Underground Hydrogen Storage in Depleted Gas Reservoirs: Opportunity Identification and Project Maturation Steps

Depleted gas reservoirs represent a great opportunity for Hydrogen underground storage(UHS). Eni’s portfolio contains several late-life assets that indeed may provide significant storage capacity. These fields, identified as potential storage sites, are producing for several decades, thus they are accompanied by deep reservoir knowledge and infrastructure availability. Moreover, the caprock, that was able to store hydrocarbon during the past centuries, represents a containment potentially effective also when the reservoir acts as H2 storage site. In the framework of the energy transition, Eni has adopted a robust workflow allowing for the identification of UHS opportunities among its depleted assets portfolio. Starting from a first selection of the sites based on multidisciplinary available data, the most promising opportunities are then deepened through lab analyses, 3D numerical modelling and special studies. The special studies are devoted to understanding interactions among injected H2 and the reservoir fluids/rock but also with the active communities of microorganisms. Accurate studies are also needed to evaluate the effects of H2 during interaction with wells materials. In this paper, we will show the steps that lead Eni to identify and mature UHS opportunities.