Development of Self-emulsifying Displacement Agent and Research of Its Stability

Self-emulsifying flooding technique is an efficient enhanced oil recovery technology for low permeability reservoirs, which can expand the sweep efficiency and improve the formation heterogeneity. But some problems, such as large dosage of surfactant and emulsion instability, limit the extensive application of the technology. In view of the above problem, the modified Al2O3 nanoparticle emulsion interface enhancer was developed in this paper. The emulsion stabilized by surfactant and Al2O3 nanoparticles with different wettability was studied through bottle test and Turbiscan Lab, and the emulsion viscosity was tested by the rheometer. The optimal formula of the enhanced self-emulsification system was selected by comparing the instability kinetic index TSI and the emulsification viscosity increasing rate. The results show that the strong water-wet α-Al2O3 nanoparticles are more likely to produce flocculation and sedimentation in the emulsion surfactant solution, which is not conducive to stabilize emulsion, while γ-Al2O3 nanoparticle with wetting angle of 103° shows good performance of stabilizing emulsion with surfactant; When 0.4% self-emulsifying surfactant is mixed with 0.5% hydrophobic γ-Al2O3 nanoparticles, the stability of formation emulsion is the best. At the same time, the emulsification viscosity is 18.5 mPa s, which can be contributed to the good oil-water interface adsorption property of Al2O3 nanoparticles. Al2O3 nanoparticles can adsorb in the surface of the emulsion droplets, which can improve the interfacial film strength and the bulk phase viscosity.