Patent US3798535A successfully refreshed from Google Patents.
US3798535A
Expired / Lapsed
US
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Methods and apparatus for investigating earth formations
Assignee: Schlumberger Technology Corp
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Filing: 1972-04-24
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Granted: 1974-03-19
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Expires: 1992-04-24
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
- 👤 N Schuster
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:58
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/20; G01V3/24
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
227 words
Apparatus for measuring a characteristic of earth formations traversed by a borehole, comprising: a plurality of electrodes including first and second currentemitting electroDes, a first return electrode located between said first and second current-emitting electrodes, a second current return electrode spaced apart from all of said electrodes, and a plurality of measuring electrodes located at various distances from said first current-emitting electrode; means for mounting said electrodes for passage through said borehole; means for supplying survey and auxiliary currents to said first current-emitting electrode, the auxiliary current returning to the first return electrode for return to the current supplying means and the survey current returning to the second return electrode for return to the current supplying means; means responsive to the potentials on at least some of said plurality of measuring electrodes for adjusting one of the auxiliary or survey currents to set up a desired potential distribution in at least one portion of said borehole so that said auxiliary current would tend to force the survey current into said formation; and means responsive to the potential on other of said measuring electrodes for supplying current to said second currentemitting electrode, said second current returning to said second current return electrode and being of sufficient magnitude to focus said survey current relatively deep into said formation to thereby obtain a measure of a characteristic of said formation.
Claim 2
Dependent Claim
227 words
Apparatus for measuring a characteristic of earth formations traversed by a borehole, comprising: a plurality of electrodes including first and second currentemitting electroDes, a first return electrode located between said first and second current-emitting electrodes, a second current return electrode spaced apart from all of said electrodes, and a plurality of measuring electrodes located at various distances from said first current-emitting electrode; means for mounting said electrodes for passage through said borehole; means for supplying survey and auxiliary currents to said first current-emitting electrode, the auxiliary current returning to the first return electrode for return to the current supplying means and the survey current returning to the second return electrode for return to the current supplying means; means responsive to the potentials on at least some of said plurality of measuring electrodes for adjusting one of the auxiliary or survey currents to set up a desired potential distribution in at least one portion of said borehole so that said auxiliary current would tend to force the survey current into said formation; and means responsive to the potential on other of said measuring electrodes for supplying current to said second currentemitting electrode, said second current returning to said second current return electrode and being of sufficient magnitude to focus said survey current relatively deep into said formation to thereby obtain a measure of a characteristic of said formation.
Claim 3
Dependent Claim
297 words
Apparatus for measuring a characteristic of earth formations traversed by a borehole, comprising: a plurality of electrodes; means for mounting said electrodes for passage through a borehole; means for supplying survey and a first current to at least one of said electrodes for emission to the media surrounding the mounting means, said survey current returning to a first electrode relatively distant from said at least one current-emitting electrode for return to the current supplying means and said first current returning to at least one electrode which is relatively near said at least one current-emitting electrode for return to the current supplying means; means responsive to the difference between the potentials at two points in said borehole for adjusting one of the survey or first currents to maintain a given potential distribution in at least a portion of said borehole so that said survey current will tend to be forced into said formation; second surrent supplying means for supplying second and third currents to at least one other current-emitting electrode, said second current returning to at least one electrode relatively near said at least one other current-emitting electrode and said third current returning to another current return electrode relatively distant from said near current return electrode; means responsive to the difference between the potentials at two other points in said borehole for adjusting one of the second or third currents to maintain a given potential distribution in at least a portion of the borehole so that said third current will tend to be forced into said formation; and means responsive to the difference between the potential at two points in said borehole for adjusting said third current to force said survey current relatively deep into said formation to thereby obtain a measure of a characteristic of said formation.
Claim 4
Dependent Claim
297 words
Apparatus for measuring a characteristic of earth formations traversed by a borehole, comprising: a plurality of electrodes; means for mounting said electrodes for passage through a borehole; means for supplying survey and a first current to at least one of said electrodes for emission to the media surrounding the mounting means, said survey current returning to a first electrode relatively distant from said at least one current-emitting electrode for return to the current supplying means and said first current returning to at least one electrode which is relatively near said at least one current-emitting electrode for return to the current supplying means; means responsive to the difference between the potentials at two points in said borehole for adjusting one of the survey or first currents to maintain a given potential distribution in at least a portion of said borehole so that said survey current will tend to be forced into said formation; second surrent supplying means for supplying second and third currents to at least one other current-emitting electrode, said second current returning to at least one electrode relatively near said at least one other current-emitting electrode and said third current returning to another current return electrode relatively distant from said near current return electrode; means responsive to the difference between the potentials at two other points in said borehole for adjusting one of the second or third currents to maintain a given potential distribution in at least a portion of the borehole so that said third current will tend to be forced into said formation; and means responsive to the difference between the potential at two points in said borehole for adjusting said third current to force said survey current relatively deep into said formation to thereby obtain a measure of a characteristic of said formation.
Claim 5
Dependent Claim
236 words
Apparatus for measuring a characteristic of earth formations traversed by a borehole, comprising: a plurality of electrodes including first and second current-emitting electrodes, a first return electrode located between said first and second current-emitting electrodes, a second current return electrode spaced apart from all of said electrodes, a plurality of measuring electrodes located at various distances from said first current-emitting electrode; means for mounting said electrodes for passage through a borehole; means for supplying survey and auxiliary currents to said first current-emitting electrode, the auxiliary current returning to the first return electrode for return to the current supplying means and the sUrvey current returning to the second return electrode for return to the current supplying means; means responsive to the potentials on at least some of said plurality of measuring electrodes for adjusting one of the auxiliary or survey currents to set up the desired potential distribution in at least one portion of the borehole so that said auxiliary current will tend to force the survey current into said formation; means responsive to the potentials on other of said measuring electrodes for supplying current between said second current-emitting electrodes and said return electrodes of sufficient magnitude to focus said survey current relatively deep into said formation; and means responsive to the potentials on a plurality of points along said borehole for obtaining a measure of a formation characteristic of at least one portion of said formation.
Claim 6
Dependent Claim
236 words
Apparatus for measuring a characteristic of earth formations traversed by a borehole, comprising: a plurality of electrodes including first and second current-emitting electrodes, a first return electrode located between said first and second current-emitting electrodes, a second current return electrode spaced apart from all of said electrodes, a plurality of measuring electrodes located at various distances from said first current-emitting electrode; means for mounting said electrodes for passage through a borehole; means for supplying survey and auxiliary currents to said first current-emitting electrode, the auxiliary current returning to the first return electrode for return to the current supplying means and the sUrvey current returning to the second return electrode for return to the current supplying means; means responsive to the potentials on at least some of said plurality of measuring electrodes for adjusting one of the auxiliary or survey currents to set up the desired potential distribution in at least one portion of the borehole so that said auxiliary current will tend to force the survey current into said formation; means responsive to the potentials on other of said measuring electrodes for supplying current between said second current-emitting electrodes and said return electrodes of sufficient magnitude to focus said survey current relatively deep into said formation; and means responsive to the potentials on a plurality of points along said borehole for obtaining a measure of a formation characteristic of at least one portion of said formation.
Claim 7
Independent Claim
266 words
A method of measuring a characteristic of earth formations traversed by a borehole, comprising: moving a plurality of electrodes through said borehole; supplying survey and a first current to at least one of said electrodes for emission into the media surrounding said electrodes, said survey current returning to a first electrode relatively distant from said at least one current-emitting electrode and said first current returning to at least one electrode which is relatively near said at least one current-emitting electrode; adjusting one of the survey or first currents to maintain a given potential distribution in at least a portion of said borehole in response to the difference between the potentials at two points in said borehole so that said survey current will tend to be forced into said formation; supplying second and third currents to at least one other current-emitting electrode, said second current returning to at least one electrode relatively near said at least one other current-emitting electrode and said third current returning to another current return electrode relatively distant from said near current return electrode; adjusting one of the second or third currents to maintain a given potential distribution in at least a portion of said borehole in response to the difference between the potentials at two other points in said borehole so that said third current will tend to be forced into said formation; and adjusting said third current in response to the difference in potential between two points in said borehole to force said survey current relatively deep into said formation to thereby obtain a measure of a characteristic of said formation.
Claim 8
Independent Claim
266 words
A method of measuring a characteristic of earth formations traversed by a borehole, comprising: moving a plurality of electrodes through said borehole; supplying survey and a first current to at least one of said electrodes for emission into the media surrounding said electrodes, said survey current returning to a first electrode relatively distant from said at least one current-emitting electrode and said first current returning to at least one electrode which is relatively near said at least one current-emitting electrode; adjusting one of the survey or first currents to maintain a given potential distribution in at least a portion of said borehole in response to the difference between the potentials at two points in said borehole so that said survey current will tend to be forced into said formation; supplying second and third currents to at least one other current-emitting electrode, said second current returning to at least one electrode relatively near said at least one other current-emitting electrode and said third current returning to another current return electrode relatively distant from said near current return electrode; adjusting one of the second or third currents to maintain a given potential distribution in at least a portion of said borehole in response to the difference between the potentials at two other points in said borehole so that said third current will tend to be forced into said formation; and adjusting said third current in response to the difference in potential between two points in said borehole to force said survey current relatively deep into said formation to thereby obtain a measure of a characteristic of said formation.
Claim 9
Independent Claim
204 words
A method of measuring a characteristic of earth formations traversed by a borehole, comprising: carrying a plurality of electrodes through said borehole said plurality of electrodes including first and second current-emitting electrodes, a first return electrode located between said first and second current-emitting electrodes, a second current return electrode spaced apart from all of said electrodes, a plurality of measuring electrodes located at various distances from said first current-emitting electrode; supplying survey and auxiliary currents to said first current-emitting electrode, the auxiliary current returning to said first return electrode and the survey current returning to said second return electrode; adjusting one of the auxiliary or survey currents to set up a desired potential distribution in at least one portion of said borehole in response to the potentials on at least some of said plurality of measuring electrodes, said auxiliary current tending to force the survey current into said formation; and supplying current to said second current-emitting electrode in response to the potential on other of said measuring electrodes, said second current returning to said second current return electrode and being of sufficient magnitude to focus said survey current relatively deep into said formation to thereby obtain a measure of a characteristic of said formation.
Claim 10
Independent Claim
204 words
A method of measuring a characteristic of earth formations traversed by a borehole, comprising: carrying a plurality of electrodes through said borehole said plurality of electrodes including first and second current-emitting electrodes, a first return electrode located between said first and second current-emitting electrodes, a second current return electrode spaced apart from all of said electrodes, a plurality of measuring electrodes located at various distances from said first current-emitting electrode; supplying survey and auxiliary currents to said first current-emitting electrode, the auxiliary current returning to said first return electrode and the survey current returning to said second return electrode; adjusting one of the auxiliary or survey currents to set up a desired potential distribution in at least one portion of said borehole in response to the potentials on at least some of said plurality of measuring electrodes, said auxiliary current tending to force the survey current into said formation; and supplying current to said second current-emitting electrode in response to the potential on other of said measuring electrodes, said second current returning to said second current return electrode and being of sufficient magnitude to focus said survey current relatively deep into said formation to thereby obtain a measure of a characteristic of said formation.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |