US4351035A
Expired / Lapsed
US
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Method of and apparatus for locating disturbances in a mineral seam
Assignee: Coal Industry Patents Ltd
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Filing: 1979-10-19
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Granted: 1982-09-21
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Expires: 1999-10-19
Abstract
Abstract Faults in an underground coal seam are located by firing a shot at one point in the seam and detecting the seismic reflections in an array of geophones. Signals from the geophones are recompressed and analyzed according to an exponential formula to give a holograph of the seam and to predict the fault pattern.
Inventors
- 👤 David J. Buchanan
- 👤 Iain M. Mason
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:09
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/28; G01V2210/00; G01V2210/50; G01V2210/55
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
91 words
A method of locating disturbances in a mineral seam characterized by locating in the seam underground at a first area an array of detector means and at a second area wave energy source means, operating the source means to generate seismic waves and detecting the waves in the detector means and converting said detections into electrical signals, processing said signals to produce recompressed signals and producing a holograph from said recompressed signals, said holograph indicating any disturbances in the form of an exponential characteristic related to wave phase and group velocities.
Claim 2
Independent Claim
91 words
A method of locating disturbances in a mineral seam characterized by locating in the seam underground at a first area an array of detector means and at a second area wave energy source means, operating the source means to generate seismic waves and detecting the waves in the detector means and converting said detections into electrical signals, processing said signals to produce recompressed signals and producing a holograph from said recompressed signals, said holograph indicating any disturbances in the form of an exponential characteristic related to wave phase and group velocities.
Claim 3
Dependent Claim
24 words
The method according to claim 1 wherein at least one of the detector means and source means comprises plural spaced means in an array.
Claim 4
Dependent Claim
27 words
The method according to claim 2 wherein the detector means comprises an array of spaced detectors and the source means comprises an array of synchronized point sources.
Claim 5
Dependent Claim
12 words
The method according to claim 1 wherein the detecting comprises detecting reflections.
Claim 6
Dependent Claim
32 words
The method according to claim 1 wherein the waves have a frequency band and wherein the exponential characteristic is related to phase and group velocities of a center frequency of the band.
Claim 7
Dependent Claim
20 words
A method as claimed in claim 1 characterized in that the recompression is performed by spectrally warping the electrical signals.
Claim 8
Dependent Claim
29 words
A method as claimed in claim 1 characterized in that the recompression is performed by passing the electrical signals through a time varying finite impulse response pulse compression filter.
Claim 9
Dependent Claim
82 words
A method as claimed in claim 1, characterized in that the exponential characteristic is identified according to the formula: ##EQU3## wherein I x,y is a point or picture cell on a map, x and y being coordinates, S n is signal amplitude at the detector t n is travel time lag associated with the picture cell and any particular detector ω c is center frequency of a bank and c p and c g are phase group velocities at the center frequency.
Claim 10
Dependent Claim
36 words
A method according to claim 8 characterized in that the said processing includes employing focussed elliptical time lag sum imaging and t n is time lag between a source, the image point (Ix,y) and a detector.
Claim 11
Independent Claim
99 words
A method of locating disturbances in a mineral seam comprising the steps of locating in the seam underground at a first area an array of detectors and at a second area a point source of sound, operating the point source to generate seismic waves and detecting reflections of the waves in the array of detectors and converting said reflections into electrical signals, processing said signals to produce a recompressed signal and producing a holograph indicating any disturbances in the form of an exponential characteristic related to the phase and group velocities of the centre frequency of the frequency band.
Claim 12
Independent Claim
99 words
A method of locating disturbances in a mineral seam comprising the steps of locating in the seam underground at a first area an array of detectors and at a second area a point source of sound, operating the point source to generate seismic waves and detecting reflections of the waves in the array of detectors and converting said reflections into electrical signals, processing said signals to produce a recompressed signal and producing a holograph indicating any disturbances in the form of an exponential characteristic related to the phase and group velocities of the centre frequency of the frequency band.
Claim 13
Dependent Claim
21 words
A method according to claim 10 in which the said processing includes employing a focussed radial time lag sum imaging technique.
Claim 14
Dependent Claim
21 words
A method according to claim 10 in which the said processing includes employing a focussed elliptical time lag sum imaging technique.
Claim 15
Dependent Claim
26 words
A method according to claim 10 in which the said processing includes employing both a focussed radial and a focussed elliptical time lag sum imaging technique.
Claim 16
Dependent Claim
21 words
A method according to claim 10 including the step of removing any noise element from the signal prior to recompressing it.
Claim 17
Dependent Claim
21 words
A method as claimed in claim 10 in which the recompression is performed by warping the spectra of the electrical signals.
Claim 18
Dependent Claim
28 words
A method as claimed in claim 10 in which the recompression is performed by passing the electrical signals through a time varying, finite impulse response pulse compression filter.
Claim 19
Dependent Claim
19 words
A method as claimed in claim 10 in which the exponential characteristic is identified according to the formula: ##EQU4##
Claim 20
Independent Claim
101 words
A method of locating disturbances in a mineral seam comprises locating disturbances in a mineral seam and including the steps of locating in the same seam underground at a first area, an array of detectors and at a second area a point source of sound, operating the point source to generate siesmic waves and detecting reflections of the waves in the array of detectors and converting said reflections into electrical signals, processing said signals to remove noise and to produce a recompressed signal, producing a holograph indicating any disturbances in the form of an exponential characteristic identified by the formula: ##EQU5##
Claim 21
Independent Claim
101 words
A method of locating disturbances in a mineral seam comprises locating disturbances in a mineral seam and including the steps of locating in the same seam underground at a first area, an array of detectors and at a second area a point source of sound, operating the point source to generate siesmic waves and detecting reflections of the waves in the array of detectors and converting said reflections into electrical signals, processing said signals to remove noise and to produce a recompressed signal, producing a holograph indicating any disturbances in the form of an exponential characteristic identified by the formula: ##EQU5##
Claim 22
Dependent Claim
21 words
A method as claimed in claim 18 in which the recompression is affected by warping the spectra of the electrical signals.
Claim 23
Dependent Claim
58 words
Apparatus for locating disturbances in a mineral seam comprising a source of seismic waves, an array of detectors for detecting the waves and processing electrical signals generated by the detectors when waves are detected, the processing means including means for recompressing the signals and further means arranged to produce a holograph of the seam from the recompressed signals.
Claim 24
Dependent Claim
58 words
Apparatus for locating disturbances in a mineral seam comprising a source of seismic waves, an array of detectors for detecting the waves and processing electrical signals generated by the detectors when waves are detected, the processing means including means for recompressing the signals and further means arranged to produce a holograph of the seam from the recompressed signals.
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) | 1985-09-20 | 1986-03-22 | 1986-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-09-20 | 1990-03-22 | 1990-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-09-20 | 1994-03-22 | 1994-09-21 | $7700.00 | Window Closed / Lapsed |