Patent ID: 7622428

Claim:
A method of tertiary mineral oil production comprising introducing a water-soluble polymer into a mineral oil deposit, wherein the water-soluble polymer is in the form of a dispersion of the water-soluble polymer and at least one water-soluble polymeric stabilizer, and wherein the water-soluble polymer comprises at least 25% by weight of monoethylenically unsaturated monomers (A) having acidic groups and optionally monoethylenically unsaturated monomers (B) differing therefrom and/or optionally crosslinking agents (C) as monomeric building blocks, where the acidic groups are selected from the group consisting of carboxyl groups, sulfo groups or phosphonic acid groups, and wherein the viscosity of the dispersion increases with a pH change and/or dilution, wherein the at least one water-soluble polymeric stabilizer is selected from the group consisting of (a) graft polymers of vinyl acetate and/or vinyl propionate on polyethylene glycols, polyethylene glycols endcapped at one or both ends with alkyl, carboxyl or amino groups, copolymers of alkylpolyalkylene glycol acrylates or alkylpolyalkylene glycol methacrylates and acrylic acid and/or methacrylic acid, polyalkylene glycols or polyalkylene glycols endcapped at one or both ends with alkyl, carboxyl or amino groups, (b) hydrolyzed copolymers of vinyl alkyl ethers and maleic anhydride in the form of the free carboxyl groups and in the form of the salts at least partly neutralized with alkali metal hydroxides and/or ammonium bases and/or a water-soluble starch from the group consisting of cationically modified potato starch, anionically modified potato starch, degraded potato starch and maltodextrin, and (c) water-soluble copolymers of (c1) nonionic monoethylenically unsaturated monomers selected from the group consisting of acrylamide, methacrylamide, N-vinylformamide, N-vinylpyrrolidone and/or N-vinylcaprolactam, (c2) cationic, monoethylenically unsaturated monomers selected from the group consisting of dialkylaminoalkyl acrylate, dialkylaminoalkyl methacrylate, partly or completely neutralized dialkylaminoalkyl(meth)acrylates, quaternized dialkylaminoalkyl(meth)acrylates, dialkyldiallylammonium halides, N-vinylimidazole and quaternized N-vinylimidazole, and optionally (c3) anionic acrylic acid, methacrylic acid, vinylsulfonic acid, vinylphosphonic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid and the alkali metal and ammonium salts of these acids, in the case of (c), the proportion of cationic monomers (c2) incorporated in the form of polymerized units being greater than that of the anionic monomers (c3), wherein the total amount of the at least one water-soluble polymeric stabilizer is from 25 to 200% by weight based on the total amount of water-soluble polymer.