Abstract Underground fractures serve as flow conduits, and they may produce unwanted migration of water and other fluids in the subsurface. An example is the migration and leakage of greenhouse gases in the context of geologic carbon sequestration. This study has generated new understanding about how acids erode carbonate fracture surfaces and the positive feedback between reaction and flow. A two-dimensional reactive transport model was developed and used to investigate the extent to which geochemical factors influence fracture permeability and transmissivity evolution in carbonate rocks. The only mineral modeled as reactive is calcite, a fast-reacting mineral that is abundant in subsurface formations. The X-ray computed tomography dataset from a previous experimental study of fractured cores exposed to carbonic acid served as a testbed to benchmark the model simulation results. The model was able to capture not only erosion of fracture surfaces but also the specific phenomenon of channelization, which produces accelerating transmissivity increase. Results corroborated experimental findings that higher reactivity of the influent solution leads to strong channelization without substantial mineral dissolution. Simulations using mineral maps of calcite in a specimen of Amherstburg limestone demonstrated that mineral heterogeneity can either facilitate or suppress the development of flow channels depending on the spatial patterns of reactive mineral. In these cases, fracture transmissivity may increase rapidly, increase slowly, or stay constant, and for all these possibilities, the calcite mineral continues to dissolve. Collectively, these results illustrate that fluid chemistry and mineral spatial patterns need to be considered in predictions of reaction-induced fracture alteration and risks of fluid migration.

中文翻译：

---

裂缝通道化和导水率演化的反应输运模拟

摘要 地下裂缝作为流动通道，它们可能会在地下产生水和其他流体的不必要迁移。一个例子是在地质固碳背景下温室气体的迁移和泄漏。这项研究对酸如何侵蚀碳酸盐裂隙表面以及反应和流动之间的正反馈产生了新的认识。开发了二维反应输运模型并用于研究地球化学因素对碳酸盐岩裂缝渗透率和输导率演化的影响程度。唯一模拟为反应性的矿物是方解石，这是一种快速反应的矿物，在地下地层中含量丰富。X 射线计算机断层扫描数据集来自先前对暴露于碳酸的破裂岩心的实验研究，用作测试模型模拟结果的基准。该模型不仅能够捕获断裂表面的侵蚀，还能够捕获导致透射率加速增加的通道化的特定现象。结果证实了实验结果，即流入溶液的更高反应性导致强通道化而没有大量矿物溶解。使用阿默斯特堡石灰岩标本中方解石矿物图进行的模拟表明，矿物异质性可以促进或抑制流动通道的发展，具体取决于活性矿物的空间模式。在这些情况下，裂缝透射率可能会迅速增加、缓慢增加或保持不变，对于所有这些可能性，方解石矿物仍在继续溶解。总的来说，这些结果表明，在预测反应引起的裂缝改变和流体迁移风险时需要考虑流体化学和矿物空间模式。