Patent ID: 6318481
Filing Date: 2001-11-20
Classification: E21B

Abstract:
Apparatus for use on fluid conducting drill strings in earth well bores to apply a lateral force against one side of the well bore to displace the drill string in the opposite lateral direction to change the course of an advancing drill head, the apparatus comprising:a) a body arranged to serve as a length of fluid conducting drill string, with means at each end for fluid tight attachment to elements of a continuing drill string, with a fluid channel to conduct drilling fluid between said elements of continuing drill string;b) an arbor comprising both said ends, and said fluid channel;c) a generally tubular housing bearingly supported on said arbor for rotation thereon;d) a piston in said housing arranged to move between a first and a second position;e) clutch means in said housing, responsive to movement of said piston to releasably secure said housing rotationally to said arbor such that said clutch is engaged when said piston is in said first position and disengaged when said piston is in said second position;f) a side loading element carried, for well bore wall engagement, by said housing, responsive to movement of said piston, to move radially outward from said housing when said piston moves toward said second position and to move radially inward when said piston moves toward said first position;g) a valve in said channel to variably resist movement of fluid therethrough in response to signals from a source external to the apparatus;h) fluid ports in said arbor to conduct drilling fluid from said channel arranged such that fluid pressure difference across said valve is conducted to opposite ends of said piston such that increasing pressure across said valve applies increasing force to said piston to move from said first toward said second position; andi) a spring situated in said housing and arranged to urge said piston toward said first position.