Unveil the role of engineering parameters on hydrogen recovery in deep saline aquifer, Rock Springs Uplift, Wyoming

Hydrogen (H₂), as a renewable energy source, holds immense importance in energy conversion and storage. Among various methods, underground hydrogen storage (UHS) stands out, especially during high energy demand in winter, owing to the vast subsurface reservoirs. This study aims to uncover the impact of engineering constraints on H₂ storage conditions and recovery processes. To begin, a geological model mirroring a genuine deep saline aquifer found in the Rock Springs Uplift of Wyoming is developed. This model is intricately linked with fluid composition and multiphase flow properties. The resulting reservoir is utilized in a series of computational experiments, shedding light on the intricate interplay between engineering constraints and H₂ storage dynamics. The research findings indicate that a longer duration of H₂ injection or production stages leads to higher H₂ retention within the aquifer. Specifically, the study reveals that a 3-month injection period (with a final recovery of 0.864) retains less H₂ compared to a 6-month injection period (with a final recovery of 0.805). Regarding well patterns, the research highlights that trapped H₂ steadily accumulates due to the mutual displacement of H₂ and water in a single-well scenario, intensifying the impact of multiphase hysteresis. The study shows that H₂ recovery increases over time for different well configurations: a single well, one injection well + one production well, and two injection wells + two production wells, reaching final values of 0.839, 0.76, and 0.778, respectively. After undergoing 9 cycles of operations, top perforation, as opposed to bottom perforation and full perforation, leads to the highest recovery rate of 0.864. These findings not only provide valuable insights for guiding the engineering design of UHS systems but also pave the way for the practical implementation of UHS on a commercial scale.