Gas leakage mechanism in bedded salt rock storage cavern considering damaged interface

During the long-time operation of salt rock storage cavern, between its formations, damaged interfaces induced by discontinuous creep deformations between adjacent layers will possibly lead to serious gas leakage. In this paper, damaged interfaces are considered as main potential leakage path: firstly in meso-level, gas flow rule along the interface is analyzed and the calculation of equivalent permeability is discussed. Then based on porous media seepage theory, gas leakage simulation model including salt rock, cavity interlayers and interface is built. With this strategy, it is possible to overcome the disadvantage of simulation burden with porous-fractured double medium. It also can provide the details of gas flowing along the damaged zones. Finally this proposal is applied to the salt cavern in Qianjian mines (East China). Under different operation pressures, gas distributions around two adjacent cavities are simulated; the evolvement of gas in the interlayers and salt rock is compared. From the results it is demonstrated that the domain of creep damage area has great influence on leakage range. And also the leakage in the interface will accelerate the development of leakage in salt rock. It is concluded that compared with observations, this new strategy provides closer answers. The simulation result proves its validity for the design and reasonable control of operating pressure and tightness evaluation of group bedded salt rock storage caverns.