Regional Geothermal model Aachen

To obtain a good understanding of the regional conductive and advective heat flow in Aachen region, a 3D-structural model is build. We discuss the following steps which are required for a numerical 3D, heat and fluid flow simulation. Step 3: Measure and infer petrophysical properties by use of cores, literature and logs. Thermal conductivity is based on measurements on cores performed at the de University of Leuven (B) and RWTH Aachen. Permeabilities and Heat generation are inferred from values published in literature. The mean properties for lithologies are translated into harmonic or geometric mean properties for each stratigraphy by use of weighting according to the percentage (see step 2).Step 1: Building a stratigraphic model based on geologic maps, boreholes and geological profiles (Hollman[1] and Winterfeld[2]). The figure below shows the topography and the Stratigraphical units. Step 4: Determine the transient heat flow as boundary condition at the bottom by estimations of the Thermal response time[5] for different tectonic thermal processes in the area such as Eifelplume[3] and erosion rates[4]. From this it can be concluded that the heat flow at a depth of 5000 m might be 0.01- 0.03 W/m2 higher than the local regional surface heat flow of 0.06 W/m2. Heat flow can be even much higher due to advective heat flow in the area:this corresponds to a 2D- Peclet number on the order of Pe = 5. Step 2: Determine the percentage of lithology for each stratigraphy from deep boreholes in the area with the same stratigraphy. Step 5: Collect all temperature data from boreholes in the area for model calibration (see figure below). Determine the original temperature and depth of the hydrothermal springs in Aachen by use of different geothermometers. The original temperatures are 115 oC to 128 oC and corresponce to a depth of 3800 to 4500 m