STEERABLE DRILLING SYSTEM

摘要

A steerable drilling system comprises a rotary drill bit 14 secured to a housing 16, a secondary rotary drill component 22 carried by the housing and rotatable therewith, the second rotary drill component 22 having a gauge dimension greater than that of the rotary drill bit 14, and a drive arrangement operable to displace the second ar- y rotary drill component 22 relative to the housing 16 whilst maintaining an axis 24 of the secondary rotary drill component 22 substantially parallel to an axis 18 of the housing 16.