Understanding the adsorption state and molecular behavior of the diverse components of shale oil in shale slits is of critical importance for exploring novel enhanced shale oil recovery techniques, but it is hard to be achieved by experimental measurements. In this paper, molecular dynamics (MD) simulations are performed to quantitatively describe the microbehavior of shale oil mixtures containing different kinds of hydrocarbon components, including asphaltene, in quartz slits. The spatial distributions of all the presenting components are given, the interaction energy between the components and quartz is analyzed, and the diffusion coefficients of all the components are calculated. It was found that asphaltene molecules play a vitally important role in restricting the detachment and diffusion movement of all hydrocarbon components, which is actually a key problem limiting the recovery efficiency of shale oil. The effects of temperature, slit aperture, and the appearance of CO2 on the adsorption behavior of the different shale oil components are examined; the results suggest that the light and medium components are the fractions with the most potential in thermal exploitation, while injection of CO2 is beneficial for the extraction of all the components, especially the medium components. This work gives insights into the effect of asphaltene on shale oil recovery in quartz slits and might provide guidance on the utilization of thermal and CO2-enhanced enhanced oil recovery (EOR) techniques in shale oil production.

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As a new type of porous material, porous ionic liquids (PILs) composed of cage-based molecules dissolved in crown ether molecules have attracted a lot of attention in recent years for the high potential in CO2 capture. Understanding the mechanisms on the molecular level is crucial and highly needed to further explore novel systems, optimize the performance, and promote the utilization process. In this work, density functional theory and molecular dynamics simulations are combined to investigate the micro-structure and molecular behaviors of PILs formed by a cage molecule anionic covalent cage (ACC) combined with K+ (KACC) in different crown ether solvents. The ability to adsorb CO2 and the effect of 10 kinds of crown ethers as solvents on the performance of PILs are systematically studied. It is found that the PILs can maintain certain fluidity and sufficient pores by using 18-crown-6 as the solvent with a specific molar ratio with the KACC and exhibit excellent CO2 adsorption capacity by intramolecular adsorption, intermolecular adsorption, interfacial layer adsorption, and strong van der Waals interaction. The adsorption capacity is higher at low temperatures and high pressure showing a better possibility of sustainable utilization than that of the existing systems. This study identifies the potential for PILs in CO2 capturing and the path of improving the performance by selecting favorable crown ether solvents, which will also provide a meaningful theoretical basis for the application of PILs in this field.

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