METHOD OF INCREASING OIL RECOVERY Russian patent published in 2021 - IPC E21B43/22 C09K8/588 

FIELD: oil industry.

SUBSTANCE: present invention relates to the field of the oil industry and can be used in the development and improvement of oil reservoirs recovery by polymer flooding. A method for increasing oil recovery during the development of oil reservoirs by polymer flooding, including the injection of a polymer solution based on polyacrylamide (hereinafter – PAA) into the oil reservoir through a well, where a preliminary analysis of reservoir temperatures and the degree of mineralization of reservoir and injected water is carried out. According to the results of the analysis, the monomers acrylamide-tret-butyl-sulfonate (hereinafter – ATBS) and N-vinyl-pyrrolidone (hereinafter – NVP) are additionally introduced into the PAA-based polymer solution. Then, the resulting polymer composition is prepared sequentially by grinding, primary wetting and dissolving the polymer particles in water. The resulting polymer solution is mixed in an oxygen-free nitrogen medium to a homogeneous consistency. Then, the polymer solution is diluted with water to the required concentration at a reservoir temperature in the range of 70-110℃ and weak mineralization from the range of the mineralization degree determined by the specified analysis as 2-150 g/l. ATBS is introduced in an amount of 15-40 mol.%. At a reservoir temperature of 110-140℃ and the degree of mineralization 150 g/l ATBS is introduced in the amount of 25-35 mol.%, and NVP is introduced in the amount of 2-5 mol.%. Finally, the solution is pumped into the oil reservoir.

EFFECT: increased oil recovery with the use of water-soluble polymers in a wide range of reservoir temperatures and mineralization of reservoir and injected water.

3 cl, 1 tbl