STABILITY ANALYSIS OF SURROUNDING ROCK OF DEEP ANHYDRITE GAS STORAGE UNDER HIGH INTERNAL PRESSURE

As an important chemical raw material and clean energy, natural gas has more and more application prospects all over the world. Therefore, it is important to develop safe and efficient natural gas storage technology for using it reasonably and effectively. This article took Anhui Hengtai anhydrite mine as an engineering example, and we got the physical mechanical parameters of the anhydrite through laboratory tests. Used ABAQUS to establish a numerical model to simulate the cavern formation and natural gas storage processes, evaluated the overall stability of anhydrite wall rock. Focus on the changes in the plastic zone surrounding the cavern, the rock strain around the cavern, and the surface displacement of the cavern under different internal pressures during natural gas loading and unloading, thereby analyzing the overall and local stability of the anhydrite cavern group, providing reasonable advice for selecting a reasonable protection project to ensure the safety of the gas storage during construction and operation. The results show that after the excavation of the anhydrite cavern is completed, there is no plastic zone in the surrounding rock mass, indicating that the stability of the anhydrite cavern group is good, with the increase of the cavern pressure, the surrounding rock deformation and the stress in the cavern first decrease and then increase, it indicates that a certain high internal pressure environment is conducive to the stability of the surrounding rock of the cavern. And the cavern formed after the end of the anhydrite mine can be used as a natural gas storage tank.