| 摘要 |
A method of operating a drilling system for drilling a subterranean bore hole. The drilling system includes a drill string which rotates during a drilling, and a sealing device which provides a substantially fluid tight seal around the drill string while the drill string is rotating during the drilling. The method includes injecting a fluid into an annular volume around the drill string directly above the sealing device, and controlling a first fluid pressure in the annular volume around the drill string above the sealing device so that the first fluid pressure is greater than a second fluid pressure in the annular volume around the drill string directly below the sealing device. |
