Patent ID: 8534380

Claim:
A method 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: using a first means to apply 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; using a second means 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 second means comprises a geostationary element disposed circumferentially around the bottomhole assembly or drill bit and configured to interact with a sidewall of the borehole to focus and/or bias the lateral motion of the bottomhole assembly, and wherein the geostationary element is configured to provide a compliance that varies circumferentially around the geostationary element and the lateral motion of the bottomhole assembly is produced by the first means; and a third means for rotating the geostationary element around the drill string to position the geostationary element on the drill string.