To better understand the CO₂ sequestration and enhanced shale gas recovery, it is of great significance to study the adsorption characteristics of CO₂ and CH₄ in different types of shale. In this study, the mineral composition, pore structure and CH₄ and CO₂ adsorption isothermals of marine and continental shale samples were determined, an adsorption model was proposed to describe the adsorption behaviors of CH₄ and CO₂, the thermodynamics parameter of adsorption was obtained, and then the influence of mineral composition and pore structure on the adsorption characteristics of CH₄ and CO₂ in shale was clarified. The results showed that the total organic carbon content (TOC), the specific surface area (SSA) and micropore volume of marine shale samples are larger than those of continental shale samples. Shale has a higher TOC and clay minerals contents corresponding to a higher adsorption capacity. Under the same conditions, the CO₂ adsorption capacity of shale is significantly higher than that of CH₄. The proposed adsorption model considered the different adsorption mechanisms in different pores and the temperature effect, which can well describe the CH₄ and CO₂ adsorption behaviors of shale in various temperatures. Based on the adsorption model, considering the real gas conditions, the variation of the calculated isosteric heat (ΔH) and entropy (ΔS) of CH₄ and CO₂ adsorption with the increasing adsorption amount experienced three stages: slow decline, rapid decline, and gradual flattening. For a certain adsorption amount, the ΔH and ΔS of CO₂ adsorption in shale are higher than those of CH₄, and with the increase in temperature, the ΔH and ΔS show a downward trend. Combining the proposed adsorption model with ideal adsorbed solution theory, the predicted selectivity factor (\(\alpha_{{{\text{CO}}_{{2}} /{\text{CH}}_{{4}} }}\)) of CO₂ over CH₄ of all shale samples at the CH₄ and CO₂ mixed gas environment is greater than 1. Shale has a lower TOC corresponding to a higher \(\alpha_{{{\text{CO}}_{{2}} /{\text{CH}}_{{4}} }}\), and thus the \(\alpha_{{{\text{CO}}_{{2}} /{\text{CH}}_{{4}} }}\) of continental shale samples is higher than that of marine shale samples. The \(\alpha_{{{\text{CO}}_{{2}} /{\text{CH}}_{{4}} }}\) increased with the increase in fugacity and CO₂ mole fraction, while decreased with the increase in temperature, and the variation of \(\alpha_{{{\text{CO}}_{{2}} /{\text{CH}}_{{4}} }}\) can be well explained by thermodynamics analysis.

为了更好地了解CO _2的固存和提高页岩气的采收率，研究CO ₂和CH ₄在不同类型页岩中的吸附特征具有重要意义。本研究确定了海相和陆相页岩样品的矿物组成，孔隙结构以及CH ₄和CO _2的吸附等温线，提出了吸附模型来描述CH ₄和CO ₂的吸附行为，吸附的热力学参数为获得，然后矿物组成和孔结构对CH ₄和CO ₂吸附特性的影响在页岩中得到澄清。结果表明，海洋页岩样品的总有机碳含量（TOC），比表面积（SSA）和微孔体积均大于大陆页岩样品。页岩的TOC和粘土矿物含量较高，对应的吸附容量较高。在相同条件下，页岩的CO ₂吸附能力明显高于CH ₄。所提出的吸附模型考虑了不同孔隙中不同的吸附机理和温度效应，可以很好地描述CH ₄和CO _2。页岩在不同温度下的吸附行为。在吸附模型的基础上，考虑实际气体条件，随着吸附量的增加，CH ₄和CO ₂吸附的等熵热（ΔH）和熵（ΔS）随吸附量的增加而经历了三个阶段：缓慢下降，快速下降。 ，并逐渐变平。在一定的吸附量下，页岩中CO _2的吸附ΔH和ΔS高于CH ₄，随着温度的升高，ΔH和ΔS呈下降趋势。将建议的吸附模型与理想吸附溶液理论相结合，得到预测的选择性因子（\（\ alpha _ {{{text {CO}} _ {{2}} / {\ text {CH}} _ {{4}}} } \） ）的CO ₂超过CH ₄的CH所有页岩样品的₄和CO ₂的混合气体的环境中是大于1页岩具有对应于较高的较低TOC \（\阿尔法_ {{{\文本{CO} } _ {{2}} / {\ text {CH}} _ {{4}}}} \}，因此\（\ alpha _ {{{\ text {CO}} _ {{2}} / {大陆页岩样品的\ text {CH}} _ {{4}}}} \）高于海洋页岩样品的\ text {CH}} _ {{4}}}} \）。的\（\阿尔法_ {{{\文本{CO}} _ {{2}} / {\文本{CH}} _ {{4}}}} \）与逸度和CO的增加而增加₂摩尔分数，而随温度的升高而降低，并且\（\ alpha _ {{{text {CO}} __ {{2}} / {\ text {CH}} _ {{4}}} } \）可以通过热力学分析很好地解释。