EA027301B8 - Method of repair in a well with a defective section and internal restriction of a casing string, and device for its implementation - Google Patents

Abstract

The invention is related to oil industry, in particular, to a method for restoring tightness of a casing string with any length of a defective interval, and to a device for implementing the method. The method for repair a casing string in a well with a defective section and internal restriction comprises acquiring all information on the defective interval, preliminary cementing of the defective section throughout its length, milling of the defective section after cement hardening, descent and installation of a shutter string in the defective zone, the shutter string being fixed at the top with mechanical rams, cementing of the shutter string through a drilled-over back-pressure valve, wherein, before descent into the well, the bottom end of the shutter string is provided with hydromechanical pushing equipment, and the top end is provided with an upper sealing collar and a ram holder mounted in a body; before descent, mounting equipment is fixed inside the body, and after descent of the shutter string, hydromechanical pushing equipment actuated by created hydraulic pressure pushes out the mechanical rams and the sealing collar and presses them to the casing string wall; after supply of a downward load, the shutter column becomes locked to the casing string with mechanical rams, and the sealing collar seals the cavity between the strings; then, by rotation of the mounting equipment, it is screwed out of the shutter string and lifted to the back-pressure well, then cementing is performed, after which, by abrupt downward movement of the mounting equipment, the ram holder is pushed out, and the upper mechanical rams are locked to the casing string, and the upper sealing collar seals the cavity between the string, after which the mounting equipment is lifted to the day surface. The device for implementing the method comprises a shutter string with a back-pressure valve on the bottom end and with mechanical rams on the top end, wherein a piston-type hydromechanical pusher interacting with the mechanical rams and the sealing collar is mounted at the bottom end of the shutter string inside a power cylinder, the upper end of the shutter string is provided with a sealing collar and a ram holder mounted in the body that contains a movable axially bumper adapter capable to transmit rotational movement; a regulating valve having a side hole and lifted slightly by a spring directed upwards from the seat along the central axis is fastened to the bottom end of the adapter at the level of the hydromechanical pusher by means of an intermediate string.