| 摘要 |
An active stabilizer 204 comprises a variable brake 302 and a system to control the torque placed on the active stabilizer 204 through contact with a wall of a borehole. The variable brake 302 may comprise a magnetorheological (MR) fluid brake, an electromagnetic actuator, a frictional brake or an electrorheological brake. The brake may be actuated for electricity generation. Alternatively, it may be used to influence directional drilling, as cyclic variations in torque will produce a net directional force on the drilling system 200. To achieve directional drilling, the active stabilizer may be used together with a rotation alteration device such as a bent sub or bend 206 on the drill string, or a mass imbalance. |
