Farther, faster, cheaper, safer. These words describe the drilling results of the newest rotary steerable systems. Substantial advances in the reliability and steerability of rotary steerable drilling systems allow engineers to plan and drill complicated well trajectories in extremely demanding environments. Better still, oil and gas companies save rig time while doing so.
Rotary steerable drilling technology made a dramatic entry into the market in the late 1990s. The technology has advanced considerably since then, offering increased flexibility, greater reliability, and higher rates of penetration. These high-performance systems facilitate the drilling of complicated wellbore trajectories in harsh environments.
With industry costs for nonproductive drilling time estimated at US$ 5 billion per year, rotary steerable systems are a key to preventing or reducing these significant losses.
The newest rotary steerable systems continuously rotate the entire drillstring. Continuous rotation offers several mechanical advantages. More efficient transfer of weight to the bit increases the rate of penetration. Rotation improves hole cleaning by agitating drilling fluid and cuttings, allowing them to flow out of the hole. Efficient cuttings removal reduces the chance for the bottomhole assembly to become stuck or pack off.
Schlumberger has developed distinct PowerDrive* rotary steerable (RSS) systems for many different applications, such as drilling soft formations, drilling vertically, avoiding differential sticking and drilling long laterals. Rapid development of additional RSSs will likely continue. Ultimately, 搒hoe to shoe?rotary steerable drilling will allow companies to drill out the casing shoe and continue drilling to the next casing point in a single run.
An interactive Oilfield Review article, "Better Turns for Rotary Steerable Drilling", describes how rotary steerable drilling technology has evolved. Examples from Brazil, Norway, Italy, the Caspian Sea, Egypt, and Canada demonstrate the versatility of the technology.
For information on rotary steerable systems, contact Mike Williams.
by Gretchen Gillis, Schlumberger Executive Editor-Books