Tubular element for use in a rotary drilling assembly and method
AssigneeShell Oil Company
InventorDjurre H. Zijsling
Life of this patent
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Abstract
A tubular drill string element, such as a stabilizer or tool joint, comprises an outer surface having in circumferential direction a ratchetted profile. The ratched profile is preferably oriented such that provides low resistance against right hand rotation but high resistance against left hand rotation of the drill string.
Claims19
A selectively rotatable tubular element for use in a rotary drilling assembly, the element comprising an outer surface which faces the borehole wall during drilling, said surface having a ratchetted profile in a plane cross-axial to a longitudinal axis of the element, said ratchetted profile presenting a leading edge and a following edge in relation to the normal rotation of the tubular element in which the leading edge is substantially smooth, and gradually and continuously increases in distance from said longitudinal axis from said leading edge to said following edge.
A tubular element for use in a rotary drilling assembly within a borehole, the element comprising:
- an outer surface which faces the borehole wall during drilling, said surface having a ratchetted profile in a plane cross-axial to a longitudinal axis of the tubular element, said ratchetted profile presenting a leading edge and a following edge in relation to the normal rotation of the tubular element in which the leading edge is substantially smooth, and gradually and continuously increases in distance from said longitudinal axis from said leading edge to said following edge.
A method for protecting a drill string in a borehole from back swing in response to fluctuations of reactive torque produced during drilling with a downhole motor, said method comprising providing a selectively rotatable tubular element in the lower portion of the drill string such that an outer surface thereof presents a ratchetted profile to the borehole wall with a smooth leading edge and a sharp following edge with respect to the driving rotation of the drill string.
Dependencies are inferred from the claim text.