Interstage Performance and Power Consumption of a Multistage Mixed-Flow Electrical Submersible Pump in Gas–Liquid Conditions: An Experimental Study

Abstract

The performance degradation of electrical submersible pump (ESP) caused by high gas volume fraction (GVF) has always been a common problem in the field of oil and gas production. Experiments are conducted to investigate the gas–liquid performances of pressurization, power, and efficiency of a 15-stage mixed-flow ESP self-designed and manufactured. A calculation method of gas–liquid useful power is proposed based on the hypothesis of isothermal compression, with the relative error of calculated results within ±2% between isothermal compression and polytropic compression. The rapid decrease of useful power is found to be the main reason for the rapid decrease of hydraulic efficiency as the pump-inlet gas volume fraction (IGVF) increases. Moreover, the interstage pressurization deterioration gradually weakens along the increasing direction of stage number. The calculation method of interstage gas volume fraction is proposed, and the gas–liquid pressurization of each booster stage is found to follow the same distribution with the variation of interstage gas volume fraction. Increasing the stage number can efficiently improve the critical gas volume fraction of interstage pressurization deterioration, as well as the pressurization boundary and maximum value of average single-stage gas–liquid pressurization. The prediction correlations of gas–liquid operating conditions of the maximum pressurization and the highest hydraulic efficiency are established, respectively, and the gas–liquid condition range of high-efficiency pressurization is discovered.