A motion compensator for drilling from a floater provides isolation of a cutting device in a well from motion of a tubular string thereabove. In a described embodiment, a motion compensator includes an anchoring device and an axial advancement device. The motion compensator is positioned in the tubular...http://www.google.com.au/patents/US6286614?utm_source=gb-gplus-sharePatent US6286614 - Motion compensator for drilling from a floater
