As home to supermajors, as well as a plethora of smaller, independent energy players, the US boasts one of the largest concentrations of energy personnel in the world. With its insatiable appetite for energy resources, the United States is the world's single largest consumer of oil, using as much as 20.73 million barrels per day as of 2008. Recently, interest has peaked in the vast quantity of untapped natural gas resources in the US, the reserves of which were inventoried in 2008 at 238 Tcf, with producers specifically targeting the nation's promising shale formations for this energy commodity.
Managed pressure drilling (MPD) is a process used to more precisely control the pressure profile throughout the wellbore, and bottomhole pressure is slightly above or equal to the reservoir pore pressure. Underbalanced drilling (UBD), while similar to MPD, is achieved when the pressure exerted on the well is less than or equal to that of the reservoir. These methods reduce common conventional drilling issues such as lost circulation, differential sticking, minimal drilling rates and formations damage.