Though not as common as overbalanced drilling, underbalanced drilling is achieved when the pressure exerted on the well is less than or equal to that of the reservoir. Performed with a light-weight ...

Drilling underbalanced, or near balancedwith lightweight drilling fluids, has practical applications offshore. Underbalanced drilling (UBD), a technique in which the hydrostatic head of drilling fluid ...

Underbalanced drilling (UBD) intentionally keeps bottomhole pressure below the formation pore pressure to allow controlled inflow while drilling. It sits at the intersection of well construction and ...