# US 11,299,663 B2 · Method for modifying well injection profile and enhanced oil recovery > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,299,663 B2 - Document ID: US11299663B2 - Status: Granted - Kind: B2 - Application number: 16/892,784 - Filed: 2020-06-04 - Published: 2021-12-09 - Granted: 2022-04-12 - Earliest claimed: 2020-06-04 - Assignees: Saudi Arabian Oil Company - Applicants: Saudi Arabian Oil Company - Inventors: Ali Abdullah Al-Taq; Zuhair AlYousif; Othman Alswaie - Web page: https://patentgrep.com/patent/US11299663B2 ## CPC - C09K 8/594: Compositions used in combination with injected gas {, e.g. CO2 orcarbonated gas}(C09K8/592 takes precedence) - E21B 43/16: Enhanced recovery methods for obtaining hydrocarbons - E21B 43/164: {Injecting CO2 or carbonated water (in combination with organic material C09K8/594)} - E21B 43/166: {Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium (CO2 injection E21B43/164; steam injection E21B43/24)} - E21B 43/24: using heat, e.g. steam injection - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract 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. ## Claims ### Claim 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. ### Claim 2 (depends on 1) The method of claim 1, wherein the aqueous solution and the supercritical carbon dioxide are co-injected. ### Claim 3 (depends on 1) 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. ### Claim 4 (depends on 3) The method of claim 3, further comprising recovering the hydrocarbons that are displaced. ### Claim 5 (depends on 3) The method of claim 3, wherein the pre-flushed hydrocarbon-containing formation comprises a zone of high permeability and a zone of low permeability. ### Claim 6 (depends on 5) 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. ### Claim 7 (depends on 1) The method of claim 1, wherein the aqueous solution comprises a mixture of a first aqueous solution and a second aqueous solution. ### Claim 8 (depends on 7) 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. ### Claim 9 (depends on 7) 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. ### Claim 10 (depends on 7) The method of claim 7, wherein one or more of the first aqueous solution and the second aqueous solutions contains the foaming agent. ### Claim 11 (depends on 1) 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. ### Claim 12 (depends on 2) The method of claim 2, wherein the supercritical carbon dioxide has a quality in the range of 10 to 90%. ### Claim 13 (depends on 1) 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. ### Claim 14 (depends on 13) The method of claim 13, wherein the pH decrease is caused by the portion of the supercritical carbon dioxide dissolving into the aqueous solution. ### Claim 15 (depends on 1) 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. ### Claim 16 (depends on 15) The method of claim 15, wherein the temperature increase is caused by the portion of the supercritical carbon dioxide dissolving into the aqueous solution. ### Claim 17 (depends on 1) The method of claim 1, wherein the foam has an apparent viscosity in a range of about 1 to 50 cP. ### Claim 18 (depends on 1) The method of claim 1, wherein the foam has a quality in a range of about 50 to 99%. ### Claim 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. ### Claim 20 (depends on 19) The method of claim 19, wherein the solution comprises a mixture of a first aqueous solution and a second aqueous solution. ### Claim 21 (depends on 20) 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. ### Claim 22 (depends on 20) 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. ### Claim 23 (depends on 20) The method of claim 20, wherein one or more of the first aqueous solution and the second aqueous solutions contains the foaming agent. ### Claim 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. ### Claim 25 (depends on 24) The method of claim 24, wherein one or more of the first aqueous solution and the second aqueous solutions contains the foaming agent. ### Claim 26 (depends on 24) The method of claim 24, wherein a pH decrease is caused by the portion of the supercritical carbon dioxide dissolving into the aqueous solution. ### Claim 27 (depends on 24) The method of claim 24, wherein the foam has a quality in a range of about 50 to 99%.