METHOD FOR ACID TREATMENT OF BOTTOM-HOLE FORMATION ZONE Russian patent published in 2023 - IPC E21B43/27 

FIELD: intensifying oil production from carbonate reservoirs.

SUBSTANCE: methods for intensifying oil production from carbonate reservoirs. In the method of acid treatment of the bottom-hole zone of a productive formation using a packer 3 to seal the annular space between the tubing string 2 and the casing string 1, a reagent container 6, filled with a hydrochloric acid solution with concentration of 22-25%, made of stainless steel tubing or pipes coated with a protective material - gummed rubber from the inside, is placed in the lower part of the tubing string 2 the maximum allowable diameter for the used casing string 1, larger than the diameter of the tubing in the upper part of the tubing string 2, and having two check valves 7 and 8 located on top at the inlet and bottom at the outlet of the reagent container 6. A bypass valve 4 in the form of a saddle made of a cylindrical sleeve with a conical funnel with through peripheral holes is located above the reagent container 6 in the tubing string 2, and the outlet from the specified bypass valve is made in the form of a branch 5 directed into the space between the tubing string 2 and the casing string 1. The assembled structure is lowered into the well so that the lower part of the reagent container 6 is opposite to the upper perforations of the casing string in the zone of the productive formation, and the bypass valve 4 in the form of a saddle is in the vertical section of the well. At the first stage, an acid composition containing 12-15% hydrochloric acid is supplied from the wellhead, which passes through the saddle of the bypass valve 4 and outlet 5 into the annulus, flows around the reagent container 6 from the outside and under the pressure drop created at the wellhead by the pump unit 11, is injected into the reservoir. At the second stage, from the wellhead through the lubricator 10, a metal ball 9, which is part of the bypass valve 4, is thrown into the tubing string 2, ensuring that the hole in the saddle of the bypass valve 4 and the outlet 5 are closed into the space between the tubing string 2 and the casing string 1, pump unit 11 pumps a liquid inert to acid into the tubing string 2, which moves through the peripheral openings of the conical funnel and two open valves 7 and 8 of the reagent container 6 under the action of the differential pressure created from the wellhead into the tubing string 2 in order to completely displace the hydrochloric acid solution with concentration of 22-25% from the reagent container 6 into the productive formation.

EFFECT: deeper penetration of the acid into the formation, which has an elevated temperature of the medium, without the manifestation of corrosion phenomena of downhole equipment.

1 cl, 2 dwg