Shale gas, which predominantly consists of methane, is an important unconventional energy resource that has had a potential game‐changing effect on natural gas supplies worldwide in recent years. Shale is comprised of two distinct components: organic material and clay minerals, the former providing storage for hydrocarbons and the latter minimizing hydrocarbon transport. The injection of carbon dioxide in the exchange of methane within shale formations improves the shale gas recovery, and simultaneously sequesters carbon dioxide to reduce greenhouse gas emissions. Understanding the properties of fluids such as methane and methane/carbon dioxide mixtures in narrow pores found within shale formations is critical for identifying ways to deploy shale gas technology with reduced environmental impact. In this work, we apply molecular‐level simulations to explore adsorption and diffusion behavior of methane, as a proxy of shale gas, and methane/carbon dioxide mixtures in realistic models of organic materials. We first use molecular dynamics simulations to generate the porous structures of mature and overmature type‐II organic matter with both micro‐ and mesoporosity, and systematically characterize the resulting dual‐porosity organic‐matter structures. We then employ the grand canonical Monte Carlo technique to study the adsorption of methane and the competing adsorption of methane/carbon dioxide mixtures in the organic‐matter porous structures. We complement the adsorption studies by simulating the diffusion of adsorbed methane, and adsorbed methane/carbon dioxide mixtures in the organic‐matter structures using molecular dynamics.

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双孔隙有机质中的甲烷和二氧化碳：吸附和扩散的分子模拟

页岩气主要由甲烷组成，是一种重要的非常规能源，近年来对全球天然气供应产生了潜在的改变游戏规则的作用。页岩由两种截然不同的成分组成：有机材料和粘土矿物，前者提供碳氢化合物的储存，后者则最大程度地减少了碳氢化合物的运输。页岩地层内甲烷交换中注入二氧化碳可以改善页岩气的采收率，同时隔离二氧化碳以减少温室气体的排放。了解页岩地层内狭窄孔隙中的甲烷和甲烷/二氧​​化碳混合物等流体的特性，对于确定采用减少环境影响的页岩气技术的方法至关重要。在这项工作中，我们应用分子水平模拟来探索甲烷（作为页岩气的代理）和甲烷/二氧​​化碳混合物在有机材料的真实模型中的吸附和扩散行为。我们首先使用分子动力学模拟来生成具有微孔和中孔的成熟和过早的II型有机物的多孔结构，并系统地表征由此产生的双孔有机物结构。然后，我们采用经典的蒙特卡洛技术研究有机物多孔结构中甲烷的吸附以及甲烷/二氧​​化碳混合物的竞争吸附。我们通过利用分子动力学模拟吸附的甲烷以及吸附的甲烷/二氧​​化碳混合物在有机物结构中的扩散来补充吸附研究。