Patent US3798533A successfully refreshed from Google Patents.
US3798533A
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 21:11
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/20; G01V3/24
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
183 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 a first current to a first one of said electrodes for emission into the media surrounding the mounting means, said first current returning to a relatively remote electrode for return to the current supplying means; means responsive to the potential difference measured between two points in said borehole for supplying a second current between said first electrode and an electrode relatively near said first electrode of sufficient magnitude to maintain said potential difference in a substantially fixed relationship; means responsive to the potential difference between two points in said borehole located a first distance apart for obtaining a measure of a characteristic of a first portion of said formation; and means responsive to the potential difference between two points in said borehole located a second distance apart for obtaining a measure of the characteristic of a second portion of said formation, said second formation portion being then different from said first formation portion.
Claim 2
Dependent Claim
183 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 a first current to a first one of said electrodes for emission into the media surrounding the mounting means, said first current returning to a relatively remote electrode for return to the current supplying means; means responsive to the potential difference measured between two points in said borehole for supplying a second current between said first electrode and an electrode relatively near said first electrode of sufficient magnitude to maintain said potential difference in a substantially fixed relationship; means responsive to the potential difference between two points in said borehole located a first distance apart for obtaining a measure of a characteristic of a first portion of said formation; and means responsive to the potential difference between two points in said borehole located a second distance apart for obtaining a measure of the characteristic of a second portion of said formation, said second formation portion being then different from said first formation portion.
Claim 3
Dependent Claim
256 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 pair of measuring electrodes located above said at least one current-emitting electrode and a second measuring electrode pair located below said one current-emitting electrode, a current return electrode pair having one electrode each located between said at least one current-emitting electrode and each of said measuring electrode pairs, and a third current return electrode spaced apart from said other electrodes; means for mounting said electrodes for passage through a borehole; means for supplying a first current to said at least one current-emitting electrode for emission into the media surrounding said mounting means, said first current returning to said third current return electrode for return to the current supplying means; means responsive to the potential difference between at least one of said pairs of measuring electrodes for supplying a second current between said at least one current-emitting electrode and one of said return electrode pairs or said third return electrode to maintain a given relationship between the potentials of said measuring electrodes; means responsive to the potential difference between two points in said borehole located a first distance apart for obtaining a measure of characteristic of a first portion of said formation; and means responsive to the potential difference measured between two points in said borehole located a second distance apart for obtaining a measure of a characteristic of a second portion of said formation which is different from said first formation portion.
Claim 4
Dependent Claim
256 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 pair of measuring electrodes located above said at least one current-emitting electrode and a second measuring electrode pair located below said one current-emitting electrode, a current return electrode pair having one electrode each located between said at least one current-emitting electrode and each of said measuring electrode pairs, and a third current return electrode spaced apart from said other electrodes; means for mounting said electrodes for passage through a borehole; means for supplying a first current to said at least one current-emitting electrode for emission into the media surrounding said mounting means, said first current returning to said third current return electrode for return to the current supplying means; means responsive to the potential difference between at least one of said pairs of measuring electrodes for supplying a second current between said at least one current-emitting electrode and one of said return electrode pairs or said third return electrode to maintain a given relationship between the potentials of said measuring electrodes; means responsive to the potential difference between two points in said borehole located a first distance apart for obtaining a measure of characteristic of a first portion of said formation; and means responsive to the potential difference measured between two points in said borehole located a second distance apart for obtaining a measure of a characteristic of a second portion of said formation which is different from said first formation portion.
Claim 5
Independent Claim
168 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 current between at least one current-emitting electrode and a first return electrode; measuring the potential distribution at borehole locations on opposite sides of said at least one current-emitting electrode; supplying auxiliary current between said at least one current-emitting electrode and two other electrodes of which one each is located between said at least one current-emitting electrode and each of said potential monitoring locations in response to measured potential distribution; measuring the potential difference between at least two points spaced a first distance apart in said borehole to obtain an indication of a characteristic of a first portion of said formation; and measuring the potential difference between at least two other points spaced a second distance apart in said borehole to obtain an indication of a characteristic of a second portion of said formation, said second formation portion being different from said first formation portion.
Claim 6
Independent Claim
168 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 current between at least one current-emitting electrode and a first return electrode; measuring the potential distribution at borehole locations on opposite sides of said at least one current-emitting electrode; supplying auxiliary current between said at least one current-emitting electrode and two other electrodes of which one each is located between said at least one current-emitting electrode and each of said potential monitoring locations in response to measured potential distribution; measuring the potential difference between at least two points spaced a first distance apart in said borehole to obtain an indication of a characteristic of a first portion of said formation; and measuring the potential difference between at least two other points spaced a second distance apart in said borehole to obtain an indication of a characteristic of a second portion of said formation, said second formation portion being different from said first formation portion.
Claim 7
Independent Claim
242 words
A method of measuring a characteristic of earth formations traversed by a borehole, comprising: moving a plurality of electrOdes through said borehole, said electrodes including at least one current-emitting electrode, a pair of measuring electrodes located above said at least one current-emitting electrode and a second measuring electrode located below said one current-emitting electrode, a current return electrode pair having one electrode each located between said at least one current-emitting electrode and each of said measuring electrode pairs, and a third current return electrode spaced apart from said other electrodes; supplying a first current to said at least one current-emitting electrode for emission into the media surrounding said borehole, said first current returning to said third current return electrode; supplying a second current between said at least one current-emitting electrode and one of said return electrode pairs or said third return electrode in response to the potential difference between at least one of said pairs of measuring electrodes to maintain a given relationship between the potentials of said measuring electrodes; providing a measure of a characteristic of a first portion of said formation in response to the potential difference between two points in said borehole located a first distance apart; providing a measure of a characteristic of a second portion of said formation in response to the potential difference between two points in said borehole located a second distance apart, said second portion being different from said first portion of said formation.
Claim 8
Independent Claim
242 words
A method of measuring a characteristic of earth formations traversed by a borehole, comprising: moving a plurality of electrOdes through said borehole, said electrodes including at least one current-emitting electrode, a pair of measuring electrodes located above said at least one current-emitting electrode and a second measuring electrode located below said one current-emitting electrode, a current return electrode pair having one electrode each located between said at least one current-emitting electrode and each of said measuring electrode pairs, and a third current return electrode spaced apart from said other electrodes; supplying a first current to said at least one current-emitting electrode for emission into the media surrounding said borehole, said first current returning to said third current return electrode; supplying a second current between said at least one current-emitting electrode and one of said return electrode pairs or said third return electrode in response to the potential difference between at least one of said pairs of measuring electrodes to maintain a given relationship between the potentials of said measuring electrodes; providing a measure of a characteristic of a first portion of said formation in response to the potential difference between two points in said borehole located a first distance apart; providing a measure of a characteristic of a second portion of said formation in response to the potential difference between two points in said borehole located a second distance apart, said second portion being different from said first portion of said formation.
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) | 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 |