ROTARY STEERABLE DRILLING TOOL

摘要

The invention refers to a rotary steerable drilling tool having a tool coll ar and a bit shaft. The bit shaft is supported within the tool collar for pivot al movement about a fixed position along the bit shaft. Moreover, the rotary steerable drilling tool includes a variable bit shaft angulating mechanism, located within the interior of the tool collar. The variable bit shaft angulating mechanism includes a motor, an offset mandrel, and a variable offset coupling. The motor is attached to the upper end of the offset mandrel and adapted to rotate the offset mandrel . The upper end of the variable offset coupling is uncoupleably attached to an offset location of the lower end of the offset mandrel, and the upper end of the bi t shaft is rotatably coupled to the variable offset coupling. The rotary steerable drilling tool also includes a torque transmitting coupling adapted to transmit torque from the tool collar to the bit shaft at the fixed position along the bit shaft. Finally, a seal system is adapted to seal between the lower end of the tool collar and the b it shaft.