MPD: Beyond Narrow Pressure Windows

Abstract

Abstract Managed Pressure Drilling (MPD) is an enabling technology that is highly sought after in the drilling industry in recent years. MPD is generally associated with narrow pressure windows, i.e., staying between either pore pressure (Pp) or formation stability and fracture pressure (Fp). However, operators are starting to realize MPD has a broader range of application, beyond navigating narrow pressure windows and other traditional applications such as Dual Gradient Drilling and Pressurized MudCap Drilling. Over the past couple of years, MPD's range of application has increased, as can be seen from the examples presented in this paper. New offshore and onshore MPD projects in the Gulf of Mexico (GoM), North Sea, North America, South America, Africa and Europe are being designed for objectives like improving Rate of Penetration (ROP), reducing formation invasion, validation of pore pressure data, reducing incidents of stuck pipe and mitigating the effects of differential sticking, reducing ballooning or hole breathing and minimizing Non-Productive Time (NPT). MPD is not a universal solution or panacea and improper application of the technique may ultimately cost more than conventional drilling methods. However, with comprehensive planning and execution by experienced engineers, MPD can help actualize project objectives that otherwise might be impossible with conventional techniques. Introduction MPD is a name for a collection of old, modified, and new technologies, referred to as VARIATIONS or METHODS of MPD. MPD can help in achieving specific purposes (such as eliminating a casing string or avoiding formation damage in a particular section of hole), or in solving particular drilling problems (such as drilling through narrow pressure windows or lost circulation zones), or in meeting definite project constraints, such as quality, time or safety (Nauduri, Medley, 2008). Although the MPD acronym was coined recently (Hannegan, Wanzer, 2003; Hannegan, 2005) in 2003, and the IADC UBD committee gave an official definition in 2004, many techniques associated with MPD have been in existence well before the turn of the Twentieth Century. There are accounts of such techniques being used even in the late 18th century and early 19th century. MPD in part evolved from its precursor, Underbalanced Drilling (UBD), in that both drilling methods typically incorporate much of the same drilling equipment and pressure management equipment. Similar equipment is used to drill both UBD and MPD wells and the benefits of the techniques are, in many cases, identical. However, since there is no continuous flow of fluids to the surface, MPD wells are often perceived to be safer than UBD. Until recently based on the applications, four major classifications or "Variations" of MPD have been recognized - Constant Bottomhole Pressure (CBHP), Dual Gradient Drilling (DGD), Pressurized Mudcap Drilling (PMCD) and Zero Discharge or Health Safety and Environmental (HSE). Some of these variations are achieved by using more than one different technique or method of MPD together (Medley, Reynolds, 2006). There are other applications of MPD, however, that do not fit into these broad categories of MPD.