Stick-Slip Reduction Using Combined Torsional and Axial Control

A method for mitigating stick-slip on a drill string, comprising:

• receiving, by a controller, torque on the drill string detected by a torque sensor, the torque being based on a response to a change in at least one of a rotation speed of a drill string rotary drive and a weight on bit of the drill string imposed by an axial drive;
• generating, by the controller, a first movement offset based on the torque and a first gain associated with the drill string rotary drive and a second movement offset based on the torque and a second gain associated with the axial drive;
• and
• sending, from the controller, the first movement offset to the drill string rotary drive for implementation to modify the rotation speed and the second movement offset to the axial drive for implementation to modify the weight on bit, to mitigate the stick-slip on the drill string during drilling operations.

A non-transitory machine-readable medium having stored thereon machine-readable instructions executable to cause a machine to perform operations comprising:

• receiving a detected amount of torque on a drill string at an interface of the drill string and a drill string drive;
• determining a first movement offset corresponding to a rotation speed of the drill string drive and a second movement offset corresponding to a weight on bit controlled by an axial drive, each based on the detected amount of torque;
• and
• sending the determined first movement offset to the drill string drive to adjust the rotation speed and the determined second movement offset to the axial drive to adjust the weight on bit, a combination of the adjustment to the rotation speed and the weight on bit mitigating stick-slip on the drill string during drilling operations.