玄武岩地层由于富含钙、镁、铁等二价金属元素，能够通过高效的矿化反应将注入的CO₂转化为碳酸盐岩，实现CO₂安全有效的永久封存。但围绕CO₂矿化封存机制的研究尚不完善，多数研究忽略了扩散作用对CO₂矿化机制的影响。通过试管填充及烧杯平铺实验，开展了不同矿物、不同粒径及不同反应时间下的CO₂−水−岩反应，并对反应后岩样开展多维度分析，包括拉曼光谱、无机碳含量以及SEM-EDS等，从而阐明了扩散作用在CO₂矿化封存中的重要性以及扩散作用控制下CO₂矿化产物的时空演变规律。同时，通过TOUGHREACT建立了扩散作用控制的试管填充实验的数值模拟模型，并通过与物理实验结果拟合，确保数值模拟模型的准确性。在此基础上，开展了更多影响因素的作用规律研究，并为物理实验现象提供机理解释。结合物理实验及数值模拟结果表明：① 在不存在扩散作用的烧杯平铺实验中，反应14 d后无矿化产物，28 d后仅有微量菱镁矿生成。② 相反，在扩散作用控制下的试管填充实验中，橄榄石填充管中的主要的沉淀物是菱镁矿，天然玄武岩填充管中的沉淀物以方解石、菱铁矿为主，菱镁矿为辅。在相同矿物粒径、相同反应时间下，天然玄武岩中CO₂矿化速率远小于橄榄石，这是由于橄榄石与玄武岩其他组成矿物相比溶解速度最快。③ 在橄榄石或玄武岩填充管中，碳酸盐沉淀物沿填充管均呈非均匀分布。通过数值模拟解释了造成这一现象的根本原因，即在扩散作用控制下，填充床中H⁺、DIC (Dissolved Inorganic Carbon)以及二价金属阳离子存在浓度梯度，且浓度梯度方向不同。④ 矿物比表面积对CO₂−水−岩反应有显著影响，不仅影响矿化效率而且影响矿化产物空间分布，并最终影响反应后多孔介质孔隙度分布。⑤ 与压力相比，温度对CO₂矿化的影响更大；当温度从65 ℃升高到85 ℃时，方解石、菱铁矿及碳酸盐沉淀总量明显增加，但从85 ℃升高100 ℃，仅菱镁矿沉淀量增加明显。压力对方解石沉淀的形成影响较小，而对菱镁矿及菱铁矿的形成几乎没有影响。

Because basalt formation is rich in calcium, magnesium, iron and other bivalent metal elements, it can transform injected CO₂ into carbonate rock through efficient mineralization reaction, so as to achieve a safe and effective permanent storage of CO₂. However, the research on the mechanism of CO₂ mineralization and storage is incomplete, and most studies ignore the effect of diffusion on the mechanism of CO₂ mineralization. By conducting experiments with the sand grains being filled in the tube or scatted in a beaker, the CO₂-water-rock reactions with different minerals, different particle sizes and different reaction time are investigated. The rock samples after the reaction are analyzed by multi-dimensional analysis, including Raman spectra, inorganic carbon content and SEM-EDS, thus clarifying the importance of diffusion in the CO₂ mineralization and the spatio-temporal evolution of CO₂ mineralization products under diffusion control. At the same time, the numerical simulation model of the tube filling experiment is established by TOUGHREACT, and the accuracy of the numerical simulation model is ensured by fitting the physical experiment results. On this basis, more studies on the law of the influencing factors are carried out, and the mechanistic explanation for the physical experimental phenomena is provided. The results of physical experiment and numerical simulation show that: ① For the experiment carried out with olivine grains scattered at the bottom of beaker, no diffusion occurred. At this situation, after 14 days’ reaction, no mineral carbonation was observed. Meanwhile, after 28 days marginal amount of magnesite was observed. ② In contrast, in the filled tubes, under the control of diffusion, the main precipitates in the olivine filled tube are magnesite, and the precipitates in the natural basalt filled tube are mainly calcite and siderite, with magnesite as auxiliary. At the same mineral particle size and the same reaction time, the CO₂ mineralization rate in natural basalt is much smaller than that of olivine, because olivine has the fastest dissolution rate compared with other constituent minerals of basalt. ③ In olivine or basalt filled tubes, the carbonate precipitates are distributed ununiformly along the filled tubes. The root cause of this phenomenon is explained by numerical simulation, i.e., under the control of diffusion, there are concentration gradients of pH, DIC and bivalent metal cations in the packed bed, and the concentration gradients are different in different directions. ④ The specific mineral surface has a significant influence on the CO₂-water-rock reaction, which not only affects the mineralization efficiency but also affects the spatial distribution of the mineralized products, and finally affects the porosity distribution of the porous media after the reaction. ⑤ Compared with pressure, temperature has more influence on CO₂ mineralization. The precipitation of calcite, siderite and carbonate increases significantly when the temperature increases from 65 ℃ to 85 ℃, but only the precipitation of magnesite increases significantly when the temperature increases from 85 ℃ to 100 ℃. The pressure has little effect on the formation of calcite precipitate, but has no effect on the formation of magnesite and siderite.