Stabilization of Produced Crude Oil Emulsion in the Presence of ASP

Abstract

Abstract The contribution of alkaline/Surfactant/Polymer to the stability of produced crude oil emulsions is neither fully understood nor thoroughly investigated although there have been reports from previous projects that implicate risk produced water treatment. This study focuses on water in oil (w/o) emulsions imposed by ASP flooding for an EOR field in Malaysia to understand the stability of the emulsion layer under typical process conditions. A series of laboratory experiments was conducted to investigate the effects of different ASP concentration that is reported to break through into the separator feed and results in the growth of a rag layer. The samples in the experiments were prepared at 50 °C, 60 °C and 70 °C to represent the temperature range of actual field conditions. Emulsion stabilities were measured at different time from 30 minutes to 24 hours in different time step, depending upon the liberation of water volume fraction. The results demonstrated that ASP concentration plays a significant role in the stabilization of emulsion. The increase in the viscosity due to the presence of polymers, which decreased the rising velocity of oil droplets, and the presence of surfactants, reduced the coalescence of oil droplets. Emulsions were exceptionally stable at high polymer concentration compared with surfactants. However, emulsion stability decreased at low polymer concentrations even in combination with high surfactant concentrations. Among the three components in ASP, polymer induced a higher effect on the stabilization of the emulsion. Moreover, the temperature subsequently affected the instability of the emulsion, in which the destabilization of emulsion which had less amount of surfactant was higher at 70 °C compared with 50 °C and 60 °C. Surprisingly, it is found that increase in temperature had insignificantly affected the destabilization of emulsion containing high amount of surfactant, around 400ppm.