Hydro-mechanical continuum modelling of fluid percolation through rock salt

Salt caverns for storing renewably produced hydrogen underground pose a promising option to reduce CO 2 emissions by improving the utilization of volatile renewable energy sources . Rock salt limits the infiltration of hydrogen into the storage cavern walls due to its favourable low permeability. However, pressure-driven percolation may create discrete pathways for the fluid and damage the cavern. Depicting this effect accurately in simulations may be crucial for assessing the long-term stability and integrity adequately. By introducing an extension to a deformation-dependent permeability model by Alonso, Olivella and Arnedo (2006) we can capture the non-linear feedback between salt deformation, permeability development and fluid migration using continuum models . Based on a quasi-isotropic arrangement of potential flow paths the model is able to reproduce pressure-driven percolation of hydrofrac experiments on rock salt specimens in terms of breakthrough pressure as well as preferential path orientation and locality. The model is implemented in the scientific open-source framework OpenGeoSys.