METHOD FOR INCREASING OIL RECOVERY ON CARBONATE RESERVOIRS OF MIDDLE CARBONIFEROUS Russian patent published in 2024 - IPC E21B43/30 E21B43/20 C09K8/584 

FIELD: mining; oil industry.

SUBSTANCE: invention relates to a method for increasing oil recovery on carbonate reservoirs of the Middle Carboniferous. Method includes drilling of production wells with opening of oil-bearing formation and injection wells with opening of productive formation. It also includes putting into operation of production wells. It also includes pumping of working agent into oil-bearing formation through injection wells at constant pressure. It also includes extraction of products from productive formation through production wells. Horizontal shafts of injection wells are drilled with formation of a circle, inside and outside of which vertical shafts of production wells are equally spaced in a circular pattern. Production wells are placed at distance of 150 m between wells. Diameter of inner circle of production wells depends on oil reserves and preliminary calculations of reserves development. Distance between circles of production wells is equal to 500 m. Horizontal injection wells are located at distance of 300–350 m from each other. Length of the horizontal shaft of the injection well is equal to 200 m. Method also includes determination of initial formation pressure P_f and interval of oil-bearing formation in production well. Besides, perforation is performed in production and injection wells. Production wells are also put into operation. As a working agent, a mixture of air, water, surfactant and a corrosion inhibitor is pumped into the injection wells in a percentage ratio by volume of 40:50:5:5, respectively, with daily volume per well equal to 40–50 m³/day, and pressure equal to 1.5⋅P_f, but not exceeding the maximum allowable pressure on the productive formation.

EFFECT: increasing oil recovery in carbonate reservoirs of the Middle Carboniferous, as well as this solution extends the range of methods for increasing oil recovery in carbonate reservoirs of the Middle Carboniferous.

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