Effect of flow field and electric field coupling on oil-water emulsion separation

The formation and treatment of oil-water emulsion during production and transportation is intrac-table challenge for the oil industry. A typical process of electric field dehydration plays an active role in the separation of oil-water emulsions. However, the flowing emulsion has flow field char-acteristics within the electric dehydrator, and the effect of emulsion under the coupling effect of flow field and electric field has not been fully understood. In this study, a set of numerical sim-ulation and laboratory experiments were used to show the relationship between flow field and electric field. According to the treatment process of a block in Daqing Oilfield, the model of elec-tric dehydrator with equal proportion to the field was established, and the electric field condition was realized by user-defined function (UDF). The separation characteristics of oil-water emulsion under the effect of electric field type, intensity, frequency, and duration time were investigated by numerical simulation. The results showed that the water content at the oil outlet was lower than 1.5% and the separation rate of emulsified water was higher than 90% after a square wave electric field with intensity of 2.0 kV/cm and frequency of 3 kHz for a duration time of 20 min. The results of laboratory experiments using the bottle test method are in general agreement with the simulation results. This study is helpful to understand the coupling effect of flow field and electric field in oil-water emulsion separation process, and the results are expected to promote the development of electric field dehydration in oilfields.