Large scale natural hydrothermal circulation at Soultz-sous-Forêts: a numerical 2D approach

Abstract

We develop a two dimensional numerical model for the Soultz-sous-Forêts reservoir, from an idealized cross section consisting of six homogenous horizontal layers. The nonlinear constitutive equations are those of homogenized saturated porous media involving THM (Thermo-Hydro-Mechanical) couplings. Most of materials properties (for brine and rocks) are taken dependent on temperature, pressure, or porosity. The entire set of constitutive equations is solved in transient regime with the finite element software Code_Aster to reach a stationary state of the reservoir. We show that a large scale natural convection can be obtained considering suitable boundary conditions, provided that the permeability of the reservoir exceeds a value close to 10-14 m2. Convection cells are of the order of 1.3 km in width and we discuss several vertical profiles.