| Title | Geoscientific Feature Update of the Larderello-Travale Geothermal System (Italy) for a Regional Numerical Modeling |
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| Authors | Alessia Arias, Ivano Dini, Michele Casini, Adolfo Fiordelisi, Iris Perticone and Paolo Dell’Aiuto |
| Year | 2010 |
| Conference | World Geothermal Congress |
| Keywords | Italy, Larderello, Travale, geothermal model, numerical model |
| Abstract | The Larderello-Travale geothermal model has been updated with all the available geoscientific data to provide input parameters for a regional numerical modeling. Data analysis has been extended over an area of 70 x 70km, which is more than ten times wider of the about 400km2 covered by the geothermal mining leases, to include the involved hydrographic basins and to minimize the boundary effects. The huge amount of existing geological and geophysical data allowed an accurate definition of the main features of the geothermal system from surface to a depth of several km. Larderello-Travale is one of the few superheated steam geothermal systems in the world, i.e. with a reservoir pressure that is much lower than the hydrostatic gradient. This peculiarity is the consequence of a natural evolution of the system from the initial water-phase to the current steam-phase. The geothermal field is characterized by widespread nearly impermeable formations constituting the “cover” of the system. The underlying geothermal reservoir is made of carbonate-anhydrite formations in the upper part and in the deeper one by metamorphic rocks of the Paleozoic basement. Usually, the shallow carbonate-anhydrite reservoir shows temperature of 220-250°C and pressure of about 20bar at 1000m depth, while the deep metamorphic reservoir has temperature of 300-350°C and pressure of about 70bar at 3000m depth. The top of the productive reservoir was set in correspondence of the first fractured level in the central areas of the field, where a great amount of well data are available. In the peripheral areas instead, where well data are lacking, it was set in correspondence of the 250°C isotherm. The seismic K horizon, strictly related to temperature of about 400°C, was considered as the bottom of the geothermal reservoir. Furthermore, on the base of the geoscientific data analyses just very local and reduced interactions can be present between the shallow geothermal reservoir and the phreatic aquifers. Also these elements have been utilized as input data for the numerical model. |