Hybrid 4-pad rotary steerable system for directional drilling of unconventional resources

As the importance of unconventional resource grows, the demand for the directional drilling technology is increasing. One of the key technologies of the directional drilling is a rotary steerable system (RSS). Among several types of RSS developed so far, `point-the-bit´ and `push-the-bit´ are the most commonly used ones. In this paper, a new rotary steerable system using hybrid 4-pad system is introduced. This mechanism improves the steering angle by taking advantages of both `point-the-bit´ and `push-the-bit´ types. We describe the detailed structure and kinematics of this system.