To assess the long-term integrity of geologic CO2 storage, samples modeling caprock were reacted under a supercritical CO2-water system at 10 MPa and 40 °C. The resultant effects on their sealing performance were analyzed. The use of calcite-containing artificial samples comprising silica particles with controlled size, configuration, and packing density quantified the relation between the dissolved amount of calcite and permeability. The solution analysis revealed that the calcium concentration was once increased by the initial calcite dissolution and was then decreased by calcite reprecipitation at the time of depressurization. In response to this mechanism, the initial increase and subsequent decrease in permeability were confirmed. Correlation between the Ca-leaching amount and permeability fell into two categories depending on porosity and specific surface area: The sensitivity to permeability rose when both parameters were large. This correlation was maintained also in the case in which the Ca-leaching amount changed along with the porosity change. The power-law fitting to the porosity–permeability relation suggested that two correlations were derived from the degree of heterogeneity. In actuality, the pore diameter distribution of samples with suspected heterogeneity indicated a broad peak of the spectrum, which supported the existence of heterogeneity. Using the formulated relation, the permeability increase was estimated as less than just 2%, even when calcite dissolved to its saturated concentration. Therefore, if any calcite is contained in caprock, the risk of CO2 leakage is apparently extremely low.

中文翻译：

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地质CO2封存条件下方解石溶解对盖层封闭性能的影响

为了评估地质 CO2 储存的长期完整性，模拟盖层的样品在 10 MPa 和 40 °C 的超临界 CO2-水系统下反应。分析了其对密封性能的影响。使用包含具有受控尺寸、构造和堆积密度的二氧化硅颗粒的含方解石人造样品量化了方解石溶解量与渗透率之间的关系。溶液分析表明，钙浓度因初始方解石溶解而增加，然后在降压时因方解石再沉淀而降低。针对这种机制，渗透率的初始增加和随后的降低得到证实。根据孔隙率和比表面积，Ca 浸出量和渗透率之间的相关性分为两类：当这两个参数都很大时，对渗透率的敏感性增加。在Ca浸出量随着孔隙率变化而变化的情况下也保持该相关性。孔隙度-渗透率关系的幂律拟合表明，两个相关性来自于非均质性程度。实际上，疑似异质性样品的孔径分布表明光谱峰较宽，支持异质性的存在。使用公式化的关系，即使方解石溶解到饱和浓度，渗透率的增加估计也小于 2%。因此，如果盖层中含有方解石，