Patent ID: 8720605

Claim:
A system for controlling a rotary drilling system, the rotary drilling system comprising a drill string and a bottom-hole assembly coupled with a drill bit, to directionally drill a borehole through an earth formation, comprising: means for applying a side force to the bottomhole assembly to generate lateral motion of the bottomhole assembly in the borehole and provide for side cutting by the drill bit; a control element configured in use to control the lateral motion of said bottomhole assembly to direct the side cutting and provide for the directional drilling of the borehole, wherein the control element is disposed circumferentially around the bottomhole assembly or drill bit and eccentrically coupled with the bottomhole assembly or drill bit so as to provide in use an interaction with a sidewall of the borehole that varies circumferentially around the bottomhole assembly or drill bit, and wherein the control element is configured in use to remain geostationary on the rotary drilling system; and means for rotating the geostationary element around the drill string to position the geostationary element on the drill string.