Stand Research and Analysis of Average-Integral Characteristics of Submersible Centrifugal Pumps Operating at Gas-Liquid Mixtures

Abstract

Abstract One of the major complicating factors in the pumping operation of oil wells is a high free gas content in the pumped fluid at the ESP’s intake. In the case of compressible media pumping by the blade machinery it is necessary to take into account the change in the density of the pumped medium with increasing pressure for determine the pump’s head. On this basis, for ESP’s operating at liquid-gas mixture with the compressibility it is required to calculate the values of the pump head on the mixture and the corresponding average-integral value of mixture’s capacity by integration from the intake pressure to the discharge pressure. The stand investigation was performed and ESP’s average-integral characteristics were obtained on the model gas-liquid mixtures "water – surfactant – gas" at different intake pressures. Consideration of the ESP’s average-integral curves for low-viscosity oil-gas mixtures showed that they are characterized by essentially the same features as on the mixtures "water – surfactant – gas". Average-integral pump performances "head – flow rate" for homogeneous liquids and gas-liquid mixtures are not dependent on the density of the pumped fluid and, consequently, coincide in the case cavitation-free operation, provided that the viscosity is so small that they do not have a noticeable influence on the pump characteristics. If the curves on the gas-liquid mixture are below the pump characteristics on a homogeneous liquid, it is evidence of the development artificial gas cavitation in the pump. The average-integral curves invariance with respect to the mixture density can compare the pump’s characteristics with a different number of stages in mixtures with dissimilar coefficients of solubility of gas and integrate consideration of pump’s performances with different values of the average density of gas-liquid mixture.