ADDITION OF ZWITTERIONIC SURFACTANT TO WATER SOLUBLE POLYMER TO INCREASE STABILITY OF POLYMERS IN AQUEOUS SOLUTIONS CONTAINING SALT AND/OR SURFACTANTS Russian patent published in 2013 - IPC C09K8/68 E21B43/22 E21B43/267 

FIELD: chemistry.

SUBSTANCE: aqueous composition which contains a mixture of water, 0.05-10 wt % of at least one water-soluble polymer for obtaining a viscoelastic gel when dissolved in water, where concentration of the polymer exceeds critical gel-formation concentration, where the water-soluble polymer has number-average molecular weight from 5 kg/mol to 20000 kg/mol and contains one or more polymers from a given group, a surfactant which contains 0.08-3 wt % crude mass from a zwitterionic surfactant selected from: alkyl betaines and alkylamidopropyl betaine, sulphobetaines and alkyl sultaines, alkyl ethers of hydroxypropyl sultaines and alkylamidopropyl hydroxysultaines, where the alkyl contains 18-22 carbon atoms, and optionally less than 0.3 wt % of each of an anionic, amphoteric and nonionic surfactant and 0.1-20 wt % of a crude mass of an inorganic salt selected from: univalent ions, divalent ions and trivalent chloride, bromide, sulphate, carbonate and nitrate ions and optionally a propping agent. A method of extracting a hydrocarbon from an underground formation involves feeding an aqueous fluid containing said composition into the formation. The aqueous composition consists of a mixture of: water, 0.05-10 wt % water-soluble polymer for producing a viscoelastic gel when dissolved in water, where concentration of the polymer exceeds critical gel-formation concentration, the water-soluble polymer has number-average molecular weight of 5-2000 kg/mol and contains one or more polymers from a given group, 0.08-3 wt % of a crude mass of a zwitterionic surfactant selected from: alkyl betaines and alkylamidopropyl betaine, sulphobetaines and alkyl sultaines, alkyl ethers of hydroxypropyl sultaines and alkylamidopropyl hydroxysultaines, where the alkyl contains 18-22 carbon atoms, less than 0.3 wt % of each of an anionic, amphoteric and nonionic surfactant, at least one component selected from: a propping agent, cosolvents, acids, bases, buffers, chelating agents for controlling multivalent cations, freezing point depressants, clay or sand stabilising materials, biopolysaccharides, cellulose ethers, acrylamide polymers, corrosion inhibitors, oxygen acceptors, bactericides, where the clay or sand stabilising materials are selected from: epoxy resins, poly(N-acrylamidomethyl-trimethylammonium chloride) and poly(vinylbenzyltrimethylammonium chloride); cosolvents are selected from: propylene glycol or glycerin, or an aliphatic alcohol having 4-24 carbon atoms; 0.1-20 wt % of a crude mass of an inorganic salt selected from: univalent ions, divalent ions and trivalent ions. The invention is developed in subclaims.

EFFECT: high resistance to salts and surfactants.

28 cl, 1 tbl, 6 ex, 8 dwg