TRANSIENT THERMO-HYDRO-MECHANICAL COUPLINGS IN HYDROTHERMAL SYSTEMS – APPLICATION TO GEOTHERMAL ENERGY AND GIANT MINERAL RESOURCES – EARTH-BEAT

The similarity between faulted geothermal reservoirs and hydrothermal ore deposits which exhibit similar features of behavior and fault activation suggests that a fundamental knowledge and better insight into the natural processes underlying the heat and mineral resources availability can be reached from a cross-analysis of these two systems. Both systems are characterized by hydrothermal pulses (cyclical increases in brine flowrate and temperature) which could correspond to modifications of the crustal stress regime marked by highly localized deformation and permeability enhancement of the geological systems. Current understanding suggest that only repeated fluid pulses in structurally-favorable contexts lead to the accumulation of giant ore deposits and could also emphasize the geothermal potential in similar contexts.
The EARTH-BEAT project aims at untangling the relative importance of the geological structures, the brine thermodynamics and the regional stress regime in this phenomenon from geological observations, quantitative analysis and numerical modeling and, in a wider way, should give better insights on the key parameters controlling fault reactivation and their potential link with giant ore deposits formation and geothermal potential. It relies on several thermo-hydro-mechanical (THM) and reactive transport modeling approaches performed from the scale of fault gouge and damage zone up to the deposit scale. Laboratory tests will be first conducted to assess petrophysical and THM properties of faults and rocks used in models. Then, we will investigate the dynamics of a fault system, with different degrees of complexity, ultimately representative of an ore deposit in the Athabasca basin context. In parallel, reactive transfer simulations will be carried out to identify dissolution and precipitation localization. Confrontation with field observations will be performed by testing numerical modeling on real 3D geometries of unconformity related deposits.