Abstract We report a series of acidified brine flow-through experiments designed to quantify the coupled alteration of geochemical, structural and fluid transport properties of a Mt. Simon sandstone core recovered at a depth of 2110.5 m as part of the Illinois Basin Decatur Project (IBDP). Flow-through experiments were completed at representative in-situ conditions to isolate the stages of initial CO2 injection: first, a single-phase (CO2–saturated brine, Stage 1) followed by a second multi-phase (CO2–saturated brine and supercritical CO2, Stage 2) experiment. During both stages, effluent major and trace cation concentrations were tracked through time. Two imaging methods were employed to analyze the structural alterations of the rock core induced by the percolation of CO2-saturated brine and supercritical CO2: (1) scanning electron microscopy-petrography before Stage 1 and after Stage 2 and (2) computed tomography (CT) scans before and after Stage 2. The time series of Stage 1 effluent solutes were used to constrain a reactive transport simulation of the system. Modeling results suggest the evolution of the solute composition is a result of coupled dissolution of K-feldspar, calcite, illite and pyrite, and precipitation of montmorillonite, mesolite, alunite, diaspore, goethite and muscovite. The model predicted a net opening of pore space and associated increased permeability at the inlet. However, across the whole core, an overall decrease in permeability of approximately 23% ± 0.01 after Stage 1 was determined experimentally. CT analysis confirmed a corresponding decrease in porosity. A comparable permeability decrease was directly measured during Stage 2, concurrent with a decrease in the volume of macro-pores based on multiple CT-resolution methods. In total, this coupled approach demonstrates that geochemical alterations exert a first order control on the evolution of fluid transport properties through time at the earliest stages of in-situ CO2 injection and suggest that chemical dynamics ultimately influence both the magnitude and timing of alterations to the physical integrity of Mt. Simon reservoir over these timescales.

中文翻译：

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一座山的反应性改变。西蒙砂岩由于富含二氧化碳的盐水置换

摘要 我们报告了一系列酸化盐水流经实验，旨在量化 Mt. 的地球化学、结构和流体输送特性的耦合变化。作为伊利诺伊州迪凯特盆地项目 (IBDP) 的一部分，在 2110.5 米深处回收的西蒙砂岩岩心。在代表性的原位条件下完成了流通实验以隔离初始 CO2 注入的阶段：首先，单相（CO2 饱和盐水，阶段 1），然后是第二个多相（CO2 饱和盐水和超临界CO2，阶段 2) 实验。在这两个阶段，流出的主要和痕量阳离子浓度随时间被跟踪。采用两种成像方法来分析由 CO2 饱和盐水和超临界 CO2 渗透引起的岩心结构变化：(1) 第 1 阶段之前和第 2 阶段之后的扫描电子显微镜 - 岩相学和 (2) 第 2 阶段之前和之后的计算机断层扫描 (CT) 扫描。 第 1 阶段流出物溶质的时间序列用于约束系统的反应输运模拟. 建模结果表明溶质组成的演变是钾长石、方解石、伊利石和黄铁矿的耦合溶解以及蒙脱石、中沸石、明矾石、硬水铝石、针铁矿和白云母沉淀的结果。该模型预测了孔隙空间的净开口和入口处相关的渗透率增加。然而，在整个岩心中，实验确定在第一阶段后渗透率总体下降约 23% ± 0.01。CT分析证实孔隙率相应减少。在第 2 阶段直接测量了可比较的渗透率下降，同时基于多种 CT 分辨率方法的大孔隙体积下降。总的来说，这种耦合方法表明，在原位 CO2 注入的最早阶段，地球化学蚀变对流体输送特性随时间的演变施加了一级控制，并表明化学动力学最终会影响变化的幅度和时间。山的物理完整性。西蒙水库在这些时间尺度上。这种耦合方法表明，在原位 CO2 注入的最早阶段，地球化学蚀变对流体传输特性随时间的演变施加了一级控制，并表明化学动力学最终会影响变化的幅度和时间对物理完整性的改变。公吨。西蒙水库在这些时间尺度上。这种耦合方法表明，在原位 CO2 注入的最早阶段，地球化学蚀变对流体传输特性随时间的演变施加了一级控制，并表明化学动力学最终会影响变化的幅度和时间对物理完整性的改变。公吨。西蒙水库在这些时间尺度上。