Molecular Dynamics Simulation of the Oil Detachment Process within Silica Nanopores

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• 作者：Hui Yan ; Shiling Yuan
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：February 11, 2016
• 年：2016
• 卷：120
• 期：5
• 页码：2667-2674
• 全文大小：636K
• ISSN：1932-7455

文摘

We investigated the effect of surfactants on the oil displacement process inside a nanoscale silica pore using molecular dynamics simulations. First, an oil cylinder was built inside a silica pore to mimic residual oil in the porosity of the reservoir rock after water flooding. In the simulations, we focused on a layering organization of oil molecules adsorbed onto the pore surface, and then a series of equilibrium MD simulations were run to obtain the organization structures of the oil drop in the presence or absence of surfactant molecules. These simulated results showed that the surfactant could disturb the layering organization of the oil drop, since the hydrophobic chains of surfactant molecules could penetrate into the oil phase. And around the polar head of the surfactant, water molecules could form water channels between the oil phase and solid surface, which is vital to the displacement process. Finally, we used steered molecular dynamics (SMD) method to mimic the displacement and migration process of an oil drop inside the pore. From SMD calculations, detailed information about the process was obtained, and the free energy of the process was calculated using the WHAM method. Through analysis of the free energy, we demonstrated the mechanism of surfactants aiding in the oil recovery at a molecular level. Our study provided information on the oil displacement within a nanoscale pore at the molecular level, which is expected to provide useful information for enhanced oil recovery (EOR) experiments.