Downhole Steering Automation and New Survey Measurement Method Significantly Improves High-Dogleg Rotary Steerable System Performance

Abstract

The first commercial high-dogleg rotary-steerable systems (RSSs) were introduced in 2011. These systems were specially designed to drill vertical, kick off, build at planned 8 to 12°/100 ft (or even higher), and drill the lateral to lengths of up to 6,000 ft in unconventional reservoirs (such as shale gas applications) in North America. Because of the improved economics and other benefits for efficient drilling a high-build-rate curve and lateral in single run, high-dogleg RSS technology has rapidly gained acceptance for drilling shale wells.The performance of the high-dogleg RSS is greatly enhanced with automated steering mode in vertical and lateral sections by reducing a human-machine interaction and minimizing wellbore tortuosity in these sections. Downhole trajectory-control algorithms make small, but frequent, adjustments to RSS steering parameters, comparing the near-bit continuous survey data against a planned well trajectory. Downhole steering automation is an integral part of the overall drilling system automation that the drilling industry is pushing forward.A new static and continuous (dynamic) survey method has been used in the near-bit sensors of a specific high-dogleg-severity (DLS) RSS. The new survey method significantly improved the inclination and azimuth measurement in near-vertical angles; thus, it not only enhanced the automated vertical drilling feature but also provided more accurate kickoff from a near-vertical position using the RSS near-bit static and continuous survey. In addition, improved continuous measurements around magnetic north and south allowed the closed-loop trajectory-following algorithm of the RSS to drill lateral sections more precisely in these directions.The software simulation and field trials were conducted to test a new survey measurement method implemented in a highdogleg RSS, along with automatic trajectory-following algorithms. In one of the field trials, the RSS drilled more than 10,750 ft (vertical, high-dogleg curve, and lateral) in one run, including 5,000 ft of vertical and 4,500 ft of lateral sections in automated steering mode, saving 4 days (about 30%) compared with the previous non-high-dogleg RSS runs. A unique combination of the new technologies has enabled increased well construction efficiency in shale plays by providing a step change in steering technology, trajectory-following algorithms, and downhole survey method.