Long-term stability analysis and evaluation of horizontal salt cavern gas storage

To study the long-term stability of horizontal salt cavern gas storage, the numerical simulation method was adopted to analyze the long-term stability of horizontal elliptical cylindrical salt cavern gas storage under different influence factors. The reasonable axial length, minimum internal pressure and pillar width of salt cavern gas storage were determined by comprehensively comparing the numerical simulation results, such as surrounding rock deformation, volume shrinkage and plastic zone distribution range. On this basis, the CRITIC method was used to calculate the weights of influence indexes of the long-term stability for salt cavern gas storage and determine the importance ranking of these indexes. Subsequently, an improved stability evaluation system was proposed. Finally, the catastrophe model of the stability influence indexes of the salt cavern gas storage was classified, then the long-term stability evaluation model based on catastrophe progression method was built, and the stability of different salt cavern gas storage cases was quantitatively evaluated by the model. The results indicate that the evaluation results of the established model are well consistent with the numerical simulation results and the stability grade of the horizontal elliptical cylindrical salt cavern gas storage is Grade II, namely the horizontal salt caverns are in stable state for an operation time of 30 years.