METHOD OF ACIDIZING BOTTOMHOLE FORMATION ZONE WITH CARBONATE RESERVOIR Russian patent published in 2018 - IPC E21B43/27 C09K8/72 E21B7/04 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the petroleum industry. Method for acidizing the bottomhole formation zone with a carbonate reservoir includes the descent of a string of pipes with a water jet perforator, making sidetracks in the form of radial holes in the casing string of the well and caverns in the formation by pumping a water-sand mixture throughout the pipe string through the water jet perforator on the basis of two sidetracks per 1 m of the thickness of the formation, acid treatment of the bottomhole formation zone in three portions, each of which includes pumping a hydrochloric acid solution in a continuous mode, a technological exposure for the reaction and recovery of the reaction products. At the wellmouth, from the top to the bottom, the following assembly is mounted onto the lower end of the pipe string: a saddle-gun, a centralizer, a water jet perforator with nozzles, an anchor. Then the pipe string and the assembly with the washer are lowered into the interval of the perforated formation, a ball is dropped into the pipe string. After the ball saddling the casing string is perforated with making the sidetracks in the form of radial holes in the casing string and the caverns in the formation by pumping the water-sand mixture throughout the pipe string through the water jet perforator. Then, without interrupting the pumping, through the sidetracks, the bottomhole formation zone with the carbonate reservoir is treated, wherein with the first portion in the continuous mode pumped is a 18–20 % solution of hydrochloric acid at the temperature of 0 °C in the volume of 0.5 m³ per one sidetrack, then in the continuous mode pumped is a 18–20 % solution of hydrochloric acid at the temperature of 30 °C in the volume of 1.0 m³ per one sidetrack, after which a pulse flush of the pumped solutions of hydrochloric acids by oil into the formation is conducted in a cycle mode: 3 min pumping at the bed intake pressure, 5 min exposure for the reaction. With the second portion pumped is a 18–20 % solution of hydrochloric acid at the temperature of 0 °C in the volume of 1.5 m³ per one sidetrack, then – a 18–20 % solution of hydrochloric acid at the temperature of 30 °C in the volume of 2.0 m³ per one sidetrack, after which a pulse flush of the pumped solutions of hydrochloric acids by oil into the formation is conducted in a cycle mode: 4 min pumping at the bed intake pressure, 10 min exposure for the reaction. With the third portion pumped is a 18–20 % solution of hydrochloric acid at the temperature of 0 °C in the volume of 2.5 m³ per one sidetrack, then – a 18–20 % solution of hydrochloric acid at the temperature of 30 °C in the volume of 3.0 m³ per one sidetrack, after which a pulse flush of the pumped solutions of hydrochloric acids by oil into the formation is conducted in a cycle mode: 5 min pumping at the bed intake pressure, 15 min exposure for the reaction, after which the reaction products are removed by swabbing along the casing string of the well.

EFFECT: increasing reliability of the method implementation; improving the processing of the bottomhole formation zone while reducing the cost of implementation and simplifying the technology.

1 cl, 1 dwg