| 摘要 |
<p>A device (20) for controlling hydraulic power supplied to a system of a plurality of hydraulic motors (10, 11) of a drill string for drilling a borehole into an earth formation, each hydraulic motor being arranged to drive a respective drill bit of the drill string, the device comprising means for dividing a stream of hydraulic fluid flowing through the drill string into a plurality of sub-streams (32, 33), each sub-stream driving a respective one of said motors, and control means for increasing the hydraulic power of a selected sub-stream and for decreasing the hydraulic power of at least one of the other sub-streams in response to an increase of fluid pressure drop across the motor driven by the selected sub-stream.</p> |
