DEVICE FOR MAKING PERFORATION PASSAGES IN CASING STRING OF WELL Russian patent published in 1999 - IPC

FIELD: oil and gas production industry. SUBSTANCE: device is used in drilling and repair of oil and gas wells. Device has tubular body which carries hydraulic cylinder case adapted for reciprocating motion. Also provided are hydraulic cylinder piston which is connected with wedge-type pusher, cutter holders with perforation cutters, wedge-type pusher, and return spring. Wedge-type pusher is made in the form of two right-angled triangles. Triangles are joined by their side surfaces over smaller leg. Each cutter holder is made for possible sliding in radial direction relative to each other and is adapted for interaction with inclined surface of wedge-type pusher. Tubular body is connected with piston and is adapted for advanced movement so as to cut perforation holes in string and productive reservoir. Reverse movement of piston is used to return device to initial position. Application of aforesaid embodiment of device ensures perforation of casing strings of small diameter. Device having cutters with large outreach is of simplified design. EFFECT: higher efficiency. 3 dwg