Abstract
Traditionally, trajectory control in the drilling industry has been performed by experienced directional drillers, using drilling tools such as mud motors, these tools are just iron components, that limits the efficiency of the drilling process and rate of penetration (ROP). The introduction of Rotary Steerable Systems (RSS) enabled faster and efficient well bore delivery. This tested the limits of human operators to assimilate the MWD data, compare the actual well trajectory with the planned and take corrective actions to get back to the desire well plan.
A hybrid approach consisting of two levels is proposed to perform the trajectory control in the oil drilling industry using RSS. Level 1, attitude control, regulates inclination and azimuth downhole. Level 2, the outer loop, monitors the performance of the inner loop and controls the directional drilling commands issued to the tool to follow a predefined plan.
A next generation nonlinear trajectory control algorithm was developed and tested. This algorithm can hold inclination and azimuth downhole, run below mud motors, and perform an automatic turn, while holding inclination with the ability to control the gains while drilling ahead. This novel algorithm has been applied in various locations worldwide to control inclination and azimuth and keep true vertical depth (TVD) within tight tolerances. Conclusions and lessons learned from the analysis will aid future applications of the hybrid approach and the new algorithm.
