Patent ID: 9206644
Filing Date: 2015-12-08
Classification: E21B

Abstract:
1. A system comprising: a bit box formed at a first end of a drill collar, the bit box configured to couple a drill bit thereto; a motor positioned within the drill collar; a magnetic coupling arrangement positioned within the drill collar and electrically coupled to the motor to provide power to the motor, wherein the magnetic coupling arrangement includes a first cylindrical coil located within a second cylindrical coil, wherein the first cylindrical coil and the second cylindrical coil are loosely coupled according to the following relationship: where k represents a coupling coefficient of the first cylindrical coil and the second cylindrical coil, M represents a mutual inductance between the first cylindrical coil and the second cylindrical coil, L wherein the first cylindrical coil is resonantly tuned with a first capacitor and the second cylindrical coil is resonantly tuned with a second capacitor such that the first cylindrical coil and the second cylindrical coil resonate at approximately the same frequency according to the following relationship: wherein a figure of merit between the first cylindrical coil and the second cylindrical coil is equal to or greater than 3 according to the following relationship: where U represents the figure of merit, Q a steering system positioned within the drill collar and coupled between the motor and the bit box for steering a direction of the bit box with respect to an axis of the drill collar in response to the operation of the motor.