| Title | Do Salt Diapirs promote the Geothermal Energy Potential of Shallow Aquifers? |
|---|---|
| Authors | Beekman F, Veldkamp JG, Seelen M, Van den Berg M, Van Wees JD |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | As rock salt has a higher thermal conductivity than most other sedimentary rocks, diapiric salt structures could act as vertical heat chimneys and cause elevated temperatures in overlying aquifers. To investigate whether salt diapirs indeed enhance the geothermal energy potential of shallow aquifers, a thermal-hydrogeological modelling study was carried out for the Onstwedde salt pillar in NE Netherlands. The case study is complicated by a paleo-glacial valley, which is filled with relatively permeable sediments and influences the regional groundwater flow. A static 3D model of the Onstwedde diapir and surrounding stratigraphy (including the glacial valley) was created using seismic data and calibrated by data from nearby boreholes. The model was depth-converted using a regional velocity model. The mechanical and thermal rock properties as well as the thermal boundary conditions were based on borehole data. Initial thermal models predict increased temperatures of up to 15-20 °C above the salt diapir, which is sufficient for direct heat applications such as heating local swimming pools. However, the predicted temperatures are not consistent with measurements in boreholes above the diapir, which show elevated temperatures of only a few degrees Celsius. Hydrological modelling shows that heat transport by the anomalous groundwater flow in the glacial valley reduces the temperature increase caused by the salt diapir. This study indicates that salt diapirs can lead to a temperature rise in overlying aquifers but also demonstrates that effects of regional groundwater flow should be considered when assessing the geothermal energy resource potential. |