Underbalanced operation. Activity where pressure exerted in the wellbore is intentionally less than the pore pressure in any part of the formations, in order to bring formation fluids to the surface.


A flexible hose used to connect instruments, for the transmission of electrical or hydraulic signals, control fluid, chemical injection, or fiber optic communications to and from a power source to a remote station. They can be single or multiple connections bundled in a single line. Umbilicals connect surface installations to subsea developments, such as a tree or manifold.

Umbilical System

AFGlobal’s Umbilical System has an integrated RGH/RCD umbilical for HMI interface, HPU power, and PLC communications between the rig and the RGH riser assembly.

Under-pressured zone

Under-pressured zones are formation in which the pore pressure is less than the hydrostatic pressure gradient. These may occur due to fluid migration or production depletion .