US3902113A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Means and method for inducing electrical polarization of an earth formation and for measuring the induced electrical polarization and for providing spontaneous potential correction
Assignee: Texaco Inc
•
Filing: 1974-03-14
•
Granted: 1975-08-26
•
Expires: 1994-03-14
Abstract
Abstract Apparatus at two different time intervals in each cycle of operation induces electrical polarization of an earth formation in a manner that each polarization is in an opposite direction to the polarization preceding and succeeding it. A measuring circuit controlled by timing logic measures the induced electrical potential at two different locations during two other time intervals in each cycle of operation. A difference amplifier provides a potential difference signal in accordance with the measured potentials. During one of the two measuring time intervals of each cycle, the difference signal is inverted. The signal which is not inverted and the inverted difference signal are integrated to provide an output to recording means to record the measured decay potentional difference.
Inventors
- 👤 James R Bridges
- 👤 Donald J Dowling
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:56
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/20; G01V3/22
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
209 words
Apparatus adapted to be passed through a borehole in an earth formation for inducing electrical polarization of the earth formation and for providing an output corresponding to the induced electrical polarization, comprising means for controlling the apparatus so that each cycle of operation covers at least four time intervals, means connected to the control means for inducing electrical polarization of the earth''s formation of one polarity during a first time interval of each cycle and of an opposite polarity during a third time interval of each cycle, means for measuring the induced electrical potential and providing a measurement signal during a second and a fourth time interval of each cycle corresponding to the measured induced electrical polarization, means connected to the measuring means for inverting the measurement signal during one time interval of each cycle, the inverting time interval being either the second or fourth time interval, and output means connected to the measuring means and to the inverting means for integrating the measurement signal during those time intervals when the measurement signal is not being inverted and for integrating the inverted measurement signal during those time intervals when the measurement signal is being inverted to provide the output corresponding to the induced electrical polarization of the earth formation.
Claim 2
Dependent Claim
209 words
Apparatus adapted to be passed through a borehole in an earth formation for inducing electrical polarization of the earth formation and for providing an output corresponding to the induced electrical polarization, comprising means for controlling the apparatus so that each cycle of operation covers at least four time intervals, means connected to the control means for inducing electrical polarization of the earth''s formation of one polarity during a first time interval of each cycle and of an opposite polarity during a third time interval of each cycle, means for measuring the induced electrical potential and providing a measurement signal during a second and a fourth time interval of each cycle corresponding to the measured induced electrical polarization, means connected to the measuring means for inverting the measurement signal during one time interval of each cycle, the inverting time interval being either the second or fourth time interval, and output means connected to the measuring means and to the inverting means for integrating the measurement signal during those time intervals when the measurement signal is not being inverted and for integrating the inverted measurement signal during those time intervals when the measurement signal is being inverted to provide the output corresponding to the induced electrical polarization of the earth formation.
Claim 3
Dependent Claim
174 words
Apparatus as described in claim 1 in which the measuring means includes a pair of electrodes spaced a predetermined distance apart, each electrode sensing an electrical potential of the earth''s formation and providing a signal corresponding thereto, means connected to the electrodes for providing a signal corresponding to the difference of the sensed potentials as the measurement signal, and first switching means connected to the difference signal means to the control means, to the inverting means and to the integrating means, and controlled by the control means for passing the measurement signal during the non-inverting time interval to the integrating means and for passing the inverted measurement signal from the inverting means to the integrating means during the inverting time interval of each cycle; and the integrating means includes summing means connected to the switching means for summing the measurement signal and the inverted measurement signal to provide an output, and an integrating circuit means for integrating the output from the summing means to provide the output corresponding to the measured induced electrical polarization.
Claim 4
Dependent Claim
127 words
Apparatus as described in claim 2 in which the inducing means includes a second pair of electrodes, a source of a constant electrical current, and second switching means connected to the control means, to the second pair of electrodes, to the constant current source and to ground and controlled by the control means to connect one electrode of the second pair of electrodes to the constant current source and the other electrode of the second pair of electrodes to ground during the first time interval of each cycle and to connect the other electrode of the second pair of electrodes to the constant current source and the one electrode of the second pair of electrodes to ground during the third time interval of each cycle of operation.
Claim 5
Dependent Claim
145 words
Apparatus as described in claim 3 in which the first mentioned switching means includes a first switch connecting the measurement signal means to the summing means and controlled by the control means which is rendered conductive by a pulse from the control means so as to pass the measurement signal from the measurement signal means to the summing means and rendered non-conducTive by the absence of a pulse from the control means so as to block the measurement signal, and a second switch connecting the inverting means to the summing means which is rendered conductive by a pulse from the control means so as to pass the inverted measurement signal from the inverting means to the summing means and to be rendered non-conductive by the absence of a pulse from the control means so as to block the inverted measurement signal from the inverting means.
Claim 6
Dependent Claim
94 words
Apparatus as described in claim 4 in which the control means includes a source of timing pulses, a manual operative switch receiving a direct current voltage, an AND gate connected to the timing pulse source and to the manual switch so that when an operator activates the manual switch the AND gate passes the timing pulses, a counter connected to the AND gate counts the passed timing pulses, and decoding means connected to the counter and to the switches for providing the pulses to the switches in accordance with the count in the counter.
Claim 7
Dependent Claim
73 words
Apparatus as described in claim 5 in which the control means provides a pulse to the third and fourth switches during the first time interval of each cycle, a pulse to the fifth and sixth switches during the fourth time interval of each cycle, a pulse to the first switch during the second time interval of each cycle, and a pulse to the second switch during the fourth time interval of each cycle.
Claim 8
Independent Claim
158 words
A method for inducing electrical polarization of an earth''s formation and for providing an output corresponding to the induced electrical polarization which comprises the following steps of: generating in a borehole in the earth formation an electric current flowing in one direction during a first time interval and in an opposite direction during a third time interval so as to induce electrical polarization of the earth formation of opposite polarity during the first and third time intervals, measuring the induced electrical polarization, providing a measurement signal during a second and a fourth time interval corresponding to the measured induced electrical polarization, inverting the measurement signal during one time interval, either the second or the fourth time interval, and integrating the measurement signal during the time interval the measurement signal is not being inverted and the inverted measurement signal during the time interval the measurement signal is being inverted to provide the output corresponding to the induced electrical polarization.
Claim 9
Independent Claim
158 words
A method for inducing electrical polarization of an earth''s formation and for providing an output corresponding to the induced electrical polarization which comprises the following steps of: generating in a borehole in the earth formation an electric current flowing in one direction during a first time interval and in an opposite direction during a third time interval so as to induce electrical polarization of the earth formation of opposite polarity during the first and third time intervals, measuring the induced electrical polarization, providing a measurement signal during a second and a fourth time interval corresponding to the measured induced electrical polarization, inverting the measurement signal during one time interval, either the second or the fourth time interval, and integrating the measurement signal during the time interval the measurement signal is not being inverted and the inverted measurement signal during the time interval the measurement signal is being inverted to provide the output corresponding to the induced electrical polarization.
Claim 10
Dependent Claim
18 words
A method as described in claim 7 further comprising repeating all of the steps on a periodic basis.
Claim 11
Dependent Claim
21 words
A method as described in claim 8 further comprising the step of recording the output corresponding to the induced electrical polarization.
Claim 12
Independent Claim
271 words
A system for inducing electrical polarization of an earth formation and for providing a record of the induced electrical polarization of the earth formation, comprising a logging tool adapted to be passed through a borehole in the earth formation including two pairs of electrodes; apparatus on the surface adjacent the borehole including means for controlling the system so that each cycle of operation covers at least four time intervals, means connected to the control means for providing an electrical current of one polarity during a first time interval of each cycle and of an opposite polarity during a third time interval of each cycle, means for measuring an induced electrical potential and providing a measurement signal during a second and a fourth time interval of each cycle, corresponding to the measured induced electrical polarization, means connected to the measuring means for inverting the measurement signal during one time interval of each cycle, the inverting time interval being either the second or fourth time interval, integrating means connected to the measuring means for integrating the measurement signal during the time intervals when the measurement signal is not being integrated and for integrating the inverted measurement signal during those time intervals when the measurement signal is being inverted to provide an integrated signal corresponding to the induced electrical polarization of the earth formation, and means for recording the integrated signal; and transmission means connecting the logging tool to the surface apparatus including first conductive means for electrically connectine one pair of electrodes to the electrical current means, and second conductive means for electrically connectine the other pair of electrodes to the measuring means.
Claim 13
Independent Claim
271 words
A system for inducing electrical polarization of an earth formation and for providing a record of the induced electrical polarization of the earth formation, comprising a logging tool adapted to be passed through a borehole in the earth formation including two pairs of electrodes; apparatus on the surface adjacent the borehole including means for controlling the system so that each cycle of operation covers at least four time intervals, means connected to the control means for providing an electrical current of one polarity during a first time interval of each cycle and of an opposite polarity during a third time interval of each cycle, means for measuring an induced electrical potential and providing a measurement signal during a second and a fourth time interval of each cycle, corresponding to the measured induced electrical polarization, means connected to the measuring means for inverting the measurement signal during one time interval of each cycle, the inverting time interval being either the second or fourth time interval, integrating means connected to the measuring means for integrating the measurement signal during the time intervals when the measurement signal is not being integrated and for integrating the inverted measurement signal during those time intervals when the measurement signal is being inverted to provide an integrated signal corresponding to the induced electrical polarization of the earth formation, and means for recording the integrated signal; and transmission means connecting the logging tool to the surface apparatus including first conductive means for electrically connectine one pair of electrodes to the electrical current means, and second conductive means for electrically connectine the other pair of electrodes to the measuring means.
Claim 14
Dependent Claim
188 words
A system as defined in claim 10 in which the electrodes of the other pair of electrodes are spaced a predetermined distance apart, each electrode sensing an electrical potential of the earth''s formation and providing a signal corresponding thereto, and the measuring means includes means electrically connected to the electrodes by the second conductive means for providing a signal corresponding to the difference of the sensed potentials as the measurement signal, and first switching means connected to the difference signal means to the control means, to the inverting means and to the integrating means, and controlled by the control means for passing the measurement signal during the non-inverting time interval to the integrating means and for passing the inverted measurement signal from the inverting means to the integrating means during the inverting time interval of each cycle; and the integrating means includes summing means connected to the switching means for summing the measurement signal and the inverted measurement signal to provide an output, and an integrating circuit means for integrating the output from the summing means to provide the integrated signal corresponding to the measured induced electrical polarization.
Claim 15
Dependent Claim
124 words
A system as described in claim 11 in which the constant current means includes a source of a constant electrical current, and second switching means connected to the control means, to the one pair of electrodes, to the constant current source and to ground and controlled by the control means to connect one electrode of the one pair of electrodes to the constant current source and the other electrode of the one pair of electrodes to ground during the first time interval of each cycle and to connect the other electrode of the one pair of electrodes to the constant current source and the one electrode of the one pair of electrodes to ground during the third time interval of each cyclor of operation.
Claim 16
Dependent Claim
145 words
A system as described in claim 12 in which the first switching means includes a first switch connecting the measurement signal means to the summing means and controlled by the control means which is rendered conductive by a pulse from the control means so as to pass the measurement signal from the measurement signal means to the summing means and rendered non-conductive by the absence of a pulse from the control means so as to block the measurement signal, and a second switch connecting the inverting means to the summing means which is rendered conductive by a pulse from the control means so as to pass the inverted measurement signal from the inverting means to the summing means ans to be rendered non-conductive by the absence of a pulse from the control means so as to block the inverted measurement signal from the inverting means.
Claim 17
Dependent Claim
103 words
A system as described in claim 13 in which the control means includes a source of timing pulses, a manual operative switch receiving a direct current voltage, an AND gate connected to the timing pulse source and to the manual switch so that when an operator activates the manual switch the AND gate passes the timing pulses, a counter connected to the AND gate and counting the passed timing pulses, and decoding means connected to the counter and to the switches for providing the pulses to the switches for providing the pulses to the switches in accordance with the count in the counter.
Claim 18
Dependent Claim
74 words
A system as described in claim 14 in which the control means provides a pulse to the third and fourTh switches during the first time interval of each cycle, a pulse to the fifth and sixth switches during the fourth time interval of each cycle, a pulse to the first switch during the second time interval of each cycle, and a pulse to the second switch during the fourth time interval of each cycle.
References Cited (Backward Citations)
US2291692A
Cited
US2728047A
Cited
US2937333A
Cited
US2988691A
Cited
US3219921A
Cited
US3254297A
Cited
US3402348A
Cited
US3810000A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |