METHOD FOR INCREASING OIL RECOVERY OF HIGH-VISCOSITY OIL OF CARBONATE RESERVOIR Russian patent published in 2024 - IPC E21B43/24 E21B43/27 C09K8/592 

FIELD: oil industry.

SUBSTANCE: in a method for increasing oil recovery of high-viscosity oil of a carbonate reservoir, which includes pumping a carbonated acid solution into production wells, then displacing a carbonated acid solution by pumping water into injection wells, extracting liquid through production wells, formation thickness and formation pressure Pform are preliminary determined, row of production wells is drilled at distance of 300 m from each other, and two rows of injection wells are drilled in parallel and symmetrically relative to row of production wells at distance of 350–400 m. Further, into the bottomhole zone of production wells is simultaneously injected a carbonated acid solution with temperature of 100–110 °C in volume of 14 m³ per 1 linear m of formation thickness, at this ratio of acid solution to gaseous agent 1:4 respectively. Acid solution used is 15% aqueous solution of hydrochloric acid with a weight fraction of hydrogen chloride of 22–24%, and the gaseous agent used is associated petroleum gas. Further, process exposure is carried out for 36–48 hours, after which simultaneous injection of carbonated acid solution with temperature of 100–110 °C to the bottomhole zone of production wells is repeated. Further, process exposure is carried out for 24–36 hours, after which two rows of injection wells are simultaneously injected with water with volume of 40–60 m³/day and pressure of 1.5*Pform, but not more than maximum allowable.

EFFECT: increased production of oil deposit in carbonate reservoirs saturated with high-viscosity oil, by reducing the oil viscosity, increasing the reservoir coverage by the action, increasing the oil displacement coefficient due to the miscible oil displacement in the reservoir with a water-gas-acid solution, accelerated flooding of low-permeability zones, increased penetration of injected agent into fractures and pores of reservoir and provision of required level of injectivity.

1 cl, 1 dwg, 1 tbl, 1 ex