One of the important mechanisms in CO₂ storage is dissolution trapping. The dissolution of CO₂ in aquifer brines increases the brine density and leads to hydrodynamic instabilities, formation of CO₂‐rich fingers, and a desirable acceleration of the CO₂ dissolution. In recent decades, there has been an intensive effort to identify suitable deep aquifers for CO₂ sequestration. Despite reports that background horizontal flow exists in many of these aquifers, few numerical studies have addressed whether background flow affects the dissolution process. These studies had no available measurements to support their results. Here, we report on laboratory experiments, using a dyed mixture of methanol and ethylene‐glycol (MEG) as a CO₂ analog. The effect of an imposed horizontal water flow was investigated by injecting MEG from above into a cell filled with glass beads. An imaging system was used to provide concentration maps, which were analyzed to calculate dissolution rates and to evaluate the characteristics of the convective fingers. The results show that background flow leads to suppression of the fingers' formation, a fivefold decrease of the fingers' wave number, and a twofold decrease in their propagation rate. Therefore, it was expected that the dissolution rate would also be suppressed, consistent with previous numerical results. However, our results show that the dissolution rate was hardly affected by the background flow. We postulate that the horizontal flow results in a trade‐off between the suppression of the convective flux and the enhancement of dispersive fluxes, resulting in negligible net influence on the dissolution rate.

中文翻译：

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深盐层含水层中水流和分散通量在溶解二氧化碳中的作用

CO ₂储存的重要机制之一是溶解捕集。CO ₂在含水层盐水中的溶解会增加盐水密度，并导致流体动力学不稳定性，富含CO _2的指状物的形成以及理想的CO ₂溶解加速。近几十年来，人们一直在努力寻找适合CO _2的深层含水层。隔离。尽管有报道说许多此类含水层中存在背景水平流，但很少有数值研究涉及背景流是否影响溶解过程。这些研究没有可用的测量来支持其结果。在这里，我们报告了实验室实验，使用甲醇和乙二醇（MEG）的染色混合物作为CO ₂模拟。通过从上方将MEG注入装有玻璃珠的电池中，研究了施加的水平水流的影响。使用成像系统提供浓度图，对其进行分析以计算溶出度并评估对流手指的特征。结果表明，背景流动导致手指的形成受到抑制，手指的波数减少了五倍，而手指的传播速率则减少了两倍。因此，预期溶解速率也将得到抑制，与先前的数值结果一致。但是，我们的结果表明，溶出速率几乎不受背景流量的影响。