Patent Number: 7,610,970

Title: Apparatus for eliminating net drill bit torque and controlling drill bit walk

Abstract: A drilling apparatus controls or eliminates reaction torque from drill bits thereby preventing loss of penetration due to undesired rotation of the drilling apparatus or controls drilling direction by intentionally manipulating reaction torque thereby inducing desired drill bit walk. The drilling apparatus has a concentrically divided drill bit in which an inner drill bit rotates simultaneously in the opposite direction from an outer drill bit. The inner drill bit can be moved axially forward from or back toward the outer drill bit. Forces produced by the inner and outer drill bits are controlled to eliminate or adjust reaction torque.

Inventors: Sihler; Joachim (Cheltenham, GB), Shepherd; Michael John (Stroud, GB)

Assignee: Schlumberger Technology Corporation

International Classification: E21B 44/00 (20060101)

Expiration Date: 1/03/02017