| 摘要 |
A hydraulic thruster (1) for generating a thrust force to a drill bit located at the lower end of a drill string is provided. The thruster comprises a first member (3) connectable to an upper part of the drill string and a second member (5) connectable to a lower part of the drill string, said members being telescopingly arranged relative to each other and being capable of transmitting torque between the upper and lower part of the drill string during drilling. A fluid passage (9) for passing through said members (3, 5) for drilling fluid flowing through the drill string towards the drill bit and means (11, 15) for generating an inward telescoping reaction of said members upon transmission of torque between the upper and lower part of the drill string during drilling are provided.
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