A holistic review on wellbore integrity challenges associated with underground hydrogen storage

Abstract

Underground Hydrogen Storage (UHS), especially in depleted oil and gas reservoirs is becoming increasingly attractive as a solution to H2 large-scale seasonal storage but there are several concerns regarding the repurposing of existing structures due to hydrogen detrimental effects on materials. This article aims to provide insight into the wellbore integrity challenges associated with UHS in depleted reservoirs. It briefly discusses past and current experiences of UHS. To identify knowledge gaps and technical barriers, an overview of wellbore integrity issues that could be encountered during UHS projects in depleted oil and gas reservoirs is presented. Since wellbore integrity issues lead to fluid migration, published work on leakage rate estimation and risk evaluation in storage projects are also discussed. Field wellbore integrity evaluation methods and analytical models are discussed as well as current potential site criteria for the UHS selection site.Based on the review, leakage through the injection and legacy wells are primary concerns on UHS projects. Wellbore integrity can be affected by hydrogen damage, microbial-induced corrosion and corrosion processes on metallic materials, cement degradation due to hydrogen and corrosive agents exposure, and the severe conditions to which the materials are exposed through the wellbore life. In addition, the existence of legacy wells in poor conditions represents a risk to the safety of UHS projects. Future works were recommended to better comprehend hydrogen damage processes, hydrogen interaction with casing, cement, and subsurface microbiological processes, and to establish multi-criteria selection methods for potential sites.