Speaker
Dr
Flavio POLETTO
(OGS - National Institute of Oceanography and Experimental Geophysics)
Description
We present the results of an integrated geophysical approach for the characterization of the geothermal reservoir on the Grado Island, northeastern Adriatic Sea (Italy), where a low-enthalpy binary pilot-plant is under development for district-heating purposes.
The initial geothermal potential assessment was based on the geophysical prospect and the results of the first exploration borehole of 1110 m depth, drilled during 2008. The study confirmed the existence of an untapped low-enthalpy geothermal reservoir within the Mesozoic carbonate platform buried beneath about 1 km of Paleogene and Neogene sediments, in correspondence of structural highs of the coastal area. The well production potential from a fossil, seawater confined aquifer, having a temperature of about 45-50 °C, was estimated to be approximately 140 tons/h.
In 2012, an integrated gravity and seismic geophysical prospecting, including borehole seismic profiles (VSP), was conducted in Grado downtown and its surrounding lagoon. The target was to extend the investigation of the geothermal reservoir and to provide adequate information on the faults/fracture systems interesting the buried external Dinaric thrust front.
The results, here presented, allowed operators to locate the second well of the geothermal doublet, planned and drilled to feed the district heating system of public buildings on the island.
Besides these results, we present a short overwiew of other seismic methods, including seismic while drilling for medium-enthalpy reservoir characterization, and a summary of recent studies on seismic full waveform propagation in high temperature rocks and melting zones, including the brittle-ductile transition.
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![F. POLETTO][8]
[8]: https://indico.cern.ch/event/263557/picture/41.jpg
Author
Dr
Flavio POLETTO
(OGS - National Institute of Oceanography and Experimental Geophysics)
