Down-hole drilling motor and method for directional drilling of boreholes

摘要

A down-hole drilling motor is provided with a bearing unit which supports the output shaft in such an inclined position relative to the motor housing, that the central axis of the output shaft intersects the longitudinal axis of the motor housing at a point of intersection located below the lower end of the housing. Directional drilling of a borehole is carried out by actuating a drill bit by means of the down-hole drilling motor, and simultaneously therewith rotating the drill string-and consequently also the motor housing-over periods that are preceded and succeeded by selected periods over which the drill string is not rotated.