| 摘要 |
This invention relates to a directional drilling apparatus. More particularly, the invention is a drilling tool including provisions for changing the direction of drilling of a borehole, the tool including a tubular body having means at the upper end for attachment of a drill string, a drill bit affixed to the lower end of the body by means of a slip clutch drill bit so that the drill bit is rotated when the tubular body is rotated while permitting the drill bit to be rotated independently of the body, means within the tubular body for rotating the drill bit, and means controllable from the surface of the earth of varying the angle of the drilling axis of the drill bit relative to the tubular body.
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