METHOD OF IN-WELL CASING STRING SLIT PERFORATION AND DEVICE TO THIS END Russian patent published in 2010 - IPC E21B43/112 

FIELD: oil-and-gas production.

SUBSTANCE: to make slits in casing strip wall, cement ring behind casing string and well productive strata, revolving disk mill axis in displaced in the slit formation plane along preset trajectory with simultaneous vertical reciprocation of perforator relative to casing string at preset speed. Note here that, with perforator moving from top extreme position to bottom extreme position, disk mill axis is simultaneously displaced from its trajectory top extreme point, first, at an angle to casing string wall generatrix, while smoothly cutting the mill into casing string wall, cement ring behind casing string and well productive strata, to trajectory point whereat mill is stopped and wherefrom mill axis is still displaced vertically to trajectory bottom extreme point. Note that casing string wall, cement ring behind casing string and well productive strata are milled at a time on produced slit depth. In lifting perforator from its bottom extreme position to top extreme position, revolving mill axis is displaced vertically from its trajectory bottom extreme point to top extreme point. Note here that remaining parts of casing string wall, cement ring behind casing string and well productive strata are milled at trajectory section whereat cut in aforesaid parts. To this end, perforator with hydraulic cylinder is used, hydraulic cylinder piston being mechanically coupled with revolving disk mill and hydraulically, on piston under side, being communicated with working pressure chamber and, on head end side, with tubular annulus via flow friction element designed to metre out fluid from head end side into hole clearance when fluid pressure acts on piston underside and rive hydraulic cylinder. Note here that said drive hydraulic cylinder makes perforator reciprocate vertically relative to casing string at design speed to distance limited by drive hydraulic cylinder stroke.

EFFECT: stable and reliable operation.

4 cl, 4 dwg