METHOD OF CONTROLLING COVERAGE OF A FORMATION BY GAS-CYCLIC PUMPING CARBON DIOXIDE AT SUPERCRITICAL CONDITIONS TO A PRODUCTION WELL USING FOAM SYSTEMS Russian patent published in 2020 - IPC E21B43/16 C01B3/32 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to production of hard-to-recover oil and gas condensate reserves. Method involves pumping two fringes - before and after pumping of carbon dioxide into production well. When implementing gas-cyclic injection of carbon dioxide at supercritical conditions - temperature more than 31.1°C and pressure of more than 7.38 MPa, pumping of the first fringe is provided to the tubing string of the production well in the form of a reagent containing a surfactant. Then, a solid foaming agent is dosed and dissolved in the liquid contained in the well bore for at least 3 hours. Further, carbon dioxide is pumped under supercritical conditions. Prior to impregnation period, second rim is pumped. Its injection involves pumping to the production tubing string a composition containing a mixture of a corrosion inhibitor and a reagent containing a surfactant. Then, a solid foaming agent is dosed and dissolved in the liquid contained in the well bore for at least 3 hours. After that, the well is closed for the period of impregnation with subsequent extraction of oil from the same production well. First rim is used to inject the ML-super reagent containing the surfactant into the well tubing string to the wellhead. Then, hard foaming agent rods are introduced at rate of 0.2-0.5 kg per 1 m³ of liquid, taking into account the volume of the tubing string for dissolution in the wellbore, and as second fringe is pumped mixture of corrosion inhibitor grade "Inkorgaz-21T-A" and reagent containing surfactant, grade "ML-super" in established ratios and in volume sufficient for filling of tubing string of well, as well as at rate of 1-5 m³ per meter of the perforated interval of the treated header depending on the permeability of the collectors. Then solid foam maker rods are introduced at 0.2-0.5 kg per 1 m³ of liquid taking into account volume of tubing string for dissolution in the well shaft.

EFFECT: increasing extraction of hard-to-recover oil reserves with reduced content of water and gas condensate due to use of liquid carbon dioxide and foam systems.

1 cl, 3 ex