US3863201A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Seismometer arrays using operational amplifiers
Assignee: BP America Production Co
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Filing: 1973-05-29
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Granted: 1975-01-28
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Expires: 1993-05-29
Abstract
Abstract A seismometer weighting apparatus is described which uses solidstate operational amplifiers for conveniently applying weighting coefficients to individual seismometer signals which are then combined to form noise-rejecting arrays. This apparatus produces improved noise attenuation while retaining use of uniform field seismometers and equal spacing of these seismometers to expedite operations.
Inventors
- 👤 Russell M Briggs
- 👤 Hesin Ab Iorwerth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 02:23
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/16; G01V1/20
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
240 words
In an improved method of seismic prospecting of the type wherein electrical signals are generated by a plurality of essentially identical individual seismometers positioned adjacent to the surface of the earth, a plurality of group arrays are formed from a selected number of said individual seismometers located adjacent to each other such that a plurality of group array signals are produced by combining said individual seismometer electrical signals, and signals from each said group array are transmitted over a multiconductor cable to a remote multichannel amplifying and recording apparatus where said signals from each group array are individually amplified and recorded, the improvement comprising: a. increasing the amplitude of selected individual seismometer electrical signals relative to others in each of said group arrays to maximize the portion of said group array signals resulting from waves arriving from subterranean reflecting interfaces, while minimizing the portion of said group array signals produced by noise waves; b. reversing the polarity of said electrical signals from selected individual seismometers when required to maximize the portion of said group array signals resulting from nonvertically arriving waves from subterranean reflecting interfaces; and c. combining said increased amplitude and reversed polarity signals from said individual seismometers to form said group array signals such that the amplitude of said combined group array signals at least equals the amplitude of the signal obtained from said group array when no increases in amplitude or reversals in polarity have been applied.
Claim 2
Dependent Claim
240 words
In an improved method of seismic prospecting of the type wherein electrical signals are generated by a plurality of essentially identical individual seismometers positioned adjacent to the surface of the earth, a plurality of group arrays are formed from a selected number of said individual seismometers located adjacent to each other such that a plurality of group array signals are produced by combining said individual seismometer electrical signals, and signals from each said group array are transmitted over a multiconductor cable to a remote multichannel amplifying and recording apparatus where said signals from each group array are individually amplified and recorded, the improvement comprising: a. increasing the amplitude of selected individual seismometer electrical signals relative to others in each of said group arrays to maximize the portion of said group array signals resulting from waves arriving from subterranean reflecting interfaces, while minimizing the portion of said group array signals produced by noise waves; b. reversing the polarity of said electrical signals from selected individual seismometers when required to maximize the portion of said group array signals resulting from nonvertically arriving waves from subterranean reflecting interfaces; and c. combining said increased amplitude and reversed polarity signals from said individual seismometers to form said group array signals such that the amplitude of said combined group array signals at least equals the amplitude of the signal obtained from said group array when no increases in amplitude or reversals in polarity have been applied.
Claim 3
Dependent Claim
30 words
A method as recited in claim 1 wherein said amplitude-increasing step is perfoRmed by amplifying each of said identical seismometer electrical signals with a plurality of integrated circuit operational amplifiers.
Claim 4
Dependent Claim
192 words
A method as recited in claim 2 further comprising: a. forming each of said operational amplifiers into a scaling-adder circuit, having a plurality of input terminals and two output terminals, each of said scaling-adder circuits including a plurality of input resistors, an adjustable feedback resistor, an adjustable drift-stabilizing resistor, and two bypass capacitors; b. forming said plurality of input resistors into a plurality of switchable input resistor networks such that any one individual seismometer may be connected to one of said input resistors; c. connecting each one of said individual seismometers to one each of said switchable input resistor networks; d. selecting one of said plurality of input resistors in each of said switchable input resistor networks for each of said individual seismometers; e. adjusting the resistance of said feedback resistor to provide the desired amplification for all individual seismometer signals in said operational amplifier by making the ratio of said feedback resistance to said selected input resistance for each individual seismometer equal to the gain desired for that particular individual seismometer signal; and f. connecting said output terminals to said multiconductor cable for transmission to said remote amplifying and recording apparatus.
Claim 5
Dependent Claim
51 words
A method as recited in claim 1 wherein said polarity reversing step is performed by inverting said electrical signals from a first group of selected individual seismometers relative to said electrical signals from a second group of individual seismometers with a plurality of integrated circuit operational amplifiers in an adder-subtractor circuit.
Claim 6
Dependent Claim
203 words
A method as recited in claim 4 further comprising: a. forming a plurality of said integrated circuit operational amplifiers each into an adder-subtractor circuit having a plurality of input terminals and two output terminals, each one of said circuits including at least one first input resistor, a first adjustable feedback resistor, at least one second input resistor, a second adjustable feedback resistor, and two bypass capacitors each connected across one of said feedback resistors; b. connecting said input terminals from said first input resistors to a first group of said individual seismometers whose electrical signals are to remain with the polarity unchanged; c. connecting said input terminals from said second input resistors to a second group of said individual seismometers whose electrical signals are to be inverted; d. subtracting said electrical signals from said second group of seismometers from said first group of seismometer electrical signals by combining said signals in said operational amplifier to form said group array signals such that said amplifier output signal is the difference of said electrical signals from said first and said second groups of individual seismometers; and e. connecting said output terminals to said multiconductor cable for remote amplification and recording of said group array signal.
Claim 7
Dependent Claim
30 words
A method as recited in claim 1 wherein said combining step is accomplished by summing said electrical signals from said individual seismometer with an operational amplifier in an averaging circuit.
Claim 8
Dependent Claim
185 words
A method as recited in claim 6 further comprising: a. forming an averaging circuit from a plurality of parallel input resistors connected between an inverting input terminal of said operational amplifier and a plurality of input terminals, a feedback resistor connected between an output terminal and said inverting input terminal, a drift-stabilizing resistor connected between a noninverting input terminal of said operational amplifier and ground, a first high-frequency bypass capacitor connected across said feedback resistor, and a second high-frequency bypass capacitor connected across said drift-stabilizing resIstor; b. connecting each of said individual seismometers to only one pair of said input terminals; c. adjusting the resistance of said input resistors such that each resistor has a value proportional to a predetermined weighting coefficient to be applied to said individual seismometer signals prior to averaging; d. adjusting the resistance of said feedback resistors such that the lowest of said individual seismometer signals will be amplified with at least unity gain when averaged; and e. connecting said output terminal and ground to said multi-conductor cable for transmitting said group array signal to said remote amplifying and recording apparatus.
Claim 9
Dependent Claim
196 words
An improved seismic prospecting system of the type having a plurality of seismometer group arrays, each formed from a plurality of interconnected individual seismometers placed in a pattern adjacent to the surface of the earth, so that the output of said interconnected seismometers becomes the signal of a group array, a remote multichannel amplifying and recording apparatus for separately amplifying and recording the said electrical signals produced by each said group array, and a multi-channel cable for transmitting said group array signals to said remote amplifying and recording apparatus, wherein the improvement comprises: a. means for selectively increasing the amplitude of said individual seismometer signals prior to combination with other of said individual seismometer signals to form said group array signal for the purpose of improving the discrimination of said group array against seismic noise; b. means for reversing the polarity of said individual seismometer electrical signals for improvement in group array directivity; and c. means for combining signals from individual seismometers after passing through means (a) and (b) to provide an average thereof as a group array signal prior to transmission of said signal by said multiconductor cable to said remote amplifying and recording apparatus.
Claim 10
Dependent Claim
196 words
An improved seismic prospecting system of the type having a plurality of seismometer group arrays, each formed from a plurality of interconnected individual seismometers placed in a pattern adjacent to the surface of the earth, so that the output of said interconnected seismometers becomes the signal of a group array, a remote multichannel amplifying and recording apparatus for separately amplifying and recording the said electrical signals produced by each said group array, and a multi-channel cable for transmitting said group array signals to said remote amplifying and recording apparatus, wherein the improvement comprises: a. means for selectively increasing the amplitude of said individual seismometer signals prior to combination with other of said individual seismometer signals to form said group array signal for the purpose of improving the discrimination of said group array against seismic noise; b. means for reversing the polarity of said individual seismometer electrical signals for improvement in group array directivity; and c. means for combining signals from individual seismometers after passing through means (a) and (b) to provide an average thereof as a group array signal prior to transmission of said signal by said multiconductor cable to said remote amplifying and recording apparatus.
Claim 11
Dependent Claim
212 words
A seismic system as recited in claim 8 in which said amplitude increasing means comprises: a. an integrated circuit operational amplifier having an inverting input terminal, a noninverting input terminal, an output terminal, and a ground terminal; b. a plurality of parallel input resistors, each being connected between only one of said individual seismometers and said inverting input terminal of said operational amplifier, each of said input resistors having a resistance selected to form a predetermined ratio with the resistance of each other input resistor whereby each respective individual seismometer signal will have a predetermined amount of relative amplification prior to interconnecting into said group array. c. a variable feedback resistor connected between said operational amplifier output and inverting input terminals, said variable feedback resistor resistance being chosen such that each individual seismometer signal is multiplied by a predetermined constant before summing and inversion of the output occurs in said operational amplifier; d. a first high-frequency bypass capacitor connected across said variable feedback resistor for bypassing undesired high-frequency signals; e. a drift-stabilizing resistor connected between ground and said noninverting input terminal to stabilize said operational amplifier; f. a second high-frequency bypass capacitor connected across said drift-stabilizing resistor; and g. means for connecting the output of said operational amplifier to said multiconductor cable.
Claim 12
Dependent Claim
180 words
A seismic prospecting system as recited in claim 8 in which said polarity changing means comprises: a. an integrated circuit operational amplifier having an inverting input terminal, a noninverting input terminal, an output terminal, and a ground terminal; b. a first plurality of parallel input resistors, each one of said resistors connected between said operational amplifier inverting input terminal and only one of said individual seismomEters whose electrical signals are to be inverted; c. a second plurality of parallel input resistors, each one of said resistors connected between said operational amplifier noninverting input and only one of said individual seismometers whose electrical signals are to remain with their original polarity; d. a first feedback resistor connected between said operational amplifier output terminal and inverting input terminal; e. a first high-frequency bypass capacitor connected across said first feedback resistor; f. a second feedback resistor connected between said operational amplifier ground and noninverting feedback terminals; g. a second high-frequency bypass capacitor connected across said second feedback resistor; and h. means for connecting the output of said operational amplifier to said multiconductor cable.
Claim 13
Dependent Claim
203 words
A seismic prospecting system as recited in claim 8 in which said combining means comprises: a. an integrated circuit operational amplifier having an inverting input terminal, a noninverting input terminal, an output terminal, and a ground terminal; b. a plurality of parallel input resistors, each one of said resistors connected between said operational amplifier inverting input terminal and only one of said individual seismometers, each one of said input resistors having a resistance chosen to form a predetermined ratio with each other input resistor; c. a feedback resistor connected between said operational amplifier output and inverting input terminals, said feedback resistor having a resistance chosen such that in combination with the resistance of said one input resistor used in the lowest level individual seismometer circuit an output signal of at least unity gain is obtained; d. a first high-frequency bypass capacitor connected across said feedback resistor; e. a drift-stabilizing resistor connected between said operational amplifier ground and noninverting input terminals, said drift-stabilizing resistor having a resistance of approximately one-half of the value of said feedback resistor; f. a second high-frequency bypass capacitor connected across said drift-stabilizing resistor; and g. means for connecting said operational amplifier output and ground terminals to said multiconductor cable.
Claim 14
Dependent Claim
151 words
An improved seismic prospecting system of the type having a plurality of essentially identical seismometers positioned adjacent to the surface of the earth, electrically connected to form a group array, a remote multichannel amplifying and recording apparatus and a multi-conductor cable, wherein the improvement comprises a small multichannel amplifier apparatus connected between said identical seismometers and said multiconductor cable for the purposes of amplifying a multiplicity of said individual seismometer signals by predetermined values designed to optimize said group array response, said multichannel amplifier including means for inverting as desired the output of selected individual seismometers to permit directing the maximum array response to an off-vertical direction when required, and said multichannel amplifier including means for combining said individual seismometer signals following amplifying and possible inversion to form a single group array signal having a level at least as great as the level attained if said individual seismometers were directly interconnected.
Claim 15
Dependent Claim
151 words
An improved seismic prospecting system of the type having a plurality of essentially identical seismometers positioned adjacent to the surface of the earth, electrically connected to form a group array, a remote multichannel amplifying and recording apparatus and a multi-conductor cable, wherein the improvement comprises a small multichannel amplifier apparatus connected between said identical seismometers and said multiconductor cable for the purposes of amplifying a multiplicity of said individual seismometer signals by predetermined values designed to optimize said group array response, said multichannel amplifier including means for inverting as desired the output of selected individual seismometers to permit directing the maximum array response to an off-vertical direction when required, and said multichannel amplifier including means for combining said individual seismometer signals following amplifying and possible inversion to form a single group array signal having a level at least as great as the level attained if said individual seismometers were directly interconnected.
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) | 1978-01-27 | 1978-07-29 | 1979-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-27 | 1982-07-29 | 1983-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-27 | 1986-07-29 | 1987-01-28 | $7700.00 | Window Closed / Lapsed |