WELL REAMER Russian patent published in 2013 - IPC E21B7/28 

FIELD: oil and gas industry.

SUBSTANCE: well reamer includes a hollow housing with an internal projection and radial holes, in which there installed are retractable rolling cutters with shanks, an annular piston with a side hole arranged in the housing cavity and fixed against being rotated, with upper and lower props on outer surface and a connection device to a drill string; a cylinder connected to the housing and forming together with the annular piston a hydraulic chamber interconnected with its side hole to the housing cavity, a fastener installed in the annular piston with possibility of interaction with shanks of rolling cutters and the internal projection of the housing and a device for locking of rolling cutters in a non-working position, which contain an additional annular piston located in the reamer hydraulic chamber below the side hole of the main piston. The device for locking of rolling cutters in the non-working position is made in the form of radially spring-loaded segments located in external slots of the piston, and counter cavities of those segments in the cylinder. Between the additional piston and annular segments of the device for locking of rolling cutters there installed is a pusher for disengagement of segments from the reamer cylinder. On the annular piston between the device of connection to a pipe string there installed is an upper fixed pusher and a lower movable pusher with opposite external inclined surfaces converging to the annular piston. Lower pusher has the possibility of interaction with the cylinder and longitudinal movement relative to the annular piston. Between pushers there uniformly arranged along the perimetre of the annular piston are pipe rams with inclined inner surfaces, which correspond to surfaces of pushers, to which they are connected with possibility of being moved along them with expansion of pipe rams to the working position.

EFFECT: obtaining a calibrated well shaft of a strictly required diameter throughout the length of the reamed interval, which creates no additional load on drill pipes and increases by many time the service life of the reamer structure.

5 dwg