From the tectonic and structural analysis towards a fracture network model for hydraulically modeling the Soultz EGS (France)

Abstract : In order to simulate the hydraulic behavior of the Soultz-sous-Forêts EGS, a 3D flow and transport model with a DFN approach (Discrete Fracture Network) is built. A fundamental step of this modeling is the construction of the 3D fracture network. This paper deals with the fracture network construction from available data and data treatment with probabilistic and statistical approaches in consistence with geological setting. Five fracture sets have been defined in accordance with tectonic history and characterized in terms of orientation (mean and dispersion). Length and density are key points of 3D network: couples fracture density/fracture length are estimated from probability of fracture/well intersection and observed data. Although tectonic history gives information on the order of magnitude of the fracture length, geological settings do not allow the efficient hydraulic fracture size to be constrained.