US3783683A
Expired / Lapsed
US
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Minimizing clay damage in a log-inject-log procedure
Assignee: BP America Production Co
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Filing: 1971-12-27
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Granted: 1974-01-08
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Expires: 1991-12-27
Abstract
Abstract This invention relates to determining the oil saturation in an underground rock reservoir penetrated by a well such as by use of a log-inject-log technique. In some such techniques thermal neutron decay time logs are taken in the native state and then after fresh water injection. These logs are used in an equation to find oil saturation. This invention is directed to a method of treating the fresh water so that clay impairment or permeability loss is prevented but such that the neutron capture cross section of the treated water is not significantly different from that of fresh water.
Inventors
- 👤 R Murphy
- 👤 F Jones
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:58
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/10; G01V5/107; E; E21; E21B; E21B49/00
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
121 words
A method of minimizing clay damage in a subsurface zone containing formation oil and formation water penetrated by a well bore in logging said zone which comprises the steps of: a. injecting a solution into the formation from the well bore, said solution being a divalent metallic salt whose cation has a thermal neutron capture cross section less than about 0.6 X 10 24 cm2 and having anions none of whose constituents has a thermal neutron capture cross section more than about 0.6 X 10 24 cm2 which upon dissolving in water generates essentially a neutral pH, the salt being at least 3,000 ppm in the solution, b. and then running a thermal neutron decay time log immediately following step (a).
Claim 2
Independent Claim
121 words
A method of minimizing clay damage in a subsurface zone containing formation oil and formation water penetrated by a well bore in logging said zone which comprises the steps of: a. injecting a solution into the formation from the well bore, said solution being a divalent metallic salt whose cation has a thermal neutron capture cross section less than about 0.6 X 10 24 cm2 and having anions none of whose constituents has a thermal neutron capture cross section more than about 0.6 X 10 24 cm2 which upon dissolving in water generates essentially a neutral pH, the salt being at least 3,000 ppm in the solution, b. and then running a thermal neutron decay time log immediately following step (a).
Claim 3
Dependent Claim
15 words
A method as defined in claim 1 in which the metallic salt is Mg SO4.
Claim 4
Dependent Claim
19 words
A method as defined in claim 2 in which the solution contains about 20,000 ppm of said Mg SO4.
References Cited (Backward Citations)
US3631245A
Cited
US3628011A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-07 | 1977-07-09 | 1978-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-07 | 1981-07-09 | 1982-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-07 | 1985-07-09 | 1986-01-08 | $7700.00 | Window Closed / Lapsed |