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This paper discusses the development, testing and optimization of a rotary steerable system (RSS) developed specifically to address the challenges around drilling wells in unconventional reservoirs in North America. As with offshore areas, rotary steerable drilling technology has rapidly gained acceptance for onshore use because of its clear advantages in directional control, wellbore placement and lateral reach, while matching or exceeding the drilling performance of conventional systems. The further growth of RSS into the drilling of unconventional reservoirs has been limited by the build-rate (BUR) capabilities of established RSS that prevent operators from successfully drilling curve and lateral sections in one run. In recent years, service companies have worked to improve the capabilities of rotary steerable drilling systems to meet the specific needs of drilling horizontal wells in unconventional oil and gas reservoirs. Due to lease spacing and limited vertical depths to achieve horizontal orientation, greater buildup rates (BUR) are required to maximize the lateral lengths in the reservoir. In addition to developing higher doglegs in the curve, the system should also enable lateral control to minimize tortuosity, facilitate easy casing running and optimize successful multistage fracturing. The authors outline how specific challenges, such as reduction in drilling time, improved wellbore placement, and more efficient completion and fracturing operations are addressed by the introduction of the new system. Included in this paper is a description of how the bottomhole assembly (BHA) and drill-bit properties are matched and optimized to deliver best directional control and drilling performance, according to formation characteristics in the Granite Wash play in the central USA. Explanations detail how the new system capabilities expand the possibilities to develop reservoirs using pad drilling, the use of more complex well profiles and real-time reservoir navigation, leading to increased hydrocarbon production. |
