Apparatus and method for damping vibration in a drill string

摘要

An apparatus and method for damping vibration, especially torsional vibration due to stick-slip, in a drill string, Sensors measure the instantaneous angular velocity of the drill string at one or more locations along the length of the drill string. One or more vibration damping modules are also spaced along the length of the drill string. When torsional vibration above a threshold is detected, the damping module imposes a reverse torque on the drill that dampens the torsional vibration. The reverse torque can be created by imparting a frictional resistance to the rotation of the drill string. The frictional resistance can be created externally, by extending friction pads from the damping module so that they contact the bore hole wall and drag along the bore hole as the drill string rotates, or internally by anchoring a housing mounted on the drill string to the wall of the bore hole and then imposing frictional resistance on a fluid, such as a magnetorheological fluid, flowing within the drill string.

主权项

1. A method of damping torsional vibration in a drill string having a drill bit and a bottom hole assembly spaced from the drill bit in an uphole direction, the drill bit configured to drill a bore hole through an earthen formation, the method comprising the steps of:
applying a torque to said drill string in a first rotational direction so as to cause said drill string to rotate in said first rotational direction; extending at least one member carried by the bottom hole assembly from a retracted position to a fully extended position where the at least one member extends outward with respect to the bottom hole assembly; sensing, via a sensor carried by the bottom hole assembly, the value of a parameter that is indicative of the presence of torsional vibration in said drill string; comparing, via a processor in communication with the sensor, said value of said parameter to a predetermined threshold of torsional vibration; applying a reverse torque to said drill string via the at least one member to dampen the torsional vibration when 1) the at least one member is in the fully extended position, and 2) said value of said parameter exceeds said predetermined threshold, wherein said reverse torque acts in a second rotational direction that is opposite to said first rotational direction and exerts a force against a wall of said bore hole so as to dampen said torsional vibration; wherein the extending step occurs when said value of said parameter indicative of torsional vibration does not exceed said predetermined threshold so that the time required to cause said at least one member to exert said force against said bore hole wall when said parameter exceeds said predetermined threshold is shortened.