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套管是地下储气库运行过程中的薄弱环节,各随机因素的变化会对套管系统安全性产生较大的影响。以三维套管-水泥环-围岩系统为研究对象,考虑几何尺寸、荷载、材料特性等多因素的随机特性,基于蒙特卡罗法对储气库运行期套管系统的失效概率及敏感性因素进行分析,通过与地质模型试验结果进行对比,验证了数值模拟结果的可靠性。结果表明,各随机因素对套管系统可靠性的影响程度不同,其中套管厚度、套管内径、工作内压、水泥环厚度为高敏感性因素,且各因素的影响效果不同,在工程中可采取不同措施提高系统可靠性;采气阶段,根据储气库腔体应力状态和体积变形规律确定的最大采气降压速率不会影响套管系统的安全性。
Casing is the weak link in the operation of underground gas storage. The changes of random factors will have a great impact on the safety of casing system. Taking the three-dimensional casing-cement-rock-surrounding rock system as the research object, considering the random characteristics of geometric factors, load, material characteristics and other factors, the failure probability and sensitivity of the casing system during operation of the gas storage based on Monte Carlo method Factors were analyzed and compared with the results of the geological model test to verify the reliability of numerical simulation results. The results show that the influence of random factors on the reliability of casing system is different. Among them, casing thickness, casing diameter, working pressure and cement sheath thickness are highly sensitive factors, and the effect of each factor is different. In engineering Different measures can be taken to improve the reliability of the system. In the gas phase, the maximum gas recovery rate determined according to the stress state and volume deformation of the cavity in the gas tank will not affect the safety of the casing system.