The properties of EDW mainly depend on crude oil. Therefore, the properties of crude oil have an effect on oil–water separation. In particular, density affects the separation performance of the centrifugal contactor, which implements separation based on density difference. The separation performances of oils with different densities were studied. Oil removal efficiencies at different oil densities ρ are shown in Fig. 10. Oil removal efficiency decreased with increasing oil density. With increasing oil density, the oil–water density difference decreased and oil–water emulsion became easier, thus hindering oil–water separation.