Several scientific fields such as global carbon sequestration, deep geological radioactive waste disposal, and oil recovery/fracking encounter safety assessment issues originating from pore-scale processes such as mineral precipitation and dissolution. These processes occur in situations where the pore solution contains chemical complexity (such as pH, ionic strength, redox chemistry, etc.…) and the porous matrix contains physical complexity (such as pore size distribution, surface charge, surface roughness, etc.…). Thus, to comprehend the participation of each physicochemical phenomenon on governing mineral precipitation, it is essential to investigate the precipitation behavior of a given mineral in different confined volumes. In this study, a counter-diffusion approach was used to investigate barite precipitation in two porous materials: micritic chalk and compacted kaolinite. The two materials present similar water and anionic tracer diffusivities and total accessible porosities but distinct pore size distributions with pore throats of c.a. 660 nm in chalk versus c.a. 35 nm in kaolinite.

X-ray tomography results obtained on the two materials showed a distinct distribution of barite precipitates: a 500 μm-thick homogeneous layer in chalk versus spherical clusters spread in a thickness of 2 mm in kaolinite. Mass balance calculations showed that barite precipitation led to a porosity decrease in the chalk reacted zone from 45% to 12% and in the kaolinite reacted zone from 36% to 34.5%. In contrast, water tracer diffusion experiments showed that diffusivity decreased by a factor of 28 in chalk and by a factor of 1000 in kaolinite. Such a discrepancy was attributed to the difference in the pore size distribution that would lead to the distinct barite precipitation patterns, capable of altering in a very different manner the connectivity within the reacted zone of the two selected porous media.

Such local alterations in connectivity linked to pore volume reduction would also magnify surface charge effects on ionic transport, as indicated by chloride diffusion experiments and electrophoric tests using zeta potential measurements. Indeed, ³⁶Cl⁻ was strongly more hindered than water, when diffused in reacted materials, with a diffusivity decrease by a factor of 450 in chalk and a total restriction of ³⁶Cl⁻ in kaolinite. These experiments clearly provide an insight of how local pore structure properties combined with mineral reactivity could help in predicting the evolution of pore scale clogging and its impact on water and ionic diffusive transport.

全球碳封存、深部地质放射性废物处理和石油回收/压裂等几个科学领域遇到了源自矿物沉淀和溶解等孔隙尺度过程的安全评估问题。这些过程发生在孔隙溶液包含化学复杂性（如 pH、离子强度、氧化还原化学等）和多孔基质包含物理复杂性（如孔径分布、表面电荷、表面粗糙度等）的情况下。……）。因此，为了理解每种物理化学现象对控制矿物沉淀的参与，有必要研究给定矿物在不同限制体积中的沉淀行为。在这项研究中，使用反扩散方法研究了两种多孔材料中的重晶石沉淀：泥晶白垩和压实高岭石。这两种材料具有相似的水和阴离子示踪剂扩散率和总可及孔隙率，但具有不同的孔径分布，白垩中的孔喉约为 660 nm，而高岭石中的孔喉约为 35 nm。

在这两种材料上获得的 X 射线断层扫描结果显示重晶石沉淀物的不同分布：白垩中 500 微米厚的均质层与高岭石中 2 毫米厚的球形团簇。质量平衡计算表明，重晶石沉淀导致白垩反应区的孔隙率从 45% 降低到 12%，高岭石反应区的孔隙率从 36% 降低到 34.5%。相比之下，水示踪剂扩散实验表明，白垩的扩散率降低了 28 倍，高岭石的扩散率降低了 1000 倍。这种差异归因于孔径分布的差异，这将导致不同的重晶石沉淀模式，能够以非常不同的方式改变两种选定多孔介质反应区内的连通性。

这种与孔隙体积减少相关的连接性局部改变也会放大表面电荷对离子传输的影响，如氯化物扩散实验和使用 zeta 电位测量的电泳测试所示。事实上，当在反应材料中扩散时，³⁶ Cl ^-比水受到更大的阻碍，在白垩中扩散率降低了 450 倍，而在高岭石中的总限制为³⁶ Cl ^- 。这些实验清楚地揭示了局部孔隙结构特性与矿物反应性如何有助于预测孔隙尺度堵塞的演变及其对水和离子扩散传输的影响。