Two-dimensional THM modelling of the large scale natural hydrothermal circulation at Soultz-sous-Forêts

Abstract

Background: A two-dimensional numerical model is developed for the Soultz-sous-Forêts reservoir from an idealized cross-section containing six homogeneous horizontal layers. The considered constitutive equations are those of homogenized saturated porous media involving Thermo-Hydro-Mechanical (THM) couplings, and most of materials properties (for brine and rocks) are taken dependent on temperature and pressure. Methods: The constitutive equations are solved in transient regime with the finite element software Code_Aster to reach a stationary state of the reservoir. Results: We show that a large scale natural convection is compatible with present boundary conditions if the permeability of the reservoir is of the order of 1.0×10−14m2. Convection cells are of the order of 1.3 km in width and we analyze several vertical profiles and maps of physical properties. Conclusions: A stationary convective solution at large scale is highlighted.