METHOD FOR DEVELOPING A HETEROGENEOUS OIL RESERVOIR Russian patent published in 2022 - IPC E21B43/00 

FIELD: oil industry.

SUBSTANCE: invention relates to a method for developing a heterogeneous oil reservoir. The method consists in applying a microbiological impact on the formation under conditions of high salinity of the injected and formation water. The method includes successive injection of a mixture of a water-soluble natural polymer - WSNP - xanthan, fermenting bacteria - sapropel, water and a solution of diammonium phosphate - DAP with hydrocarbon-oxidizing bacteria - HOB into an injection well, followed by technological exposure. When the injectivity of the injection well is from 100 to 250 m³/day, the injection of the solution and the mixture into the formation is carried out by rims. The first slug is pumped with a solution of DAP with HOB, which additionally contains xanthan and water, at a ratio of components, wt.%: DAP solution with HOB - 10.0-15.0%, xanthan - 0.03-0.5%, water - rest. The second rim is pumped with a mixture of WSNP - xanthan, sapropel and water, which additionally contains a solution of DAP with HOB and a non-ionic surfactant - ethoxylated isononylphenol with a degree of oxyethylation of 12, at the ratio of the components of the mixture, wt.%: DAP solution with VR - 10.0-15.0%, xanthan - 0.03-0.5%, non-ionic surfactants - 0.1-0.5%, sapropel - 0.5 -2.5%, water - the rest. The first and second rims are pumped in a 1:1 volume ratio. After injection of the rims, the well is stopped for a technological exposure lasting 5-10 days and waterflooding is resumed. When the injectivity of the injection well is from 251 m³/day or more, first, a mixture of WSNP - xanthan or a dispersed component and water is injected, at a ratio of components, wt.%: xanthan or a dispersed component - 0.5-2.5%, water - the rest. The injection of the mixture is carried out until the injection pressure is increased by 10-50% of the initial injection pressure. After that, a DAP solution with HOB and a mixture of WSNP - xanthan and fermentative bacteria are pumped into the reservoir. The first slug is pumped with a solution of DAP with HOB, which additionally contains xanthan and water, at the ratio of the components of the mixture, wt.%: DAP solution with HOB - 10.0-15.0%, xanthan - 0.03-0.5%, water - the rest. The second rim is pumped with a mixture of WSNP - xanthan, sapropel, water and a solution of DAP with HOB, which additionally contains a nonionic surfactant - non-ionic surfactant - ethoxylated isononylphenol with a degree of oxyethylation of 12, at a ratio of the components of the mixture, wt.%: solution of DAP with HOB - 10 0-15.0%, xanthan - 0.03-0.5%, non-ionic surfactants - 0.1-0.5%, sapropel - 0.5-2.5%, water - the rest. The solution and mixture are pumped in a 1:1 volume ratio. After injection of the rims, the well is stopped for a technological exposure lasting 5-10 days and waterflooding is resumed. Powdered cellulose or technical microcrystalline cellulose is used as a dispersed component.

EFFECT: increase in oil recovery of production wells by changing and equalizing filtration flows in heterogeneous reservoirs, reducing the permeability of high-permeability zones of the reservoir, involving in the development of previously undeveloped low-permeability oil-saturated interlayers.

2 cl, 8 tbl