Sealing properties of the cap rock for underground gas storage safety.

Climate change mitigation requires a multifaced approach. One of the most promising technologies is subsurface fluid storage in porous media. However, this technology is not exempt of risks. The leakage of fluid stored through the cap rock is one of the most critical concerns and, in consequence, a key parameter to determine in these operations is the capillary sealing efficiency of the cap rock determined by the capillary threshold pressure, a property obtained in long and expensive laboratory experiments in core samples. The effects of the conditions —such as temperature, confining pressure, and core sample length—and the capillary threshold pressure are still under investigation. This work conducts a series of experiments to evaluate the influence of each of those variables in the capillary threshold pressure. Additionally, numerical models using the software COMSOL Multiphysics® were performed to replicate the experiments. The results from the simulations showed good agreement with the experimental data, showing their potential to optimize the experiments and giving an alternative approach to obtain the capillary threshold pressure when laboratory data are not available.