Qualification of Downhole Safety Valves for Use in Underground Hydrogen Storage Wells

Hydrogen, as an energy vector, presents an opportunity to accelerate the energy transition movement, while ensuring both energy sufficiency and security. The acceleration in the adoption of hydrogen as an energy vector requires that plants used in handling hydrogen be tested, verified, and upgraded if necessary for this new scenario. Regarding the large-scale storage of hydrogen, various studies have confirmed the feasibility of underground storage in depleted gas fields, salt caverns and aquifers. Of these, the most promising is storage in depleted gas fields since they are readily available with a significant amount of knowledge about their parameters. However, even though hydrogen would still be transported and stored in gas form, just like natural gas, it is still a very different molecule than natural gas. For one, hydrogen is much smaller than the methane molecule meaning that it can slip through seals where methane could not. Secondly, hydrogen has a proven embrittlement effect on metals when in atomic form. If mixed with fluids containing water, CO2 or H2s, it can lead to varying levels of corrosion. All this ultimately can reduce the ability of storage systems to safely seal against hydrogen. Underground Gas Storage (UGS) has always played a pivotal role in ensuring a country's energy reserves are sufficient to compensate demanding situations like harsh winters, low provisions, or unexpected market conditions. Gas can be provisioned when demand and prices are low, injected into underground wells, and then produced when demand increases again. UGS can also mitigate peaks of usage during periods of cold weather or peak electricity consumption by increasing production rate and ensuring transport pressures are constant. UGS in depleted hydrocarbon reservoirs is the most diffused form of storage.