Laboratory Testing, Evaluation and Qualification of Suitable Metallic and Elastomeric Materials for Underground Hydrogen Storage Projects Aiming to Decarbonization Solutions
Authors: Iorio V. S. , Torri L. , Nutricato G. , Guernelli R. , Sammartino F. , Alleva L. , Arbani M. H. 
Published: June 2024

Underground hydrogen storage (UHS) has been identified as a technology for the practice of storing hydrogen aiming to reduce the carbon fossil footprint. Hydrogen injection in depleted Oil&Gas reservoirs requires a careful evaluation of the material integrity degradation. This paper aims to evaluate the compatibility of metallic materials and elastomers with hydrogen using exposure tests in a high-pressure environment at testing pressures and temperatures, and by comparing material properties after exposure. The objective is to evaluate materials commonly used for gas and oil wells, in the context of UHS. The tests are performed on standard OCTG carbon steel metallurgies API/ISO grades J55, L80, T95, and P110, and elastomers NBR, HNBR, and two different types of FKM. The compatibility was evaluated through tests in autoclaves for 720 hours with a combination of two pressures (3-30 MPa), and two temperatures (4°C and room temperature). The program involves several gas mixtures including different concentrations of hydrogen (20% and 100%) and contaminants (H2O and CO2). Eight different conditions in pressure, temperature, and mix of gas were analyzed.

The purpose of these tests is to determine which metallic and non-metallic materials are suitable for UHS application considering different hydrogen mixtures. This will help to ensure the safe and efficient operation of such storage facilities, which are becoming increasingly important for energy storage. Before the aging, the metallurgies were pre-cracked according to ASTM-E1820, and after the exposure time, metallographic investigations were performed to assess the crack propagation due to Hydrogen, and KIH was determined (as per ASME B31.12, ASME BPVC Sec. VIII, ASTM E1681 (2003) procedures requirements). The post-test activities for elastomers evaluated whether exposure to hydrogen affected the physical (mass, volume, hardness) and mechanical properties (stiffness and ductility). Also, the susceptibility to form Blisters, cracks, bubbles was evaluated under rapid gas decompression (RGD) conditions. Overall, the study highlights the need for careful selection of materials for underground hydrogen storage facilities. By improving the compatibility of materials with hydrogen, the safety and efficiency of underground hydrogen storage can be enhanced, paving the way for wider adoption of this promising technology.

This paper contributes novel insights by comprehensively evaluating the compatibility of traditional oil and gas well materials with pure or not pure hydrogen, a critical aspect for emerging underground hydrogen storage. The study encompasses metallurgy and elastomers presenting unique findings from autoclave tests. These results constitute a pivotal initial step for de-risking the activity. They not only enrich the current literature but also lay a robust foundation for subsequent in-depth analyses and studies under specific project conditions.