| 摘要 |
Systems and methods usable for drilling wells and performing other well operations include a drilling tool having inner and outer, counter-rotating drill bits. Opposing reactive torques generated by the inner bit and the outer bit can reduce or cancel the net reactive torque transmitted upwell, through the drill string. Counter rotation of the inner and the outer drill bits can be achieved by a gear system, which transfers torque from a single rotating tubular shaft to a tubular sleeve positioned concentrically about the tubular shaft. The gear system transfers torque from a first gear to a second gear, at a one-to-one rotation/torque ratio, but with an opposite direction of rotation. Tools connected to the tubular sleeve and tubular shaft can thereby be provided with opposing rotational motion. |
