Underground Gas Storage (UGS) is an efficient technology that has become an indispensable link in the gas supply chain to respond to the market’s needs. At Neuquén Province, a depleted unit of an old gas reservoir formation was analyzed to become a UGS at 550 m depth on average. The study was carried out in a comprehensive and multidisciplinary way due to the need to understand the reservoir and its caprock’s mechanical behavior. This paper aims to show the design of laboratory tests, results obtained, and its analysis realized owing to the requirement of determining the mechanical capacity of de UGS, which allowed a better understanding of the state of stresses and sealing capacity of the reservoir. This analysis seeks to reduce the uncertainties and risks related to injection-extraction cycles of the UGS.