Salt Dome Geometry, Caprock Deformation, and Implications for Subsurface Energy Storage

Salt domes represent one of the most robust geological media for subsurface energy storage, including hydrogen, due to the low permeability, ductile behavior, and self-sealing properties of halite, as well as the extensive legacy infrastructure present along the U.S. Gulf Coast. Regional assessments of energy storage potential in salt basins have demonstrated large aggregate capacity, but these studies commonly rely on simplified geometric representations of salt bodies, most often treating domes as vertically uniform cylinders with minimal internal or external complexity. Such assumptions obscure the influence of salt dome morphology on both workable salt volume and cavern engineering feasibility, and can lead to over- or under-estimation of storage potential at the individual dome scale.

This study advances volumetric assessment methods by explicitly incorporating salt dome geometry and structural complexity into storage evaluations. Using a suite of modeled endmember geometries modify total salt volume, the distribution of salt within depth intervals suitable for cavern development, and the resulting cumulative cavern storage potential. These models are applied to selected salt domes from the East Texas Salt Basin, a region with a long history of salt tectonics research and subsurface storage applications. Results demonstrate that geometric features that promote overhang within the workable depth window, including positive conic taper and primary axis tilt, systematically increase usable salt volume and enable more efficient cavern placement. In contrast, domes characterized by strong ellipticity or negative taper experience disproportionate losses in workable salt, despite large total salt volumes.

In addition to external geometry, we integrate observations of caprock deformation from onshore Gulf Coast domes as indirect evidence for macro-scale intra-salt heterogeneity, including the possible presence of shear zones or salt spines. These features are not typically resolved in regional datasets but may influence solution-mining behavior and long-term cavern performance. By considering both morphological controls and structural indicators, this work provides a more realistic framework for estimating storage capacity and engineering constraints.

Overall, the results highlight the importance of transitioning from basin-scale screening to prospect-scale evaluation when assessing energy storage in salt domes. Incorporating dome-specific geometry and structural context reduces uncertainty in volumetric estimates, improves down-selection of candidate sites, and supports safer and more efficient cavern design. This approach is directly applicable to emerging hydrogen storage projects, as well as to conventional energy resources that include liquid hydrocarbons and natural gas. This study contributes to the development of scalable subsurface energy storage systems that support long-term decarbonization efforts, as well as energy security in general.