US4458753A
Expired / Lapsed
US
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Stabilizing polysaccharide solutions for tertiary oil recovery at elevated temperature with borohydride
Assignee: Pfizer Inc
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Filing: 1982-10-15
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Granted: 1984-07-10
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Expires: 2002-10-15
Abstract
Abstract A method of tertiary oil recovery from petroleum-containing formations at elevated temperature comprises injecting a substantially oxygen-free aqueous saline solution of water-soluble polysaccharide biopolymer treated at pH of at least 5 by the addition of alkali metal borohydride as viscosity stabilizer.
Inventors
- 👤 Judson C. Philips
- 👤 Bryce E. Tate
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 14:50
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/60; C09K8/84; C09K8/86; C09K8/88; C09K8/90; C09K8/905; Y; Y10; Y10S; Y10S507/00; Y10S507/935; Y10S507/936
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
76 words
A method of oil recovery from a subterranean petroleum-containing formation at elevated temperature penetrated by at least one injection well and by one production well in fluid communication with the formation, which comprises injecting into said formation a substantially oxygen-free aqueous saline solution of a water-soluble polysaccharide biopolymer which has been treated in solution at a pH of at least about 5 by the addition of an effective amount of alkali metal borohydride as viscosity stabilizer.
Claim 2
Independent Claim
76 words
A method of oil recovery from a subterranean petroleum-containing formation at elevated temperature penetrated by at least one injection well and by one production well in fluid communication with the formation, which comprises injecting into said formation a substantially oxygen-free aqueous saline solution of a water-soluble polysaccharide biopolymer which has been treated in solution at a pH of at least about 5 by the addition of an effective amount of alkali metal borohydride as viscosity stabilizer.
Claim 3
Dependent Claim
24 words
The method of claim 1 wherein said biopolymer is derived from a fermentation broth containing cells of an organism belonging to the genus Xanthomonas.
Claim 4
Dependent Claim
18 words
The method of claim 2 wherein said addition is from about 10 to 50 ppm of sodium borohydride.
Claim 5
Dependent Claim
20 words
The method of claim 2 wherein said saline solution has a dissolved salt content of at least about 20,000 ppm.
Claim 6
Dependent Claim
18 words
The method of claim 1 wherein said addition is from about 5 to 100 ppm of said borohydride.
References Cited (Backward Citations)
US3096293A
Cited
US4218327A
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US4141842A
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US4256590A
Cited
GB2000823A
Cited
US4232739A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-07-10 | 1988-01-09 | 1988-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-10 | 1992-01-09 | 1992-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-10 | 1996-01-09 | 1996-07-10 | $7700.00 | Window Closed / Lapsed |