US4706752A
Expired / Lapsed
US
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Method for foam emplacement in carbon dioxide enhanced recovery
Assignee: Union Oil Company of California
•
Filing: 1984-12-03
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Granted: 1987-11-17
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Expires: 2004-12-03
Abstract
Abstract The permeability of higher permeability zones of a subterranean reservoir of heterogeneous permeability is reduced by injecting an aqueous solution of a water soluble surface active agent and then a gas mixture comprising carbon dioxide and a noncondensible, non-hydrocarbon gas insoluble in viscous crude. A stable foam forms in situ useful for blocking escape of solvent fluids into the higher permeability zones of the reservoir during enhanced recovery, typically by carbon dioxide flooding. Preferably, the solution of surface active agent and the gas mixture are injected in alternating slugs to enhance foam formation.
Inventors
- 👤 LeRoy W. Holm
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 09:06
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/60; C09K8/92; C09K8/94; E; E21; E21B; E21B43/00; E21B43/16; E21B43/164
Claims Analysis
Total Claims: 61
Claim 1
Independent Claim
127 words
A method for reducing the permeability of higher permeability zones of an oil bearing subterranean reservoir having heterogeneous permeability and being penetrated by at least one well, said method comprising: (1) injecting through a well and into said reservoir: (a) an aqueous liquid solution of a water soluble surface active agent; (b) a foam emplacement gas mixture consisting essentially of carbon dioxide and a crude oil-insoluble, noncondensible, non-hydrocarbon gas, the injection being under conditions such that the gas mixture maintains a density between 0.01 and 0.42 grams per centimeter in the reservoir; (2) allowing stable foam to form in said higher permeability zones; (3) diverting subsequently injected gases into lower permeability zones of the reservoir without destroying the stable foam; and (4) producing oil from said reservoir.
Claim 2
Independent Claim
127 words
A method for reducing the permeability of higher permeability zones of an oil bearing subterranean reservoir having heterogeneous permeability and being penetrated by at least one well, said method comprising: (1) injecting through a well and into said reservoir: (a) an aqueous liquid solution of a water soluble surface active agent; (b) a foam emplacement gas mixture consisting essentially of carbon dioxide and a crude oil-insoluble, noncondensible, non-hydrocarbon gas, the injection being under conditions such that the gas mixture maintains a density between 0.01 and 0.42 grams per centimeter in the reservoir; (2) allowing stable foam to form in said higher permeability zones; (3) diverting subsequently injected gases into lower permeability zones of the reservoir without destroying the stable foam; and (4) producing oil from said reservoir.
Claim 3
Dependent Claim
26 words
The method of claim 1 wherein the foam emplacement gas mixture contains between about 0.5 and 20 volume percent of the crude oil-insoluble, noncondensible, non-hydrocarbon gas.
Claim 4
Dependent Claim
47 words
The method of claim 1 wherein the solution of surface-active agent contains between about 0.1 and 2.0 weight percent active surface-active agent and the amount of the solution injected is between about 0.1 and 10 volume percent of the total fluids injected in steps (1) and (2).
Claim 5
Dependent Claim
44 words
The method of claim 3 wherein between about 0.01 and 0.2 effective pore volume of the foam emplacement gas mixture and between about 0.01 and 0.1 effective pore volume of a 0.1 to 2.0 weight percent active solution of said surface-active agent is injected.
Claim 6
Dependent Claim
13 words
The method of claim 4 wherein the surface-active agent is dissolved in seawater.
Claim 7
Dependent Claim
25 words
The method of claim 1 wherein the crude oil-insoluble, noncondensible, non-hydrocarbon gas is selected from the group consisting of nitrogen, air, argon, or mixtures thereof.
Claim 8
Dependent Claim
13 words
The method of claim 6 wherein the crude oil-insoluble, noncondensible gas is nitrogen.
Claim 9
Dependent Claim
23 words
The method of claim 4 wherein a total of between about 0.01 and 0.05 effective pore volume of the gas mixture is injected.
Claim 10
Dependent Claim
47 words
The method of claim 4 wherein a total of between about 0.01 and 0.05 effective pore volume of the gas mixture is injected and between about 0.01 and 0.05 effective pore volume of a 0.5 to 1.0 weight percent active solution of surface active agent is injected.
Claim 11
Independent Claim
219 words
A method for reducing the permeability of higher permeability zones of a subterranean reservoir containing viscous crude oil, having heterogeneous permeability, and being penetrated by at least one injection well and one producing well comprising: (1) injecting sequentially through an injection well and into said reservoir: (a) a quantity of a gas flooding mixture comprising carbon dioxide sufficient to result in breakthrough of carbon dioxide at a producing well, said injection being at conditions such that the gas flooding mixuture maintains a density between about 0.01 and 0.42 grams per centimeter in the reservoir; (b) a liquid solution comprising a surface-active agent and a solvent for said surface-active agent selected from the group consisting of aqueous and hydrocarbon solvents; (c) a foam emplacement gas mixture consisting essentially of carbon dioxide and a crude oil-insoluble, noncondensible, non-hydrocarbon gas, said injection being at conditions such that the foam emplacement gas mixture maintains a density between about 0.01 and 0.42 grams per centimeter in the reservoir; (2) allowing a stable foam to form in said higher permeability zones by interaction of the solution of surface active agent and the crude oil-insoluble, noncondensible, non-hydrocarbon gas so that the permeability of said zones is thereby reduced; and (3) diverting subsequently injected gases into lower permeability zones of the reservoir without destroying the stable foam.
Claim 12
Independent Claim
219 words
A method for reducing the permeability of higher permeability zones of a subterranean reservoir containing viscous crude oil, having heterogeneous permeability, and being penetrated by at least one injection well and one producing well comprising: (1) injecting sequentially through an injection well and into said reservoir: (a) a quantity of a gas flooding mixture comprising carbon dioxide sufficient to result in breakthrough of carbon dioxide at a producing well, said injection being at conditions such that the gas flooding mixuture maintains a density between about 0.01 and 0.42 grams per centimeter in the reservoir; (b) a liquid solution comprising a surface-active agent and a solvent for said surface-active agent selected from the group consisting of aqueous and hydrocarbon solvents; (c) a foam emplacement gas mixture consisting essentially of carbon dioxide and a crude oil-insoluble, noncondensible, non-hydrocarbon gas, said injection being at conditions such that the foam emplacement gas mixture maintains a density between about 0.01 and 0.42 grams per centimeter in the reservoir; (2) allowing a stable foam to form in said higher permeability zones by interaction of the solution of surface active agent and the crude oil-insoluble, noncondensible, non-hydrocarbon gas so that the permeability of said zones is thereby reduced; and (3) diverting subsequently injected gases into lower permeability zones of the reservoir without destroying the stable foam.
Claim 13
Dependent Claim
25 words
The method of claim 10 wherein the foam emplacement gas mixture contains between about 0.5 and 20 volume percent of the crude oil-insoluble, noncondensible gas.
Claim 14
Dependent Claim
26 words
The method of claim 10 wherein the foam emplacement gas mixture contains between about 10 and 15 volume percent of the crude oil-insoluble, noncondensible, non-hydrocarbon gas.
Claim 15
Dependent Claim
46 words
The method of claim 10 wherein the solution of surface-active agent contains between about 0.1 and 2.0 weight percent active surface-active agent and the amount of the solution injected is between about 0.1 and 10 percent of the total fluids injected in steps (1) and (2).
Claim 16
Dependent Claim
42 words
The method of claim 10 wherein between about 0.01 and 0.2 pore volume of the foam emplacement gas mixture and between about 0.01 and 0.2 effective pore volume of a 0.1 to 2.0 weight percent active solution of surface-active agent is injected.
Claim 17
Dependent Claim
44 words
The method of claim 10 wherein between about 0.01 and 0.05 effective pore volume of a 0.5 to 1.0 percent solution of surface-active agent is injected followed by injection of between about 0.01 and 0.05 effective pore volume of the foam emplacement gas mixture.
Claim 18
Dependent Claim
55 words
The method of claim 13 wherein the surface-active agent is selected from the group consisting of dioctyl sodium sulfosuccinates, modified ether alcohol sulfate sodium salts, sodium lauryl sulfate, dioctyl sodium sulfosuccinate, and alkyl polyethylene oxide sulfates and the crude oil-insoluble, noncndensible gas is selected from the group consisting of nitrogen, air, argon, and mixtures thereof.
Claim 19
Dependent Claim
14 words
The method of claim 13 wherein the crude oil-insoluble, noncondensible, non-hydrocarbon gas comprises nitrogen.
Claim 20
Dependent Claim
136 words
A method of enhanced recovery of viscous oil from a subterranean formation having a heterogeneous permeability and containing viscous crude oil, said formation being penetrated by at least one injection well and at least one recovery well comprising: (1) utilizing the method of claim 10 for reducing the permeability of the higher permeability zones of the heterogeneous formation to form a stable foam therein; (2) injecting through the injection well and into the less permeable zones of the formation a gas flooding mixture comprising carbon dioxide so that the viscosity of the viscous oil is thereby reduced without destroying the stable foam; (3) injecting sufficient drive fluid through said injection well so that reduced viscosity oil is displaced from said reservoir; and (4) recovering the reduced viscosity oil displaced from said reservoir through a recovery well.
Claim 21
Dependent Claim
25 words
The method of claim 18 wherein the foam emplacement gas mixture contains between about 0.5 and 20 volume percent of a crude oil-insoluble, noncondensible gas.
Claim 22
Dependent Claim
46 words
The method of claim 18 wherein the solution comprising a surface active agent contains between about 0.5 and 1.0 percent active surface-active agent and the amount of the solution injected is between about 0.1 and 10 volume percent of the total fluids injected in step (1).
Claim 23
Dependent Claim
13 words
The method of claim 20 wherein the surface-active agent is dissolved in seawater.
Claim 24
Dependent Claim
36 words
The method of claim 20 wherein the surface-active agent is selected from the group consisting of dioctyl sodium sulfosuccinates, modified ether alcohol sulfate sodium salts, sodium lauryl sulfate, dioctyl sodium sulfosuccinate, and alkyl polyethylene oxide sulfates.
Claim 25
Independent Claim
15 words
The method of 20 wherein the surface active agent is an alkyl polyethylene oxide sulfate.
Claim 26
Independent Claim
15 words
The method of 20 wherein the surface active agent is an alkyl polyethylene oxide sulfate.
Claim 27
Independent Claim
185 words
A method for reducing the permeability of higher permeability zones of a subterranean reservoir containing viscous crude oil and having heterogeneous permeability, said reservoir being penetrated by at least one producing well and one injection well comprising: (1) injecting through a well and into said reservoir: (a) a quantity of a gas flooding mixture comprising carbon dioxide sufficient to result in breakthrough of carbon dioxide gas at a producing well, the injection being under conditions such that the gas flooding mixture maintains a density between about 0.01 and 0.42 grams per centimeter in said reservoir; (b) alternate slugs of (1) an aqueous liquid solution of a water soluble surface-active agent and (2) a gas mixture consisting essentially of carbon dioxide and a crude oil-insoluble, noncondensible, non-hydrocarbon gas; (2) allowing a stable foam to form in said higher permeability zones by interaction of said solution of surface active agent and said crude oil-insoluble, noncondensible, non-hydrocarbon gas so that the permeability of said zones is thereby reduced; and (3) diverting subsequently injected flooding gases into the lower permeability zones of the reservoir without destroying the stable foam.
Claim 28
Independent Claim
185 words
A method for reducing the permeability of higher permeability zones of a subterranean reservoir containing viscous crude oil and having heterogeneous permeability, said reservoir being penetrated by at least one producing well and one injection well comprising: (1) injecting through a well and into said reservoir: (a) a quantity of a gas flooding mixture comprising carbon dioxide sufficient to result in breakthrough of carbon dioxide gas at a producing well, the injection being under conditions such that the gas flooding mixture maintains a density between about 0.01 and 0.42 grams per centimeter in said reservoir; (b) alternate slugs of (1) an aqueous liquid solution of a water soluble surface-active agent and (2) a gas mixture consisting essentially of carbon dioxide and a crude oil-insoluble, noncondensible, non-hydrocarbon gas; (2) allowing a stable foam to form in said higher permeability zones by interaction of said solution of surface active agent and said crude oil-insoluble, noncondensible, non-hydrocarbon gas so that the permeability of said zones is thereby reduced; and (3) diverting subsequently injected flooding gases into the lower permeability zones of the reservoir without destroying the stable foam.
Claim 29
Dependent Claim
26 words
The method of claim 24 wherein the foam emplacement gas mixture contains between about 0.5 and 20 volume percent of a crude oil-insoluble, noncondensible, non-hydrocarbon gas.
Claim 30
Dependent Claim
45 words
The method of claim 24 wherein the solution comprising a surface-active agent contains between 0.1 and 2.0 weight percent active surface-active agent and the amount of the solution injected is between about 0.1 and 10 volume percent of the total fluids injected in step (1).
Claim 31
Dependent Claim
24 words
The method of claim 24 wherein the foam emplacement gas mixture contains between 10 and 15 volume percent of crude oil-insoluble, noncondensible, non-hydrocarbon gas.
Claim 32
Dependent Claim
40 words
The method of claim 27 wherein the solution comprising a surface active agent contains between 0.5 and 1.0 weight percent active surface-active agent, and between 4 and 10 alternate slugs of surface-active solution and foam emplacement gas mixture are employed.
Claim 33
Dependent Claim
14 words
The method of claim 24 wherein the surface active agent is dissolved in water.
Claim 34
Dependent Claim
13 words
The method of claim 24 wherein the surface-active agent is dissolved in seawater.
Claim 35
Dependent Claim
13 words
The method of claim 24 wherein the surface-active agent is dissolved in brine.
Claim 36
Dependent Claim
14 words
The method of claim 24 wherein the crude oil-insoluble, noncondensible, non-hydrocarbon gas is nitrogen.
Claim 37
Dependent Claim
36 words
The method of claim 24 wherein the surface-active agent is selected from the group consisting of dioctyl sodium sulfosuccinate, modified ether alcohol sulfate sodium salts, sodium lauryl sulfate, dioctyl sodium sulfosuccinate, and alkyl polyethylene oxide sulfates.
Claim 38
Dependent Claim
14 words
The method of claim 24 wherein the surface-active agent comprises alkyl polyethylene oxide sulfates.
Claim 39
Dependent Claim
68 words
The method of claim 24 wherein the slugs of the solution of surface-active agent are between 0.001 and 0.01 effective pore volume of the reservoir in size; the slugs of the foam emplacement gas mixture containing crude oil-insoluble, noncondensible gas are between 0.002 and 0.1 effective pore volume of the reservoir in size; and between about 4 and 10 alternating cycles of injection are performed in step (1)(b).
Claim 40
Dependent Claim
56 words
The method of claim 24 wherein the crude oil-insoluble, noncondensible, non-hydrocarbon gas is selected from the group consisting of nitrogen, air, argon, or mixtures thereof and the surface-active agent is selected from the group consisting of dioctyl sodium sulfosuccinate, modified ether alcohol sulfate sodium salts, sodium lauryl sulfates, dioctyl sodium sulfosuccinate, and alkyl polyethylene oxide sulfates.
Claim 41
Dependent Claim
14 words
The method of claim 36 wherein the crude oil-insoluble, noncondensible, non-hydrocarbon gas is nitrogen.
Claim 42
Dependent Claim
78 words
The method of claim 36 wherein the solution of surface-active agent contains between about 0.1 and 2.0 weight percent of active surface-active agent, the slugs of the solution of surface active agent are between about 0.001 and 0.01 effective pore volume in size, and the slugs of the foam emplacement gas mixture are between about 0.002 and 0.1 effective pore volume in size, and between about 5 and 7 alternating cycles of injection are preformed in step (1)(b).
Claim 43
Dependent Claim
148 words
A method for enhanced recovery of viscous oil from a subterranean formation having heterogeneous permeability and containing viscous crude oil, said formation being penetrated by at least one injection well and one recovery well comprising: (1) utilizing the method of claim 24 for reducing the permeability of the higher permeability zones of the heterogeneous formation by formation of a stable foam therein; (2) injecting through the injection well and into the lower permeability zones of the formation a gas flooding mixture comprising carbon dioxide so that the density of the gas flooding mixture is between about 0.01 and 0.42 grams per cubic centimeter within the reservoir, the viscosity of the crude oil thereby being reduced; (3) injecting sufficient drive fluid to displace the crude oil having reduced viscosity from the formation; and (4) recovering crude oil of lowered viscosity from a producing well without destroying the stable foam.
Claim 44
Dependent Claim
148 words
A method for enhanced recovery of viscous oil from a subterranean formation having heterogeneous permeability and containing viscous crude oil, said formation being penetrated by at least one injection well and one recovery well, said method comprising: (1) utilizing the method of claim 35, 36, or 38 for reducing the permeability of the higher permeability zones of the heterogeneous formation to place a stable foam therein; (2) injecting through an injection well and into the less permeable zones of the formation a gas flooding mixture comprising carbon dioxide so that the gas flooding mixture has a density between 0.01 and 0.42 grams per centimeter within the reservoir without substantial damage to the stable foam in the higher permeability zones; (3) injecting sufficient drive fluid through said injection well to displace crude oil from said reservoir; and (4) recovering crude oil displaced from said reservoir through a recovery well.
Claim 45
Independent Claim
142 words
A method for reducing the permeability of higher permeability zones of an oil bearing subterranean reservoir having heterogeneous permeability and being penetrated by at least one well, said method comprising: (1) injecting through a well and into said reservoir: (a) an aqueous liquid solution of a water soluble surface-active agent; (b) a foam emplacement gas mixture comprising carbon dioxide and a crude oil-insoluble, noncondensible, non-hydrocarbon gas, said gas being in a concentration between 5 and 20 volume percent of the mixture and the injection being under conditions such that the gas mixture maintains a density between 0.01 and 0 42 grams per centimeter in the reservoir; (2) allowing a stable foam to form in said higher permeability zones; (3) diverting subsequently injected gases into lower permeability zones of the reservoir without destroying the stable foam; and (4) producing oil from said reservoir.
Claim 46
Independent Claim
142 words
A method for reducing the permeability of higher permeability zones of an oil bearing subterranean reservoir having heterogeneous permeability and being penetrated by at least one well, said method comprising: (1) injecting through a well and into said reservoir: (a) an aqueous liquid solution of a water soluble surface-active agent; (b) a foam emplacement gas mixture comprising carbon dioxide and a crude oil-insoluble, noncondensible, non-hydrocarbon gas, said gas being in a concentration between 5 and 20 volume percent of the mixture and the injection being under conditions such that the gas mixture maintains a density between 0.01 and 0 42 grams per centimeter in the reservoir; (2) allowing a stable foam to form in said higher permeability zones; (3) diverting subsequently injected gases into lower permeability zones of the reservoir without destroying the stable foam; and (4) producing oil from said reservoir.
Claim 47
Dependent Claim
47 words
The method of claim 41 wherein the solution of surface-active agent contains between about 0.1 and 2.0 weight percent active surface-active agent and the amount of the solution injected is between about 0.1 and 10 volume percent of the total fluids injected in steps (1) and (2).
Claim 48
Dependent Claim
25 words
The method of claim 41 wherein the crude oil-insoluble, noncondensible, non-hydrocarbon gas is selected from the group consisting of nitrogen, air, argon, or mixtures thereof.
Claim 49
Dependent Claim
13 words
The method of claim 41 wherein the crude oil-insoluble, noncondensible gas is nitrogen.
Claim 50
Dependent Claim
23 words
The method of claim 41 wherein a total of between about 0.01 and 0.05 effective pore volume of the gas mixture is injected.
Claim 51
Independent Claim
234 words
A method for reducing the permeability of higher permeability zones of a subterranean reservoir containing viscous crude oil, having heterogeneous permeability, and being penetrated by at least one injection well and one producing well comprising: (1) injecting sequentially through an injection well and into said reservoir: (a) a quantity of a gas flooding mixture comprising carbon dioxide sufficient to result in breakthrough of carbon dioxide at a producing well, said injection being at conditions such that the gas flooding mixture maintains a density between about 0.01 and 0.42 grams per centimeter in the reservoir; (b) a liquid solution comprising a surface-active agent and a solvent for said surface-active agent selected from the group consisting of aqueous and hydrocarbon solvents; (c) a foam emplacement gas mixture comprising carbon dioxide and a crude oil-insoluble, noncondensible, non-hydrocarbon gas, said gas being in a concentration between 5 and 20 volume percent of the mixture and said injection being at conditions such that the foam emplacement gas mixture maintains a density between about 0.01 and 0.42 grams per centimeter in the reservoir; and (2) allowing a stable foam to form in said higher permeability zones by interaction of the solution of surface active agent and the crude oil-insoluble, noncondensible, non-hydrocarbon gas so that the permeability of said zones is thereby reduced; and (3) diverting subsequently injected gases into lower permeability zones of the reservoir without destroying the stable foam.
Claim 52
Independent Claim
234 words
A method for reducing the permeability of higher permeability zones of a subterranean reservoir containing viscous crude oil, having heterogeneous permeability, and being penetrated by at least one injection well and one producing well comprising: (1) injecting sequentially through an injection well and into said reservoir: (a) a quantity of a gas flooding mixture comprising carbon dioxide sufficient to result in breakthrough of carbon dioxide at a producing well, said injection being at conditions such that the gas flooding mixture maintains a density between about 0.01 and 0.42 grams per centimeter in the reservoir; (b) a liquid solution comprising a surface-active agent and a solvent for said surface-active agent selected from the group consisting of aqueous and hydrocarbon solvents; (c) a foam emplacement gas mixture comprising carbon dioxide and a crude oil-insoluble, noncondensible, non-hydrocarbon gas, said gas being in a concentration between 5 and 20 volume percent of the mixture and said injection being at conditions such that the foam emplacement gas mixture maintains a density between about 0.01 and 0.42 grams per centimeter in the reservoir; and (2) allowing a stable foam to form in said higher permeability zones by interaction of the solution of surface active agent and the crude oil-insoluble, noncondensible, non-hydrocarbon gas so that the permeability of said zones is thereby reduced; and (3) diverting subsequently injected gases into lower permeability zones of the reservoir without destroying the stable foam.
Claim 53
Dependent Claim
26 words
The method of claim 46 wherein the foam emplacement gas mixture contains between about 10 and 15 volume percent of the crude oil-insoluble, noncondensible, non-hydrocarbon gas.
Claim 54
Dependent Claim
42 words
The method of claim 46 wherein between about 0.01 and 0.2 pore volume of the foam emplacement gas mixture and between about 0.01 and 0.2 effective pore volume of a 0.1 to 2.0 weight percent active solution of surface-active agent is injected.
Claim 55
Dependent Claim
136 words
A method of enhanced recovery of viscous oil from a subterranean formation having a heterogeneous permeability and containing viscous crude oil, said formation being penetrated by at least one injection well and at least one recovery well comprising: (1) utilizing the method of claim 41 for reducing the permeability of the higher permeability zones of the heterogeneous formation to form a stable foam therein; (2) injecting through the injection well and into the less permeable zones of the formation a gas flooding mixture comprising carbon dioxide so that the viscosity of the viscous oil is thereby reduced without destroying the stable foam; (3) injecting sufficient drive fluid through said injection well so that reduced viscosity oil is displaced from said reservoir; and (4) recovering the reduced viscosity oil displaced from said reservoir through a recovery well.
Claim 56
Independent Claim
180 words
A method for reducing the permeability of higher permeability zones of a subterranean reservoir containing viscous crude oil and having heterogeneous permeability, said reservoir being penetrated by at least one producing well and one injection well comprising: (1) injecting through a well and into said reservoir: (a) a quantity of a gas flooding mixture comprising carbon dioxide sufficient to result in breakthrough of carbon dioxide gas to a producing well, the injection being under conditions such that the gas flooding mixture maintains a density between about 0.01 and 0.42 grams per centimeter in said reservoir; (b) alternate slugs of (1) an aqueous liquid solution of a water soluble surface-active agent and (2) a gas mixture comprising carbon dioxide and a crude oil-insoluble, noncondensible, non-hydrocarbon gas, said gas being in a concentration between about 5 and 20 volume percent of the mixture; and (2) allowing a stable foam to form in said higher permeability zones by interaction of said solution of surface active agent and said crude oil-insoluble, noncondensible, non-hydrocarbon gas so that the permeability of said zones is thereby reduced.
Claim 57
Independent Claim
180 words
A method for reducing the permeability of higher permeability zones of a subterranean reservoir containing viscous crude oil and having heterogeneous permeability, said reservoir being penetrated by at least one producing well and one injection well comprising: (1) injecting through a well and into said reservoir: (a) a quantity of a gas flooding mixture comprising carbon dioxide sufficient to result in breakthrough of carbon dioxide gas to a producing well, the injection being under conditions such that the gas flooding mixture maintains a density between about 0.01 and 0.42 grams per centimeter in said reservoir; (b) alternate slugs of (1) an aqueous liquid solution of a water soluble surface-active agent and (2) a gas mixture comprising carbon dioxide and a crude oil-insoluble, noncondensible, non-hydrocarbon gas, said gas being in a concentration between about 5 and 20 volume percent of the mixture; and (2) allowing a stable foam to form in said higher permeability zones by interaction of said solution of surface active agent and said crude oil-insoluble, noncondensible, non-hydrocarbon gas so that the permeability of said zones is thereby reduced.
Claim 58
Dependent Claim
24 words
The method of claim 50 wherein the foam emplacement gas mixture contains between 10 and 15 volume percent of crude oil-insoluble, noncondensible, non-hydrocarbon gas.
Claim 59
Dependent Claim
40 words
The method of claim 50 wherein the solution comprising a surface active agent contains between 0.5 and 1.0 weight percent active surface-active agent, and between 4 and 10 alternate slugs of surface-active solution and foam emplacement gas mixture are employed.
Claim 60
Dependent Claim
14 words
The method of claim 50 wherein the crude oil-insoluble, nonncondensible, non-hydrocarbon gas is nitrogen.
Claim 61
Dependent Claim
68 words
The method of claim 50 wherein the slugs of the solution of surface-active agent are between 0.001 and 0.01 effective pore volume of the reservoir in size; the slugs of the foam emplacement gas mixture containing crude oil-insoluble, noncondensible gas are between 0.002 and 0.1 effective pore volume of the reservoir in size; and between about 4 and 10 alternating cycles of injection are performed in step (1)(b).
References Cited (Backward Citations)
US3342256A
Cited
US3376924A
Cited
US3529668A
Cited
US3491832A
Cited
US3599715A
Cited
US3893511A
Cited
US3782470A
Cited
US3948323A
Cited
US4088190A
Cited
US4113011A
Cited
US4330038A
Cited
US4495995A
Cited
US4390068A
Cited
US4572294A
Cited
USPTO Annuity & Maintenance Windows
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| 3.5 Years (Year 4) | 1990-11-16 | 1991-05-18 | 1991-11-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-16 | 1995-05-18 | 1995-11-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-16 | 1999-05-18 | 1999-11-17 | $7700.00 | Window Closed / Lapsed |