Rheological behavior of the stable water-in-oil emulsion associated to water droplets arrangement

Abstract

Water-in-oil emulsion is a flow pattern that may occur during the oil production and generate flow assurance issues due to its rheological behavior. In addition to the increase of effective viscosity with water content increment, the emulsion has a complex rheological behavior regarding the fluid’s physicochemical properties, and surfactant presence. In this work, the rheology of stable water-in-oil emulsion formed by the shearing of a multistage centrifugal pump is investigated. The emulsion analyzed was composed of a mineral oil, SPAN 80 and tap water for different water cut and temperatures. The shear rate hysteresis analysis on emulsion flow curve were performed to analyze the rheological behavior. From this analysis, the steady-state shear stress condition was investigated regarding water droplet arrangement based on the Peclet number. Furthermore, the droplet arrangement was observed during acquisition of flow curve using a microscopy coupled on rheometer. To investigate the clustering mechanics in emulsion during rheometry, we present a surface boundary to separate the suspending and clustering droplets based on critical shear stress, droplet Reynolds number, and the water cut for different temperatures.