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

FIELD: oil and gas industry.

SUBSTANCE: reamer comprises a body with inclined slots outside and a stem installed in it, a piston interacting with the stem, which is made circular and is arranged in the chamber formed by the external wall of the stem and the internal wall of the body, feet with bits on the working surface fixed in inclined slots of the body and connected hingedly by means of traction rods with a piston, and a lower mandrel with an internal narrowing channel, connected at the bottom with the body, besides, the piston at the bottom is equipped with a hollow bushing with side channels, below which inside the hollow bushing there is a narrowing and a cylindrical external surface, which is made as capable of sliding interaction with a narrowing channel of the lower mandrel and with the possibility of exit from this narrowing channel as the piston moves upwards relative to the body. Areas of traction rods connection with the piston are arranged as tight. The piston is equipped with calibrated longitudinal holes arranged between areas of traction rods connection with the piston evenly along the diameter.

EFFECT: possibility to considerably increase resource of reamer operation as a whole, possibility to operate on a loaded drilling mud without washout of its elements and without mudding of closed sections of the reamer.

3 cl, 3 dwg