Patent ID: 11885223
Assignee: THE CHARLES MACHINE WORKS, INC.
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 17:
18. A method for rotating a drill string, the drill string comprising an outer pipe string and an inner pipe string disposed within the outer pipe string, the method comprising:
providing a backreamer at a distal end of the drill string, the backreamer being rotationally coupled to the outer pipe string;
providing a first motor, the first motor rotationally coupled to the inner pipe string;
rotating the outer pipe string using a second motor;
measuring a first rotation rate of the inner pipe string;
measuring a second rotation rate of the outer pipe string;
determining if the first rotation rate exceeds a predetermined threshold; and
if the first rotation rate exceeds a predetermined threshold, rotating the inner pipe string with the first motor such that the first rotation rate and the second rotation rate are equal.