FIELD: oil and gas industry.
SUBSTANCE: repair of crushed casing columns in order to restore their tightness. The device includes a milling mechanism to which a centering mechanism is coaxially and rigidly attached. During operation and transportation, the device is attached to the end of the drill string and placed inside the casing. The milling mechanism is a cylindrical body with a central axial channel, in which there is an internal annular protrusion. The side wall of the housing has through longitudinal windows in which cams with carbide cutting blades are installed. A rock cutting tool is rigidly attached to the lower end of the body. The main piston and the pusher are interconnected and placed in the central axial channel of the housing with the possibility of axial reciprocating movement. The pusher is made in the shape of a truncated cone, the larger of the bases of which faces the main piston. In the central axial channel of the pusher there is an internal annular protrusion, at the level of which radial channels are made in the pusher, hydraulically connected to its central axial channel. A return spring is installed in the central axial channels of the housing and the pusher, interacting with its ends with the end milling cutter and the pusher. An adjusting washer is located outside the return spring with the ability to interact with the smaller of the pusher bases. Outside the branch pipe, in the direction from the sub to the body, a hydraulic drive unit, a thrust bearing, at least two sliding sections and a thrust bearing are coaxially and sequentially placed, and a central axial channel is made in the bottom of the cup to accommodate the bushing. Sliding sections include reels, eyes, skis and rollers.
EFFECT: increasing reliability and efficiency of the device.
1 cl, 9 dwg
