Cavern integrity for underground hydrogen storage in the Brazilian pre-salt fields

Abstract

Over the years, energy has depended on petroleum-based fuels. However, global warming and the energy crisis have drastically impacted the markets. It urges investing in renewable energy resources, such as hydrogen. Therefore, this work focuses on the hydrogen storage process in salt caverns, as these rocks have relevant properties, such as low permeability, relevant creep, and self-healing. A workflow for cavity integrity analysis is proposed. Hydrogen storage provokes variations in temperature and pressure inside the cavern. The gas thermodynamics is represented through a diabatic solution, which updates the gas pressure and temperature at each time step. The thermomechanical formulation is implemented into an in-house framework GeMA, which couples different physics. Four case studies are analyzed, and the discussions compared mechanical and thermomechanical models. Results demonstrate the importance of thermal effects, as temperature amplitudes may compromise rock integrity, for instance, inducing tensile stresses and affecting permeability.