| 摘要 |
Systems and methods of down-hole communication are disclosed, which facilitate communication across a mud motor. The systems and methods can employ a hysteresis brake that selectively slows a turbine shaft to thereby produce local pressure pules in a drilling fluid in a predetermined pattern. The hysteresis brake can be operated by providing a relatively small control current to produce a relatively large counter torque, which can be transmitted the turbine shaft. The turbine and the hysteresis brake may be provided below a mud motor, and the local pressure pulses may be transmitted to a receiver disposed above the mud motor while the mud motor is operating. The hysteresis brake can be employed when other communication systems fail, and thus can provide a back-up system to permit a drilling operation to be continued. |
