Reliability Calculation And Risk Assessment For Salt-rock Gas Storage Caverns During Operation Time

Energy storage is greatly demanded by the national strategy, so large-scale underground salt rock storage constructions have been begun to build. The cavity reliability directly relates to the energy storage implementation. Although much work had been done on the mechanical property and deformation characteristic of salt rock, utilizing stochastic mechanical theory in time-variant reliability calculation and risk analysis of salt rock storage were scarcely published all over the world. Therefore, reliability risk research of the storages have great practical significance. Taking an underground gas storage engineering as an example, which is in Jintan salt mine of Jiangsu province, reliability calculations and risk analysis were carryed out. The main contents are as follows:First, introduce correlative physical mechanics property and creep deformation mechanism of salt rock, promote 3D geological mechanics model test and numerical finite element simulation about strength mechanics characteristic of salt rock gas storage. Second, explore relevant theoretical basis of stochastic reliability calculations, identificate major risk factors which having significant effect on reliability of the gas storage. Meanwhile, salt rock is a typical rheological material, creep property has a significant influence on stability of the underground storage, and the reliability has strong time-variant property. Therefore, basing on stochastic reliability theory and creep mechanics theory, the reliability performance function was established. Taking volumetric shrinkage as a risk controlling criterion, and adopting response surface and Monte-Carlo methods, the changing regularity of time-variant reliability and the law of failure risk reliability were researched during the storages operation time. Major random parameters sensitivity to reliability index were further discussed. Last, basing on performance-based design (PBD) method, risk classification and assessment criteria index system were established. Risk level of the gas storage was evaluted and predicted during service time.Through the analysis results, laws of reliability index with time and risk level of the gas storages were obtained, and the equation between volumetric shrinkage limitation within reliability requirements and intrinsic pressure of the storage was fitted. Major random parameters sensitivity to risk reliability of the gas storages were further discussed. Some measures using to control and manage the gas storages risk were put forward. Some useful conclusions were finally obtained, which could provide scientific basis for the storage safety operation and maintance.