In order to reduce uncertainties around CO₂ containment for the South West Hub CCS site (Western Australia), conceptual fault hydrodynamic models were defined and numerical simulations were carried out. These simulations model worst-case scenarios with a plume reaching a main compartment-bounding fault near the proposed injection depth and at the faulted interface between the primary and secondary containment interval.

The conceptual models incorporate host-rock and fault properties accounting for fault-zone lithology, cementation and cataclastic processes but with no account made for geomechanical processes as the risk of reactivation is perceived as low. Flow simulations were performed to assess cross-fault and upfault migration in the case of plume–faults interaction.

Results near the injection depth suggest that the main faults are likely to experience a significant reduction in transmissivity and impede CO₂ flow. This could promote the migration of CO₂ vertically or along the stratigraphic dip.

Results near the interface between the primary and secondary containment intervals show that none of the main faults would critically control CO₂ flow nor would they act as primary leakage pathways. CO₂ flow is predicted to be primarily controlled by the sedimentological morphology. The presence of baffles in the secondary containment interval is expected to be associated with local CO₂ accumulations; additional permeability impacts introduced by faults are minor.

Thematic collection: This article is part of the Geoscience for CO₂ storage collection available at: https://www.lyellcollection.org/cc/geoscience-for-co2-storage

为了减少西南枢纽CCS站点（西澳大利亚州）CO ₂围堵的不确定性，定义了概念性断层流体动力模型并进行了数值模拟。这些模拟对最坏情况进行建模，其中羽流在建议的注入深度附近以及主要和次要安全壳层之间的故障界面处达到主隔室边界断层。

概念模型包含了解释断层带岩性，胶结作用和碎裂过程的岩体和断层特性，但由于重新活化的风险较低，因此没有考虑地质力学过程。在羽流－断层相互作用的情况下，进行了流动模拟以评估跨断层和上升断层的迁移。

注入深度附近的结果表明，主要断层可能会经历透射率的显着降低并阻碍CO ₂流动。这可以促进CO ₂垂直或沿地层倾角的迁移。

主要和次要安全区间之间的界面附近的结果表明，主要故障均不会严重控制CO ₂流量，也不会充当主要泄漏途径。预计CO ₂流量主要受沉积形态控制。预计在二级围堵间隔中挡板的存在与局部CO _2的积累有关。断层带来的其他渗透率影响很小。

专题收集：本文是可用于以下位置的Geoscience for CO ₂储存集合的一部分：https://www.lyellcollection.org/cc/geoscience-for-co2-storage