With increased well complexity, difficulty matching the actual well profile with the planned well profile increases. This study discusses building a workflow for automating the bottomhole assembly (BHA) to take corrective actions upon detection of a deviation from the planned well path in a 3D coordinate space, and constructing and programming a prototype demonstrating the proposed theory. The corrective paths would be conventional constant curvature curve and unconventional curves, such as catenary and spline, which are proven to be smooth, thereby reducing torque and drag in the well. The main constraint governing the unknown parameters of the corrective path is the minimum well profile energy criterion, which is excellent in terms of producing smooth curves because it minimizes the curvature and torsion of the curve together. Balanced tangential and minimum curvature methods are used for building the corrective trajectory.
Previous work on downhole drilling automation showed that the minimum energy method, compared to proportional, integral, and derivative (PID) control and fuzzy control, where the model was built for 2D and 3D coordinate space by considering conventional constant curvature curves for correction, yields much smoother wellbore trajectories. The work was continued for unconventional well profiles in 2D wells, where spline, catenary, and clothoid curves were used to return the deviated well to the original planned path. This work focuses on building the model to determine the corrective paths based on unconventional curves for wells in a 3D coordinate space. The model first determines the point on the planned path where the bit needs to join and then estimates the best possible path to do so. The whole corrective workflow is demonstrated with a small scale working prototype. Finally, the results of various optimization models obtained by combining different unconventional curves and trajectory calculation methods are compared.