Physical model test and numerical simulation for the stability analysis of deep gas storage cavern group located in bedded rock salt formation

The stability of gas storage cavern complex constructed in bedded salt rock formation might be influenced by multiple factors during the operation process. In order to assess these effects, three-dimensional rheological model tests were conducted in this study. Physical model with four ellipsoid caverns were constructed with scaled in-situ stresses applied through independent sets of hydraulic jacks and internal pressure applied by digital-controlled latex balloons. Influences of different factors on the deformation properties of surrounding rock were systematically evaluated, including the gas recovery and injection rate, the loss of pressure, the extremely low and high gas pressure, and the pillar width and pressure difference between adjacent caverns. Test results revealed that the deformation of the cavern wall was accelerated when the gas extraction/injection rate exceeds 0.65 MPa/d. Loss of internal pressure dramatically promoted the deformation. Tertiary creep stage arose when the internal pressure was too low (3 MPa) or too high (22 MPa). Internal pressure difference and pillar width worked together to affect the deformation properties. Tests results obtained in this study provided physical evidence for the safety analysis of cavern group as well as the optimization of design and operation scheme. These results can also serve as benchmark for the validation of numerical models.