US4523642A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Oil recovery process employing CO2 produced in situ
Assignee: Mobil Oil AS
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Filing: 1984-04-09
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Granted: 1985-06-18
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Expires: 2004-04-09
Abstract
Abstract Recovery of oil from an oil-containing formation is effected by injection of steam followed by a soak period, if desired, and then injecting a mixture of sodium bicarbonate and citric acid that react in the formation to form carbon dioxide in situ. A driving fluid, preferably hot water or low quality steam (less than 20%), is then injected to displace the carbon dioxide and oil toward a production well for recovery. The process may be operated under conditions wherein the carbon dioxide formed in situ is miscible with the formation oil at the pressure and temperature of the formation thereby effecting miscible displacement and enhancing oil recovery.
Inventors
- 👤 Valadi N. Venkatesan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:05
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/58; C09K8/592; E; E21; E21B; E21B43/00; E21B43/16; E21B43/164; E21B43/24
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
127 words
A method for the recovery of oil from a subterranean, permeable, viscous oil-containing formation penetrated by at least one injection well and at least one spaced-apart production well, said wells being in fluid communication with a substantial portion of the formation, comprising: (a) injecting a predetermined amount of steam into the formation via said injection well; (b) injecting a sufficient amount of a mixture of sodium bicarbonate and citric acid into the formation via said injection well that react in the formation to form a predetermined amount of carbon dioxide; (c) injecting a driving fluid into the formation via said injection well to force said carbon dioxide through said formation to displace said oil; and (d) recovering fluid including oil from said formation via said production well.
Claim 2
Independent Claim
127 words
A method for the recovery of oil from a subterranean, permeable, viscous oil-containing formation penetrated by at least one injection well and at least one spaced-apart production well, said wells being in fluid communication with a substantial portion of the formation, comprising: (a) injecting a predetermined amount of steam into the formation via said injection well; (b) injecting a sufficient amount of a mixture of sodium bicarbonate and citric acid into the formation via said injection well that react in the formation to form a predetermined amount of carbon dioxide; (c) injecting a driving fluid into the formation via said injection well to force said carbon dioxide through said formation to displace said oil; and (d) recovering fluid including oil from said formation via said production well.
Claim 3
Dependent Claim
24 words
The method of claim 1 wherein the amount of steam injected during step (a) is within the range of 1.3 to 1.8 pore volumes.
Claim 4
Dependent Claim
39 words
The method of claim 1 wherein the amount of carbon dioxide formed during step (b) is within the range of about 350 to 600 SCF of CO 2 per barrel of steam (cold water equivalent) injected during step (a).
Claim 5
Dependent Claim
44 words
The method of claim 1 wherein the steam is injected at an injection rate within the range of 1 to 1.5 barrels of steam (cold water equivalent) per day per acre-foot of formation and steam quality is within the range of 50 to 90%.
Claim 6
Dependent Claim
37 words
The method of claim 1 wherein the driving fluid is selected from the group consisting of air, nitrogen, combustion gas, separator gas, natural gas, methane, water, hot water, low quality steam (less than 20%) and mixtures thereof.
Claim 7
Dependent Claim
12 words
The method of claim 1 wherein the driving fluid is hot water.
Claim 8
Dependent Claim
24 words
The method of claim 1 further including shutting in the injection well and allowing the formation to undergo a soak period after step (a).
Claim 9
Independent Claim
199 words
A method for the recovery of oil from a subterranean, permeable, viscous oil-containing formation penetrated by at least one injection well and at least one spaced-apart production well, said wells being in fluid communication with a substantial portion of the formation, comprising: (a) determining the minimum conditional miscibility pressure at the temperature of said formation at which carbon dioxide forms a miscible transition zone with said oil; (b) injecting a fluid into said formation to repressure said formation to a pressure at least that at which conditional miscibility exists at the temperature of said formation between said carbon dioxide and said oil; (c) injecting a predetermined amount of steam into the formation via said injection well at said pressure of step (b); (d) injecting a sufficient amount of a mixture of sodium bicarbonate and citric acid into the formation via said injection well at said pressure of step (b) that react in the formation to form a predetermined amount of carbon dioxide; (e) injecting a driving fluid into the formation via said injection well to force said carbon dioxide through said formation to displace said oil; and (f) recovering fluid including oil from said formation via said production well.
Claim 10
Independent Claim
199 words
A method for the recovery of oil from a subterranean, permeable, viscous oil-containing formation penetrated by at least one injection well and at least one spaced-apart production well, said wells being in fluid communication with a substantial portion of the formation, comprising: (a) determining the minimum conditional miscibility pressure at the temperature of said formation at which carbon dioxide forms a miscible transition zone with said oil; (b) injecting a fluid into said formation to repressure said formation to a pressure at least that at which conditional miscibility exists at the temperature of said formation between said carbon dioxide and said oil; (c) injecting a predetermined amount of steam into the formation via said injection well at said pressure of step (b); (d) injecting a sufficient amount of a mixture of sodium bicarbonate and citric acid into the formation via said injection well at said pressure of step (b) that react in the formation to form a predetermined amount of carbon dioxide; (e) injecting a driving fluid into the formation via said injection well to force said carbon dioxide through said formation to displace said oil; and (f) recovering fluid including oil from said formation via said production well.
Claim 11
Dependent Claim
24 words
The method of claim 8 wherein the amount of steam injected during step (c) is within the range of 1.3 to 1.8 pore volumes.
Claim 12
Dependent Claim
39 words
The method of claim 8 wherein the amount of carbon dioxide formed during step (d) is within the range of about 350 to 600 SCF of CO 2 per barrel of steam (cold water equivalent) injected during step (c).
Claim 13
Dependent Claim
44 words
The method of claim 8 wherein the steam is injected at an injection rate within the range of 1 to 1.5 barrels of steam (cold water equivalent) per day per acre-foot of formation and steam quality is within the range of 50 to 90%.
Claim 14
Dependent Claim
41 words
The method of claim 8 wherein the driving fluid injected during step (e) is selected from the group consisting of air, nitrogen, combustion gas, separator gas, natural gas, methane, water, hot water, low quality steam (less than 20%) and mixtures thereof.
Claim 15
Dependent Claim
16 words
The method of claim 8 wherein the driving fluid injecting during step (e) is hot water.
Claim 16
Dependent Claim
27 words
The method of claim 8 wherein said repressuring fluid is selected from the group consisting of air, nitrogen, combustion gas, natural gas, methane, water and mixtures thereof.
Claim 17
Dependent Claim
24 words
The method of claim 8 further including shutting in the injection well and allowing the formation to undergo a soak period after step (c).
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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) | 1988-06-17 | 1988-12-17 | 1989-06-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-06-17 | 1992-12-17 | 1993-06-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-06-17 | 1996-12-17 | 1997-06-18 | $7700.00 | Window Closed / Lapsed |