Numerical investigation of a high temperature heat injection test

High Temperature-Aquifer Thermal Energy Storage (HT-ATES) is a promising option to compensate for the seasonal mismatch between heating supply and demand in the heating sector based on renewable energies. To test and verify numerical and experimental methods for predicting HT-ATES thermo-hydraulic impacts, a small-scale heat injection test with injection temperatures of >70 °C was conducted in a shallow aquifer and monitored using a dense temperature sensor network. Prior to the heat injection test, the hydraulic and thermal properties of the field site were investigated and a predictive high-resolution numerical simulation model of the coupled thermo-hydraulic processes was derived based only on this a priori information. The comparison of measured and predicted temperature breakthrough curves showed a good correspondence, suggesting that the model is able to predict the overall thermal behavior. The model predictions were most accurate for long-term and far-field temperature evolution, with lower accuracy for temperature peaks closer to the injection well. Density-driven buoyancy flow was identified as an active heat transport process, due to the relatively high vertical hydraulic conductivity. The numerical model, parameterized based only on a priori site investigation data, is shown suitable for predicting heat transport processes due to a high temperature heat injection, as well as the induced thermal impacts of an HT-ATES system.