steps for a plurality of pairs of said pressure and velocity signals; and averaging said determined water bottom reflectivities.
Claim 17
Dependent Claim
65 words
The method of claim 13, wherein the optimization algorithm comprises the steps of: squaring the amplitudes of said filtered signal, generating a squared signal; summing said squared signals, generating a power; repeating said selecting, calculating, convolving, squaring and summing steps, using different values for said water bottom reflectivity; and determining the value for said water bottom reflectivity which yields the lowest value for said power.
Claim 18
Dependent Claim
17 words
The method of claim 15, wherein said determining lowest value step is accomplished using the Levenberg-Marquardt method.
Claim 19
Dependent Claim
75 words
The method of claim 15, wherein said determining lowest value step comprises the following steps: selecting an initial value and a final value defining a range of values for said water bottom reflectivity; selecting an increment value; and selecting said different values for said water bottom reflectivity in said repeating step as all values between said initial value and said final value which are an integral number of said increment values from said initial value.
Claim 20
Dependent Claim
16 words
The method of claim 15, wherein the summing step is performed in a restricted frequency band.
Claim 21
Dependent Claim
17 words
The method of claim 18, wherein said frequency band is the range from 15 to 80 Hertz.
Claim 22
Dependent Claim
45 words
The method of claim 15, further comprising the steps of: repeating all previous steps at a plurality of said pressure and velocity detecting positions; and summing said powers from said pressure and velocity detecting positions to generate said power for said selecting lowest value step.
Claim 23
Dependent Claim
52 words
The method of claim 15, further comprising the steps of: repeating all previous steps at a restricted offset range of said pressure and velocity detecting positions; and summing said powers from said restricted offset range of said pressure and velocity detecting positions to generate said power for said selecting lowest value step.
Claim 24
Dependent Claim
39 words
The method of claim 13, further comprising the steps of: applying a time window to said pressure signal, generating the pressure signal for combining; and applying said time window to said velocity signal, generating the velocity signal for combining.
Claim 25
Dependent Claim
41 words
The method of claim 22, further comprising the steps of: determining an occurrence time for first break of said pressure signal; determining an occurrence time for first break of said velocity signal; and placing said time window after said occurrence times.
Claim 26
Dependent Claim
21 words
The method of claim 23, wherein said time window is the range from 0.8 to 2.5 seconds after said occurrence times.
Claim 27
Independent Claim
127 words
A method for eliminating first-order peg-leg multiples in dual sensor seismic surveys, comprising the steps of: detecting water pressure at a first position in a water layer and generating a pressure signal correlative to said detected pressure; detecting water velocity at a position substantially near said first position in said water layer and generating a velocity signal correlative to said detected velocity; summing said pressure and velocity signals to generate a summed signal containing only upwardly-travelling energy; determining the water bottom reflectivity in said water layer; calculating an inverse Backus operator (1+RZ) 2 in the time domain, where R is said water bottom reflectivity and Z is the two-way travel time delay operator in said water layer; and convolving said summed signal with said inverse Backus operator.
Claim 28
Independent Claim
127 words
A method for eliminating first-order peg-leg multiples in dual sensor seismic surveys, comprising the steps of: detecting water pressure at a first position in a water layer and generating a pressure signal correlative to said detected pressure; detecting water velocity at a position substantially near said first position in said water layer and generating a velocity signal correlative to said detected velocity; summing said pressure and velocity signals to generate a summed signal containing only upwardly-travelling energy; determining the water bottom reflectivity in said water layer; calculating an inverse Backus operator (1+RZ) 2 in the time domain, where R is said water bottom reflectivity and Z is the two-way travel time delay operator in said water layer; and convolving said summed signal with said inverse Backus operator.
Claim 29
Dependent Claim
90 words
The method of claim 25, wherein said determining water bottom reflectivity step comprises the following steps: transforming said summed signal from the time domain to the frequency domain, generating a transformed signal; selecting a value R for said water bottom reflectivity; calculating an inverse Backus Operator (1+RZ) 2 in the frequency domain for said value R of said water bottom reflectivity; multiplying said transformed signal by said inverse Backus operator, generating a filtered signal; and applying an optimization algorithm to said filtered signal to determine said water bottom reflectivity R.
References Cited (Backward Citations)
US4146871A
Cited
US4234938A
Cited
US4486865A
Cited
US4935903A
Cited
US4979150A
Cited
US5163028A
Cited
US5396472A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-06-04 | 1999-12-04 | 2000-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-06-04 | 2003-12-04 | 2004-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-06-04 | 2007-12-04 | 2008-06-04 | $7700.00 | Window Closed / Lapsed |