Gas Interference is one of the main difficulties in ESP Operation. High gas interference might reduce the pump volumetric efficiency (lower liquid production) and in the worst situation might stop the pump operation due to Gas Lock. In longer operation, it might even damage the motor due to frequent start-stop.
ESP at SK-0178 installed in Nov-2016, and directly having problem with High Gas Interference & Gas lock (frequent underload alarm) resulting 3-4 times shutdown daily. Several troubleshooting steps have been taken:
Venting the annulus gas: Resulting no shutdown, could handle the gas issue but not an environmentally friendly solution and wasting valuable gas production (200 KSCFD)
VSD - PIP (Pump Intake Pressure) feedback: Resulting no shutdown, but ESP operated with fluctuating load and with lower production rate (gas interference, dropped by 40-60 BOPD)
Detailed discussion with technology provider and reference case study come up with a proposal to trial New VSD Logic: Motor Current Feedback. The logic worked immediately after it is applied. All pump parameters (Frequency-Hz, Motor Load-A, PIP-Psig) shortly monitored to be stable unlike the previous PIP-feedback mode. The logic works better for high gas interference condition. It keeps the pump from having an accumulated gas inside the impeller-diffuser, hence preventing the pump from the possibility of having gas lock condition. Well test performed after the mode-change also showing a return to normal production. In longer monitoring period, the pump also showing a stable operation, thus we can say the approach is successfully mitigating the high gas interference ESP case in SK-0178: No shutdown, saving 200-KSCFD gas and 120-BOPD production.