With the increasing demand for CO₂ storage in the subsurface, it is important to recognize that candidate formations may present complex stress conditions and material characteristics. Consequently, modelling of CO₂ injection requires the selection of the most appropriate constitutive material model for the best possible representation of the material response. The authors focus on modelling the geomechanical behaviour of the reservoir material, coupled with a multiphase flow solution of CO₂ injection into a saline-saturated medium. It is proposed that the SR3 critical-state material model is used, which considers a direct link between strength–volume–permeability that evolves during the simulation; furthermore, the material is considered to yield prior to reaching a peak strength in agreement with experimental observations. Verification of the material model against established laboratory tests is conducted, including multiphase flow accounting for relative permeabilities and fluid densities. Multiphase flow coupled to advanced geomechanics provides a holistic approach to modelling CO₂ injection into sandstone reservoirs. The resulting injection pressures, CO₂ migration extent and patterns, formation dilation, and strength reduction are compared for a range of in situ porosities and incremental material enhancements. This work aims to demonstrate a numerical modelling framework to aid in the understanding of geomechanical responses to CO₂ injection for safe and efficient deployment, and is particularly applicable to CO₂ sequestration in less favourable aquifers with a relatively low permeability, receiving CO₂ from a limited number of injection wells at high flow rates. The proposed framework can also enable additional features to be incorporated into the model such as faults and detailed overburden representation.

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

随着对地下储存CO _{2 的}需求不断增加，重要的是要认识到候选地层可能呈现复杂的应力条件和材料特性。因此，CO ₂注入建模需要选择最合适的本构材料模型，以尽可能最好地表示材料响应。作者专注于模拟储层材料的地质力学行为，并结合 CO ₂的多相流解决方案注入盐水饱和培养基中。建议使用 SR3 临界状态材料模型，该模型考虑了模拟过程中强度-体积-渗透率之间的直接联系；此外，材料被认为在达到与实验观察一致的峰值强度之前屈服。根据已建立的实验室测试对材料模型进行验证，包括考虑相对渗透率和流体密度的多相流。多相流与先进的地质力学相结合，提供了一种对 CO ₂注入砂岩储层进行建模的整体方法。对产生的注入压力、CO ₂迁移范围和模式、地层扩张和强度降低进行了比较。原位孔隙率和增量材料增强。这项工作旨在展示的数值模型框架中的地质力学响应的理解援助CO ₂注射安全高效的部署，以及特别适用于CO ₂封存在不太有利的含水层具有相对低的磁导率，接收CO ₂从一个在高流速下注入井的数量有限。所提出的框架还可以将附加特征合并到模型中，例如断层和详细的覆盖层表示。

专题收藏：本文是 CO ₂储存地球科学收藏的一部分，可从以下网址获取：https://www.lyellcollection.org/cc/geoscience-for-co2-storage