DEVICE FOR CUTTING OUT PART OF CASING STRING IN WELL Russian patent published in 2014 - IPC E21B29/00 

FIELD: mining.

SUBSTANCE: device comprises a housing with a grooves, the pull-out cutters hingedly attached in the grooves of the housing, radial channels formed in the housing in the plane of pulling-out of the cutters and directed into the cutting zone, at that the cutters are made with the ability to fix them in the pulled-out and the transport positions, the hydraulic drive capable of interacting with the surface of the cutters in the plane of their cutting edge. The drive is made in the form of a hollow piston spring-loaded from the housing with the shoulder and ends with a wedge surface, the latter has a cutout for the bearing surface of the cutters. The drive is placed in an annular cavity made in the housing above the pull-out cutters. The hollow piston is equipped with a fitting. In the housing above the drive three radial channels are made, tightly overlapped by the hollow sleeve, fixed relative to the housing by the breakable screw. Below the hollow sleeve in the housing the inner annular groove is made, in which the stopping split ring is located. On the top the hollow sleeve is provided with a plug catching baffle for the ball thrown from the wellhead. The hollow sleeve is made with the ability to move axially downwards under the action of the excess hydraulic pressure in the device cavity and fixing by the stopping split ring the upper end after its interaction with the stopper.

EFFECT: increased reliability and service life.

2 dwg