| Title | Hydrothermal Circulation in the Acqui Terme District, Tertiary Piedmont Basin (NW Italy) |
|---|---|
| Authors | Massirno Verdoya, Vincenzo Pasquale & Paolo Chiozzi |
| Year | 1999 |
| Conference | European Geothermal Conference |
| Keywords | Geothermal system, medium enthalpy reservoir, convective heat transfer, hot springs |
| Abstract | We investigated the deep hydrothermal circulation of the Acqui Terme district, Tertiary Piedmont Basin (TPB), which is characterised by hot springs, with a maximum temperature of about 70 "C. A thermal gradient increasing from about 70 to 90 mK m'l towards the hot spring area was determined in two conduction-dominated boreholes. Calculations on convection-dominated boreholes again yielded anomalously high thermal gradients compared to those expected for TPB. The hydrothermal circulation mainly affects the crystalline basement beneath the impermeable sedimentary cover. The maximum depth of the hydrothermal system is 3400 m, and the top of the permeable zone ruled by convection is at a depth of about 1000 m. Models of ascending flow show that the water rises from the reservoir through a relatively narrow fracture zone. |