Drilling Automation: Novel Trajectory Control Algorithms for RSS

Abstract Operators traditionally have been drilling in easy reservoirs that allow for large target TVD tolerances, in the order of few 10s of feet. However, with the maturity of reservoirs, the tolerances and accuracy required to draw out the residual oil has become quite narrow, to the order of one to two feet. Traditionally, trajectory control in the drilling industry has been performed by experienced directional drillers, using drilling technologies such as motors. These technologies were dumb iron components, and were limited in their efficiency (ROP), which gave enough time for making control decisions. 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. Rotary Steerable Systems are very sophisticated tools with downhole intelligence. This provides the framework to implement advanced and automatic downhole trajectory control algorithms, which have no lag times, and can perform consistent, accurate, and reliable corrective actions. This paper discusses the development and testing of a next generation non-linear trajectory control algorithm, which can Hold Inclination and Azimuth downhole, run below mud motors and perform an automatic turn, while holding inclination with ability to control the gains while drilling ahead. This paper also presents case studies of the runs from various locations worldwide, which used this novel algorithm to control inclination, azimuth, and keep TVD within tight tolerances. The paper ends with analyses, lessons learned and conclusions from the field trial runs.