1
Bernhard Prevedel, Warren E Askew, Alan Eddison: Directional drilling methods and apparatus. Anadrill, David L Moseley, John J Ryberg, August 18, 1992: US05139094 (77 worldwide citation)

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 effe ...


2
Trevellyn M Coltman, Alfred E W Fletcher, Bernhard Prevedel: Device for steering a drilling tool and/or drill string. Preussag Aktiengesellschaft, Herbert Dubno, August 14, 1990: US04947944 (53 worldwide citation)

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 sprin ...


3
Bernhard Prevedel: Apparatus for a pipe string of a geological drill hole, pipe string, method for operating a geological drilling gear and method for producing a pipe string for a geological drill hole. February 2, 2012: US20120024603-A1

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 ...