Steerable directional drilling reamer

摘要

A reamer with a planetary gear train for use in horizontal directional drilling allows a reaming surface of the reamer to rotate at slower speeds while simultaneously conveying more power to the reamer via fast drill string rotational speeds. The reamer may also include mixing elements that may rotate at the same speed as the drill string. The reamer may further be steerable and include an offset mount that is rotatably coupled to the reamer. The offset mount being configured to couple a ream string to the reamer in such a manner that a longitudinal axis of the ream string is not collinear with the axis of rotation of the reamer. The reamer may also include u-joints which couple the reamer to a drill string and ream string, the u-joints allowing for a greater range of angles to be achieved when tilting the reamer by means of rotating and positioning the ream line.