ABSTRACT
The cyclic injection and withdrawal of gas during Compressed Air Energy Storage and Hydrogen Energy Storage in a salt cavern causes variations in the internal cavern pressure and temperature. This can have an adverse effect on the mechanical integrity and stability of the salt cavern. We conducted geomechanical numerical simulations to assess the integrity of salt caverns used for storage. Two axial symmetric geomechanical models of a single storage cavern were constructed in the numerical finite element simulator DIANA: one for CAES and one for HES. Salt deformation was modelled taking into account steady-state creep driven by the differential stress. The constitutive model for the steady-state salt creep used in the simulations combines two different terms: (i) a branch for the non-linear power law creep (i.e. a dislocation creep branch) and (ii) a linear creep branch (i.e. a solution-precipitation creep branch). We investigated the influence of the different scenarios for pressure and temperature cycling on cavern convergence, temperature fluctuations in the cavern wall and cavern integrity. The simulations addressed the potential for tensile failure and dilation of the rock salt in the cavern wall. The implications for subsurface energy storage applications are also discussed.
