WELL PERFORATOR Russian patent published in 2003 - IPC

FIELD: oil industry, well drilling, formation of perforation ducts in casing string. SUBSTANCE: well perforator has body coming in the form of wedge with grooves, main cylinder with piston and cutting tool in the form of cutters. Cutters are mounted in grooves for movement. From above body is connected to rope and has low-pressure chamber. Main and additional cylinders linked stably are positioned under this chamber. Pistons are set in cylinders. Piston of additional cylinder is provided with flow conduit communicating part of main cylinder above piston with part of additional cylinder above piston. Pistons are rigidly interjoined and are so positioned that part of cylinders under pistons interacts with internal space of well. Cylinders are filled with liquid. Non-return valve and dynamic spring- loaded valve with internal flow conduit are located between low-pressure chamber and cylinders. In working position dynamic valve shuts non-return valve off. Support with radial grooves in upper part is linked to piston of main cylinder via rod. EFFECT: reliable and effective operation of well perforator in wells of any diameter and in all perforation intervals. 2 cl, 3 dwg