Apparatus for optional straight or directional drilling underground formations

摘要

A device for selective straight or directional drilling in subterranean rock formations consists of a rotary drilling tool having a tool main axis and comprising a housing which comprises several sections and can be connected to a drill string, the housing having a downhole motor for driving a drill bit via a driven shaft. For straight drilling, the housing can be set in independent, slow rotation about the tool main axis by being turned by the drill string, and for directional drilling can be aligned and fixed against turning. The lower section of the housing adjacent to the drill bit and mounting the driven shaft is deflected relative to the tool main axis, and this section is connected to an upper section by an intermediate section which has an axis which intersects the axes of the upper and lower section. The device may include a plurality of interchangeable intermediate sections.