EFFECTS OF HIGH FLUID VISCOSITY ON PRESSURE LOSSES OF THE SINGLE-PHASE FLOW INSIDE AN ESP STAGE

The Electrical Submersible Pump (ESP) system is among the most widely used artificial lift methods in the world. This work studies the effects of high fluid viscosity on pressure losses of the flow in an ESP stage. A theoretical model was applied to four different flow cases. First, curves for head and pressure losses at the pump stage were generated and, based on literature formulations available in the model, as well as on adjusted empirical coefficients (for highly viscous fluids), implemented in the model. Subsequently, the heads were estimated and evaluated using experimental data and statistical analyses based on mean square error. The results showed that high fluid viscosity impacted considerably pressure losses and pump performance. In 50% of the cases studied, statistical analyses alone could estimate the head in the pump stage with good accuracy. However, in the remaining cases, it was also necessary to consider the physical behavior of the highly viscous fluids studied. The variability of the selected formulations from the literature (for pump head and pressure losses) with pump rotation, and especially with high fluid viscosity, was considerably larger than the ones found in previous studies for less viscous fluids.