The world’s first economically viable hydrocarbons resource well was drilled underbalanced. Given formation pore pressure depletion over time, the last economically viable well drilled on this earth, whether onshore or offshore, will undoubtedly have to be drilled underbalanced as well. From cable tool rig drilling when no blowout meant no discovery to today’s mix of conventional overbalanced drilling, Underbalanced Drilling (UBD) and Managed Pressure Drilling (MPD)…we can expect the future to hold a steadily increasing practice of the latter two technologies. UBD is drilling with an effective wellbore pressure less than the pressure of the formation being drilled into and where hydrocarbons may be produced while safely drilling ahead. MPD is enabled by UBD technology and it’s specialized equipment. However, the intent is not to achieve a true state of UB and no hydrocarbons are produced to the surface. Instead, the intent is to more precisely control and manage wellbore pressures with least interruptions to drilling ahead. Low Head (near-balanced), balanced, pressurized mud cap, several variations of deepwater dual gradient, and riserless drilling of deepwater top holes are all variations of MPD. This topical luncheon presentation speaks to the differences between UBD and MPD, with the key focus being on the specialized equipment required for offshore applications of both technologies. Don Hannegan, P.E. 479-806-1216 don.hannegan@weatherford.com