COMPREHENSIVE SIMULATION AND ASSESSMENT OF UNDERGROUND HYDROGEN AND GAS STORAGE IN PARTIALLY DEPLETED OIL AND GAS RESERVOIRS IN QATAR

Abstract

Hydrogen (H2) has the long-term potential to minimize reliance on fossil fuels and reduce carbon emissions globally. Owing to large-scale capacity and seasonal storage capability, underground H2 storage could be a feasible H2 storage option due to its economic, technical, and safety factors. However, the current knowledge of underground H2 storage is minimal, making it difficult for large-scale implementation. This thesis investigates the feasibility, performance, and risks of underground hydrogen storage (UHS) systems in partially depleted oil and gas reservoirs, providing strategic insights for large-scale H₂ storage in Qatar. The study started by conducting two QASRbased simulations to i) investigate H₂ and CH₄ injection, storage, and production as working gases in short, medium, and long durations for a partially depleted oil reservoir. It has first focused on UGS system as a baseline for the study and then UHS was conducted with the same reservoir specifications and conditions to discuss the differences in injectivity, storage, and production cycles and its behaviour with different cushion gases (CO2 and N2). CO₂ enhances CH₄ storage and production while minimizing reinjection. In short-duration scenarios, N₂ produced 312,231 m³ of oil, while CO₂ outperformed N₂ in medium and long durations (17% and 46% more oil). However, UHS demonstrated higher H₂ storage and working gas production, with CO₂ enabling H₂ injection of 151,370,707 m³ and short-duration H₂ storage of 3.6 × 10⁹ m³. The second study examined a partially depleted gas reservoir (North Field, Qatar) under scenarios with no cushion gas, N₂, and CO₂; while the base case allowed the highest H₂ injection, recovery was lower (69.6 %) than with cushion gases, emphasizing the critical role of reservoir characteristics and cushion gas selection in optimizing H₂ storage and recovery. A HAZOP-LMH risk assessment was performed to provide a system-level evaluation of the UHS, identifying potential deviations, their causes, and recommended mitigations to ensure safe and efficient operation. The highest-risk nodes were identified as the cushion gas injector (Node 3), H₂ compressor (Node 5), H₂ injector well (Node 7), and H₂ producer (Node 8), where excessive pressure deviations could compromise well integrity and potentially affect H₂ containment if not properly managed. Utilizing partially depleted reservoirs for H₂ storage enables Qatar to deliver a stable, low-emission H2 supply, supporting future blue ammonia production, carbon capture initiatives, and the country’s sustainable domestic and global energy goals.

Date of Award	2026
Original language	American English
Awarding Institution	HBKU College of Science and Engineering