Abstract: The invention relates to an apparatus for a pipe string of a geological drill hole, with a pipe string element and a fluid supply line which is arranged outside the pipe string element, extends along the pipe string element and is connected to a fluid injection device on the pipe string element, by means of which a fluid supplied through the fluid supply line can be introduced into an inner space of the pipe string element. The invention furthermore relates to a pipe string of a geological drill hole, in particular of a geothermal drill hole, a method for operating a geological drilling machine and a method for producing a pipe string for a geological drill hole.

Abstract: Methods are provided for controlling the direction of a borehole drilled by a downhole motor, including the steps of positioning downhole adjustable bent housing and near-bit stabilizer in the drill string, adjusting the bent housing from its normally straight condition to its bent condition to effect borehole curvature, and using the stabilizer in its undergage condition to enhance the inclination. The Measurements are made from which the inclination with respect to the vertical and the azimuth can be determined and telemetered uphole for processing, display, and recording. Preferably the directional measurements are made at two locations, one below the bent point and one above it. These two sets of measurements can be compared to confirm the bend angle and to obtain a definition of the orientation of the plane of the bend angle so that the drilling path can be accurately controlled.

Abstract: An outer tube (26) provided with rolling bearings (28) is rotatably mounted on an inner tube (10) which can be connected to a drilling tool or a pipe string. Radially mobile guiding rails are arranged in longitudinal channel-like recesses on the outer surface of the outer tube (26). Belleville springs lodged in spring housings (36) arranged in recesses in the guide rails (35) press against the outer tube (26) and force the guide rails (35) radially outward. The guide rails (35) help prevent rotation of the outer tube, enable it to slide longitudinally in the bore, and guide the inner tube (10) mounted in the outer tube (26) and the drilling tool or pipe string attached to the inner tube (10).