Analysis of Experimental Data of ESP Performance Under Two-Phase Flow Conditions

Abstract

Abstract Electrical Submersible Pumps (ESP's) are well known to have a good predictable performance for single phase, low viscosity liquids. In the oil industry, oil production is associated with the production of gas. The presence of gas deteriorates the performance of the pump. The performance deterioration varies with the amount of gas and the intake pressure at which the pump is operated. So far no good predictive method is available to predict the performance of the ESP under two-phase conditions. Presently the industry is using the homogeneous model, correlations and other models to predict this performance. In the homogeneous model the two-phase flow head is assumed to be the same as single-phase head (provided by the manufacturer) at a total mixture flow rate. The available correlations are specific to the tested type of pump and to the tested number of stages. Finally to predict performance on model, no general model has been developed to predict two-phase performance of the ESP due to complexity of two-phase flow, pump geometry and speed at which it is operated. Researchers, Lea and Bearden (1982), Cirilo (1998)), Romero (1999) and Pessoa (2000) have concluded through experimental results that the application of the homogeneous model gives good prediction only at low gas fractions (in the order of 2 to 5 %) at the intake. At higher gas fraction the experimental results shows that performance is well away from the homogeneous model predicted performance. The University of Tulsa Artificial Lift Projects – TUALP is currently conducting experimental and theoretical research on the two-phase behavior of electrical submersible centrifugal pumps, using a 22-stage Mixed flow type, series 513 pump with best efficiency flow rate of 6100 BPD to gather data on stage wise performance under two-phase flow conditions. Air and water were used as working fluids. This is a unique facility that has pressure gauges fitted across each stage. It not only helps to study the stage wise behavior but also the effect of number of stages on cumulative performance of pump under two-phase flow conditions. This paper focuses on analysis of data collected at TUALP facility.