地质埋存下CO_(2)在盖层中吸附扩散行为的微观机理研究

Study on the Microscopic Mechanism of Adsorption and Diffusion Behavior of CO_(2)Storage in the Cap Bed

为解决温室气体减排领域中二氧化碳(CO_(2))地质埋存的关键问题,采用分子模拟手段(巨正则蒙特卡洛模拟、分子动力学模拟、密度泛函理论),对CO_(2)在SiO_(2)纳米狭缝中的吸附扩散行为进行了理论计算研究。研究表明:在SiO_(2)纳米狭缝中,CO_(2)吸附量随着压力的升高和温度的降低而增强,且亲水性的SiO_(2)纳米狭缝比亲油性SiO_(2)纳米狭缝的CO_(2)吸附量大;随着狭缝宽度的增加,CO_(2)吸附和扩散能力也逐渐增强。此外,根据吸附能、吸附高度和电荷转移量等参数分析了CO_(2)在不同润湿性SiO_(2)表面吸附的微观机理。研究结果为理解不同岩石物性的SiO_(2)狭缝表面与CO_(2)的相互作用机制提供了分子水平上的见解,这对于解释CO_(2)分子在盖层中的吸附机理以及在地层中的长期封存具有重要的理论指导意义。

To address the critical issues related to carbon dioxide(CO_(2))geological sequestration in the context of greenhouse gas mitigation,The adsorption and diffusion behaviors of CO_(2)within SiO_(2)slits were investigated using molecular simulation techniques,including grand canonical Monte Carlo simulations,molecular dynamics simula⁃tions,and density functional theory.The findings reveal that the adsorption of CO_(2)intensifies with increasing pres⁃sure and decreasing temperature.Additionally,hydrophilic SiO_(2)slits exhibit a higher CO_(2)adsorption capacity com⁃pared to hydrophobic SiO_(2)slits.Moreover,as the width of SiO_(2)slits increases,both the adsorption and diffusion ca⁃pabilities of CO_(2)gradually enhanced.Furthermore,the adsorption energy,adsorption height,and charge transfer were conducted to elucidate the microscopic mechanisms governing CO_(2)adsorption on SiO_(2)surfaces with varying wettability.The results provide molecular-level insights into the interaction mechanisms between CO_(2)molecules and SiO_(2)nano confinement surfaces with different rock properties.The result contributes valuable theoretical guidance for understanding the adsorption mechanisms of CO_(2)in caprock formations and its long-term sequestration in geo⁃logical reservoirs.