Fabrication and Mechanism Study of the Fast Spontaneous Emulsification of Crude Oil with Anionic/Cationic Surfactants as an Enhanced Oil Recovery (EOR) Method for Low-Permeability Reservoirs

An emulsion that can be fast and spontaneously formed in reservoirs will be greatly beneficial to the oil recovery improvement in low-permeability reservoirs. Herein, an ultralow interfacial tension spontaneous emulsification (SE) system consisting of a novel anionic alkyl polyglucoside sodium hydroxypropyl sulfonate surfactant (APGSHS) surfactant and a cationic cetyltrimethylammonium bromide (CTAB) surfactant was proposed and studied for low-permeability reservoirs. The spontaneous emulsions were characterized in terms of morphology and size distribution of droplets. Multiple-light scattering method was applied to evaluate the stability and dynamic instability mechanism of O/W emulsions. In addition, the viscoelasticity and shear-recovery performance of emulsions were also investigated. The combined SE systems can form the spontaneous emulsions via once bottom-up cycle, and the average droplets size of optimum emulsion with 6:4 molar ratio is ∼0.2 μm, which is small enough to migrate in the porous media ...