Managed Pressure Drilling 101: Moving Beyond “It’s Always Been Done That Way"

Tech 101 - The basics of managed pressure drilling. In his book The Nature of Technology, W. Brian Arthur remarked, “The story of this century will be about the clash between what technology offers and what we feel comfortable with.” Although Arthur meant this in technology’s general sense, the same can be said about the clash between underbalanced drilling (UBD) and managed pressure drilling (MPD). The International Association of Drilling Contractors (IADC) defines UBD as follows: A drilling activity employing appropriate equipment and controls where the pressure exerted in the wellbore is intentionally less than the pore pressure in any part of the exposed formations with the intention of bringing formation fluids to the surface. While the benefits of UBD technology include reservoir damage prevention and increases in production and rate of penetration, users can experience discomfort—mainly from operational and safety standpoints, especially offshore—because the well continuously flows to surface while drilling. It can also be expensive, requiring more complex modeling and prediction of compressible drilling fluids behavior during operation. Furthermore, it is not always possible to maintain a continuously underbalanced condition and, since there is no filter cake in the wellbore, any period of overbalance might cause severe damage to the unprotected formation.