| Title | Glacial Influence on Hydrogeology and Geothermal Potential in the North Alpine Foreland Basin - A Fossil Temperature Imprint in the Upper Jurassic Carbonate Aquifer? |
|---|---|
| Authors | Tom SCHINTGEN, Inga MOECK |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | Late Glacial Maximum, North Alpine Foreland Basin, Molasse Basin, Upper Jurassic, Malm, coupled heat and fluid flow, gravity-driven groundwater flow, Play Type |
| Abstract | The North Alpine Foreland Basin, more specifically the Molasse Basin in southern Germany and Austria, has been studied for decades, first for oil & gas, and more recently for geothermal energy. Among the three main German geothermal provinces of Upper Rhine Graben, North German Basin and Molasse Basin, the latter shows the highest geothermal potential. Many boreholes tap the Upper Jurassic (Malm) carbonate aquifer mainly for district heating but also for electricity production. The classical approach consists in cataloguing geothermal resources according to temperature or depth mainly for technical and economic reasons. The recent Play-Type concept aims at classifying geothermal resources according to geological criteria and heat transport mechanisms to assess reservoir quality. Internationally applicable criteria allow worldwide comparisons between resources of similar geological settings and structures (play type). The Molasse basin has been studied hydrogeologically, and recently by coupled heat and fluid flow. However, the geostatistical assessment of the 3D thermal structure based on temperature measurements in boreholes to date represents the most reliable prognosis of subsurface temperature in the Molasse Basin. Strikingly, a prominent cold temperature anomaly to the east and northeast of Munich could not yet be satisfactorily explained. Cross-formational gravity-flow of groundwater is long known to act on geological timescales. Similar to studies in the Alberta, North German and Paris basins, we perform thermal-hydraulic modelling of the glacial influence on the present-day thermal and flow regime in the Molasse Basin. The result is compared with the geostatistically evaluated 3D thermal field. The calculation of the Péclet number for the heterogeneous carbonate aquifer permits to differentiate zones with a dominance of heat convection versus heat conduction. |