# US 5,706,895 A · Polymer enhanced foam workover, completion, and kill fluids > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,706,895 A - Document ID: US5706895A - Status: Granted - Kind: A - Application number: 08/568,869 - Filed: 1995-12-07 - Granted: 1998-01-13 - Earliest claimed: 1995-12-07 - Assignees: Marathon Oil Company - Inventors: Robert D. Sydansk - Web page: https://patentgrep.com/patent/US5706895A ## CPC - C09K 8/94: Foams - C09K 8/50: Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls (compositions for consolidating loose sand or the like around wells C09K8/56) - Y10S 507/925: Completion or workover fluid - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract Polymer enhanced foam fluid is utilized for completion, workover, and kill operations in wells penetrating subterranean formations. The foam is formed by appropriately adding a gas to an aqueous solution of a substantially noncrosslinked water soluble polymer and a surfactant. The solution and the foam are substantially free of crosslinking agents. The foam may be generated at the surface or in a wellbore. ## Claims ### Claim 1 A process for use during hydrocarbon well completion, workover, and kill operations, the process comprising the steps of: (a) preparing an aqueous solution of a water-soluble, substantially noncrosslinked polymer and a water-soluble surfactant, the aqueous solution being substantially free of agents capable of crosslinking the polymer; and (b) adding a gas to said aqueous solution so as to form a polymer enhanced foam; and (c) placing said foam in a well penetrating a subterranean formation during a completion, workover, or kill operation. ### Claim 2 (depends on 1) The process of claim 1 wherein said gas is added to said solution prior to placing said solution in said well. ### Claim 3 (depends on 1) The process of claim 1 wherein said gas is added to said solution as said solution is placed in said well. ### Claim 4 (depends on 1) The process of claim 1 wherein said gas is added to said solution within said well. ### Claim 5 (depends on 1) The process of claim 1 wherein said foam is a well completion fluid and step (c) involves placing said foam in said well penetrating said subterranean formation during a completion operation. ### Claim 6 (depends on 1) The process of claim 1 wherein said foam is a workover fluid and step (c) involves placing said foam in said well penetrating said subterranean formation during a workover operation. ### Claim 7 (depends on 1) The process of claim 1 wherein said process additionally comprises the step of adjusting the pH of said aqueous solution to a value between about 4 and about 10. ### Claim 8 (depends on 1) The process of claim 1 additionally comprising the step of mixing a foam breaker with said foam. ### Claim 9 (depends on 1) The process of claim 1 wherein said formation is hydrocarbon bearing. ### Claim 10 (depends on 1) The process of claim 1 wherein said surfactant is selected from the group consisting of ethoxylated alcohols, ethoxylated sulfates, refined sulfonates, petroleum sulfonates, alpha olefin sulfonates, and mixtures thereof. ### Claim 11 (depends on 1) The process of claim 1 wherein said surfactant is present in an amount between about 20 ppm and 50,000 ppm of said solution. ### Claim 12 (depends on 1) The process of claim 1 wherein said surfactant is present in and amount between about 50 ppm and 20,000 ppm of said solution. ### Claim 13 (depends on 1) The process of claim 1 wherein said surfactant is present in an amount between about 1,000 ppm and 20,000 ppm of said solution. ### Claim 14 (depends on 1) The process of claim 1 wherein said gas is selected from the group consisting of nitrogen, air, carbon dioxide, flue gas, produced gas, natural gas, and mixtures thereof. ### Claim 15 (depends on 1) The process of claim 1 wherein said gas is selected from the group consisting of nitrogen, carbon dioxide, and mixtures thereof. ### Claim 16 (depends on 1) The process of claim 1 wherein said foam has a gas content between about 20 per cent and about 99 per cent by volume. ### Claim 17 (depends on 1) The process of claim 1 wherein said foam has a gas content between about 60 per cent and about 98 per cent by volume. ### Claim 18 (depends on 1) The process of claim 1 wherein said foam has a gas content between about 70 per cent and about 97 per cent by volume. ### Claim 19 (depends on 1) The process of claim 1 wherein said polymer is selected from the group consisting of biopolymers, acrylamide polymers, and mixtures thereof. ### Claim 20 (depends on 19) The process of claim 19 wherein said biopolymers are selected from the group consisting of xanthan gum, guar gum, succinoglycan, scleroglycan, polyvinylsaccharides, carboxymethylcellulose, o-carboxychitosans, hydroxyethylcellulose, hydroxypropylcellulose, modified starches, and mixtures thereof. ### Claim 21 (depends on 19) The process of claim 19 wherein said acrylamide polymer is selected from the group consisting of polyacrylamide; partially hydrolyzed polyacrylamide; acrylamide copolymers; acrylamide terpolymers containing acrylamide, a second species, and a third species; tetrapolymers containing acrylamide, acrylate, a third species, and a fourth species; and mixtures thereof. ### Claim 22 (depends on 21) The process of claim 21 wherein said acrylamide polymer has a molecular weight between about 10,000 and about 50,000,000. ### Claim 23 (depends on 21) The process of claim 21 wherein said acrylamide polymer has a molecular weight between about 250,000 and about 20,000,000. ### Claim 24 (depends on 21) The process of claim 21 wherein said acrylamide polymer has a molecular weight between about 1,000,000 and about 18,000,000. ### Claim 25 (depends on 21) The process of claim 21 wherein said acrylamide polymer is present in said solution in an amount between about 100 ppm and about 80,000 ppm. ### Claim 26 (depends on 21) The process of claim 21 wherein said acrylamide polymer is present in said solution in an amount between about 500 ppm and about 12,000 ppm. ### Claim 27 (depends on 21) The process of claim 21 wherein said acrylamide polymer is present in said solution in an amount between about 2,000 ppm and about 10,000 ppm. ### Claim 28 (depends on 1) The process of claim 1 wherein said aqueous solution comprises a solvent selected from the group consisting of fresh water and brine. ### Claim 29 (depends on 1) The process of claim 1 wherein said foam is stable in glassware at atmospheric pressure for at least about 6 hours. ### Claim 30 (depends on 1) The process of claim 1 wherein said gas becomes a liquid or a supercritical fluid under temperature and pressure conditions encountered in said well thereby causing said polymer enhanced foam to become an emulsion. ### Claim 31 A process for use during a hydrocarbon well kill operation, the process comprising the steps of: (a) preparing an aqueous solution of a water-soluble, substantially noncrosslinked polymer and a water-soluble surfactant, the aqueous solution being substantially free of agents capable of crosslinking the polymer; and (b) adding a gas to said aqueous solution so as to form a polymer enhanced foam; and (c) placing said foam in a well penetrating a subterranean formation during a kill operation. ### Claim 32 A process for use during hydrocarbon well completion, workover, and kill operations, the process comprising the steps of: (a) preparing an aqueous solution of a water-soluble, substantially noncrosslinked polymer and a water-soluble surfactant, the aqueous solution being substantially free of agents capable of crosslinking the polymer; and (b) adding a gas to said aqueous solution so as to form a polymer enhanced foam which is a shear thinning fluid; and (c) placing said foam in a well penetrating a subterranean formation during a completion, workover, or kill operation. ### Claim 33 A process for use during hydrocarbon well completion, workover, and kill operations, the process comprising the steps of: (a) preparing an aqueous solution of a water-soluble, substantially noncrosslinked polymer and a water-soluble surfactant, the aqueous solution being substantially free of agents capable of crosslinking the polymer; and (b) adding a gas to said aqueous solution so as to form a polymer enhanced foam which is rehealable; and (c) placing said foam in a well penetrating a subterranean formation during a completion, workover, or kill operation.