Visualization Of Oil-Water Emulsion Formation In A Centrifugal Pump Stage

Abstract

Electrical submersible pumps are assembled in oil wells to act as artificial lift methods. When water is present in the reservoir, oil-water emulsions are formed in the pump. These two-phase mixtures affect the performance and promote instabilities that lead the machine to operate inefficiently and fail prematurely. Therefore, this paper aims to investigate the formation of emulsions and behavior of mineral oil drops in a transparent centrifugal pump through a flow visualization approach. Shut-off, best efficiency point, and open-flow condi tions are investigated at three impeller rotational speeds with high-speed imaging and particle image velocimetry. As the oil fraction increases, large drops accumulate in the impeller channels, while some escape to the volute and circulate until the water flow carries them out of the pump stage. Regions with vortices and water recirculation explain the accumulation of oil drops in the impeller and reduced pump performance at low water flow rates. Intense velocity fluctuations at the impeller and impeller-volute boundary indicate the main causes for oil drop rotation, deformation, and fragmentation at high water flow rates. The new findings can be used to improve models and numerical simulations for pumps operating with multiphase flows and help the creation of new pump designs.