| 摘要 |
<p>A method and apparatus for creating a telemetry signal in a drillstring is disclosed. Opposite torsional forces are imparted on the drillstring at two or more different locations. A steel shaft inside the drillstring is coupled to the drillstring via electromagnetic actuators at end and rigidly attached to the drillstring at the other end. A similar method and apparatus for generating axial telemetry signal in the drillstring is also disclosed.</p> |
