OIL FORMATION TREATMENT METHOD Russian patent published in 2022 - IPC E21B43/24 C09K8/58 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil and gas industry, in particular to methods for thermal gas chemical treatment of the bottomhole zone of production wells in heterogeneous carbonate and terrigenous formations, and can be used for activation or resumption of operation of oil wells with high viscosity of oil, as well as to control the development process and increase oil recovery of formations with non-uniform permeability. Method involves sequential pumping and forcing into the productive formation of a binary mixture prepared at the wellhead, an interaction initiator and an acid composition. Preliminary determining the injectivity of the production well, the viscosity of the oil in the formation conditions and the mineralization of the produced water, depending on the injectivity, determining the volume of the binary mixture, with injectivity from 48 to 249 m³/day 2–4 m³ of the binary mixture is pumped per 1 m of the penetrated thickness of the productive formation, at injectivity from 250 m³/day to 360 m³/day, 4–7 m³ of a binary mixture is pumped per 1 m of the penetrated thickness of the productive formation, binary mixture used is solution containing 50–55 % aqueous solution of ammonium nitrate and 45–50 % aqueous solution of sodium nitrite in volume ratio of said aqueous solutions of 1:1, then, interaction initiator is injected, at viscosity of oil in formation conditions from 30 mPa·s to 500 mPa·s and mineralization of produced water from 200 g/dm³ and more as initiator of interaction the reagent Jel is used in volume of 1–3 % of volume of binary mixture, with oil viscosity in formation conditions from 30 mPa·s to 500 mPa·s and mineralization of produced water below 200 g/dm³, formalin is used as initiator of interaction in amount of 1–3 % of volume of binary mixture, at viscosity of oil in formation conditions of up to 30 mPa·s, 15 % aqueous solution of sulfamic acid is used as initiator of the interaction in amount of 3–5 % of volume of binary mixture, then acid composition is pumped in volume equal to half the volume of binary mixture, and 12 % aqueous solution of inhibited hydrochloric acid is used as acid composition.

EFFECT: increase in the oil formation bottomhole zone treatment efficiency due to the whole formation and borehole zone coverage increase, expansion of the technological capabilities of the method by regulating the temperature range of the thermal gas-chemical reaction to the formation in a partial load mode with simultaneous reduction of corrosion of the tubing string and the production string in the zone of the productive formation.

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