Coupled Effects of Reservoir Curvature, Thickness, and Well Configuration on Hydrogen Storage Efficiency in Saline Aquifers

Site selection evaluation is a crucial step in the research of hydrogen storage in saline aquifers. Geometric characteristics of the reservoir are one of the key factors determining the site selection evaluation. However, for the anticlinal saline aquifers with effective trap capacity, the coupled effects of reservoir curvature, thickness, and well configuration on hydrogen storage efficiency remain unclear. Thus, based on the Ordos Basin, various 3D computational models with different curvatures, thicknesses, and well configurations are designed to conduct the simulation analysis. The results show that (1) the greater the curvature, the stronger the trap effect. Hydrogen recovery rises first and then declines, reaching a peak of 79.58% at 170° and dropping to 55.17% at 90°. (2) Increasing thickness suppresses lateral hydrogen migration. The maximum gas saturations in the caprock are 0.12, 0.08, and 0.05 for thicknesses of 100%, 200%, and 300%, respectively, indicating that greater thickness reduces gas diffusion into the caprock. (3) The coupling effect between curvature and thickness affects the recovery rate. Thin reservoirs are suitable for small curvatures, while thick reservoirs are more suitable for high curvatures. (4) Top hydrogen injection significantly reduces the sensitivity of the recovery rate to curvature and thickness. When the curvature is between 180° and 100°, lowering recovery differences across thicknesses are lowered from 16.20% under bottom injection to 2.51% under top injection. These results provide support for the site selection and design of hydrogen storage in saline aquifers.