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
Prevedel Bernhard, Askew Warren, Eddison Alan: Directional drilling methods and apparatus.. Anadrill Int, Schlumberger Services Petrol, August 5, 1992: EP0497420-A1 (21 worldwide citation)

In accordance with illustrative embodiments of the present invention, more accurate directional drilling is carried out by providing a downhole adjustable bent housing that is selectively operated to produce a bend angle in the drill string between a downhole motor and the drill bit, providing a nea ...


3
Malone David L, Orban Jacques J: Directional drilling methods and apparatus. Anadrill Int, Schlumberger Services Petrol, December 13, 1995: EP0686752-A1 (4 worldwide citation)

Appts. for use in drilling a directional borehole, comprises (a) tubular telescopic members connected in a rotary drilling string, one of the members carrying a piston having upper and lower faces that are subject respectively to the pressure of drilling fluids inside and outside the members, the on ...