Patent RU-2656255-C1 (RU)
Inventor: Gazizov Ilgam Garifzyanovich
IPC: E21B43/25
Filed: 2017-08-01
Granted: 2018-06-04
Abstract: FIELD: oil and gas industry. 
     SUBSTANCE: invention relates to oil and gas production industry, to well operation, namely to methods of secondary opening and processing a bottom-hole carbonate formation zone. Method comprises lowering a tubing string with a hydromechanical piercing perforator at the lower end into a production string, opening the production string by feeding a working fluid into the perforator under pressure, piercing perforations in the production string by punches, washing up cavities by feeding the working fluid into the formed perforations of the production string through the hydro-jet channels of the perforator punches. At the mouth at the lower end of the tubing string, an assembly is performed from the bottom upwards: a hydromechanical piercing perforator, circulation valve and sweep limiter, assembly is lowered on the tubing string to the production string so that the perforator punches are 0.2 m above the bottom of the productive formation. Stepped piercing hydromechanical perforation – PHMP is performed with caving from the bottom upwards in the productive formation with a step of 0.2 m. At each stage, a pressure of 5.0 – 8.0 – 10.0 – 12.0 MPa is stepwise generated in the tubing string and the perforator, with a holding time of 10 seconds when each value is reached. Perforator punches pierce two symmetrical perforations in the production string, located at an angle of 180° in the interval of the productive formation. Without removing the perforator punches from the perforations in the production string, the injection pressure is adjusted to 15.0 MPa and through the hydro-jet perforator, the cavities are washed by the working fluid for 15 minutes. Pressure in the tubing string and the perforator is reset to zero, then all the above-described technological operations, starting from generation of the pressure and ending with the pressure release, are repeated, depending on the height of the productive formation. At the end of the stepwise PHMP with washing of cavities, the formation is processed and the reaction products are extracted, for this, the tubing string is sent to the production string so that the circulation valve is in the middle of the productive formation, the ball is dropped into the tubing string, pressure in the tubing string is increased before opening the perforations in the circulation valve, then when an annular valve is open, a 15 % aqueous hydrochloric acid solution is pumped into the tubing string at a rate of 1.5 m 3  per 1 m of the height of the productive formation, 15 % aqueous hydrochloric acid solution is brought up to the interval of opening, annular valve is closed and the 15 % aqueous hydrochloric acid solution is pressed through the cavities into the bottom-hole formation zone, swab is lowered into the tubing string, by swabbing through the tubing string, reaction products of the 15 % aqueous hydrochloric acid solution are removed with a formation rock and the well is developed. 
     EFFECT: increased carbonate formation bottom-hole zone processing efficiency; improved cleaning of the carbonate formation bottom-hole zone, increased reliability of the method, and reduced material costs of the method are provided. 
     1 cl, 5 dwg