Experiments with a seven-stage Electrical Submersible Pump (ESP) have been carried out to study the effect of liquid viscosity on the gas-liquid two-phase stage performance. The experimental tests provided data about the stage pressure increment as a function of the liquid flow rate at constant rotational speed, inlet pressure, and volumetric gas flow rate. Two different mineral oils were used so that the ESP two-phase stage performance was measured for 1 cP, 1.2 cP and 8.5 cP liquid viscosities, and for 8 different gas flow rates.
The experimental results demonstrate that the increase of liquid viscosity causes gas surging in the stage to initiate at lower normalized gas flow rates, reducing the gas handling capability of the stage. Increasing the liquid viscosity also causes the stage to reach a zero pressure increment at a higher normalized liquid flow rate. The pressure increment deterioration caused by the gas worsens with increased liquid viscosity. The performance map is analyzed and compared with that of another pump (GC-6100) with a higher inlet stage pressure.