Patent attributes
Apparatus and methods for controlling release of torsional energy from a drill string having a lower portion that is stuck against a subterranean formation and a top end rotated by a top drive. The method may include decreasing a rotational speed set-point of the top drive, decreasing a torque set-point of the top drive, and/or decreasing flow rate of drilling mud being pumped downhole via the drill string, thereby decreasing torque output by a mud motor rotating a drill bit. The method may further include lifting the drill string to free the drill string. Decreasing the torque set-point of the top drive may comprise decreasing the torque set-point of the top drive to a minimum torque level that the top drive can output. Decreasing the rotational speed set-point of the top drive may comprise decreasing the rotational speed set-point of the top drive to zero.
