At Soultz-sous-Forêts geothermal site, the fluid flow paths between the injection and 
production boreholes are mainly composed by a set of structures existing from the hectometric 
to micrometric scales. The objective of our work is to define the architecture of these paths 
within the heat exchanger, what is not obvious due to the great depth of the heat exchanger (5 
km).
We thus propose a coupled approach with first, a direct investigation of the geometry of the 
faults affecting the Soultz site in the vicinity of the geothermal wells by using borehole 
geophysical data (Vertical Seismic Profiling). Second, an analog field made of outcrops of a 
granite similar than the Soultz one will be studied: in Catalunia (Spain), complex structures 
can indeed be directly observed, such as the alterated granitic contact between pink and grey 
granitic massifs, relays zones between two major faults, hydrothermal alterations… whereas in 
the Rhine graben these structures are located at 5 km in depth.

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