HR: 0800h
AN: V41A-0401    [Abstracts]
TI: 3-D Thermal Modelling of the Western Area of Mt. Amiata Geothermal Field, Italy.
AU: * Bellani, S
EM: sbellani@igg.cnr.it
AF: CNR - Istituto di Geoscienze e Georisorse, 1, Via Moruzzi, Pisa, 56124, Italy
AU: Gherardi, F
EM: f.gherardi@igg.cnr.it
AF: CNR - Istituto di Geoscienze e Georisorse, 1, Via Moruzzi, Pisa, 56124, Italy
AB: Mount Amiata, a quiescent quaternary volcano located in Tuscany, central Italy, hosts a high enthalpy water- dominated geothermal field. We focus our modelling on an adjacent area, west of the geothermal field, where thermal and gravity surveys highlighted a probable continuity of the geothermal features at depth. The model domain extends over an area 15 by 12 km. The model thickness is 5 km, corresponding to the average depth to the K-horizon, a regional seismic reflector underlying the area. Deep geothermal wells existing in the field nearby allow a temperature control down to about 4 km. The model is composed by three main layers, according to the generalized stratigraphy of the area. The 3-D numerical modelling was performed using the code SHEMAT 7.1, considering various boundary conditions, inner geometries and hydraulic permeabilities. The model was realized by means of unsteady forward simulations, under the assumptions of impervious and isothermal top and bottom boundaries, lateral adiabatic faces and variable internal physical properties. Several sets of simulations were carried out, with different bottom boundary temperatures and different hydraulic permeability values for the two deeper layers. The results indicate that the present temperature and pressure distribution with depth in the Mount Amiata field requires deep reservoir rocks with permeability locally much higher than the overlying cover units, to allow fluid convection and favour the upwards migration of over- pressurized fluids, which may break through the overburden, feeding the currently exploited geothermal field.
DE: 1847 Modeling
DE: 5114 Permeability and porosity
DE: 8130 Heat generation and transport
DE: 8135 Hydrothermal systems (0450, 1034, 3017, 3616, 4832, 8424)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting