| Title | Applied Thermo-Hydro-Mechanical Coupled Modeling of Geothermal Prospection in the Northern Upper Rhine Graben |
|---|---|
| Authors | Wolfram RÜHAAK & Ingo SASS |
| Year | 2013 |
| Conference | Stanford Geothermal Workshop |
| Keywords | thermo-hydro-mechanical coupling, modeling, induced seismicity, Upper Rhine Graben |
| Abstract | Several geothermal power plants are planned for one of the most promising regions in Germany, the Upper Rhine Graben. Induced seismicity can have a strong impact on the viability of such projects. For instance at the Basel/Switzerland Deep Heat Mining site, located at the southern end of the Upper Rhine Graben, after massive hydraulic fracturing in 2006/2007 several earthquakes with magnitudes of up to 3.5 occurred. Due to this seismicity a definite stop of the project resulted. To prevent other geothermal projects from this fate a prognostic of possible induced seismicity and measures to limit the maximum magnitude are currently one of the most important geothermal research topics. Based on a geometric GOCAD model of the German federal state Hessian, covering the northern part of the Upper Rhine Graben, a large scale heat transport model was developed. For regions where geothermal exploration is planned, coupled thermo-hydro-mechanical (THM) models can be computed. The THM modeling is based on a FEFLOW model for the thermo-hydro coupling together with a plug-in for the (linear elastic) mechanical coupling. The approach will be demonstrated exemplary for a site, using literature data together with data from the World-Stress-Map. One of the main problems in THM modeling of geothermal projects is the lack of data for the mechanical properties. Different ways of improving the data base using outcrop analogue studies and inverse modeling together with geophysical results will be shown and discussed. |