| 摘要 |
A pendulum is mounted in the drill pipe close to the drill bit to assume a vertical position in the azimuthal plane of the drill pipe. When the position of the pendulum is such that the inclination of the drill pipe is not a preselected amount or the azimuthal direction of the pipe is not the preselected direction, a lateral force is imposed on the drill bit urging it to drill in a direction that will return the drill pipe to said preselected inclination or azimuthal direction. The pendulum and its associated apparatus is rotated in the direction opposite the direction that the drill pipe is rotated and at the same speed, so that the pendulum is substantially nonrotative relative to the earth.
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