WELL UNDERREAMER Russian patent published in 2025 - IPC E21B7/28 

FIELD: earth or rock drilling.

SUBSTANCE: invention relates to drilling equipment for oil and gas industry, in particular to devices for increasing diameter of well in a given interval. Well underreamer includes a housing with inclined slots, a piston made as annular and arranged in a hydraulic chamber, legs with teeth on the working surface, which are fixed in inclined slots of the housing and connected by means of tie-rods to the piston, which are located in longitudinal rows. Hydraulic chamber is formed by a groove on the outer surface of the housing, made below the inclined slots, and the inner surface of an adapter connected to the lower part of the housing by a thread. Piston is equipped with inner groove for spring, which rests from below on inner end of piston, and on top – in protrusion of housing groove. Rods of the annular piston are made integral with the piston and provided with T-shaped projections for T-shaped slots of the legs. Central channel of the housing is equipped with a hole for communication with the hydraulic chamber and flushing holes of inclined slots of the housing.

EFFECT: ensures the reliability of the design, eliminating emergency situations during work and lifting operations.

1 cl, 2 dwg