Geologic sequestration in sedimentary formations has been identified as a potential technology to prevent climate-change inducing carbon dioxide (CO₂) from being emitted to the atmosphere. To achieve safe and effective storage underground, accurate understanding, and predictions of supercritical CO₂ (scCO₂) behavior in subsurface rock formations is required; including quantifying how much scCO₂ is trapped within pore spaces by capillarity (vs. how much remains mobile), and constraining the occurrence of physio-chemical reactions between scCO₂ and the mineral matrix. Experiments where multiple cycles of scCO₂ and brine are injected into rock samples have produced conflicting results regarding the consistency of trapping as cycles progress; likely due to differences in mineral content, pressure-temperature conditions, aqueous chemistry parameters, and experimental setups. We present a new set of experiments, replicating the conditions of a previous study, but with a new experimental design, apparatus, and timeline. We confirm previous results that demonstrated shifts in injection pressure and scCO₂ trapping behavior over multiple injection cycles, and we conduct additional analyses to discern the fluid-fluid macroscopic contact angle, interface mean and Gaussian curvatures, scCO₂ interfacial area, and topology of trapped scCO₂ ganglia. We also performed lattice-Boltzmann simulations approximating experimental conditions where solid wettability was systematically altered over multiple injections cycles; trends in scCO₂ ganglia characteristics compare well between experiment and simulation. The results indicate that this system undergoes a transition to a “patchy” mixed-wet state, and we observe that this wettability alteration renders scCO₂ more stable in the rock pore space, increasing capillary trapping over four injection cycles.

中文翻译：

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循环 scCO2-盐水注入期间 Bentheimer 砂岩润湿性的演变

沉积地层中的地质封存已被确定为防止气候变化引起的二氧化碳 (CO ₂ ) 排放到大气中的潜在技术。为了实现地下安全有效的封存，需要准确理解和预测地下岩层中的超临界 CO ₂ (scCO ₂ ) 行为；包括量化有多少 scCO ₂被毛细管作用捕获在孔隙空间内（与多少保持移动），并限制 scCO ₂和矿物基质之间发生物理化学反应。多循环 scCO _{2 的}实验并且将盐水注入岩石样品中，在循环过程中捕集的一致性产生了相互矛盾的结果；可能是由于矿物质含量、压力-温度条件、水性化学参数和实验设置的差异。我们提出了一组新的实验，复制了先前研究的条件，但具有新的实验设计、设备和时间表。我们证实了先前的结果，这些结果表明注射压力和 scCO ₂捕集行为在多个注射循环中发生了变化，并且我们进行了额外的分析以辨别流体-流体宏观接触角、界面均值和高斯曲率、scCO ₂界面面积和捕集的拓扑结构二氧化碳₂神经节。我们还进行了近似实验条件的格子-玻尔兹曼模拟，其中固体润湿性在多次注射循环中被系统地改变；scCO ₂神经节特征的趋势在实验和模拟之间比较良好。结果表明该系统经历了向“片状”混合湿态的转变，我们观察到这种润湿性改变使 scCO ₂在岩石孔隙空间中更加稳定，在四个注入周期内增加了毛细管捕集。