Case Study: Hitting the Bullseye: The Evolution of RSS and LWD Technology in Horizontal Wells
Authors: Loreto Julio , Zukiwsky Brad , Bassiouny Aly , Okorie Onochie Michael 
Published: January 2023

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For nearly a century, conventional directional drilling served as the benchmark for drilling nonvertical wellbores. It enabled operators to access multiple parts of a reservoir from a single surface location, reducing the overall environmental impacts. Traditional directional drilling used some type of nonrotating bent sub to tilt the drill bit in a different direction from the central axis.
But with the demands of the modern energy industry driven by the unconventional horizonal well market, the industry needed a step change. Operators required a system that could precisely steer through extended-reach wells, often traversing complex trajectories, with precision control and greater reliability. The evolution of rotary steerable systems (RSS) and logging-while-drilling (LWD) technology in the early 2000s addressed this demand by deploying fit-for-purpose tools and services to improve the economic viability of oil and gas fields around the world.

High-Performance Drilling With Full Directional Control
With more operators needing an RSS system that could drill through longer horizontals and deliver quality wellbores in as few runs as possible, Weatherford recognized the demand and responded with the Magnus RSS. Using a push-the-bit design, the system combines reliable, high-performance drilling with precise directional control to enable operators to extend the performance of each drilling run, providing faster drilling, better wellbore quality, and high-quality measurements.
Directional drilling requires tools to stay in the wellbore for extended periods of time. To keep costs as low as possible, the optimal solution is to perform all drilling operations in one run. To account for the downhole stresses, a rugged design was developed for the RSS. A streamlined design, featuring a ¼-in. undergauge stabilizer and 20% junk-slot area, a fully rotating bias unit, minimal bottomhole assembly (BHA) stabilization, and an optimized junk-slot area combine to reduce the risk of expensive stuck-pipe events. The system also incorporates metal-on-metal piston seals in the mud-actuated pad, enhancing mechanical integrity in harsh and high-pressure drilling environments and greater overall system reliability.
Operators also need the ability to precisely steer the bit to stay on the well plan no matter if the plan requires verticals, curves, or laterals. Three independent pads and valves provide proportional control and allow the pads to fully retract for reaming, cement/shoe drilling, or tight-hole applications. This independence also provides redundancy in the system in the event of pad or valve failure. The three pads actively manage the direction through the entire wellbore and achieve a true-inclination hold in the lateral.
In many conventional directional drilling operations, even a successful run can leave the wellbore in need of underreaming to prepare it for the installation of contingency liners and casing or completions equipment. Ideally, to optimize drilling efficiency, the directional drilling and underreaming should be performed in the same run. To meet operators’ desire for hole enlargement while drilling, our engineers developed the RipTide drilling reamer, which is often coupled with the Magnus RSS, to drill a smooth, concentric underreamed hole to total depth in one trip.