US4529938A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High frequency induction method for locating the interface between formations having the same resistivity
Assignee: Shell USA Inc
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Filing: 1983-02-14
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Granted: 1985-07-16
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Expires: 2003-02-14
Abstract
Abstract A method for locating the interface between two formations wherein the two formations have different dielectric constants but may have the same resistivity. The method utilizes a high frequency induction logging tool having at least two receivers positioned equal distances on either side of the transducer. The difference in the phase angle and the logarithm ratio of the amplitudes between the two receiver signals are recorded with respect to depth to locate the interface.
Inventors
- 👤 Teruhiko Hagiwara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:53
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/26; G01V3/28
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
166 words
A method for locating the interface between two formations having the same resistivity but different dielectric constants and determining the thickness of the second formation comprising: inducing a high frequency current into the formations at a first position; measuring the depth at which said high frequency current was induced into the formation; measuring the resulting voltage induced at second and third positions spaced equal distances on each side of said first position; determining the difference in phase between the induced high frequency current and each of the measured voltages at said second and third positions to determine the phase of the measured voltages at said second and third positions; plotting the difference between the phases at said second and third positions in relation to the depth at which said high frequency current was induced in the formation to determine the interface between said two formations; and determining the thickness of said second formation by measuring the distance between negative and positive peaks in the phase difference.
Claim 2
Independent Claim
166 words
A method for locating the interface between two formations having the same resistivity but different dielectric constants and determining the thickness of the second formation comprising: inducing a high frequency current into the formations at a first position; measuring the depth at which said high frequency current was induced into the formation; measuring the resulting voltage induced at second and third positions spaced equal distances on each side of said first position; determining the difference in phase between the induced high frequency current and each of the measured voltages at said second and third positions to determine the phase of the measured voltages at said second and third positions; plotting the difference between the phases at said second and third positions in relation to the depth at which said high frequency current was induced in the formation to determine the interface between said two formations; and determining the thickness of said second formation by measuring the distance between negative and positive peaks in the phase difference.
Claim 3
Dependent Claim
32 words
The method of claim 1 wherein the second and third positions are located a distance from the first position no more than twice the thickness of the thinnest formation to be located.
Claim 4
Dependent Claim
36 words
The method of claim 1 and in addition, determining the relative logarithm ratio of the amplitude of the voltages measured at the second and third locations and plotting the relative logarithm ratio with relation to depth.
Claim 5
Dependent Claim
20 words
The method of claim 1, 2, or 3 wherein one formation is water bearing and the other is hydrocarbon bearing.
References Cited (Backward Citations)
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US2264318A
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US3249858A
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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) | 1988-07-15 | 1989-01-14 | 1989-07-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-07-15 | 1993-01-14 | 1993-07-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-07-15 | 1997-01-14 | 1997-07-16 | $7700.00 | Window Closed / Lapsed |