An understanding of fault seal is crucial for assessing the storage capacity and containment risks of CO₂ storage sites, as it can significantly affect the projects on across-fault and along-fault migration/leakage risk, as well as reservoir pressure predictions. We present a study from the Smeaheia area in the northern Horda Platform offshore Norway, focusing on two fault-bounded structural closures, namely the Alpha and Beta structures. We aim to use this study to improve the geological understanding of the northern Horda Platform for CO₂ storage scale-up potentials and illustrate the importance of fault seal analysis in containment risk assessment and storage capacity evaluation of a CO₂ storage project. Our containment risk assessment shows that the Alpha structure has low fault-related containment risks; thus, it has a potential value to be an additional storage target. The Beta structure shows larger fault-related containment risks due to juxtaposition of the prospective storage aquifer with the basement across the Øygarden Fault System. The storage capacity of Smeaheia will be determined by the long-term dynamic interplay between pressure depletion and recharging. Our study shows that across-fault pressure communication between Smeaheia and the depleting Troll reservoir is likely to be through several relay ramps of the Vette Fault System. However, Smeaheia also shows pressure-recharging potentials, such as through the subcropping areas at the Base Nordland Unconformity. The depletion observed in the newly drilled well 32/4-3S gives a good validation point for our fault seal predictions and provides valuable insights for future dynamic simulations.

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

对断层密封的理解对于评估CO ₂储存地点的存储容量和封闭风险至关重要，因为它会严重影响跨断层和沿断层迁移/渗漏风险以及储层压力预测的项目。我们目前从挪威海上霍达平台北部的Smeaheia地区进行的一项研究，重点研究了两个以断层为界的结构性封闭，即Alpha和Beta结构。我们旨在利用这项研究来提高北部霍达平台对CO ₂储存放大潜力的地质认识，并说明断层密封分析在对CO _2的围堵风险评估和储存能力评估中的重要性存储项目。我们的安全隐患评估表明，Alpha结构具有较低的与故障相关的安全隐患。因此，它具有作为附加存储目标的潜在值。Beta结构显示较大的与断层有关的围堵风险，这是由于预期储层与Øygarden断层系统的地下室并置所致。Smeaheia的存储能力将取决于压力消耗和补给之间的长期动态相互作用。我们的研究表明，斯梅厄亚与耗尽的巨魔储层之间的跨断层压力连通可能是通过维特断层系统的几个中继坡道实现的。但是，斯梅厄尼亚州也表现出压力补给的潜力，例如通过北诺德兰不整合面的次作物种植区。

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