Modeling two high-temperature aquifer thermal energy storage cases under uncertain geological frameworks

High-Temperature Aquifer Thermal Energy Storage (HT-ATES) manages the temporal mismatch between heat supply and demand periods. Up to 50 % of consumed energy by residents of metropolitans can be provided through this huge underground battery systems. This study evaluates risks and effects of geological structures for two HT-ATES candidates designed close to populated areas in central Europe. DeepStor, as the first example, is designed to store surplus heat in Meletta beds beneath the campus of the Karlsruhe Institute of Technology (KIT). A synthetic sealing fault is embedded in real topology of the Meletta beds to numerically simulate the temperature and pressure under such structural feature. The synthetic fault is relocated 16 times in the geological model and proved to only increase the pressure value up to 7 % in comparison to fault-free (base case) realization. The real tilted morphology of Meletta beds revealed that hot temperature tends to accumulate in the western side of the model while pressure increase is more notable in the reverse side, i.e. down dip. A simple function fitted to the pressure change and fault to well distance shows acceptable levels of reliability. Another showcase designed for the Greater Geneva Basin confirmed the insensitivity of the temperature and pressure to surfaces morphology of the Malm reservoir with 100 m thickness. Despite modulating the top and bottom contacts of the Malm from flat planes to randomly rugged surfaces, the results remain the same. The upper and lower surfaces are moved ± 8 and ± 10 m, respectively. This insensitivity indicates the local natures of the induced thermal regime in thick reservoirs and dispensability of some expensive exploration campaigns like 3D seismic.