METHOD OF INCREASING OIL RECOVERY IN AREAS OF NON-STATIONARY WATER FLOODING Russian patent published in 2024 - IPC E21B43/20 E21B43/18 

FIELD: oil and gas industry.

SUBSTANCE: in the method of increasing oil recovery in sections of non-stationary water flooding, sections are selected for non-stationary water flooding with an compartmentalization factor of 1.5 and more, permeability of not less than 0.001 mcm², oil viscosity up to 300 mPa⋅with, as well as the average value of water cut for all production wells in the area of not more than 98% and exceeding the depletion index of the recoverable reserves in the area, with the section development system — intra-contour waterflooding, type of injected water — fresh, waste and mineralized water with density of up to 1.18 g/cm³, containing weighted average solid-weighted particles up to 50 mg/dm³, oil products up to 60 mg/dm³, wherein all wells of the area — injection and production — represent a single hydrodynamic system. Results of geophysical investigations are used to determine duration of decreasing injectivity of the least permeable formation by 40%. Then, duration of half-cycles of cyclic mode of water injection and shutdown of injection wells after each half-cycle for depression-repression action on formations is determined as follows: with reduction of formation injectivity by 40% for 1–5 days, performing a semi-cycle of cyclic water injection for 5 days with depression-repression effects between semi-cycles of cyclic water injection in amount of 6 pieces, with reduction of formation injectivity by 40% for 6–15 days — for 12 days with depression-repression effects between semi-cycles of cyclic water injection mode in amount of 5 pcs, with reduction of formation injectivity by 40% for 16–30 days — for 22 days with depression-repression effects between semi-cycles of cyclic water injection mode in amount of 3 pcs, at reduction of formation injectivity by 40% for 31 and more days — during 30 days with depression-repression effects between semi-cycles of cyclic mode of water injection in amount of 3 pcs. Depression-repression action on formations is carried out after a half-cycle of water injection into the well immediately after its shutdown.

EFFECT: increasing oil recovery of the developed section due to prevention of colmatation of low-permeability interlayers, maintaining the profile of injectivity and oil displacement.

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