Within the context of broad industry recognition of two drilling technologies, Underbalanced Drilling predates Managed Pressure Drilling (MPD) by at least a decade. While there are some similarities in some of the equipment and possibly in some of the techniques, the applications are different in their intent. This paper will discuss methodologies comparing Conventional, Underbalanced, and Managed Pressure Drilling Operations with respect to objectives, planning, drilling equipment and operations, and well control. The application of Managed Pressure Drilling was specifically created to give it an identity apart from Conventional Drilling and apart from Underbalanced Drilling. There appears to be some confusion with respect to methodology for Managed Pressure Drilling. What constitutes a Managed Pressure Drilling Operation? What constitutes an Underbalanced Drilling Operation? Are they actually the same? Does it matter?
Malloy K.P., Stone C.R., Medley G.H., Jr., Hannegan D., Coker O., Reitsma D., Santos H., Kinder J., Eck-Olsen J., McCaskill J., May J., Smith K., and Sonneman P., “Managed Pressure Drilling: What It Is and What It Is Not”, IADC/SPE 12281, IADC/SPE Managed Pressure Drilling and Underbalanced Operations Conference, San Antonio, Texas, February 2009.