CO2地质封存（GCS）是一项将CO2注入并且永久封存于地下含水层或废弃油气储层等地质体内的CO2减排技术。由于场地地质条件和人类开发活动导致的不确定性，注入储层的CO2可通过泄漏废弃井、断层或裂缝以及盖层的“薄弱带”等途径发生泄漏。基于对国内外文献的广泛调研，综述了GCS泄漏及封存安全的研究进展。CO2沿钻井泄漏一般是因为化学或力学作用导致CO2沿钻井环空水泥、井筒桥塞或围岩破碎带发生泄漏。CO2注入储层可能导致盖层破裂，激活原本闭合的断层或断层面滑动。CO2沿断层/裂缝泄漏主要受有效渗透率、裂缝开度等因素影响。盖层泄漏的方式可归纳为渗透泄漏、扩散泄漏和沿裂隙泄漏3种。CO2透过盖层的扩散泄漏对于大时空尺度CO2地质封存泄漏评估不应忽视。CO2泄漏通常会导致受影响的含水层内地下水的pH值减小、盐度升高、离子增多等地球化学响应，甚至存在自由态CO2。含水层内流体压力和地球化学特征可用于有效监测封存CO2、咸水与其他流体的泄漏。GCS泄漏研究目前还十分有限，我国尤其缺乏泄漏的定量研究。
Geological CO2 storage(GCS) is a technology for carbon emission-cut, by injecting anthropogenic CO2 for long-term storage into underground aquifers or depleted hydrocarbon reservoirs. Because of the uncertainties induced by geological site condition and human activities, injecting CO2 into the reservoir may lead to leakage through abandoned wells, faults, fractures, and the "weak zones" in the caprock. A comprehensive review on GCS-associated leakage and safety issues was made, based on an extensive investigation of both domestic and international literature. Leakage from a wellbore may occur through the annulus cement, well plugs or the fracture zone of the contact rocks, due to chemical corrosion and/or mechanical failure. Injecting massive amount of CO2 into reservoirs may induce fractures in the seal, activation of potential faults and their slip. Leakage of CO2 along faults/fractures is mainly affected by factors such as the effective permeability and fracture aperture. Leakage through the caprock can be seepage, diffusive or one that occurs through fissures. The diffusive leakage through the caprock should not be neglected when assessing leakage for large-scale GCS projects. Leakage of CO2/brine into the overlying aquifer causes its variation in geochemistry such as a lower pH, higher salinity, more ions, or even the presence of free CO2. Monitoring of pressure and sampling in the overlying aquifer can be effective to identify CO2 leakage from the underlying reservoir. Research on GCS-associated leakage is very limited, with a particular lack of quantitative studies in China.
