Geochemical impact of CO2 and H2 injection on geomechanical and petrophysical properties of caprock to ensure safe containment: an experimental and an

二氧化碳和氢气储存的开发商有道德、社会和法律责任，以确保在地质时间尺度上的安全遏制。在地质介质中安全、可预测地长期储存CO2和H2的关键是需要了解潜在反应流体存在时盖层的行为。将二氧化碳和氢气注入含盐含水层和/或枯竭的油气藏中进行储存，将改变当地的地球化学环境，可能导致与盖层的反应。反过来，这可能会改变盖层的地质力学和岩石物理性质，可能会增加运移出宿主储层的风险。尽管地球化学和地质力学在CO2或H2存在下对盖层的耦合影响是岩石强度和密封能力的关键控制因素，但人们对其了解甚少，研究也不足。通过研究这两个学科之间的相互作用，可以对岩石强度控制器和随后的泄漏路径有一个新的认识，有助于降低未来CCUS和潜在的氢气储存项目的风险。这项开创性的实验研究将直接揭示典型储层条件下地球化学对盖层关键地质力学性质的影响。测量注入流体对盖层强度、渗透率、弹性和声学特性以及活性表面积的影响，将为CO2和H2注入点的盖层完整性提供基本约束。这项工作将有助于识别CO2和H2注入对关键盖层性质的独特地球化学和地质力学差异，这是同类研究中的第一次比较研究，通过提供标准来区分和排序盖层的长期稳定性，从而帮助未来的选址。

CO2 and H2 storage developers have a moral, social, and legal responsibility to ensure safe containment over geological time scales. Critical to safe and predictable long-term storage of CO2 and H2 within geological media, is the need to understand caprock behaviour in the presence of potentially reactive fluids. Injection of CO2 and H2 for storage into saline aquifers and/or depleted hydrocarbon reservoirs will alter the in-situ geochemical environment, potentially leading to reactions with the caprock. This, in turn, may alter the geomechanical and petrophysical properties of the caprock, possibly increasing the risk of migration out of the host reservoir. The coupled geochemical and geomechanical effects on caprocks in the presence CO2 or H2 are poorly understood and under-researched despite being key controls on rock strength and sealing capacity. By investigating the interplay between these two disciplines, a new understanding on controllers of rock strength and subsequent leakage pathways can be constrained, helping de-risk future CCUS and potential H2 storage projects. This pioneering experimental study will directly reveal the geochemical effects on key geomechanical properties of caprocks under representative reservoir conditions. Measurements of how the strength, permeability, elastic and acoustic properties, and reactive surface area of caprocks are affected by the presence of injected fluids will provide fundamental constraints on caprock integrity for CO2 and H2 injection sites. This work will enable identification of the unique geochemical and geomechanical differences between CO2 and H2 injection upon key caprock properties, the first comparison study of its kind, aiding future site selection by providing criteria to differentiate and rank sites by the long-term stability of the caprock.