Guo Detang, Zhang Lie-Hui, Li Xiao-Gang, Yang Xu, Zhao Yu-Long, Chen Xin
Center for Computational Chemistry and Molecular Simulation, College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, China.
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China.
Langmuir. 2024 Jan 9;40(1):818-826. doi: 10.1021/acs.langmuir.3c03011. Epub 2023 Dec 26.
It is significant to understand the adsorption mechanisms of shale gas (CH) and CO in shale formations to enhance CH recovery rates and enable geological CO storage. This study provides a comprehensive investigation into the adsorption behaviors of CO and CH within dry and hydrous calcite nanopores, utilizing a combination of grand canonical Monte Carlo simulations, molecular dynamics simulations, and density functional theory calculations. In dry calcite slits, the calculated results for the adsorption capacity, density profile, and isosteric heat of CO and CH reveal that CO possesses a stronger adsorption affinity, making it preferentially adsorb on the pore surface compared to CH. In hydrous calcite slits, calculating the adsorption capacity and density profile of CO and CH, the results show that the gas adsorption sites become progressively occupied by HO molecules, leading to a substantial decrease in the adsorption capacity of CO and CH. Furthermore, by analysis of the adsorption energy and electronic structure, the reason for the reduction of gas adsorption capacity caused by HO is further revealed. This work has a deep understanding of the adsorption mechanisms of shale gas and CO in calcite and can offer valuable theoretical insights for the development of a CO-enhanced shale gas recovery technology.
了解页岩地层中页岩气（CH）和CO的吸附机制对于提高CH采收率和实现地质CO封存具有重要意义。本研究结合巨正则蒙特卡罗模拟、分子动力学模拟和密度泛函理论计算，对干态和含水方解石纳米孔内CO和CH的吸附行为进行了全面研究。在干方解石狭缝中，CO和CH的吸附容量、密度分布和等量吸附热的计算结果表明，CO具有更强的吸附亲和力，使其比CH更优先吸附在孔表面。在含水方解石狭缝中，计算CO和CH的吸附容量和密度分布，结果表明气体吸附位点逐渐被HO分子占据，导致CO和CH的吸附容量大幅下降。此外，通过对吸附能和电子结构的分析，进一步揭示了HO导致气体吸附容量降低的原因。这项工作深入了解了方解石中页岩气和CO的吸附机制，可为开发CO强化页岩气采收技术提供有价值的理论见解。
