High frequency torsional oscillation mitigation tool
A high frequency torsional oscillation mitigation tool for use in a downhole drilling assembly. The tool has a first end, a second end, and a one-way coupling therebetween. The one-way coupling has a first part connected to rotate with the first end and a second part connected to rotate with the second end. The one-way coupling has an engaged condition in which the first part and the second part can rotate together in a first rotational direction whereby drill string rotation can be communicated to the drill bit. The one-way coupling has a disengaged condition in which the first part can rotate relative to the second part in a second rotational direction. The one-way coupling can have multiple sets of driving elements along its longitudinal axis. The tool can include a locking mechanism to override the one-way coupling for recovering a stuck downhole assembly.
1 . A high frequency torsional oscillation mitigation tool comprising:
a first end,
a second end,
a one-way coupling between the first end and the second end,
a first connector at the first end,
a second connector at the second end,
wherein the one-way coupling comprises a first part and a second part, the first part being connected to rotate with the first connector and the second part being connected to rotate with the second connector,
wherein the one-way coupling further comprises
an engaged condition in which the first part and the second part can rotate together in a first rotational direction, and
a disengaged condition in which the first part can rotate relative to the second part in a second rotational direction,
a locking mechanism for the one-way coupling.
2 . The high frequency torsional oscillation mitigation tool according to claim 1 , wherein the locking mechanism is actuated by a tensile force between the first connector and the second connector which exceeds a predetermined threshold.
3 . The high frequency torsional oscillation mitigation tool according to claim 1 , wherein the locking mechanism comprises a locked condition in which a relative rotation between the first part and the second part of the one-way coupling is restricted, and an unlocked condition in which the relative rotation between the first part and the second part is permitted.
4 . The high frequency torsional oscillation mitigation tool according to claim 3 , wherein the locking mechanism is biased to said unlocked condition thereof by a resilient biasing means.
5 . The high frequency torsional oscillation mitigation tool according to claim 1 , wherein the first part of the one-way coupling is movable axially relative to the second part of the one-way coupling, such that relative axial movement transfers the locking mechanism between its unlocked and locked conditions.
6 . The high frequency torsional oscillation mitigation tool according to claim 1 , wherein the locking mechanism comprises respective sets of interlocking components.
7 . The high frequency torsional oscillation mitigation tool according to claim 6 , wherein the respective sets of interlocking components comprise a first set of gears which is rigidly connected to the first part of the one-way coupling and a second set of gears which is rigidly connected to the second part of the one-way coupling.