Autonomous Directional Drilling with Rotary Steerable Systems

An autonomous borehole-drilling methodology is proposed using a rotary steerable system (RSS) as the drilling tool. Directional drilling for hydrocarbon exploration is commonly executed by following a predefined well plan that consists of a combination of curves and straight sections, which connect drilling targets to reach. A three-dimensional (3D) trajectory-tracking problem is formulated using model predictive control (MPC), where the trajectory is governed by a borehole propagation model. Downhole inclination and azimuth measurements are used in combination with the depth assessment at the surface to estimate the instantaneous bit position. Next, MPC-based control strategy is used to determine the control actions required to reach the targets based on the discrepancy between the well plan and bit position, while satisfying state and control constraints. The proposed autonomous system can be implemented either on the surface or down-hole on the RSS. The autonomous drilling method has been validated with field tests, the results are presented and discussed.