Transforming the Trajectory Control from Conventional Motor Drilling to Autonomous Rotary Steerable Systems

The most challenging section in drilling directional wells is the curve section. This curve section used to be drilled by a conventional steerable motor with a slide/rotate decision with the greater challenges of poor hole cleaning efficiency and increased drilling time. The Rotary Steerable System (RSS) was introduced in a turnkey project by eliminating slide and rotate limitations to reduce the cost per foot. Initially, the downhole automation of the RSS was limited to holding verticals and inclinations. Later, the closed-loop control progressed to hold inclination and azimuth, but the curve section remained unautomated. The driller continued to drill the curve section manually by adjusting the steering parameters. A new Autonomous Downhole Control System (ADCS) recently integrated into the RSS enables autonomous drilling of the curve section, further reducing human inconsistencies and improving borehole quality, drilling efficiency, well economic, and reducing carbon footprint. Multiple offset wells were analyzed. Different BHA configurations were studied with various stabilizations to increase the dogleg capability. Bit records were gathered and analyzed for steerability and stability. The trajectory design was revisited to ensure minimum dogleg severity was considered at the planning stage. This ensured staying within the RSS's technical limits and avoiding unplanned pulling out of the hole due to failure to maintain the trajectory. The specific field strategy was prepared with the digital journey of intelligent planning, intelligent execution, surface automation, and downhole automation. The RSS was incorporated with the newly developed ADCS, placing the driller into the supervisory role to monitor the digital drilling system. The RSS was introduced in a turnkey project to reduce the cost per foot by improving the ROP, drilling shoe-to-shoe in one run, having efficient hole cleaning to avoid stuck pipe incidents, and having a smoother borehole for running casing and liner. The new ADCS incorporated into the RSS completed the automation puzzle and has been tested successfully in many wells on the same project. It transfers human decision-making to the downhole control, further increasing ROP in some cases by up to 100% and up to three days saved on each well drilled. This paper will illustrate the detailed BHA change in curved and horizontal sections from mud motor to the RSS with the significant progression of downhole automation and a future view for autonomous drilling in similar fields worldwide.