PROCEDURE FOR MAKING BOREHOLE SLIT-LIKE PERFORATED HOLES OF CASING AND FACILITY FOR IMPLEMENTATION OF THIS PROCEDURE Russian patent published in 2010 - IPC E21B43/112 

FIELD: oil and gas production.

SUBSTANCE: according to procedure slits in casing are cut in wall of casing, in cement ring behind casing and in producer by means of rotating cutting tool in form of disk cutter. Slits are cut in an interval of the borehole perforation with slit-like sections arranged along a spiral line at a specified step relative to one another around axis of the string. To form a slit in each section axle of the mill travels in plane of slit-forming along a specified trajectory and simultaneously a perforator performs reciprocal motions in a vertical direction relative to the casing. From an upper end position the perforator is lowered to a lower end position at a specified rate; when the perforator is lowered, the axle of the mill rotation is simultaneously transferred in the beginning from an upper initial point of the trajectory at angle to generatrix of the casing. Also at a dosed feed the mill smoothly cuts into the wall of the casing, the cement ring beyond the casing and the producer of the well to the point of the trajectory, whereat mill cutting is stopped. Further, transfer of the axle of the mill is continued in the vertical direction to the lower end point of the trajectory with simultaneous milling the wall of the casing, the cement ring beyond the casing and the producer at depth of the slit made with cutting. The perforator is lifted from its lower end position to the upper end position at independent rate. When the perforator is lifted, the axle of the mill does not rotate, but simultaneously is transferred from the lower end point of the trajectory to the upper initial point of the trajectory at accelerated feed away from the wall of the casing. In the procedure there is used the perforator with a hydro-cylinder. The piston of the hydro-cylinder is mechanically coupled with the disk cutter and hydraulically on a sub-piston side - with the cavity of working pressure, on an over-piston side - with tube space via hydraulic resistance and a one-way valve of big port area. Hydraulic resistance functions as metering device for feed from the above-piston cavity of the hydro-cylinder into tube space, when working pressure of fluid actuates the piston on the sub-piston side. After pressure release in the perforator fluid is quickly supplied from tube space into the sub-piston cavity via the one-way-valve. Changes of string length due to flexible properties of the production string facilitate reciprocal travels of the perforator during operation. Metered axial load facilitated by metered feed of pressure in the production string actuates perforator lowering, while lifting is achieved by unloading after pressure release.

EFFECT: facilitating stable and reliable operation at forming slit in casing.

3 cl, 3 dwg