Numerical Reservoir Simulations of Potential Gas Leakage Through Abandoned Wells During Hydrogen Storage in Depleted Reservoirs

Underground hydrogen storage (UHS) in depleted reservoirs is a promising solution for large-scale energy storage and decarbonization. However, abandoned wells within these reservoirs pose significant risks to storage integrity and environmental safety, necessitating thorough assessment of potential leakage pathways and mitigation strategies. This study presents a numerical reservoir simulation of gas leakage from abandoned wells into the overlying aquifer during UHS in a depleted gas reservoir, serving as a reference case for future underground H2 storage projects. Predicting hydrogen leakage over time under varying geological and operational conditions involves considerable uncertainty. To improve model reliability, sensitivity analysis was performed to evaluate the impact of key geophysical and operational parameters on gas leakage including formation permeability, formation porosity, caprock thickness, leakage accessibility (abandoned well permeability), well location (distance to the abandoned well), and injection rate. In the model, the abandoned well is represented as a porous medium with higher permeability than the surrounding formation, consistent with previous studies. The storage operation involves a 3-years injection of cushion gas (CH₄) to establish a pressure plume, followed by 13 years of hydrogen injection. Flow dynamics of gases in the reservoir, abandoned well, and overlying aquifer were successfully simulated using the PFLOTRAN reservoir simulator at the first. Then sensitivity analysis reveals that the most influential parameters affecting leakage into the overlying aquifer are the well pattern, reservoir porosity, and injection rate. Understanding the influence of these parameters is essential for optimizing storage design and ensuring long-term safety, contributing to the development of secure and sustainable underground hydrogen storage systems.

• Publication year

  2025

• Venue

  SPE Symposium - Asia Pacific Decommissioning and Well P&A

• Publication date

  2025-11-11

• Fields of study

  Not labeled

• Identifiers
  DOI 10.2118/228604-ms
• External record

  Open on Semantic Scholar

• Source metadata

  Semantic Scholar

• No claims are published for this paper.

• No concepts are published for this paper.

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