US4398151A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for correcting an electrical log for the presence of shale in a formation
Assignee: Shell USA Inc
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Filing: 1982-04-22
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Granted: 1983-08-09
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Expires: 2002-04-22
Abstract
Abstract An apparatus is disclosed for borehole measurements of the induced polarization of earth formations. The apparatus consists of an induced polarization logger capable of measuring both in-phase and quadrature conductivities in the frequency domain. A method is described which uses these measurements to determine cation exchange capacity per unit pore volume, Qv, brine conductivity, Cw, and oil and water saturations, So and Sw, in shaly sands.
Inventors
- 👤 Harold J. Vinegar
- 👤 Monroe H. Waxman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:17
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/38; G01V3/18; G01V3/20; G01V3/24
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
93 words
A method for providing a corrected electrical log of shaly sand formations penetrated by a wellbore using measurements made in-situ in the wellbore, said method comprising: inducing an electrical current in the formation; measuring both the in-phase C I and quadrature conductivity C Q of the formation in response to said induced current; determining the conductivity of C* of the formation from the relation ##EQU14## and recording the values of C* with respect to depth to provide an electrical log corrected for the presence of shale in said formations penetrated by the borehole.
Claim 2
Independent Claim
93 words
A method for providing a corrected electrical log of shaly sand formations penetrated by a wellbore using measurements made in-situ in the wellbore, said method comprising: inducing an electrical current in the formation; measuring both the in-phase C I and quadrature conductivity C Q of the formation in response to said induced current; determining the conductivity of C* of the formation from the relation ##EQU14## and recording the values of C* with respect to depth to provide an electrical log corrected for the presence of shale in said formations penetrated by the borehole.
Claim 3
Dependent Claim
17 words
The method of claim 1 wherein the in-phase and quadrature conductivities are measured in the frequency domain.
Claim 4
Dependent Claim
21 words
The method of claim 1 wherein the modulus of the conductivity and the phase angle are measured in the frequency domain.
Claim 5
Dependent Claim
17 words
The method of claim 1 wherein the electrical current has a frequency of less than 100 kHz.
Claim 6
Dependent Claim
22 words
The method of claim 1 and in addition determining the oil saturation of a shaly sand formation by using the equations ##EQU15##
Claim 7
Dependent Claim
52 words
The method of claim 1 and in addition determining the oil saturation of a shaly sand formation by first determining the formation water conductivity C w opposite an oil-free formation and then measuring the in-phase and quadrature conductivities opposite the oil-containing formation and determining the oil saturation from the following equations: ##EQU16##
Claim 8
Dependent Claim
50 words
The method of claim 1 wherein the current is generated in the formation using a first pair of spaced electrodes and the in-phase and quadrature voltage is measured between a second pair of spaced electrodes and where the in-phase and quadrature conductivity is determined from the aforementioned current and voltages.
References Cited (Backward Citations)
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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) | 1986-08-08 | 1987-02-07 | 1987-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-08 | 1991-02-07 | 1991-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-08 | 1995-02-07 | 1995-08-09 | $7700.00 | Window Closed / Lapsed |