纳米颗粒表面活性剂对多孔介质中黏性指进现象的抑制
摘要
<p indent="0mm">Two-phase flow in porous media is common in many natural and industrial processes, i.e., oil displacement in underground porous media, where the competition and replacement between the invading and defending phases is crucial. In particular, the efficiency of two-phase displacement is governed by various factors, such as the two-phase interfacial tension, pore structure, and fluid viscosity. It is important to study the mechanism of flow regulation to improve the replacement efficiency. However, the interfacial instability of two-phase displacement in porous media can lead to the viscous fingering phenomenon. It is characterized by finger-like protrusions at the displacement interface, which may significantly decrease the two-phase displacement efficiency. Therefore, it is usually required to realize a stable displacement mode and avoiding the emergence of finger displacement mode in the practical application process. Recently, it has been demonstrated that nanoparticles dispersed in water and end-functionalized polymers in oil can react at the oil-water interface to form nanoparticle surfactants. These surfactants can significantly reduce the water-oil interfacial tension and induce interfacial viscoelasticity. Therefore, in this study, a new method is proposed to inhibit viscous fingering in porous media by using nanoparticle surfactants. A microfluidic visualization system was established to explore the influence of nanoparticle surfactants on the interfacial stability of water-oil two-phase flow in porous media. The interfacial dynamical properties with the addition of different displacement agents were investigated, i.e., nanoparticles alone, polymers alone, and nanoparticle surfactants. It is demonstrated that nanoparticle surfactants can effectively inhibit the viscous fingering phenomenon. Under the same conditions of fluid viscosities and interfacial tension, nanoparticle surfactants induce a higher fractal dimension and larger displacement