Design of Offsetting Steerable Mechanism for Rotary Steerable Drilling Tool Based on Double Eccentric Rings

Precise control of the inclination and azimuth is of great significance for the efficient drilling of dynamic point-the-bit rotary steerable drilling tool. The design details of offsetting steerable mechanism for rotary steerable drilling tool based on inner and outer double eccentric rings are demonstrated in the paper. While drilling, the tool collar rotates and passes the torque and drilling pressure to the drill bit efficiently, and the stable platform mounted inside the collar is maintained geostationary by rotating it counter to collar rotation at the same frequency. And an offsetting steerable mechanism in the stable platform provides selectively and axially inclination to the collar by adjusting the relative position of the inner to the outer double eccentric rings. It is shown that the maximum oriented inclination can be reached as 1.0 degree flexibly for the presented structure.