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.