| 摘要 |
<p>A drilling system and method for drilling a borehole into an earth formation is provided. The drilling system comprises a drill string (1) having a lower section provided with a sleeve (7) which is radially expandable from a retracted mode in which the sleeve extends around said lower drill string section and is releasably connected thereto, to an expanded mode in which the sleeve is released from the lower drill string section and is expanded against the borehole wall. The drilling system further comprises control means (10) for selectively releasing the sleeve (7) from the lower drill string section and expanding the sleeve against the borehole wall.</p> |
