US3882376A
Expired / Lapsed
US
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Methods and apparatus for investigating earth formations
Assignee: Schlumberger Technology Corp
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Filing: 1973-12-20
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Granted: 1975-05-06
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Expires: 1993-12-20
Abstract
Abstract In accordance with illustrative embodiments of the present invention, an electrode array is utilized for investigating earth formations surrounding a mud filled borehole without undue influence from a conductive mud column. One manner of accomplishing this is to establish a potential distribution in the borehole as if the mud column were of the same resistivity as the formation. Alternatively, a zero potential gradient can be established at various regions in the mud column to effectively block current flow up or down the mud column.
Inventors
- 👤 Nick A Schuster
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:08
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/20; G01V3/24
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
248 words
Apparatus for measuring a characteristic of earth formations traversed by a borehole, comprising: a plurality of electrodes including at least one currentemitting electrode, a first pair of measuring electrodes, a first return electrode located between said at least one current-emitting electrode and said first pair of measuring electrodes, a second pair of measuring electrodes, a second current-emitting electrode located between said first and second pairs of measuring electrodes and a second current return electrode located between said second current-emitting electrode and said second pair of measuring electrodes; means for mounting said electrodes for passing through said borehole; means for supplying survey current to said at least one currentemitting electrode for emission into the media surrounding said mounting means said survey current being returned to an electrode spaced from said plurality of electrodes; means responsive to the potentials on said first pair of measuring electrodes for supplying a first auxiliary current between said at least one current-emitting electrode and said first return electrode of sufficient magnitude to maintain a given potential relationship between the electrodes of said first measuring electrode pair; and means responsive to the potentials on said second pair of measuring electrodes for supplying a second auxiliary current between said second current-emitting electrode and said second current return electrode of sufficient magnitude to maintain a given relationship between the potentials of said second measuring electrode pair whereby said survey current will be forced into said formation to thereby obtain a measure of a characteristic of said formation.
Claim 2
Dependent Claim
248 words
Apparatus for measuring a characteristic of earth formations traversed by a borehole, comprising: a plurality of electrodes including at least one currentemitting electrode, a first pair of measuring electrodes, a first return electrode located between said at least one current-emitting electrode and said first pair of measuring electrodes, a second pair of measuring electrodes, a second current-emitting electrode located between said first and second pairs of measuring electrodes and a second current return electrode located between said second current-emitting electrode and said second pair of measuring electrodes; means for mounting said electrodes for passing through said borehole; means for supplying survey current to said at least one currentemitting electrode for emission into the media surrounding said mounting means said survey current being returned to an electrode spaced from said plurality of electrodes; means responsive to the potentials on said first pair of measuring electrodes for supplying a first auxiliary current between said at least one current-emitting electrode and said first return electrode of sufficient magnitude to maintain a given potential relationship between the electrodes of said first measuring electrode pair; and means responsive to the potentials on said second pair of measuring electrodes for supplying a second auxiliary current between said second current-emitting electrode and said second current return electrode of sufficient magnitude to maintain a given relationship between the potentials of said second measuring electrode pair whereby said survey current will be forced into said formation to thereby obtain a measure of a characteristic of said formation.
Claim 3
Dependent Claim
335 words
Apparatus for measuring a characteristic of earth formations traversed by a borehole, comprising: a plurality of electrodes including at least one current-emitting electrode, a first pair of measuring electrodes, a first return electrode located between said at least one current-emitting electrode and said first pair of measuring electrodes, a second pair of measuring electrodes, a second current-emitting electrode located between said first and second pairs of measuring electrodes and a second current return electrode located between said second current-emitting electrode and said second pair of measuring electrodes; means for mounting said electrodes for passage through said borehole; means for supplying survey current to said at least one current-emitting electrode for emission into the media surrounding said mounting means said survey current being returned to an electrode spaced from said plurality of electrodes; means responsive to the potentials on said first pair of measuring electrodes for supplying a first auxiliary current between said at least one current-emitting electrode and said first return electrode of sufficient magnitude to maintain a given potential relationship between the electrodes of said first measuring electrode pair; means responsive to the potentials on said second pair of measuring electrodes for supplying a second auxiliary current between said second current-emitting electrode and said second current return electrode of sufficient magnitude to maintain a given relationship between the potentials of said second measuring electrode pair; means responsive to the difference in potential of a point in said borehole proximate said first pair of measuring electrodes and a potential at a point lying between said at least one current-emitting electrode and said first return electrode to obtain a first indication of the resistivity of a first formation portion near said borehole; and means responsive to the difference in potential of a point in said borehole proximate said second pair of measuring electrodes and the potential at another point in said borehole for obtaining a second indication of the resistivity of a portion of said formation further removed from said borehole thAn said first formation portion.
Claim 4
Dependent Claim
335 words
Apparatus for measuring a characteristic of earth formations traversed by a borehole, comprising: a plurality of electrodes including at least one current-emitting electrode, a first pair of measuring electrodes, a first return electrode located between said at least one current-emitting electrode and said first pair of measuring electrodes, a second pair of measuring electrodes, a second current-emitting electrode located between said first and second pairs of measuring electrodes and a second current return electrode located between said second current-emitting electrode and said second pair of measuring electrodes; means for mounting said electrodes for passage through said borehole; means for supplying survey current to said at least one current-emitting electrode for emission into the media surrounding said mounting means said survey current being returned to an electrode spaced from said plurality of electrodes; means responsive to the potentials on said first pair of measuring electrodes for supplying a first auxiliary current between said at least one current-emitting electrode and said first return electrode of sufficient magnitude to maintain a given potential relationship between the electrodes of said first measuring electrode pair; means responsive to the potentials on said second pair of measuring electrodes for supplying a second auxiliary current between said second current-emitting electrode and said second current return electrode of sufficient magnitude to maintain a given relationship between the potentials of said second measuring electrode pair; means responsive to the difference in potential of a point in said borehole proximate said first pair of measuring electrodes and a potential at a point lying between said at least one current-emitting electrode and said first return electrode to obtain a first indication of the resistivity of a first formation portion near said borehole; and means responsive to the difference in potential of a point in said borehole proximate said second pair of measuring electrodes and the potential at another point in said borehole for obtaining a second indication of the resistivity of a portion of said formation further removed from said borehole thAn said first formation portion.
Claim 5
Dependent Claim
243 words
Apparatus for measuring a characteristic of earth formations traversed by a borehole, comprising: a plurality of electrodes including at least one current-emitting electrode, a first pair of measuring electrodes, a first return electrode located between said at least one current-emitting electrode and said first pair of measuring electrodes, a second pair of measuring electrodes, another current-emitting electrode and current return electrode located between said first and second pairs of measuring electrodes, a third return electrode located at a greater distance from said at least one current-emitting electrode than the first return electrode; means for mounting said electrodes for passage through said borehole; means for supplying survey current between said at least one current-emitting electrode and said third return electrode; means responsive to the potentials on said first pair of measuring electrodes for supplying a first auxiliary current between said at least one current-emitting electrode and said first return electrode of sufficient magnitude to maintain a given potential relationship between the electrodes of said first measuring electrode pair; means responsive to the potentials on said second pair of measuring electrodes for supplying a second auxiliary current between said second current-emitting electrode and said second current return electrode of sufficient magnitude to maintain a given relationship between the potentials of said second measuring electrode pair; and means responsive to the potentials at a plurality of points through the borehole for obtaining a measure of a formation characteristic of at least one portion of said formation.
Claim 6
Dependent Claim
243 words
Apparatus for measuring a characteristic of earth formations traversed by a borehole, comprising: a plurality of electrodes including at least one current-emitting electrode, a first pair of measuring electrodes, a first return electrode located between said at least one current-emitting electrode and said first pair of measuring electrodes, a second pair of measuring electrodes, another current-emitting electrode and current return electrode located between said first and second pairs of measuring electrodes, a third return electrode located at a greater distance from said at least one current-emitting electrode than the first return electrode; means for mounting said electrodes for passage through said borehole; means for supplying survey current between said at least one current-emitting electrode and said third return electrode; means responsive to the potentials on said first pair of measuring electrodes for supplying a first auxiliary current between said at least one current-emitting electrode and said first return electrode of sufficient magnitude to maintain a given potential relationship between the electrodes of said first measuring electrode pair; means responsive to the potentials on said second pair of measuring electrodes for supplying a second auxiliary current between said second current-emitting electrode and said second current return electrode of sufficient magnitude to maintain a given relationship between the potentials of said second measuring electrode pair; and means responsive to the potentials at a plurality of points through the borehole for obtaining a measure of a formation characteristic of at least one portion of said formation.
Claim 7
Independent Claim
194 words
A method of measuring a characteristic of earth formations traversed by a borehole, comprising: carrying a plurality of electrodes through said borehole, said electrodes including at least one current-emitting electrode, a first pair of measuring electrodes, a first return electrode located between said at least one current-emitting electrode and said first pair of measuring electrodes, a second pair of measuring electrodes, a second current-emitting electrode located between said first and second pair of measuring electrodes and a second current return electrode located between said second current-emitting electrode and said second pair of measuring electrodes; supplying survey current to said at least one current-emitting electrode for emission into the media surrounding the electrodes said survey current being returned to an electrode spaced apart from said plurality of electrodes; supplying a first auxiliary current between said at least one current-emitting electrode and said first return electrode of sufficient magnitude to maintain a given relationship between the potentials of said second measuring electrode pair in response to the potentials on said second pair of measuring electrodes whereby said survey current will be forced into said formation to thereby obtain a measure of a characteristic of said formation.
Claim 8
Independent Claim
194 words
A method of measuring a characteristic of earth formations traversed by a borehole, comprising: carrying a plurality of electrodes through said borehole, said electrodes including at least one current-emitting electrode, a first pair of measuring electrodes, a first return electrode located between said at least one current-emitting electrode and said first pair of measuring electrodes, a second pair of measuring electrodes, a second current-emitting electrode located between said first and second pair of measuring electrodes and a second current return electrode located between said second current-emitting electrode and said second pair of measuring electrodes; supplying survey current to said at least one current-emitting electrode for emission into the media surrounding the electrodes said survey current being returned to an electrode spaced apart from said plurality of electrodes; supplying a first auxiliary current between said at least one current-emitting electrode and said first return electrode of sufficient magnitude to maintain a given relationship between the potentials of said second measuring electrode pair in response to the potentials on said second pair of measuring electrodes whereby said survey current will be forced into said formation to thereby obtain a measure of a characteristic of said formation.
Claim 9
Independent Claim
194 words
An apparatus for measuring the characteristics of earth formations traversed by a borehole comprising: a plurality of electrodes including current-emitting electrodes, first, second and third current return electrodes spaced from said current-emitting electrodes; means for mounting said electrodes for passage through a borehole; means for emitting from said current-emitting electrodes both survey current and at least two auxiliary currents into the media surrounding said mounting means, said survey current returning to said first return electrode for return to the current supplying means and said auxiliary currents returning to the second or third current return electrodes; a pair of potential monitoring electrodes mounted on said carrier between said second and third current return electrodes for measuring the potential gradient in the borehole; means operative in response to the meAsured potential gradient for adjusting one of the survey or auxiliary currents to set up a given potential distribution in at least a portion of a borehole whereby at least one auxiliary current will tend to force the survey current into the formation to thereby obtain a measure of the formation characteristic; and, means for measuring the survey current to obtain a measure of a formation characteristic.
Claim 10
Independent Claim
194 words
An apparatus for measuring the characteristics of earth formations traversed by a borehole comprising: a plurality of electrodes including current-emitting electrodes, first, second and third current return electrodes spaced from said current-emitting electrodes; means for mounting said electrodes for passage through a borehole; means for emitting from said current-emitting electrodes both survey current and at least two auxiliary currents into the media surrounding said mounting means, said survey current returning to said first return electrode for return to the current supplying means and said auxiliary currents returning to the second or third current return electrodes; a pair of potential monitoring electrodes mounted on said carrier between said second and third current return electrodes for measuring the potential gradient in the borehole; means operative in response to the meAsured potential gradient for adjusting one of the survey or auxiliary currents to set up a given potential distribution in at least a portion of a borehole whereby at least one auxiliary current will tend to force the survey current into the formation to thereby obtain a measure of the formation characteristic; and, means for measuring the survey current to obtain a measure of a formation characteristic.
Claim 11
Independent Claim
170 words
An apparatus for measuring the characteristics of earth formations traversed by a borehole, comprising: a plurality of electrodes including current-emitting electrodes, first, second and third current return electrodes spaced from said current-emitting electrodes and a pair of potential monitoring electrodes positioned between said second and third current return electrodes; means mounting said electrodes for passage through the borehole; means for emitting from said current-emitting electrodes both survey current and at least two auxiliary currents into the media surrounding said mounting means, said survey current returning to said first current return electrode for return to the current supply means and said auxiliary currents returning to said second and third current return electrodes; means responsive to the potentials on said pair of monitoring electrodes for adjusting one of the survey or auxiliary currents to set up a given potential distribution in at least a portion of the borehole; and means for measuring the survey current and at least one of said auxiliary currents to obtain measurements of characteristics of the earth formations.
Claim 12
Independent Claim
170 words
An apparatus for measuring the characteristics of earth formations traversed by a borehole, comprising: a plurality of electrodes including current-emitting electrodes, first, second and third current return electrodes spaced from said current-emitting electrodes and a pair of potential monitoring electrodes positioned between said second and third current return electrodes; means mounting said electrodes for passage through the borehole; means for emitting from said current-emitting electrodes both survey current and at least two auxiliary currents into the media surrounding said mounting means, said survey current returning to said first current return electrode for return to the current supply means and said auxiliary currents returning to said second and third current return electrodes; means responsive to the potentials on said pair of monitoring electrodes for adjusting one of the survey or auxiliary currents to set up a given potential distribution in at least a portion of the borehole; and means for measuring the survey current and at least one of said auxiliary currents to obtain measurements of characteristics of the earth formations.
Claim 13
Dependent Claim
29 words
The apparatus of claim 6 wherein said formation characteristics are the resistivity of the formation relatively distant from the borehole and resistivity of the formation relatively near the borehole.
Claim 14
Independent Claim
158 words
A method of measuring the characteristics of earth formations traversed by a borehole, comprising: carrying a plurality of electrodes through said borehole, said electrodes including current-emitting electrodes and at least three current return electrodes spaced from said current-emitting electrodes, and a pair of potential monitoring electrodes positioned between said second and third current return electrodes; emitting survey and at least two auxiliary currents into the media surrounding the electrodes, said survey current returning to said first current return electrode for return to the current-supplying means and said auxiliary currents returning to said second and third current return electrodes; measuring the potential gradient between said pair of potential monitoring electrodes; and adjusting one of said survey or auxiliary currents in response to the measured potential gradient to establish a given potential relationship in at least one portion of the borehole whereby said survey current will be forced into the formation to thereby obtain a measure of a formation characteristic.
Claim 15
Independent Claim
158 words
A method of measuring the characteristics of earth formations traversed by a borehole, comprising: carrying a plurality of electrodes through said borehole, said electrodes including current-emitting electrodes and at least three current return electrodes spaced from said current-emitting electrodes, and a pair of potential monitoring electrodes positioned between said second and third current return electrodes; emitting survey and at least two auxiliary currents into the media surrounding the electrodes, said survey current returning to said first current return electrode for return to the current-supplying means and said auxiliary currents returning to said second and third current return electrodes; measuring the potential gradient between said pair of potential monitoring electrodes; and adjusting one of said survey or auxiliary currents in response to the measured potential gradient to establish a given potential relationship in at least one portion of the borehole whereby said survey current will be forced into the formation to thereby obtain a measure of a formation characteristic.
Claim 16
Independent Claim
209 words
A method of measuring a characteristic of earth formations traversed by a borehole, comprising: carrying a plurality of electrodes through said boreholes, said electrodes including current-emitting electrodes, at least first, second and third current return electrodes spaced from said current-emitting electrodes, and pairs of potential monitoring electrodes positioned to control the flow of current to said second and third current return electrodes; emitting survey and at least two auxiliary currents into the media surrounding the electrodes, said survey current returning to said first current return electrode for return to the current supply means and said auxiliary currents returning to said second and third current return; measuring the potential gradient between a first pair of potential monitoring electrodes; adjusting one of said auxiliary currents in response to the measured potential between said first pair of potential monitoring electrodes for controlling the current to said second current return electrode; measuring the potential gradienT between a second pair of potential monitoring electrodes; adjusting the other of said auxiliary currents in response to the measured potential gradient between said second pair of potential monitoring electrodes to control the current to said third current return electrode; and measuring said survey current and one of said auxiliary currents to obtain measurements of two formation characteristics.
Claim 17
Independent Claim
209 words
A method of measuring a characteristic of earth formations traversed by a borehole, comprising: carrying a plurality of electrodes through said boreholes, said electrodes including current-emitting electrodes, at least first, second and third current return electrodes spaced from said current-emitting electrodes, and pairs of potential monitoring electrodes positioned to control the flow of current to said second and third current return electrodes; emitting survey and at least two auxiliary currents into the media surrounding the electrodes, said survey current returning to said first current return electrode for return to the current supply means and said auxiliary currents returning to said second and third current return; measuring the potential gradient between a first pair of potential monitoring electrodes; adjusting one of said auxiliary currents in response to the measured potential between said first pair of potential monitoring electrodes for controlling the current to said second current return electrode; measuring the potential gradienT between a second pair of potential monitoring electrodes; adjusting the other of said auxiliary currents in response to the measured potential gradient between said second pair of potential monitoring electrodes to control the current to said third current return electrode; and measuring said survey current and one of said auxiliary currents to obtain measurements of two formation characteristics.
Claim 18
Dependent Claim
32 words
The method of claim 9 wherein said two formation characteristics are the resistivity of the formation relatively distant from the borehole wall and the resistivity of the formation relatively near said borehole.
Claim 19
Independent Claim
323 words
A method for measuring a characteristic of earth formations traversed by a borehole, comprising: carrying a plurality of electrodes through said borehole, said electrodes including at least one current-emitting electrode, a first pair of measuring electrodes, a first return electrode located between said at least one current-emitting electrode and said first pair of measuring electrodes, a second pair of measuring electrodes, a second current-emitting electrode located between said first and second pairs of measuring electrodes and a second current return electrode located between said second current-emitting electrode and said second pair of measuring electrodes; supplying survey current to said at least one current-emitting electrode for emission into the media surrounding said electrodes, said survey current being returned to an electrode spaced from said plurality of electrodes; supplying a first auxiliary current between said at least one current-emitting electrode and said first return electrode of sufficient magnitude to maintain a given potential relationship between the electrodes of said first measuring electride pair in response to the potentials on said first pair of measuring electrodes; supplying a second auxiliary current between said second current-emitting electrode and said second current return electrode of sufficient magnitude to maintain a given relationship between the potentials of said second measuring electrode pair in response to the potentials on said second pair of measuring electrodes; measuring the difference in potential of a point in said borehole proximate said first pair of measuring electrodes and a potential at a point lying between said at least one current-emitting electrode and said first return electrode to obtain a first indication of the resistivity of a first formation portion near said borehole; and measuring the difference in potential of a point in said borehole proximate said second pair of measuring electrodes and the potential at another point in said borehole for obtaining a second indication of the resistivity of a portion of said formation further removed from said borehole than said first formation portion.
Claim 20
Independent Claim
323 words
A method for measuring a characteristic of earth formations traversed by a borehole, comprising: carrying a plurality of electrodes through said borehole, said electrodes including at least one current-emitting electrode, a first pair of measuring electrodes, a first return electrode located between said at least one current-emitting electrode and said first pair of measuring electrodes, a second pair of measuring electrodes, a second current-emitting electrode located between said first and second pairs of measuring electrodes and a second current return electrode located between said second current-emitting electrode and said second pair of measuring electrodes; supplying survey current to said at least one current-emitting electrode for emission into the media surrounding said electrodes, said survey current being returned to an electrode spaced from said plurality of electrodes; supplying a first auxiliary current between said at least one current-emitting electrode and said first return electrode of sufficient magnitude to maintain a given potential relationship between the electrodes of said first measuring electride pair in response to the potentials on said first pair of measuring electrodes; supplying a second auxiliary current between said second current-emitting electrode and said second current return electrode of sufficient magnitude to maintain a given relationship between the potentials of said second measuring electrode pair in response to the potentials on said second pair of measuring electrodes; measuring the difference in potential of a point in said borehole proximate said first pair of measuring electrodes and a potential at a point lying between said at least one current-emitting electrode and said first return electrode to obtain a first indication of the resistivity of a first formation portion near said borehole; and measuring the difference in potential of a point in said borehole proximate said second pair of measuring electrodes and the potential at another point in said borehole for obtaining a second indication of the resistivity of a portion of said formation further removed from said borehole than said first formation portion.
References Cited (Backward Citations)
US2712631A
Cited
US2806201A
Cited
US2872637A
Cited
US2880389A
Cited
US3068401A
Cited
US3054046A
Cited
US3262050A
Cited
US3337794A
Cited
US3365658A
Cited
US3452269A
Cited
USPTO Annuity & Maintenance Windows
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| 3.5 Years (Year 4) | 1978-05-05 | 1978-11-04 | 1979-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-05 | 1982-11-04 | 1983-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-05 | 1986-11-04 | 1987-05-06 | $7700.00 | Window Closed / Lapsed |