Abstract: Abstract：Objective Salt cavern compressed air energy storage (CAES) is a critical technology for mitigating power fluctuations associated with renewable energy integration, with the long-term operational safety of its underground storage being paramount. The open-hole section, an uncased borehole interval within the salt formation, directly endures the coupled effects of high-frequency cyclic injection-production pressures and salt rock creep. Its stability is a core determinant of reservoir sealing efficiency and gas injection-withdrawal performance. However, quantitative understanding of the long-term deformation evolution, failure mechanisms, and multi-well instability risks of the open-hole section under high-frequency cyclic loading remains limited, leading to a lack of reliable criteria for safe well spacing design..Methods Based on a typical salt rock block as the study subject, a three-dimensional geomechanical model was established using Rhino software, incorporating geological stratification data and physico-mechanical parameters obtained from laboratory rock mechanics tests. The model was then imported into FLAC3D for numerical simulation. A 30-year simulation was conducted to replicate the daily cyclic operational conditions of a compressed air energy storage power plant in China. A parametric study was performed to compare the evolution of plastic zones, displacement fields, and stress fields in the surrounding rock mass for open hole section spacings of 5 m, 10 m, 15 m, and 20 m..Results The long-term deformation of the open-hole section shows significant anisotropy : axial tension is dominant ( 30-year cumulative strain is 0.8 % ), radial shrinkage ( cumulative strain is 0.2 % ), and salt rock creep is the core driving mechanism. The development of plastic zone has the characteristics of lithology differentiation : the interlayer is dominated by shear failure, and the salt rock layer is dominated by tensile failure. The initial stress concentration at the salt rock-interlayer interface gradually eases with the creep process. The analysis of the naked eye distance shows that when the distance is 5m, the plastic zone of the adjacent naked eye section is completely connected, forming a high-risk channel of synergistic instability. When the spacing is ≥ 10 m, the plastic zone is isolated and the stability of the system is significantly improved.  Conclusion The long-term deformation mechanism of ' axial tension-dominated and creep-driven ' and the differentiation failure mode of ' interlayer shear and salt rock tension ' under high frequency cyclic loading are revealed. Based on the connectivity criterion of plastic zone, 10 m is proposed for the first time as the recommended design threshold for the safety spacing of open hole section under the conditions of the study area. This value is the mechanical safety lower limit of the long-term stability of surrounding rock, and can be used as the basic constraint for comprehensive decision-making such as drilling engineering and wellhead layout. In the future, physical model test and field monitoring verification should be carried out to further improve the evaluation method.