The M-I SWACO LOW PRESSURE AUTOCHOKE CONSOLE (LPAC) is engineered for low-surface pressure Managed Pressure Drilling (MPD) and Underbalanced Drilling (UBD) up to 1,500 psi. The LPAC is precision- built to provide accurate control of the AUTOCHOKE unit.
The LPAC enables operators to seamlessly transition between AUTOCHOKE units, while simultaneously controlling two units. Both AUTOCHOKE units can maintain pressure for over two hours after loss of rig air and up to one hour after loss of rig power thanks to the hydraulic accumulator, air storage tank, and uninterruptible power supply.
The LPAC unit works at a higher resolution so that choke operators have control of pressure accuracy within a range of +/-50 PSI. With the LPAC system, operators gain the confidence that the pressure set is what they get. It was recommended when an operator in Texas planned on drilling a series of laterals underbalanced, while holding near-constant bottomhole pressure during connections. During the drilling phase, the LPAC unit held 350 psi back-pressure on the casing, allowing the operator to strip to the bottom under pressure.
The unit’s sunlight-readable touch screen panels ensure accurate readings in any weather condition and allow for precise pressure inputs to the AUTOCHOKE units. Screens display additional operating parameters including casing and drill pipe pressures, pump rates, strokes and diagnostics. The LPAC system has been designed with backup power storage devices; an internal air tank, hydraulic accumulator and an uninterruptible power supply. Under normal operation, once the backup devices are charged, the LPAC system can maintain back pressure for more than two hours after loss of rig air and up to one hour after loss of rig power. The backup devices work seamlessly so the AUTOCHOKE operator can continue operation without any interruption in control.