METHOD OF OIL RECOVERY BY TERTIARY METHODS Russian patent published in 2018 - IPC E21B43/22 C09K8/588 

FIELD: oil and gas industry.

SUBSTANCE: method of oil recovery in which an injected aqueous agent containing at least water-soluble polyacrylamide PAA (co)polymer dissolved in water-based liquid, pumped through at least one injection well into oil-bearing deposit, and crude oil is extracted from deposit through at least one production well. The method includes at least the following stages: providing liquid dispersion polymer composition, at least, containing, wt %: 20-59.9 of organic hydrophobic liquid with boiling point above 100°C, 40-79.9 of particles of at least one water-soluble of PAA (co)polymer with average particle size from 0.4 mcm to 5 mcm dispersed in organic liquid, where soluble in water PAA (co) polymer contains 30-100 wt % of acrylamide units relative to total amount of all monomer units in (co)polymer and has average molecular weight M_w from 5,000,000 g/mol to 30,000,000 g/mol, and 0.1-10 of at least two surface-active substances (SAS), where SAS (C) contains 0.05-5 wt % of at least one surfactant (C1) capable of stabilising water-in-oil emulsions and 0.05-5 wt % of at least one surfactant (C2) capable to stabilizing the dispersion, the water content in liquid dispersion of polymer composition is less than 10 wt % and the quantity of each component of liquid dispersion polymer composition are presented on the basis of total number of its all components, adding at least one activating surfactant (D) in the liquid dispersion polymer composition. Wherein the surfactant (D) is different from the surfactant (C) and has HLB index greater than 9, mixing the liquid dispersion polymer composition containing at least one activating surfactant (D), with water-based liquid, thereby producing the aqueous injected agent containing at least one PAA (co)polymer dissolved therein, where the concentration PAA (co)polymer in the injected agent amounts to 0.05-0.5 wt % based on the total amount of all components of the injected agent, and pumping water injected agent produced by the method into the oil-bearing deposit. The invention has been developed in the dependent claims.

EFFECT: increased treatment efficiency.

18 cl, 2 ex, 1 tbl, 1 dwg