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Core-Scale Investigation of Hydrogen Storage and Withdrawal

Shams, Mahdi | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58154 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Mahani, Hassan; Ayatollahi, Shahaboddin
  7. Abstract:
  8. With the growing demand for clean energy and the need to mitigate the environmental impacts of fossil fuels, underground hydrogen storage has gained significant importance as a renewable energy carrier. Saline aquifers, featuring large pore volumes and favorable permeabilities, represent one of the most promising subsurface storage options. However, evaluating storage capacity and hydrogen withdrawal performance from such reservoirs requires accurate hydrogen–water two‐phase flow functions, yet data are scarce due to reservoir heterogeneity. This study investigates hydrogen–water two‐phase flow behavior in porous media across low (≈16.5 mD), medium (≈153 mD), and high (≈1220 mD) permeability ranges and evaluates core‐scale storage and recovery performance. To achieve this, an innovative core‐scale experimental apparatus was designed and constructed. Separate hydrogen injection (drainage) and water injection (imbibition) tests were conducted in multiple cycles on sandpack cores of varying permeability. Hysteresis effects and shut in effects were also examined. Results indicate that initial gas saturation (Sgi) in the first cycle reached 27.0 %, 64.3 %, and 76.0 % for low‐, medium‐, and high‐permeability cores, respectively; first‐cycle hydrogen recoveries were 41.1 %, 79.2 %, and 85.7 %. These findings demonstrate that increasing rock permeability substantially enhances both storage capacity and hydrogen recovery. Higher permeability reduces residual gas trapping because, in low‐permeability cores, smaller pore throats and the water‐wet rock surface cause greater nonwetting‐phase hydrogen entrapment, lowering recovery efficiency. In contrast, high‐permeability cores not only achieve higher initial gas saturation but also narrow the saturation difference between injection (storage) and withdrawal phases. Absolute permeability also improves relative permeability for both hydrogen and water, which is critical for optimizing injection and withdrawal processes. Notably, hydrogen relative permeability endpoints remain below 0.1 due to its low viscosity. A detailed analysis of hydrogen–water relative permeability curves across these permeability classes enables selection of reservoirs with optimal pore structure, minimizing trapped hydrogen. Examining differences in relative permeability slopes and crossover saturation improves two‐phase flow predictions and reduces capillary‐trapping losses. Cycle testing further reveals that, as the number of injection– withdrawal cycles increases, gas saturation in cores rises substantially and system performance converges to acceptable levels: the gap between initial and subsequent‐cycle saturations decreases, improving overall storage capacity. Additionally, allowing cores to rest after drainage experiments—due to Ostwald ripening—promotes formation of larger hydrogen clusters and slightly increases final storage volumes. The insights gained from this research offer a comprehensive understanding of hydrogen–water flow in porous media and establish a foundation for developing optimized underground hydrogen storage and withdrawal technologies at field scale
  9. Keywords:
  10. Underground Hydrogen Storage ; Hydrogen Recovery ; Hysteresis Effects ; Hydrogen-Water Flow ; Ostwald Ripening ; Hydrogen Relative Permeability

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