LAUSR

Abstract Numerous studies and field application tests have shown that emulsification is an important mechanism to improve oil recovery. Fine emulsion (FE) with small droplets can improve oil recovery by displacing residual oil after water flooding at a low cost. In this work, a series of core displacement experiments were conducted to compare the effectiveness of different chemical flooding for crude oil. Then, the oil-water interfacial tension (IFT), viscosity and rheological properties were studied thoroughly to understand the displacement mechanism by using an interfacial tensiometer, a viscometer or a rheometer. Finally, micromodel flooding tests were performed to demonstrate the suitability and effectiveness of FE flooding for oil recovery for low permeability reservoirs. The displacement results show that the oil recovery efficiency can reach 16.8% after water flooding by the optimum FE flooding system. The FE flooding system has viscoelastic properties, strong emulsifying performance and stability. Such behavior can reduce the IFT value to the magnitude of 10−1 mN/m and improve the mobility ratio. The displacement mechanism of FE enhanced oil recovery (EOR) is that emulsification can improve the displacement efficiency and increase the swept efficiency. The micromodel tests indicate that the emulsification mechanisms include emulsification carrying-on and the performance control of the O/W emulsion. The FE flooding system has powerful EOR potential for low permeability reservoirs.