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鉴于盐岩地下储库界面对储气(油)库稳定性和密闭性的重要影响,分别从细观和宏观方面对其变形与破损特性开展研究。细观方面:开展含界面盐岩的电镜扫描试验,分析表明:盐岩与夹层界面处颗粒结合紧密、相互嵌合,胶结良好,为储库密闭性提供有利条件。宏观方面:基于复合岩体理论构建层状盐岩交接界面的应力表达式,进而分析界面的变形及破损特性。分析表明,界面附近应力状态极为复杂,硬夹层对盐岩体具有约束锚固作用,且界面处易产生应力集中,进而诱发储库围岩体裂纹扩展直至破坏。综合细观、宏观分析表明,裂纹起裂机制和渗透通道形成是界面的细观结构特性及其应力状态共同影响的结果。研究成果为进一步分析地下盐岩储库的稳定性和密闭性提供一定参考。
In view of the important influence of the interface of the salt rock reservoir on the stability and airtightness of gas reservoirs, the deformation and fracture characteristics of the rock salt reservoir are investigated respectively from the aspects of meso-scale and macroscopic. In the aspect of microscopic view, the scanning electron microscope test of salt rock with interface is carried out. The analysis shows that the particles in the interface of salt rock and interlayer are closely combined with each other and well cemented, which provides favorable conditions for the airtightness of the reservoir. Macroscopically, the stress expression of layered rock salt interface is constructed based on the theory of composite rock mass, and then the deformation and damage characteristics of the interface are analyzed. The analysis shows that the state of stress in the vicinity of the interface is extremely complicated. The hard interlayer exerts restraining anchorage on the salt rock mass, and the stress concentration is easy to occur at the interface, which then induces the crack propagation in the surrounding rock mass of the reservoir to rupture. The comprehensive meso-macroscopical analysis shows that the mechanism of crack initiation and the formation of infiltration channel are the result of the mesostructural characteristics and the stress state of the interface. The results provide some reference for further analysis of the stability and confinement of underground salt reservoir.