流动剪切对原油乳化含水率的影响及基于焓的定量表征

油水两相的乳化特性对两相流的流型和压降规律有显著影响。流动条件下的原油乳化含水率是影响油水两相流动特性的关键。针对4种原油,通过油水两相的乳化实验,研究了搅拌转速、水相比例、温度及搅拌时间对原油乳化含水率的影响。研究发现,当水相比例低于某一临界值时,在一定搅拌转速范围内会发生完全乳化现象,当水相比例高于该临界值时,只发生部分乳化。不同原油发生完全乳化的临界水相比例不同,与原油物性相关;对于非完全乳化的情况,原油乳化含水率随搅拌转速的增大而增大,随水相比例、温度的升高而减小,随搅拌时间的增加而增大;油水两相乳化过程中消耗的能量可采用比焓进行表征,不同剪切条件下的原油乳化含水率可以与比焓进行归一化关联,并且二者符合幂律关系。

Effect of Shear of Flowing on Emulsified Water Fraction and Correlation between Emulsified Water Fraction and Shear based on Enthalpy

Emulsification behaviors of crude oil-water two phase have significant effect on the flow pattern and pressure drop of multiphase flow. The emulsified water fraction under flowing conditions acts as the essential factor affecting the characteristics of multiphase flow. In this work, 4 kinds of crude oils were used in the emulsification experiments, and the effect of stirring speed, water fraction, temperature, and stirring time on the emulsified water fraction under flowing conditions was studied. It was found that full emulsification was happened in a range of stirring speed when the water fraction below a critical value, and only partial emulsification occurred above this critical water fraction. The critical water fractions for full emulsification are different for different crude oils, relating to the properties of crude oils. For partial emulsification, the emulsified water fraction under flowing conditions increased with the increase of stirring speed and stirring time, and decreased with the rise of water fraction and temperature. The specific enthalpy was used to characterize the energy consumption during the emulsification process, the emulsified water fraction under flowing conditions was found to correlate well with the specific enthalpy regardless of the differences in shearing conditions, and a power law equation well fit the data.