| 摘要 |
A drill string apparatus for the controlled absorption of both axial and torsional forces exhibited on the well string during drilling operations. The device is adapted to be connected in the drill string above the drilling tool in order to control the forces acting on the bit and to arrange the mean weight on bit for the selected drilling operation. Generally, the apparatus includes an outer casing coupled at its upper end to the drill string and an inner assembly telescopically received within the outer casing and connected at its lower end to the lower part of the bottom hole assembly or the drilling tool. Rotational torque is transferred from the drill string and outer casing to the inner assembly and drill bit by a series of helical splines. The mean weight on bit is controlled through an interchangeable pressure control nozzle mounted at the top of the inner assembly. Dual pistons with corresponding fluid chambers dampen axial forces while the helical splines decouple the torsional forces from axial vibrations to ensure proper control of the drill bit. In addition to attenuating vibration in conventional drilling operations, the present invention can be utilized in highly deviated holes and in drill strings using coiled tubes.
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