System and method for damping vibration in a drill string

摘要

A method for damping vibration of a drill bit 13 involves providing a valve assembly 16 capable of exerting a damping force on the drill bit 13 and automatically varying the damping force in response to at least one operating parameter of the drill bit 13. The variation in the damping force can be achieved by varying the flow resistance of a magnetorheological fluid of the valve 16 assembly by directing electrical current of varying magnitude to a coil associated with the valve assembly 16.