DEVICE FOR STAGE CEMENTING OF CASING STRING Russian patent published in 2003 - IPC

FIELD: oil producing industry; applicable in casing string cementing in two stages in oil and gas wells. SUBSTANCE: device has valve-coupling, case and check valve. Valve-coupling includes body with radial channels. Case is fitted on body and forms cavity with it. Check valve includes shutoff member in form of metal cylinder. Cylinder lower end is made in form of cone contacting case cone end, and cylinder upper end is spring-loaded. Body radial channels accommodate dead plugs extending inside body for engagement with shear unit. Shear unit is lowered into well on rope or cable. Shear unit consists of rod with conical external shoulder in lower part. Shear unit is connected from atop with weighing member and cable head. Rod from external side is made with cylindrical hollow over large part of length. Located in cylindrical hollow is circular stop and movable collet with two-sided circular stop on upper end and one-sided external stops on lower ends. EFFECT: higher reliability of cement mortar injection of the second stage. 2 dwg