Static and dynamic behavior of foam stabilized by modified nanoparticles: Theoretical and experimental aspects

Gas flooding is a practical secondary scenario for enhanced oil recovery. Channeling and fingering of the injected gas are the major problems facing this technique. These challenges can be mitigated by the injection of gas as foam. However, foam stability influences the overall efficiency of the process, which could be improved by nanoparticles (NPs). This work provides a theoretical and experimental analysis of the NPs wettability effects on foam behavior, in both static and dynamic states. The treated calcite (CaCO3) NPs along with a cationic surfactant (HTAB) were used for this purpose. By comparison of theoretical and experimental data, it was shown that the foam stability in the presence of NPs can be forecasted qualitatively using Reynold's formula and the extended Derjaguin–Landau–Verwey–Overbeek (xDLVO) theory. According to the theoretical results, the disjoining pressure decreases by increasing of NPs hydrophobicity, while the destructive effect of capillary pressure reduced. Based on the rheological measurements, the behavior of foam in the presence of NPs was less pseudo-plastic with the increasing of NPs hydrophobicity. For a fixed shear rate, the shear stress passed through a maximum by passing of the time, which could be justified by theoretical predictions. Finally, a series of flooding tests was carried out to evaluate the effect of NPs wettability on the Implicit Texture model parameters. It was concluded that while fmmob (foam mobility parameter) increased for more hydrophobic NPs, they suffered from large value of epdry (foam dry-out parameter), which indicated a sharp transition between high-quality and the low-quality regions.