Measurement of water content of oil-water emulsions under shear conditions

The water content in stable crude oil emulsions has been widely researched. However, the emulsion in the flowing conditions has higher emulsified water content, which affecting the flow characteristics of oil-water two-phase in gathering lines. This study focusses on exploring the electrical characteristics associated with water content of the flowing emulsions. To describe the impedance characteristics of the flowing emulsions, a RC equivalent circuit model was established basing on the frequency dispersion phenomenon due to interfacial polarization of emulsions. A stirring system with different rotating rates was developed to simulate flowing conditions of the emulsion. Emulsions with varied amount of emulsified water content (0~0.9) were prepared and their impedance spectroscopy were measured with frequency from 50Hz to 1MHz.The experimental results demonstrated that within the observed range, the frequency of interfacial polarization in impedance exhibited a linear relationship with the water content of the crude oil, in strong agreement with the established theoretical model. The principle of linearity can be used to measure the water content of flowing crude oil.