A Novel Method to Characterize Dynamic Emulsions Generation and Separation of Crude Oil–Water System

The evaluation of the ease to generate emulsions and emulsions stability of oil–water system is essential for the investigation and application of chemical flooding technology for the enhanced oil recovery (EOR). However, the previous characterization methods have mainly focused on emulsion stability. To fill this gap, this study designed a novel instrument for visualizing the presence of emulsions and the separation of an oil–water system. Thereafter it also proposed quantitative methods: the emulsification index (EI) for characterizing the ease of surfactants to generate emulsions with crude oil and the demulsification index (DI) for describing emulsion stability. The results show that EI and DI can accurately characterize the dynamic characteristics of emulsions generation and demulsification, respectively. On the basis of the numerous test data composed by three crude oils and seven surfactants with different concentrations, the emulsifying capability and emulsion stability of different oil–water samples can be quantitatively determined. More importantly, these differences between various oil–water samples caused by surfactant concentration, surfactant types and crude oil property can also be accurately distinguished. Besides, the core flooding tests also provide support for the EI and DI and are reasonable parameters for characterization of the emulsification capability and emulsion stability of oil–water systems. Therefore, the overall investigations ultimately revealed that the parameters EI and DI can be used to determine ease of emulsion generation and separation of oil–water systems with an acceptable level of accuracy. The findings of this study provide a novel method for preparing effective chemical agents, which is useful for EOR fields with economic returns.