Adjustable bent sub

Abstract

There is disclosed an adjustable bent sub for use in directional drilling in earth formations which is adapted to be placed between the power unit and bearing assembly components of a downhole motor and which can be angularly adjusted without requiring disassembly of the downhole motor unit. The bent sub is comprised of a first member having a primary axis and an external, cylindrical surface defining a secondary axis disposed at a predetermined offset angle with respect to the primary axis; a tubular second member secured to the first member against axial displacement and having a primary axis, an internal, cylindrical surface defining a secondary axis disposed at a predetermined offset angle with respect to the second member primary axis, the internal surface being adapted to telescopically receive the first member external surface in sliding fit relation for rotation about the secondary axis, and a first clutch extending axially from one end thereof; a locking sleeve telescopically receiving and non-rotatably coupled to the external surface of the first member and having a second clutch extending axially of one end thereof toward the second member, the sleeve being axially moveable on the first member between an engaged position whereat the first and second clutch are interengaged and non-rotatably couple the second member and the first member in a predetermined angular position and a disengaged position whereat the locking sleeve is axially displaced from the second member and the first and second clutch are disengaged from one another so as to permit angular adjustment of the second member with respect to the first member; and threads on the external surface of the first member for securing the sleeve in the engaged position thereof.