地质封存中CO2-咸水-盖层互馈演化机制及CO2逃逸风险研究

Sealing mechanism of complex caprocks is the theoretical basis of modelling, evaluation, and site selection of CO2 geological sequestration in deep saline aquifers.The on-going funds application takes the CO2-brine-caprock system as the main concern of CO2 sequestration in deep saline aquifers. The proposed macro-micro experiments testing, mutual feedback evolution theoretical analysis, multiscale modelling techniques and typical engineering case analysis are planned to combined, to study CO2-brine-caprock multiphase seepage-mechanical-chemical mutual feedback evolution mechanism, as well as the multiple fractures network development and unsteady seepage alteration process in caprocks under synergy of high in-situ stress and strong osmotic pressure. The studies is aimed at revealing the breakthrough-migration law of CO2 in caprock with multiple fractures network and the key influencing factors, as well as the high osmotic pressure perturbation effect on the complex caprock and fault reactivation risk. Based on the research, the control conditions and criteria of CO2 breakthrough caprocks are to be proposed, and the caprock safety assessment criteria and CO2 escape risk prediction model during geological CO2 sequestration in deep saline aquifers will be established. Additional, site monitoring data of large-scale projects home and abroad on CO2 geological sequestration in deep saline aquifers are to be used to validate the research results. This research has important theoretical significance and application value for the promotion of understanding caprock sealing mechanism of CO2 geological storage, and it also provides a theoretical basis for site selection, engineering design, caprock stability as well as CO2 escape risk assessment and other key issues in CO2 geological sequestration.

复杂盖层对CO2的密封机制是CO2地质封存建模、评价和选址的理论基础。本课题以深部咸水层封存场中CO2-咸水-盖层系统为研究对象，拟采用宏细观实验测试、互馈演化理论分析、多尺度数值模拟和典型工程案例分析相结合的手段，研究CO2-咸水-盖层多相渗流-力学-化学互馈演化机理，以及高地应力和强渗压协同作用下盖层多重裂隙网络发展与非稳态渗流变异过程，揭示CO2在多裂隙复杂盖层中的突破-运移规律和关键影响因素，以及高渗透压对复杂盖层的扰动效应和断层活化风险，提出封存场中CO2突破盖层的控制条件，构建CO2地质封存过程中盖层安全性评价指标和CO2逃逸风险预测模型。结合国内外已建大型CO2深部咸水层封存工程现场监测资料，对成果进行验证。本研究对于推动CO2地质封存中盖层的密封机制研究具有重要的理论意义和应用价值，并可以为CO2地质封存工程选址与设计、盖层稳定以及CO2逸出风险评估等关键问题提供理论依据。

复杂盖层对CO2的密封机制是CO2地质封存建模、评价和选址的理论基础。本课题以深部咸水层封存场中CO2-咸水-盖层系统为研究对象，采用宏细观实验测试、互馈演化理论分析、多尺度数值模拟和典型工程案例分析相结合的手段，研究CO2-咸水-盖层多相渗流-力学-化学互馈演化机理，以及高地应力和强渗压协同作用下盖层多重裂隙网络发展与非稳态渗流变异过程，揭示了CO2在多裂隙复杂盖层中的突破-运移规律和关键影响因素，以及高渗透压对复杂盖层的扰动效应和断层活化风险，提出了封存场中CO2突破盖层的控制条件，构建了CO2地质封存过程中盖层安全性评价指标和CO2逃逸风险预测模型。结合国内外已建大型CO2深部咸水层封存工程现场监测资料，对成果进行了验证。本研究对于推动CO2地质封存中盖层的密封机制研究具有重要的理论意义和应用价值，并可为CO2地质封存工程选址与设计、盖层稳定以及CO2逸出风险评估等关键问题提供理论依据。