METHOD FOR CASING STRINGS TIGHTNESS RECOVERY AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2016 - IPC E21B29/10 

FIELD: oil industry.

SUBSTANCE: group of inventions relates to oil and gas industry, in particular, to remedial cementing at recovery of casing strings tightness. Method involves covering the leakage zone from inside with a deformed pipe as a casing patch liner, and its expansion along the whole length by creation of water excess pressure. Deformed pipe used is in fact a shaped pipe with cylindrical ends plugged on the extreme ends. Upper cylindrical end of the pipe together with the conical section are separated after expansion of the deformed pipe creating excessive pressure inside the pipe, which exceeds the pressure to expand the deformed pipe. Lower cylindrical end of the pipe together with the conical section are separated after separation of the upper cylindrical end of the pipe together with the conical section from the extended pipe by deforming the lower conical section and moving this section together with the lower cylindrical end of the pipe upward. On the outer side wall at both ends of the shaped part of the pipe a closed slot is made located in the plane perpendicular to the shaped pipe axis. Upper plug has the shape of a cap with a central hole, two eccentric holes and internal taper thread on the side wall. Lower plug has the shape of a cylinder, on the upper end of which the lower end of a rod is rigidly secured, located with the ability of axial movement in the central hole of the upper plug. On the rod between the upper and the lower plugs, with the ability of axial movement, there is a two-piece gripper with wedges on the lower end spring-loaded by a compression spring. On the lower extreme end the two-piece gripper has a threaded recess, provided with a screw in the form of bushing. To the inner wall of the lower cylindrical end of the shaped pipe the lower rod end is welded, which upper end is fixed to the side wall of the two-piece gripper.

EFFECT: reduced time costs, preventing contamination of the well.

2 cl, 5 dwg