| Title | Progress of the GeoLaB URL exploration in the Odenwald (Germany): towards the final site construction decision |
|---|---|
| Authors | Deon F, Sass I, Kamrani-Mehni S, Lüth S, Giese R, Jaksch K, Pierdominici S, Grimmer JC, Neuwirth N |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | The GeoLaB (Geothermal Laboratory in the Crystalline Basement) project (a Helmholtz initiative) aims to realize an underground geothermal research laboratory in crystalline rocks (i.e. granite). Considerable efforts were and are implemented exploring the area of the Tromm, Odenwald Germany. The Otzberg fault, the occurrence of fractured and permeable granites makes the region very promising for the realization of the underground laboratory. The first exploration stage was completed by means of fieldwork campaigns (rock sampling), a pilot seismic campaign, potential geophysics, hydrogeological measuring-monitoring spots, installation of weather stations. The first fully cored exploration well GeoLaB-1 was recently drilled. Mineralogical investigations on outcrop samples confirmed the dominant granitic composition of the Tromm granite with traces of hydrothermal alteration. Important results from the seismic interpretation and a preliminary assessment of the core material indicate a change in the lithology at approximately 410 m depth. Two units named Granitoid 1 (above 410 m showing granitic mineral assemblage with macrocrysts and porphyritic structure) and Granitoid 2 (darker with finer texture featuring calcite-quartz filled veins-fractures) characterize the subsurface of the area. A broad investigation program with geomechanical experiments on the cores, a second exploration drilling (GeoLaB-2) and a broader seismic camping will progressively deliver additional surface and subsurface details of the granite rock bodies, fluid pathways and structural geology features. Once the Tromm site will be confirmed as a location to build the GeoLaB underground laboratory we will be closer to realize a unique research platform to investigate the use of crystalline rocks for geothermal purposes. |