Method for modifying well injection profile and enhanced oil recovery
A method for treating a hydrocarbon-containing formation includes injecting an aqueous solution that contains an alkali nitrite, an ammonium halide, and a foaming agent into the formation, injecting supercritical carbon dioxide into the formation, allowing a portion of the carbon dioxide to dissolve in the aqueous solutions, causing the alkali nitrite and ammonium halide to react and generate nitrogen gas, and allowing a foam to form by the interaction of the nitrogen gas with the foaming agent.
1. A method for treating a hydrocarbon-containing formation, comprising:
pre-flushing the hydrocarbon-containing formation with a flushing solution comprising a foaming agent to form a pre-flushed hydrocarbon-containing formation;
injecting an aqueous solution that contains an alkali nitrite, an ammonium halide, and the foaming agent into the pre-flushed hydrocarbon-containing formation; and
injecting a supercritical carbon dioxide into the pre-flushed hydrocarbon-containing formation;
where a portion of the supercritical carbon dioxide dissolves into the aqueous solution causing the alkali nitrite and the ammonium halide to react and generate a nitrogen gas; and
where a foam forms by the interaction of the nitrogen gas with the foaming agent.
2. The method of claim 1 , wherein the aqueous solution and the supercritical carbon dioxide are co-injected.
3. The method of claim 1 , further comprising displacing hydrocarbons from the pre-flushed hydrocarbon-containing formation by forcing the portion of the supercritical carbon dioxide and the aqueous solution through the pre-flushed hydrocarbon-containing formation.
4. The method of claim 3 , further comprising recovering the hydrocarbons that are displaced.
5. The method of claim 3 , wherein the pre-flushed hydrocarbon-containing formation comprises a zone of high permeability and a zone of low permeability.
6. The method of claim 5 , wherein the at least a portion of the supercritical carbon dioxide and the aqueous solution are forced through the zone of low permeability.
7. The method of claim 1 , wherein the aqueous solution comprises a mixture of a first aqueous solution and a second aqueous solution.
8. The method of claim 7 , wherein the first aqueous solution contains the ammonium halide in a concentration of the range of 0.5 to 13 M.
9. The method of claim 7 , wherein the second aqueous solution contains the alkali nitrite in a concentration of the range of 1 to 15 M.
10. The method of claim 7 , wherein one or more of the first aqueous solution and the second aqueous solutions contains the foaming agent.
11. The method of claim 1 , wherein a molar ratio of the ammonium halide to the alkali nitrite that are injected into the formation is of the range of 1:1 to 1:3.
12. The method of claim 2 , wherein the supercritical carbon dioxide has a quality in the range of 10 to 90%.
13. The method of claim 1 , wherein the reaction between the alkali nitrite and the ammonium halide is triggered by a pH of the aqueous solutions decreasing to 5 or less.
14. The method of claim 13 , wherein the pH decrease is caused by the portion of the supercritical carbon dioxide dissolving into the aqueous solution.
15. The method of claim 1 , wherein the reaction between the alkali nitrite and the ammonium halide is triggered by a temperature of the aqueous solutions increasing to 60° C. or more.
16. The method of claim 15 , wherein the temperature increase is caused by the portion of the supercritical carbon dioxide dissolving into the aqueous solution.
17. The method of claim 1 , wherein the foam has an apparent viscosity in a range of about 1 to 50 cP.
18. The method of claim 1 , wherein the foam has a quality in a range of about 50 to 99%.
19. A method for enhanced oil recovery, comprising:
pre-flushing the hydrocarbon-containing formation with a flushing solution comprising the foaming agent to form a pre-flushed hydrocarbon-containing formation;
injecting a solution comprising an alkali nitrite, an ammonium halide, and the foaming agent into a high permeability zone of the pre-flushed hydrocarbon-containing formation;
decreasing a pH of the solution by injecting a supercritical carbon dioxide into the high permeability zone of the pre-flushed hydrocarbon-containing formation such that the alkali nitrite and the ammonium halide react to generate a nitrogen gas that forms a foam with the foaming agent in the high permeability zone and such that wormholes form in a low permeability zone of the pre-flushed hydrocarbon-containing formation such that hydrocarbons in the low permeability zone of the pre-flushed hydrocarbon-bearing formation are stimulated; and
producing hydrocarbons from the pre-flushed hydrocarbon-containing formation.
20. The method of claim 19 , wherein the solution comprises a mixture of a first aqueous solution and a second aqueous solution.
21. The method of claim 20 , wherein the first aqueous solution contains the ammonium halide in a concentration of a range of 0.5 to 13 M.
22. The method of claim 20 , wherein the second aqueous solution contains the alkali nitrite in a concentration of a range of 1 to 15 M.
23. The method of claim 20 , wherein one or more of the first aqueous solution and the second aqueous solutions contains the foaming agent.
24. A method for treating a hydrocarbon-containing formation, comprising:
pre-flushing the hydrocarbon-containing formation with a flushing solution comprising the foaming agent to form a pre-flushed hydrocarbon-containing formation;
injecting an aqueous solution that contains an alkali nitrite, an ammonium halide, and the foaming agent into the pre-flushed hydrocarbon-containing formation, wherein the aqueous solution comprises a mixture of a first aqueous solution containing the ammonium halide in a concentration of a range of 0.5 to 13 M and a second aqueous solution containing the alkali nitrite in a concentration of a range of 1 to 15 M, and a molar ratio of the ammonium halide to the alkali nitrite of a range of 1:1 to 1:3;
injecting a supercritical carbon dioxide into the pre-flushed hydrocarbon-containing formation such that a portion of the supercritical carbon dioxide dissolves in the aqueous solution and causes the alkali nitrite and the ammonium halide to react and generate a nitrogen gas,
wherein the reaction between the alkali nitrite and the ammonium halide is triggered by a pH of the aqueous solutions decreasing to 5 or less; and such that a foam having a viscosity in a range of about 1 to 50 cP to forms by an interaction of the nitrogen gas with the foaming agent.
25. The method of claim 24 , wherein one or more of the first aqueous solution and the second aqueous solutions contains the foaming agent.
26. The method of claim 24 , wherein a pH decrease is caused by the portion of the supercritical carbon dioxide dissolving into the aqueous solution.
27. The method of claim 24 , wherein the foam has a quality in a range of about 50 to 99%.