Structural trapping is known to be the primary storage mechanism in geological carbon sequestration (GCS), where the injected CO₂ rises upwards due to buoyancy forces and becomes trapped under an ultra‐low permeability layer. Although it is relatively common in GCS studies to assume a planar caprock for the synthesised models, in a real scenario this is not always the case as the caprock might exhibit some small‐ or large‐scale topography changes. Moreover, little is known about the impact of the caprock morphology on the CO₂ plume migration and the storage capacity. In this work, we performed a preliminary study of the effects of boundary conditions on the CO₂ plume migration and dissolution. This was performed because most of the case study models which are employed for GCS studies are part of larger reservoirs. The obtained results were used in the simulation models of the second part of the work, to model an infinite‐acting reservoir appropriately. Three different volume modifier values of 10⁵, 10⁷ and 10⁹ were considered on either one side or both sides of the reservoir for both horizontal and tilted caprock models. The CO₂ dissolution in the tilted models was seen to be higher once the multiplier was on the opposite side of the slope. Horizontal models closed on one side (closed faults, salt walls, etc.) were also found to exhibit more significant dissolution than models which were open from both sides. We subsequently investigated the impact of caprock morphology on the CO₂ plume advancement and its structural and dissolution trapping mechanisms by performing numerical simulations on nine synthetic models. The dissolution and migration distance are seen to be at a maximum for tilted reservoirs, where the CO₂ has more space to migrate upwards and to interact with more formation water. The lowest dissolution occurred where the significant portion of the injected CO₂ was trapped in a sand ridge or an anticline. Moreover, the possibility and also the amount of structural trapping was evaluated using an analytical method, and the results showed a fair match with the ones from the numerical simulation. We believe that this methodology could be applied for site screening prior to performing numerical simulations. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.

中文翻译：

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盐分含水层中储存边界和盖层形态对固碳的影响研究

已知结构捕集是地质碳固存（GCS）的主要存储机制，在该机制中，注入的CO ₂由于浮力而向上上升，并被捕集在超低渗透率层之下。尽管在GCS研究中为合成模型假设一个平面的盖层是比较普遍的，但在实际情况下，情况并非总是如此，因为盖层可能会出现一些小规模或大范围的地形变化。此外，关于盖层形态对CO ₂羽流迁移和储存能力的影响知之甚少。在这项工作中，我们对边界条件对CO ₂的影响进行了初步研究。羽流迁移和溶解。之所以这样做，是因为用于GCS研究的大多数案例研究模型都是大型油藏的一部分。所得结果用于工作第二部分的模拟模型中，以适当地模拟无限作用油藏。的10三种不同体积修正因子值⁵，10 ⁷ 和10 ⁹ 被认为在任一侧或贮存器的两侧横向和倾斜盖层模型。一氧化碳₂一旦乘数位于斜率的相对侧，则可以看到倾斜模型中的溶出度更高。还发现一侧封闭的水平模型（闭合的断层，盐壁等）比两侧开放的模型表现出更大的溶解性。随后，我们通过对9种合成模型进行了数值模拟，研究了盖层形态对CO ₂羽流进展及其结构和溶出捕集机理的影响。对于倾斜的油藏，溶解度和运移距离最大，在该处，CO ₂具有更多向上移动并与更多地层水相互作用的空间。最低的溶解发生在注入的CO ₂的显着部分被困在沙脊或背斜中。此外，使用解析方法评估了结构陷获的可能性以及数量，结果表明与数值模拟的结果相当吻合。我们认为，该方法可以在进行数值模拟之前应用于现场筛选。©2020年化学工业协会和John Wiley＆Sons，Ltd.