|
Hamburg
Rheingraben EON ERC
Den
Haag
Australia
India
References
A
Conductive Geothermal Model of the Upper Rhine Graben
Improved
understanding of subsurface geothermal potentials
By
order of the Baden-Württemberg Geological Survey, Geophysica
constructed a large scale 3-D numerical model. The
objective of this study was to characterize the subsurface
properties as precise as possible using all available drill hole
information (core, logs and cuttings) and to construct a numerical
model which predicts temperatures down to 5 km depth. The
geothermal model is based on a geological 3-D model which was
provided by the Baden-Württemberg Geological Survey. This
structural model has been built up within the EU-project
“Geopotentials of the deep Upper Rhine Graben (GeORG).
http://www.geopotenziale.org/
The
GeORG project group provided all necessary information of the
subsurface. Logging data and borehole reports including
information to lithology and stratigraphy were allocated for 28
boreholes. Additionally, a very few laboratory measurements of
porosity and thermal conductivity were made available. Finally, we
worked on 11 key wells to derive specific thermal-hydraulic values
for the model. These boreholes were selected with respect to the
best geographic and stratigraphical coverage of the studied area
and due to the amount and the quality of available log and core
data.
Using
this information, a regional numerical model was set up covering
the geothermal sites of Bruchsal, Landau and Soultz-sous-Forets.
We performed heat transport simulations by a finite difference
code for temperature predictions, assuming a fully conductive
regime. Bottom hole temperatures and a few temperature logs were
available, which allowed to calibrate the model. The ends up in a
geothermal model which allows to visualize the steady-state
temperatures within the Upper Rhine Graben. The strong contrast
between thermal properties of tertiary sediments and the
crystalline bedrock yields large lateral temperature variations
within one depth layer. For 4 km depth differences of up to 50 K
were calculated. This might be important for geothermal
exploration.
By
comparison of model results with measured data in boreholes it is
possible to highlight zones of thermal anomalies and thus to
better characterize the geothermal potential of the area.
Temperature
distribution at the top of tertiary basis, calculated under
conductive conditions.
|