Design and Demonstration of Autonomous Directional Drilling With a Miniature Scale Rig

Drillbotics, an international student competition hosted by SPE/DSATS, directed the 2020/2021 competitors to design, build and implement a 1.5″ (3.8cm) hole size, fully autonomous drilling rig capable of intersecting multiple pre-set targets within a rock sample with up to 30-degree inclination and 15-degree azimuth adjustments from the KOP. The Norwegian University of Science and Technology (NTNU) won the competition using a fixed bent Bottom Hole Assembly (BHA) and a simulated mud-motor stator with a rod inside the drillpipe transferring rotational torque from a top drive. The team designed and created a custom drill bit, bi-directional hydraulic swivel, and BHA. Trajectory control was achieved by changing the BHA bend orientation over time, rotating the drillpipe with inputs from a nonlinear Model Predictive Controller (nMPC) following a pre-planned Bezier-curve well path. Capabilities of the rig were demonstrated by drilling a 37-degree inclination well path in 6 minutes in a 60 cm sandstone replica.