CO2地质封存盖层密闭性研究现状与进展

CO₂地质封存是应对全球性气候变化、减排温室气体的关键技术之一。大规模CO₂注入地层容易出现泄漏问题，尤其是通过盖层的泄漏，包括毛细管泄漏、盖层水力破裂和沿盖层既有断层的泄漏等。因此，盖层密闭性评价对CO₂地质封存长期安全稳定性的预测至关重要的。通过对密闭机理、影响因素、破坏模式等影响CO₂地质封存盖层密闭性的研究现状进行总结，发现盖层密闭机理包括毛细管封闭、水力封闭和超压封闭，影响盖层密闭性的主要因素有盖层岩性、盖地比特征、盖层厚度、盖层岩石力学性质和封存压力，进而对CO₂注入过程中盖层密闭性的破坏模式进行评价，并对盖层密闭性研究的不足提出了一些见解。

Status and Advances of Research on Caprock Sealing Properties ofCO2 Geological Storage

CO₂ Geological storage is one of the key technologies to address global climate changes and reduce greenhouse gas emissions. Large-scale CO₂ injection into the formation is prone to inducing CO₂ leakage problem. In particular, the leakage problem of CO₂ through caprock includes capillary leakage, hydraulic fracture and leakage along pre-existing faults crossing caprock. Therefore, evaluation of caprock seal is crucial for prediction of long-term safety and stability of CO₂ geological storage. This paper provides an overview of the current status of research on sealing mechanisms, influencing factors, and damage modes affecting caprock seal of CO₂ geological storage. It is concluded that caprock seal mechanisms include capillary seal, hydraulic seal, and overpressure seal. The main influencing factors of caprock seal characteristics include caprock lithology, mudrock-sand ratio, caprock mechanical properties, and sequestration pressure. Then, the damage modes of caprock seal during CO₂ injection are illustrated, and some insight into the shortcoming of caprock seal is provided.