The Role of Salt Tectonics in the Energy Transition: An Overview and Future Challenges

Abstract

The fundamental properties of salt have long been exploited in the search for hydrocarbons, as they influence many of the hydrocarbon play elements. This industrial application has driven the pursuit of salt tectonic knowledge over the last century and led to major conceptual advances in the field. However, the current need, and social-political demand, to decarbonize suggests that the applicability of salt tectonic knowledge will expand to other aspects of the subsurface that are relevant to the energy transition. The pace of this change leaves the field of salt tectonics grappling with a fundamental question – what role does salt tectonics have as part of the energy transition? Here, we discuss the role salt tectonics can play in a number of key energy transition technologies, namely, energy storage as gas in salt caverns (e.g. hydrogen and compressed air), CO2 storage, and geothermal energy. For each of these technologies we explore: i) fundamental concepts and driving forces; ii) how and why the properties of salt are of importance; and iii) the key salt-related technical challenges, potential future research directions, and technical approaches needed for large-scale development. We highlight how salt basins offer vast potential for development throughout the energy transition including, but not limited to: i) the likely demand for thousands of new hydrogen storage caverns inside salt bodies by 2050; ii) a likely early focus for porous media CO2 storage sites in basins strongly influenced by salt tectonics; and iii) enhanced geothermal energy potential in and around salt bodies. Effective exploitation of these resources will require a deeper understanding of the internal composition, geometry, and evolution of salt structures and their surrounding sediments, and potentially the development of more predictive models of salt tectonic behaviour. Critically, we see the need to integrate learnings of salt tectonics gained in the academic, mining, solution mining, and oil and gas communities, and apply a fresh perspective to answer research questions of relevance to the energy transition. Developing this new understanding will help optimise design, reduce geotechnical risk, and improve efficiency for energy transition technologies, thus indicating a strong future demand for salt tectonic research.

Compositional variation of the Zechstein Group in the Norwegian North sea: Implications for underground storage in salt caverns

“…Other structures such as faults and veins have been observed at diapir crests. Characterizing the internal deformation of salt structures is relevant because they can be associated with preferential shear zones, which are important to understand both in terms of geometry and kinematics to minimize risk (Duffy et al, 2022).…”

“…LES deform in the subsurface, creating a wide variety of salt structures including bedded salt, pillows, anticlines and diapirs (walls and stocks) (e.g., Gillhaus & Horvath, 2008;Jackson & Hudec, 2017). The prediction of lithological heterogeneities in the different salt structures is crucial to select the best cavern location and minimize drilling risks (Duffy et al, 2022). However, this is difficult to achieve because of often poor well control and seismic quality (Duffy et al, 2022;Rowan et al, 2019).…”

“…The prediction of lithological heterogeneities in the different salt structures is crucial to select the best cavern location and minimize drilling risks (Duffy et al, 2022). However, this is difficult to achieve because of often poor well control and seismic quality (Duffy et al, 2022; Rowan et al, 2019).…”

“…Salt caverns are safe storage sites of varied energy carriers and waste due to the properties of halite: impermeability, high solubility and low contamination rates (Allsop et al, 2023;Caglayan et al, 2020;Crotogino, 2016;Duffy et al, 2022;Gillhaus & Horvath, 2008;Koyi, 2001;Kruck et al, 2013;Tarkowski, 2019). Halite is the target for underground storage caverns.…”

Syn‐depositional halokinesis in the Zechstein Supergroup (Lopingian) controls Triassic minibasin genesis and location

“…Reservoir quality within these units might vary downdip, with marginal grainstones passing basinward into rock types of lower reservoir quality, such as wackestones. Depending on their permeability, extent and connectivity, these carbonates could, however, facilitate leakage of CO 2 stored in underlying, Rotliegned Group clastics, and they may impact the geometry and volume of caverns engineered to store H 2 (see review by Duffy et al, 2022).…”