HYDROMECHANICAL CENTRALIZER Russian patent published in 2006 - IPC E21B17/10 E21B33/13 

FIELD: well drilling, particularly hole clearance cementing, namely for casing pipe cementing in well.

SUBSTANCE: centralizer comprises cylinder connected with bore and provided with bushes and working piston arranged in cylinder interior. The piston is fixed relative cylinder by shear pin. Centralizer also has valve bush, centering levers pivotally connected to bore by lower ends thereof, lock means. Three bushes are made as semi-bushes connected one with another in pairs by pins. Lock means are created as T-shaped slots made on lower part of working piston and brought into cooperation with T-shaped pins fixedly secured to centering arms. Valve bush is installed in cylinder interior above semi-bushes. Outer bush diameter is less than inner cylinder diameter. Outer surface of lower working piston part is made as a cone to cooperate with conical surfaces made in upper parts of centering levers. Working piston is made as semi-pistons fixedly secured one to another in conical parts. Threaded radial orifice is formed in bore to communicate inner cavities of cylinder and bore. Breakable plug is screwed into the threaded orifice.

EFFECT: increased operational reliability and simplified structure thereof.

3 cl, 5 dwg