废弃盐穴中压缩空气蓄能薄互层状顶板密闭性基础研究

A large number of salt caverns by solution mining are abandoned widely. After reasonable reformation, some of these caverns are expected to store and improve the utilization of the intermittent energy such as wind and solar energy as compressed air energy storages (CAES). Due to the scarcity of salt dome, the underground gas storages of China can only be constructed in thin interbedded salt formations with multiple interlayers and interfaces. In order to improve efficiency, solution mining with double well convection are widely adopted, which bring more horizontal cavities with larger span. When these horizontal cavities are transformed for underground energy storage, the layered roofs are easily suffered from unbalanced deformation and fatigue damage, and then become the channels of gas leakage. Therefore, based on the project of CAES in abandoned salt caverns, further researches are carried out to research the tightness of the interbedded roof above abandoned salt caverns used as compressed air energy storage. Finally, the damage and failure mechanism of thin interbedded salt formations will be developed; the evolution of the creep, fatigue, damage and penetration mechanism of the thin interbedded roof will be put forward under the cyclic loading; then a more reliable seepage instability criterion of the thin interbedded salt formations can be acquired; and then a more reasonable criteria for evaluating the ultimate safety thickness and span of the roof can be revealed. This project can be expected to provide the theoretical basis and technical support for safe operation and disaster avoidance of CAES in abandoned salt caverns.

盐矿水溶开采会遗留大量的废弃盐穴，加以适当改造可作为压缩空气储存风能和太阳能的地下场所。然而，我国盐岩地层具有薄互层状特性，废弃盐穴多为双井对流开采形成的跨度更大的水平腔体，在其被改造成压气蓄能储库时，极易因层状顶板密闭性不足而导致气体泄漏。本项目拟针对这一问题，依托我国废弃盐穴压气蓄能示范工程，深入研究废弃盐穴在被选作压气蓄能储库时其层状顶板的密闭性。通过研究，揭示卤水长期作用后废弃盐穴薄互层状顶板的损伤弱化机理；揭示低频循环荷载条件下薄互层状顶板蠕变疲劳损伤机理，及其渗透特征演化规律；建立废弃盐穴中压气蓄能储库运营过程中薄互层状顶板渗透失稳判据；提出薄互层状顶板极限跨度和厚度的判别准则和优化方案。为我国废弃盐穴中压气蓄能工程的顺利实施和灾害规避提供重要的理论依据和技术支持。

盐矿水溶开采遗留的废弃盐穴，可用于压缩空气储存风能和太阳能。然而，将废弃盐穴改造成压气蓄能储库时，层状顶板极易因密闭性不足而导致气体泄漏。本项目开展了废弃盐穴中压缩空气蓄能顶板密闭性基础研究，主要研究内容和结论如下：.1、调研了示范区盐矿地质特征和采矿方法工艺，获得了目标废弃盐穴薄互层状顶板埋深、跨度和厚度等空间展布特征，确定了三种典型赋存形态的水平腔体；.2、简化并建立了上述三种形态腔体的计算模型；对比研究了腔体内压和运营时间两个关键因素对水平老腔塑性区、体积收缩率、位移各方面的影响规律；.3、依托定远盐矿三次地表塌陷事故，根据三维地震勘探和理论解释，提出了盐矿上覆岩层逐层破断的垮塌模式，建立了单层顶板破断力学模型，得到了泥质硬石膏顶板为盐穴地表塌陷与否的关键层的重要论断。.4、构建了盐穴上覆岩层大面积突然沉陷的陷落柱模型和漏斗模型，并提出了沉陷与否的判别准则，制定了溶腔上部预留盐岩保留层、保持井管密闭性以及严格控制顶板尺寸等预防措施，并给出了预警地表沉陷的关键时刻点。.5、将我国湖相沉积盐岩地层的韵律特征，用于多夹层盐穴储库群矿柱宽度的优化设计之中，并给出了盐穴储气库群矿柱稳定性的判别方法。.6、在考虑盐岩品位和蠕变性能的基础上，假设水平腔体为圆柱体，构建了盐岩腔体体积和体积收缩量随时间演化的数学模型，利用该模型预测了造腔和存储两个阶段不同形状盐腔上覆地层移动和地表缓慢沉降的过程，实现了盐穴地表沉降、倾斜和曲率的实时模拟。.在基金(41877277)资助下，项目负责人以第一作者发表学术论文11篇（SCI论文5篇，EI论文2篇），出版英文专著1部；申请并授权发明专利2项；获得中国发明协会、中国产学研合作促进会等科研奖励4项；参加国际国内学术会议8次；培养或协助培养博士和硕士毕业4人。上述研究结果和结论，将为废弃盐穴中压气蓄能储库的选址和安全运营提供重要的理论依据。