Geo-Mechanical Modeling of Underground Hydrogen Storage Undergoing Cyclic Injection and Production

Abstract

Summary Underground hydrogen storage sites undergo numerous cyclic loadings during injection and production. This makes operating underground hydrogen storage sites different from natural gas storage sites where injection/production cycles are less frequent. Reviewing the literature, very limited studies investigated the stress change during cyclic injection and production in poroelastic media. These studies mainly focused on just one cycle of production and injection, a situation that is not like underground hydrogen storage. In this study, the effect of cyclic fluid injection and production on the stress path was investigated by applying poroelasticity theory. By applying the superposition approach and based on the Rudnicki analytical model for pore pressure and stress change during constant injection rate the effect of cyclic pore pressure changes was investigated. The results show the dependence of both tangential and radial stress paths on cycle numbers. At higher cycles, the dependence of stress on pore pressure change (stress path) decreases. This approach cannot be verified due to a lack of data in this area. However, this approach is conducted based on some real facts and logic and still, it can help for the initial estimation of stress path variation during cyclic loading in poroelastic media.