CO_(2)地质封存系统泄漏风险评价

Leakage risk assessment of geological CO_(2) storage system

CO_(2)地质封存是缓解温室效应的重要手段,而封存系统的泄漏风险评价是安全封存的基础。首先,综合分析影响CO_(2)地质封存系统泄漏的因素,认为诱发泄漏风险的原因主要是CO_(2)低温冷流体产生对井筒和盖层的交变应力和CO_(2)-水-岩腐蚀反应综合作用下导致井筒和盖层的完整性失效。考虑多因素综合作用对CO_(2)地质封存系统泄漏的影响,并基于模糊综合评价理论(FCE),建立了CO_(2)泄漏风险因素间的层次关系模型,进行了CO_(2)地质封存系统泄漏风险评价,其过程包括应用非线性正态隶属函数建立CO_(2)泄漏风险因素对评语的隶属度矩阵,并应用层次分析方法构建泄漏风险影响因素间的比较矩阵,以获得泄漏风险因素的权重子集,并对给定实例CO_(2)地质封存系统泄漏风险进行评价,进而得出所评价的CO_(2)地质封存井筒当前处于泄漏低风险,盖层处于泄漏中风险,封存系统处于泄漏中风险。通过采集CO_(2)地质封存过程中泄漏风险影响因素的变化并进行模糊运算模型更新,可动态跟踪CO_(2)地质封存系统泄漏风险。

Geological CO_(2) storage has been thought of as an important technical means for alleviating the greenhouse effect,and the leakage risk assessment of the storage system is the basis of safe storage.In this study,the influencing factors in the leakage of the geological CO_(2) storage system were comprehensively analyzed.It is believed that the leakage risk is mainly induced by the alternating stress on the wellbore and caprock produced by cryogenic fluids of CO_(2) and the integrity failure of the wellbore and caprock caused by the comprehensive action of CO_(2)-water and rock corrosion reactions.Hence,the multi-factor influence on the leakage of the geological CO_(2) storage system was taken into account.Then,the fuzzy comprehensive evaluation(FCE)theory was used to construct a model for the hierarchical relationships between factors leading to CO_(2) leakage risks,and the model was employed to assess the leakage risks of the geological CO_(2) storage system.Specifically,the nonlinear normal membership function was applied to construct the membership matrix of the influencing factors with regard to comments.The analytic hierarchy process(AHP)was used to construct the comparison matrices between the influencing factors to obtain the weight subset of these influencing factors.In addition,a geological CO_(2) storage system was taken as an example for leakage risk assessment.It is concluded that the wellbore for geological CO_(2) storage faces a low risk of leakage while the cap rock and the storage system have a moderate leakage risk.Moreover,the leakage risk of the geological CO_(2) storage system can be dynamically tracked upon the collection of the changes of influencing factors in the process of CO_(2) storage for the update of the fuzzy calculation model.