Features and imbibition mechanisms of Winsor I type surfactant solution in oil-wet porous media

The relationship between NaCl concentration and the phase change behavior of microemulsion of anionic surfactant was characterized by the salinity scan experiments. The wettability of Winsor I type surfactant solution (WI solution) and the effect of NaCL concentration on phase change behavior of WI solution and imbibition in oil-wet porous media were investigated by microfluidic experiments in this study. The WI solution and Winsor I type microemulsion are similar in wetting phase with stronger wettability than other phases. Two main mechanisms of WI solution enhancing imbibitions recovery in oil wet porous media are the wetting phase drive and residual oil solubilization. Under the salinity condition of Winsor I type microemulsion, the NaCl concentration has strong impact on the imbibition mechanism of WI solution, the higher the NaCl concentration, the complex the imbibition process and the higher the imbibition efficiency will be. The NaCl concentration has strong impact on the solubilization ability to oil of the WI solution, the higher the NaCl concentration, the stronger the solubility of the WI solution to residual oil will be.