Simulation of Flow and Heat Transport in a High-Enthalpy Reservoir in Tuscany, Italy

Abstract

The choice of injection/extraction or exploratory borehole positions and depths in geothermal fields of high enthalpy is a key issue in ensuring the success of the exploitation of such fields. These have to be chosen based on a very limited amount of information, making a proper handling of uncertainties inevitable. The area of interest in this study spans an area of 22 km × 15 km, encompasses a largely unexploited geothermal field in southern Tuscany, Italy, and is characterized by geothermal gradients of over 100°C/km. Even though a relatively large amount of data from seismic profiles, boreholes, and laboratory measurements is available, the geological model, which comprises two target horizons in fractured metamorphic and sedimentary rocks as well as several faults, suffers from a large amount of uncertainty. For example, rock permeability distribution and fault location/type are crucial for the proper description of advective heat transport. This work: 1) establishes a realistic reservoir model based on various interpretations of reflection seismic data and petrophysical core and cutting studies; 2) reproduces temperature measurements at various depths in a numerical simulation; 3) determines promising locations for production boreholes within the reservoir.