Methods and apparatus for mitigating downhole torsional vibration

摘要

A well tool apparatus for damping torsional vibration of a drill string comprises stabilizing members projecting radially outwards from a housing that is, in operation, rotationally integrated in the drill string, to stabilize the drill string by engagement with a borehole wall. The stabilizing members are displaceably mounted on the housing to permit limited angular movement thereof relative to the housing about its rotational axis. The well tool apparatus includes a hydraulic damping mechanism to damp angular displacement of the stabilizing members relative to the housing, thereby damping torsional vibration of the housing and the connected drill string, in use.

主权项

1. A well tool apparatus for use in a drill string in a borehole defined by borehole sidewalk, comprising:
a housing assembly having a connection configured to co-axially connect the housing to the drill string the housing having a central longitudinal axis; one or more stabilizing members that project radially outwards from the housing for engagement with the borehole sidewalls, the stabilizing members configured to radially space the housing from the borehole wall; a mounting assembly configured to mount each of the one or more stabilizing members in rotationally moveable relation to the housing to permit relative angular displacement of the entirety of each of the one or more stabilizing members about the housing central longitudinal axis, the mounting assembly configured to resist relative longitudinal displacement between the housing assembly and the stabilizing members, the mounting assembly including a hydraulic damping mechanism configured to damp relative angular displacement between the housing and the one or more stabilizing members.