Patent ID: 6513606
Filing Date: 2003-02-04
Classification: E21B

Abstract:
A drill string for drilling wellbores, comprising:(a) a rotatable tubular member conveyable from a surface location into the wellbore; and (b) a drilling assembly coupled at a first upper end to the tubular member, said drilling assembly comprising; (i) a drill bit at a second bottom end of the drilling assembly; (ii) a drilling motor uphole of the drill bit for rotating the drill bit; (iii) a first set of ribs containing a plurality of ribs arranged around a section of the drilling assembly, said first set of ribs rotating at the same rotational rate as the tubular member in the wellbore when said rotatable tubular member rotates, each rib in said first set extending radially outward from the drilling assembly to apply force to the wellbore, upon the application of power thereto; (iv) a power unit supplying power to the ribs; and (v) a controller selectively causing the ribs to apply different forces to the wellbore during drilling of a first section of the wellbore and to apply substantially the same force to each of the ribs in said first set of ribs during drilling of a second section of the wellbore.