Stability influence factors and mechanism of produced emulsion from CO2 flooding

Abstract

CO2 flooding has been widely applied for enhanced oil recovery (EOR) in recent years, while the difficulty in demulsification of the produced fluid has become an urgent problem due to the specific physical and chemical properties of CO2 flooding process. In this study, the crude oil from Block Hei-59 by CO2 flooding was used to prepare simulated produced emulsions and the influence of CO2 pressure, temperature, salinity, pH and solid particles on the stability of emulsions are investigated. The results indicated that the stability of simulated emulsions gradually increased with CO2 pressure but decreased with the increase of temperature, while the change of NaCl concentration and pH had little effects on the stability of emulsions. Moreover, the solid particles had great influences on the stability of the emulsion, and the emulsion prepared by the particles initially dispersed in the oil phase was more stable than in water. This study can provide a theoretical basis for the future dehydration and demulsification treatment of produced fluids from the formation developed by CO2 flooding.