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US3866174A
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Method of exploring a medium and its applications in seismic exploration
Assignee: Societe Nationale des Petroles dAquitaine SA
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Filing: 1973-05-15
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Granted: 1975-02-11
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Expires: 1993-05-15
Abstract
Abstract A method of exploring a medium, in which a sequence of waves is produced in the medium in the form of long continuous oscillatory signals emitted by a number of sources, the reflected waves are received by at least one receiver, and the times taken by the waves to travel are determined by crosscorrelating the signals received and recorded with the references for the signals emitted. This method is characterized by the fact that the interval between the times at which two sources or emitters begin to emit consecutively is less than the sum of the duration of emission by the first emitter and the time Alpha taken for the longest distance covered by the waves in the medium being explored, and that the times at which the various sources begin to emit and the polarities of their signals, are such that when the sequence of times at which emission of all sources beings, each combined to the polarities of the emitted signals, are crosscorrelated with the sequence of times at which at least an emission of one of these sources begins combined to the polarities of the signals it emits a function is obtained which presents negligible correlation residues for the length of time Alpha . This method can be applied to seismic exploration in several dimensions, with a marked reduction under certain conditions in organized surface noise reaching the receivers.
Inventors
- 👤 Maurice Barbier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 16:31
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/003; G01V1/005
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
289 words
A method of exploring a medium which comprises the steps of: transmitting into sAid medium a sequence of waves in the form of a long continuous signal from a plurality of spaced emission sources, at least two of said sources transmitting signals of opposite polarity, actuating said plurality of emission sources for transmission at different times, the time interval between successive emissions of any two sources being less than the sum of the duration of emission by the first of said plurality of emission sources and the time Alpha corresponding to the largest distance covered by the waves in the medium explored, said times of actuating the emission sources and the polarity of the signals selected such that the cross-correlation function over the length of time Alpha of the sequence of times at which emission of all sources begin, each time being combined with the polarity of the corresponding emitted signal, with the sequence of times at which at least one source begins emitting, said times being each combined with the polarity of the corresponding emitted signal, has a ratio of the amplitude of the maximum peak to the amplitude of each of the secondary residues which is greater than the ratio of the amplitude of the long signals received after intercorrelation with a reference of the long signals emitted by each of the sources for intervals of time corresponding to the intervals separating the maximum peak from said secondary residues, receiving by means of a receiver unit and recording said long signals after reflection from reflectors in said medium, and crosscorrelating the recorded signals with a reference of the long oscillatory signal emitted by each source for determining the travel time of the reflected signals in said medium.
Claim 2
Independent Claim
289 words
A method of exploring a medium which comprises the steps of: transmitting into sAid medium a sequence of waves in the form of a long continuous signal from a plurality of spaced emission sources, at least two of said sources transmitting signals of opposite polarity, actuating said plurality of emission sources for transmission at different times, the time interval between successive emissions of any two sources being less than the sum of the duration of emission by the first of said plurality of emission sources and the time Alpha corresponding to the largest distance covered by the waves in the medium explored, said times of actuating the emission sources and the polarity of the signals selected such that the cross-correlation function over the length of time Alpha of the sequence of times at which emission of all sources begin, each time being combined with the polarity of the corresponding emitted signal, with the sequence of times at which at least one source begins emitting, said times being each combined with the polarity of the corresponding emitted signal, has a ratio of the amplitude of the maximum peak to the amplitude of each of the secondary residues which is greater than the ratio of the amplitude of the long signals received after intercorrelation with a reference of the long signals emitted by each of the sources for intervals of time corresponding to the intervals separating the maximum peak from said secondary residues, receiving by means of a receiver unit and recording said long signals after reflection from reflectors in said medium, and crosscorrelating the recorded signals with a reference of the long oscillatory signal emitted by each source for determining the travel time of the reflected signals in said medium.
Claim 3
Dependent Claim
25 words
A method of exploring a medium as defined in claim 1, in which said plurality of sources emit signals that are identical except for polarity.
Claim 4
Dependent Claim
102 words
A method of exploring a medium as defined in claim 2, in which the sources are aligned with the receiver unit, so that all the sources between the one emitting first and the receiver unit emit in reverse order of their distance from the receiver, and the distances between the emitters correspond to the intervals separating the times at which they begin to emit, the polarity and amplitude of the signals they emit, and the speed of propagation of organized surface noise created during emission, whereby the organized surface noise resulting from all the emissions and reaching the receiver is considerably reduced.
Claim 5
Dependent Claim
59 words
A method of exploring a medium as defined in claim 3, in which any two consecutive sources emit signals with opposite polarities, and the distance between the two sources is equal to the product of the interval separating the times at which they begin to emit and the speed of propagation of the organized surface noise created during emission.
Claim 6
Dependent Claim
65 words
A method of exploring a medium as defined in claim 1, in which the emission sources are aligned at right angles to the direction of the receiver unit, with one of the sources on the same axis as the receiver unit, and the distance between two consecutive sources being equal to the distance between the receiver and the emitter on the same axis as it.
Claim 7
Dependent Claim
37 words
A method of exploring a medium as defined in claim 1, in which several receiver units are used, and the waves emitted by each source and reflected on the different reflectors are recorded by each receiver unit.
Claim 8
Dependent Claim
36 words
A method of exploring a medium as defined in claim 1, in which the sources emit sinusoidal signals in which at least one of the two parameters, frequency and amplitude, is a linear function of time.
Claim 9
Dependent Claim
59 words
A method of exploring a medium as defined in claim 1, in which any two consecutive times at which one source begins emission are separated by an interval at least equal to the sum of the duration of emission by the source and the time corresponding to the longest distance covered by the waves in the medium being explored.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-10 | 1978-08-12 | 1979-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-10 | 1982-08-12 | 1983-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-10 | 1986-08-12 | 1987-02-11 | $7700.00 | Window Closed / Lapsed |