Technology Update: Managed-Pressure Drilling Advances Expand Options of Onshore Drillers

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Technology Update This is an update on several managed-pressure drilling (MPD) technologies and downhole drilling performance-enhancing tools in use onshore and is the first of a two-part series. The second article on offshore MPD technologies will appear in the February issue of JPT. Numerous recent advances in managed-pressure drilling (MPD) technology have led to the increased use of MPD and an expanded repertoire of solutions for a variety of drilling challenges. This article will focus on several such advances in onshore drilling, including new rotating control devices (RCDs), additional MPD applications, new downhole tools activated by radio frequency identification (RFID), and a rate-of-turn gyroscope, which is based on a microelectromechanical system (MEMS) and uses smart algorithms to alert drillers when harmful rotational dynamics are occurring in the drillstring. Conventional Systems vs. MPD The hydraulics of conventional drilling was founded in the Spindletop field in Beaumont, Texas, circa 1901. After the initial gushers, the celebration of such quickly waned, and the industry learned to drill with a weighted fluid—literally mud from a cattle pond at the time—to enable drilling into the reservoir without inviting a blowout. The rig pumps returned mud and cuttings to an open-to- atmosphere drilling nipple beneath the rig floor. Thus, the hydrostatic head pressure of the annulus returns column became the primary well-control barrier. A precipitous fall of the returns compromises that barrier and an overflow signals a potential well-control situation. For more than a century, this system has served the land drilling industry well. However, most of the “easy” prospects that can be drilled that way have already been drilled. An inherent weakness of the system has become more troublesome, and a growing number of otherwise promising prospects have proved undrillable with the conventional approach. The only way to adjust the pressure on the exposed formation without interrupting drilling is to change the circulating rate, which slightly increases or decreases the equivalent mud weight (EMW). The closed-loop system of MPD adds an important component to the equation, enabling more precise management of the wellbore pressure profile, whether circulating or not. EMW may be managed with mud pumps on the front side or with discrete applications of backpressure on the back side. Specialized enabling tools include a fitfor- purpose RCD, nonreturn valves in the drillstring, and a dedicated drilling choke manifold. The choke may be manual, semiautomatic (a typical hydraulic or more precise electric set-point choke) or automatic (controlled by programmable logic). EMW complements the primary well-control barrier.