US4502541A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Staged preformed-surfactant-optimized aqueous alkaline flood
Assignee: Shell USA Inc
•
Filing: 1983-11-07
•
Granted: 1985-03-05
•
Expires: 2003-11-07
Abstract
Abstract Oil is recovered from an acidic oil reservoir by injecting an alkaline, saline, aqueous solution containing proportions of preformed cosurfactant which are decreased as increasing amounts of the solution are injected.
Inventors
- 👤 Jimmie B. Lawson
- 👤 David R. Thigpen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 02:46
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/58; Y; Y10; Y10S; Y10S507/00; Y10S507/935; Y10S507/936
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
82 words
A process for recovering oil from an acidic oil reservoir comprising: injecting into the reservoir an oil displacing fluid consisting essentially of a substantially oil-free aqueous alkaline solution containing at least one each of a dissolved alkaline material, a substantially neutral salt and a preformed cosurfactant material; arranging the composition of the injected fluid so that the initially injected portion contains a larger proportion of the cosurfactant than later injected portions of the fluid; and recovering oil displaced by the injected fluid.
Claim 2
Dependent Claim
82 words
A process for recovering oil from an acidic oil reservoir comprising: injecting into the reservoir an oil displacing fluid consisting essentially of a substantially oil-free aqueous alkaline solution containing at least one each of a dissolved alkaline material, a substantially neutral salt and a preformed cosurfactant material; arranging the composition of the injected fluid so that the initially injected portion contains a larger proportion of the cosurfactant than later injected portions of the fluid; and recovering oil displaced by the injected fluid.
Claim 3
Dependent Claim
24 words
The process of claim 1, in which the dissolved alkaline material consists essentially of at least one alkali metal salt of a weak acid.
Claim 4
Dependent Claim
40 words
The process of claim 1, in which the proportion of cosurfactant in later injected portions of the oil displacing fluid having a cosurfactant concentration which is from about 10 to 100 percent less than that of the initially injected portion.
Claim 5
Dependent Claim
22 words
The process of claim 1, in which the dissolved alkaline material consists essentially of a mixture of alkali metal carbonates and bicarbonates.
Claim 6
Dependent Claim
20 words
The process of claim 4, in which the pH of the oil displacement fluid is from about 10 to 13.
Claim 7
Dependent Claim
49 words
The process of claim 1 in which the proportion of alkali contained in the injected oil displacing fluid is sufficient to restrict the lag of the high pH to only from about 0.1 to 0.2 pore volumes during the injection of one pore volume of the oil displacing fluid.
Claim 8
Dependent Claim
24 words
The process of claim 6, in which the dissolved alkaline material consists essentially of at least one alkali metal salt of a weak acid.
Claim 9
Dependent Claim
40 words
The process of claim 6, in which the proportion of cosurfactant in later injected portions of the oil displacing fluid having a cosurfactant concentration which is from about 10 to 100 percent less than that of the initially injected portion.
Claim 10
Dependent Claim
22 words
The process of claim 6, in which the dissolved alkaline material consists essentially of a mixture of alkali metal carbonates and bicarbonates.
Claim 11
Dependent Claim
20 words
The process of claim 9, in which the pH of the oil displacement fluid is from about 10 to 13.
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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) | 1988-03-04 | 1988-09-03 | 1989-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-04 | 1992-09-03 | 1993-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-04 | 1996-09-03 | 1997-03-05 | $7700.00 | Window Closed / Lapsed |