PERFORATOR FOR OPERATION IN WELLS WITH LOW FORMATION PRESSURE AND/OR IN DEPRESSION MODE Russian patent published in 2010 - IPC E21B43/112 

FIELD: oil and gas industry.

SUBSTANCE: perforator lowered on pipe string includes tubular housing with radial channels in upper part, support housing with wedge pusher equipped with cutter supports with working cutters, piston connected by means of stock to wedge pusher and pressed with spring upwards from outer casing installed outside the piston with possibility of tight longitudinal movement relative to it upwards and rigidly connected to support housing which has the possibility of interaction from below with cutter supports, start-up spool-type housing installed with possibility of longitudinal movement downwards relative to tubular housing with tight covering of its radial channels and rigidly connected to pipe string, and cylindrical connection pipe equipped from outside on upper end with upward expanding cone protrusion and armature installed with possibility of back-and-forth and rotary movement, which consists of housing with guide pin, outward spring-loaded centralisers with inward spring-loaded cutter arms having the possibility of interacting with cone protrusion in operation position. At that, on outer surface of cylindrical connection pipe there are grooves interacting with guide pin and consisting of longitudinal short and long slots connected by means of shaped slots, the upper one of which connected to middle part of long slot is equipped with process recess so that at uncontrolled back-and-forth movement of armature relative to cylindrical connection pipe the guide pin is located outside upper part of long slot, and at design restricted downward movement of the armature relative to cylindrical connection pipe with further lift the guide pin will be located in upper part of long slot - operating position. Cylindrical connection pipe is rigidly connected with cone expansion from below to support housing, tubular housing is provided from below with plate external stop, and below radial channels - with annular external restrictor having the possibility of interacting from below with the casing, and from above - with spool-type housing. Tubular housing is plugged from above, and below the plugged part and above the radial channels it is equipped with radial holes having the possibility of tight shutoff at upward movement of spool-type housing relative to tubular housing. Tubular housing is telescopically inserted in the piston in the stock of which there are longitudinal radial cut-outs for plate stop of tubular housing. Casing above the support housing is equipped on inner side with annular stop, stock of piston below longitudinal cut-outs - with external annular protrusion, and spring is installed between external protrusion of stock and annular stop of casing, and additional spring is installed between plate stop and piston outside the stock.

EFFECT: reliable operation of perforator in depression mode and at low formation pressure, and economic efficiency of perforator.

3 dwg