【摘要】 CO₂在页岩储层中的吸附/解吸行为是CO₂驱替页岩油气及CO₂地质封存的理论基础，研究驱替过程中的弥散特征对于评估二者混合程度、产出气纯度、采收率提高及CO₂封存效果具有重要意义。为此，以四川盆地下志留统龙马溪组和鄂尔多斯盆地上三叠统延长组页岩储层为研究对象，通过CO₂等温吸附和CO₂驱替CH₄物理模拟实验，采用体积法和动态柱突破法，系统研究了不同页岩储层CO₂吸附量与温度、压力、页岩物性（有机碳含量、矿物组成、孔隙度和比表面积）的关系以及CO₂注入速度对弥散系数的影响规律。研究结果表明：（1） CO₂在页岩储层的吸附量随压力增加逐渐增大，当压力大于12 MPa后吸附量达到饱和状态，饱和吸附量为1.8～8.1 cm³/g；（2） CO₂饱和吸附量与温度呈负相关关系，而与压力、页岩有机碳含量、比表面积和孔隙体积呈正相关关系；（3） CO₂驱替CH4的弥散过程处于对流与扩散共同主导的过渡区域，其表观弥散系数在10^-7m²/s数量级且与CO₂注入速度呈线性相关关系。结论认为，研究成果揭示了CO₂弥散规律，初步证实了页岩储层注CO₂提高页岩油气采收率与碳封存的可行性，同时为开发方案优化设计提供了关键参数，为相关研究和工程实践奠定了理论基础。更多还原

【Abstract】 CO₂ adsorption/desorption behaviors in shale reservoirs are the theoretical base of CO₂ flooding and geological storage in shale. Studying the dispersion characteristics in the process of displacement is of great significance in evaluating the mixing degree of CO₂ and oil/gas, the purity of produced gas, the enhanced oil recovery and the CO₂ storage effect. Taking the shale reservoirs in the Lower Silurian Longmaxi Formation of the Sichuan Basin and the Upper Triassic Yanchang Formation of the Ordos Basin as examples, this paper analyzes the relationships of CO₂ adsorption capacity of shale reservoirs with temperature, pressure, and shale physical properties（TOC, mineral composition, porosity, and specific surface area）, and the influence of CO₂ injection rate on dispersion coefficient by using the volume and dynamic column breakthrough methods, through physical simulation experiments of CO₂ isothermal adsorption and CO₂ displacing CH₄. The following results are obtained. First, the CO₂ adsorption capacity of shale reservoirs increases gradually with pressure. When the pressure exceeds 12 MPa, the adsorption capacity gets saturated, with a saturation adsorption capacity between 1.8cm³/g and 8.1 cm³/g. Second, the CO₂ saturation adsorption capacity is negatively correlated with temperature, and positively correlated with pressure, shale TOC, specific surface area, and pore volume. Third, the dispersion process of CO₂ displacing CH₄ occurs in the transitional zone dominated by convection and diffusion, whose apparent dispersion coefficient is in the order of 10^-7 m²/s and in a linear correlation with the CO₂ injection rate. The research results reveal the dispersion patterns of CO₂, and preliminarily confirm the feasibility of injecting CO₂ to improve shale oil and gas recovery and carbon storage in shale reservoirs, while providing key parameters for the optimal development planning and laying a theoretical basis for related researches and engineering practices.更多还原