Despite the numerous studies on changes within the reservoir following CO₂ injection and the effects of CO₂ release into overlying aquifers, little or no literature is available on the effect of CO₂ release on rock between the storage reservoirs and subsurface. This is important, because the interactions that occur in this zone between the CO₂ storage reservoir and the subsurface may have a significant impact on risk analysis for CO₂ storage projects. To address this knowledge gap, relevant rock materials, temperatures and pressures were used to study mineralogical and elemental changes in this intermediate zone. After rocks reacted with CO₂-acidified 0.01 M NaCl, liquid analysis showed an increase of major elements (e.g., Ca and Mg) and variable concentrations of potential contaminants (e.g., Sr and Ba); lower aqueous concentrations of these elements were observed in N₂ control experiments, likely due to differences in pH between the CO₂ and N₂ experiments. In experiments with As/Cd and/or organic spikes, representing potential contaminants in the CO₂ plume originating in the storage reservoir, most or all of these contaminants were removed from the aqueous phase. SEM and Mössbauer spectroscopy results showed the formation of new minerals and Fe oxides in some CO₂-reacted samples, indicating potential for contaminant removal through mineral incorporation or adsorption onto Fe oxides. These experiments show the interactions between the CO₂-laden plume and the rock between storage reservoirs and overlying aquifers have the potential to affect the level of risk to overlying groundwater, and should be considered during site selection and risk evaluation.

尽管对注入CO ₂后储层内的变化以及CO ₂释放到上覆含水层中的影响进行了大量研究，但关于CO ₂释放对储层和地下储层之间岩石的影响的文献很少或没有。这很重要，因为在此区域中发生的CO ₂储存储层与地下之间的相互作用可能会对CO ₂储存项目的风险分析产生重大影响。为了解决这一知识鸿沟，使用了相关的岩石材料，温度和压力来研究该中间带的矿物学和元素变化。岩石与CO ₂反应后-酸化0.01 M NaCl，液体分析显示主要元素（例如Ca和Mg）增加，潜在污染物（例如Sr和Ba）浓度变化；在N ₂对照实验中观察到这些元素的水含量较低，这很可能是由于CO ₂和N ₂实验之间的pH值差异所致。在用As / Cd和/或有机尖峰表示来自存储库的CO ₂羽流中的潜在污染物的实验中，大多数或所有这些污染物已从水相中去除。SEM和Mössbauer光谱结果表明在某些CO _2中形成了新的矿物和Fe氧化物-反应的样品，表明可能通过矿物掺入或吸附到氧化铁上而去除污染物。这些实验表明，充满CO _2的羽流与储层和上覆含水层之间的岩石之间的相互作用可能会影响上覆地下水的风险水平，因此在选址和风险评估时应予以考虑。