Correlations between emulsification behaviors of crude oil-water systems and crude oil compositions

Abstract

The emulsification behavior of a crude oil-water system is greatly related to the compositions of a crude oil. However, there was lack of quantitative description on the relationship between emulsification behaviors and crude oil compositions. As the first part of this work which was published recently, full and partial emulsification were found which were dependent upon shear rate and water fraction; For the partial emulsification under high water fraction, the relationship between the emulsified water fraction under flowing conditions and entropy production rate was found to obey a power law equation; Moreover, the critical value of water fraction, the range of shear rate for full emulsification, and the coefficient and power law index were highly dependent on the compositions of crude oil. As a continued study, this paper further investigates quantitatively the relationship between the above-mentioned characteristic parameters of emulsification behaviors and the crude oil compositions. In terms of the mechanism on the emulsification behaviors, the crude oil compositions are classified into four categories, i.e. the content of asphaltenes and resins (ca+r), the sum of the concentration of precipitated wax and the content of mechanical impurities (cw+m), acid value (AV), and the average carbon number of crude oil (CNoil). By data regression based on emulsification experiments for eight crude oils, correlations were developed between these emulsification parameters and the oil compositions, helping to understand quantitatively the relationship between emulsification behaviors and crude oil compositions. In addition, the influence of the four compositions was found to be ranked as CNoil>ca+r>AV>cw+m.