The Euganean Geothermal Field (EGF) is the most important thermal field in northern Italy. This field is located in the alluvial plain of Veneto region where approximately 14*106 m3 of thermal water with temperatures of 60-86°C is exploited annually. The thermal water is of meteoric origin and infiltrates approximately 80 km to the north of the EGF in the Veneto Prealps. The regional Schio-Vicenza fault system and its highly permeable damage zone act as preferential flowpath for fluid migration in the subsurface. In the EGF, the thermal water is exploited from rocky aquifers located at different depths within Mesozoic carbonate formations. The potentiometric level of the most exploited, 300-500 m deep aquifer, and the well discharge have been continuously monitored since the end of the 1970s. The annual regime analysis indicates two periods (spring and autumn) of drop of the potentiometric level, due to the intense exploitation, and two periods (winter and summer) of recovery, due to a decrease of the exploitation. Although the potentiometric level in 800-1000 m deep wells is different from the level of the monitored wells, the potentiometric variation of deeper wells is in agreement with the seasonal artificial regime (due to exploitation), showing a hydraulic connection between different aquifer layers. The potentiometric level differences are linked to the high exploitation of the shallower carbonate reservoir and to its moderate transmissivity ranging from 13 m2/day to 500 m2/day. The monitoring evidences a recovery of the potentiometric level from 1995 due to a gradual decrease of the exploitation. At present the groundwater level is, on average, about 7-10 m in depth. Taking into account the monthly flow rate, a black-box model is implemented to estimate an hypothetical potentiometric level in the BTE considering a decrease of the flow rate. Results indicate a slow recovery of potentiometric level according to the flow rate trend. Finally hypothesizing a natural spring flow rate of 5 L/s in Abano Terme (PD), the black-box model suggests a natural potentiometric level of about 12 m above ground level, i.e. 23 m a.s.l. After that simple black-box approach we are aiming to implement a 3D numerical model to simulate flow and heat transport in the EGF based on a detailed conceptual hydrogeological model, and based on available monitoring data.
The artificial potentiometric level in the Euganean Geothermal Field (NE, Italy): can we hypothesize a natural potentiometric level ?
PICCININI, LEONARDO
2016
Abstract
The Euganean Geothermal Field (EGF) is the most important thermal field in northern Italy. This field is located in the alluvial plain of Veneto region where approximately 14*106 m3 of thermal water with temperatures of 60-86°C is exploited annually. The thermal water is of meteoric origin and infiltrates approximately 80 km to the north of the EGF in the Veneto Prealps. The regional Schio-Vicenza fault system and its highly permeable damage zone act as preferential flowpath for fluid migration in the subsurface. In the EGF, the thermal water is exploited from rocky aquifers located at different depths within Mesozoic carbonate formations. The potentiometric level of the most exploited, 300-500 m deep aquifer, and the well discharge have been continuously monitored since the end of the 1970s. The annual regime analysis indicates two periods (spring and autumn) of drop of the potentiometric level, due to the intense exploitation, and two periods (winter and summer) of recovery, due to a decrease of the exploitation. Although the potentiometric level in 800-1000 m deep wells is different from the level of the monitored wells, the potentiometric variation of deeper wells is in agreement with the seasonal artificial regime (due to exploitation), showing a hydraulic connection between different aquifer layers. The potentiometric level differences are linked to the high exploitation of the shallower carbonate reservoir and to its moderate transmissivity ranging from 13 m2/day to 500 m2/day. The monitoring evidences a recovery of the potentiometric level from 1995 due to a gradual decrease of the exploitation. At present the groundwater level is, on average, about 7-10 m in depth. Taking into account the monthly flow rate, a black-box model is implemented to estimate an hypothetical potentiometric level in the BTE considering a decrease of the flow rate. Results indicate a slow recovery of potentiometric level according to the flow rate trend. Finally hypothesizing a natural spring flow rate of 5 L/s in Abano Terme (PD), the black-box model suggests a natural potentiometric level of about 12 m above ground level, i.e. 23 m a.s.l. After that simple black-box approach we are aiming to implement a 3D numerical model to simulate flow and heat transport in the EGF based on a detailed conceptual hydrogeological model, and based on available monitoring data.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
