Analysis of Rotary Steerable Systems Versus Conventional Mud Motors for Vertical and Horizontal Wells in the Caney Formation, Southwest Oklahoma

ABSTRACT Rotary steerable systems (RSS) have transformed directional drilling over the years and are becoming widely accepted throughout the world. RSS technology has been proven to provide the required strength and agility in challenging and abrasive environments as well as provide a higher rate of penetration (ROP) by allowing more weight transfer to the bit. Due to the higher price of RSS, some companies have stayed loyal to the conventional bent housing (CBH) with a performance drilling motor, regardless of the RSS benefits. This paper examines the performance and cost benefits of standalone RSS (SA-RSS), motor driven RSS (MD-RSS), and CBH systems. Three wells drilled in the Caney formation in Southwestern Oklahoma were selected for the analysis. Results showed that using RSS in the 12.25" intermediate vertical section and the 8.75"/8.5" lateral section was more cost-effective than a CBH system. The cost per foot for the CBH was 1.6 to 2.3 times higher than RSS in the vertical section and 1.7 times higher in the lateral section. The RSS ROP was 2.3 to 4.8 times faster than CBH in the vertical section and 1.6 times faster in the lateral section. INTRODUCTION In the USA and worldwide unconventional oil and gas wells are pushing the technical limits of existing drilling tools and technology to drill longer horizontal and extended reach wells (ERW), with ERW becoming the mainstream technology. For example, horizontal wells in the United States averaged about 10,000 feet of lateral length in the early 2000s but averaged 18,000 feet in 2019 (USA Energy Administration, 2020). One of the longest ERW wells drilled in the world (offshore Orlan, Russia) was in 2017 and reached a total depth (TD) of 49,000 feet (Slav, 2019). In Oklahoma, the test area for this paper, 1,379 horizontal wells were completed between 2020 and 2022, with an average well length of 18,624 feet and an average perforated length of 8,000 feet (Oklahoma Corporation Commission, 2023).