Impact of oil-displacing agent on the emulsification stability of oily wastewater in alkali-free ternary composite flooding
In order to investigate the mechanism of alkali-free ternary oil-displacing agents in stabilizing the emulsification of produced fluids and to provide a basis for the treatment of these fluids,a study was conducted.This study focused on the oil content in free water,the dynamic interfacial tension between oil and water,the lifetime of droplet interfaces,and the distribution state and size variation of oil droplets as influenced by the concentration of the displacement agent.It was found that upon the addition of a low concentration of surfactant(100 mg/L),a significant reduction in dynamic interfacial tension,interface li-fetime,and oil droplet size was observed,along with a significant increase in the oil content in water.As the concentration of the surfactant increased,changes in dynamic interfacial tension,interface lifetime,particle size,and oil content became less noticeable.With an increase in NaCl concentration,there were insignificant changes in dynamic interfacial tension and interface lifetime,but an increase in oil droplet size and the oil content in water was observed.Furthermore,an increase in polymer concentration led to insignificant changes in dynamic interfacial tension and interface lifetime,but exerted a dual effect on oil droplet size and oil content.These findings indicate that surfactants and NaCl contribute to the stabiliza-tion of emulsions,with the effect of surfactants being substantially greater than that of NaCl.Low polymer concentrations are not conducive to emulsion stability,but as their concentration increases,they become beneficial for emulsion stabilization.
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