This study discusses experiment‐induced alterations of shale rocks collected across the ordovician and silurian boundary at a potential site for carbon dioxide sequestration located in the Polish part of the Baltic Basin. Mudstone samples submerged in brine in custom‐built reactors were subjected to CO₂ pressures of 30–35 MPa at a temperature of 80°C for 40 days. After the experiments were completed, the mineralogical composition of the studied rocks, their porosity characteristics, and chemistry of brines were analyzed and compared to the original compositions in order to detect experiment‐induced changes. Comparison of mineral composition before and after the experiments demonstrate a set of subtle but systematic mineral changes. The most conspicuous was a presence of Fe in the form of Fe‐oxyhydroxides that was related to the corrosion of the Fe‐bearing steel pipes supplying the experimental setup with CO₂. This effect is important from the perspective of industrial carbon dioxide sequestration. However, the second source of Fe ions in experimental brines was related to the decomposition of chlorites, pyrite, and chloritized biotites. The suggested breakdown of pyrite is in line with the modification of the chemical composition of the experimental brines and observed transfer of S ions to the solution. The appearance of Mg and K ions in the experimental brines was related to the decomposition of chlorites and biotites. In turn, observed transfer of Sr cations to the solution could be attributed to the dissolution of biotites and K‐feldspars. The effects of analogue experiments were confronted with the results of geochemical modeling performed using the PHREEQC program. The numerical modeling not only allowed to reproduce all the main mineral and chemical changes postulated on the basis of our analogue experiment, but also enabled to put constraints on the time scale of occurring geochemical processes. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.

中文翻译：

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在原位模拟条件下，波罗的海盆地波兰部分早古生代泥岩中CO2-岩石-岩石相互作用的实验和数值研究

这项研究讨论了在波罗的海盆地波兰部分的潜在固存二氧化碳的地点，在奥陶纪和志留系边界上采集的页岩岩石的实验诱发变化。将定制反应器中浸没在盐水中的泥岩样品暴露于CO ₂在80°C的温度下30-35 MPa的压力持续40天。实验完成后，对研究岩石的矿物学组成，孔隙率特征和盐水化学成分进行分析，并与原始成分进行比较，以检测实验引起的变化。实验前后矿物成分的比较显示出一组细微但系统的矿物变化。最明显的是以羟基氧化铁的形式存在的Fe，这与为实验装置提供CO ₂的含铁钢管的腐蚀有关。从工业二氧化碳隔离的角度来看，这一作用很重要。但是，实验盐水中第二种铁离子源与亚氯酸盐，黄铁矿和氯化黑云母的分解有关。所建议的黄铁矿分解与实验盐水化学成分的改变以及观察到的S离子向溶液的转移相一致。实验盐水中Mg和K离子的出现与亚氯酸盐和黑云母的分解有关。反过来，观察到的Sr阳离子向溶液的转移可能归因于黑云母和钾长石的溶解。模拟实验的效果与使用PHREEQC程序进行的地球化学建模结果相对。数值模型不仅可以再现模拟实验基础上假设的所有主要矿物和化学变化，而且还可以限制发生的地球化学过程的时间尺度。©2020年化学工业协会和John Wiley＆Sons，Ltd.