US4087741A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Downhole geoelectric remote sensing method
Assignee: BP Corp North America Inc
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Filing: 1976-08-24
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Granted: 1978-05-02
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Expires: 1996-08-24
Abstract
Abstract A simple geoelectric remote sensing cable comprising a single current electrode and a relatively large number of sensing, or potential, electrodes. The current electrode is at the center of the logging cable and the sensing electrodes are arranged symmetrically about the current electrode in such a manner that the spacing between adjacent sensing electrodes increases with distance from the current electrode. In the preferred embodiment, the sensing electrode spacings are all integral multiples of a basic interval unit, such as two and one-half feet. The cable is pulled from the bottom of a borehole to the top at a fixed rate while a fixed current is supplied to the current electrode and the voltage differences between each adjacent pair of sensing electrodes are recorded after each movement of a distance equal to the basic interval or an integral fraction thereof. In the preferred embodiment, four-point electrode type of resistivity calculations are then made using the recorded data and the superposition principle.
Inventors
- 👤 Irshad R. Mufti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 02:36
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/20; G01V3/24
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
173 words
A method of exploring for electrically resistive geological anomalies lateral to but not penetrated by a borehole comprising: traversing the borehole with an electrode array comprising a current electrode for passing current into earth formations cut by the borehole and a plurality of upper and a plurality of lower voltage sensing electrodes positioned above and below, respectively, the current electrode, passing current into the earth formations by means of the current electrode and a ground electrode at the earth's surface; recording the potential differences induced by said current in the formations between each adjacent pair of said upper and lower voltage sensing electrodes at each of a plurality of positions of said electrode array in the borehole, and combining a first potential difference from said upper voltage sensing electrodes recorded at a first of said electrode array positions with a second potential difference from said lower voltage sensing electrodes recorded at a second of said electrode array positions to obtain a potential difference from which a symmetrical formation resistivity value may be determined.
Claim 2
Independent Claim
173 words
A method of exploring for electrically resistive geological anomalies lateral to but not penetrated by a borehole comprising: traversing the borehole with an electrode array comprising a current electrode for passing current into earth formations cut by the borehole and a plurality of upper and a plurality of lower voltage sensing electrodes positioned above and below, respectively, the current electrode, passing current into the earth formations by means of the current electrode and a ground electrode at the earth's surface; recording the potential differences induced by said current in the formations between each adjacent pair of said upper and lower voltage sensing electrodes at each of a plurality of positions of said electrode array in the borehole, and combining a first potential difference from said upper voltage sensing electrodes recorded at a first of said electrode array positions with a second potential difference from said lower voltage sensing electrodes recorded at a second of said electrode array positions to obtain a potential difference from which a symmetrical formation resistivity value may be determined.
Claim 3
Dependent Claim
63 words
A method of exploring for electrically resistive geological anomalies according to claim 1 wherein said upper and lower voltage sensing electrodes are symmetrically spaced about the current electrode and the voltage sensing electrodes are spaced apart by distances which are integral multiples of a preselected minimum electrode spacing and said spacing increases with distance of the voltage sensing electrodes from the current electrode.
Claim 4
Dependent Claim
33 words
A method according to claim 2 wherein the voltage sensing electrode potential differences are recorded at electrode array positions which are spaced apart in the borehole by one-half the preselected minimum electrode spacing.
Claim 5
Dependent Claim
64 words
A method according to claim 2 wherein said first and second potential differences are recorded from electrode pairs which are spaced symmetrically about said current electrode and said first and second electrode array positions are selected so that said first and second potential differences are recorded at substantially the same borehole position and said first and second potential differences are combined by algebraic summation.
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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) | 1981-05-01 | 1981-10-31 | 1982-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-05-01 | 1985-10-31 | 1986-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-05-01 | 1989-10-31 | 1990-05-02 | $7700.00 | Window Closed / Lapsed |