Tubular element for use in a rotary drilling assembly

Claim 2

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 ratcheted 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 increases in protrusion from the outer surface in the direction from said leading edge to said following edge.

Claim 3

The element of claim 1, wherein said ratchetted profile is formed by blades of a bladed drill string stabilizer, which blades comprise each the smooth leading edge and the sharp following edge.

Claim 4

The element of claim 2, wherein said blades have a radius which gradually increases in a direction from said leading edge to said following edge.

Claim 5

The element of claim 1, wherein said ratchetted profile is formed by inserts which are circumferentially distributed over said surface and which have in circumferential direction a toothed shape.

Claim 6

The element of claim 4, wherein each insert forms in longitudinal direction an elongate triangular shaped protrusion.

Claim 7

The element of claim 4, wherein each insert is mounted on a blade of a bladed stabilizer near a following edge thereof.

Claim 8

The element of claim 1, wherein the tubular element is formed by a tool joint of a drill string section.

Claim 9

The element of claim 7, wherein the ratchetted profile is formed by longitudinal saw-tooth shaped grooves in the outer surface of the tool joint.

Claim 10

The element of claim 1, wherein said ratchetted profile is oriented such that it provides high resistance against left hand rotation and low resistance against right hand rotation of the element about the longitudinal axis as such rotations are viewed from the surface.

Claim 11

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 increases in protrusion from the outer surface in the direction from said leading edge to said following edge.

Claim 12

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 increases in protrusion from the outer surface in the direction from said leading edge to said following edge.

Claim 13

A tubular element in accordance with claim 10, wherein the tubular element is a drill string stabilizer and said ratchetted profile is formed by blades of the drill string stabilizer, said blades each comprising: the smooth leading edge; and the sharp following edge.

Claim 14

A tubular element in accordance with claim 11, wherein said blades have a radius which gradually increases in a direction from said smooth leading edge to said sharp following edge.

Claim 15

A tubular element in accordance with claim 10, wherein said ratchetted profile is formed by a plurality of inserts which are circumferentially distributed over said surface and which have a toothed shape in circumferential direction.

Claim 16

A tubular element in accordance with claim 13, wherein each insert forms in longitudinal direction an elongate triangular shaped protrusion.

Claim 17

A tubular element in accordance with claim 13, wherein each insert is mounted on a blade of a bladed stabilizer near a following edge thereof.

Claim 18

A tubular element in accordance with claim 10, wherein the tubular element is formed by a tool joint of a drill string section.

Claim 19

A tubular element in accordance with claim 16, wherein the ratchetted profile is formed by a plurality of longitudinal saw-tooth shaped grooves in the outer surface of a tool joint.

Claim 20

A tubular element in accordance with claim 10, wherein said ratchetted profile is oriented such that it provides high resistance against left hand rotation and low resistance against right hand rotation of the element about the longitudinal axis as viewed from the upstream end of the drill string.

Claim 21

A continuous bit steering method comprising: providing a selectively rotatable tubular element in a 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; orienting a directional downhole motor mounted on the end of the drill string adjacent the tubular element by rotating the drill string in the direction of the smooth leading edge of the ratchetted profile of the tubular member; and drilling in an orienting mode by not rotating the drill string and engaging the directional downhole motor, transferring the reactive torque fluctuations to the borehole wall by engagement of the sharp following edge of the ratchetted profile of the tubular element to the borehole wall.

Claim 22

A continuous bit steering method comprising: providing a selectively rotatable tubular element in a 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; orienting a directional downhole motor mounted on the end of the drill string adjacent the tubular element by rotating the drill string in the direction of the smooth leading edge of the ratchetted profile of the tubular member; and drilling in an orienting mode by not rotating the drill string and engaging the directional downhole motor, transferring the reactive torque fluctuations to the borehole wall by engagement of the sharp following edge of the ratchetted profile of the tubular element to the borehole wall.