GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.1 - POSTER GNGTS 2023 To properly define the structural setting of the Valle Latina, we analysed a large dataset of hydrocarbon exploration dataset that consists of geophysical and stratigraphic well-logs and seismic reflection profiles. The geophysical dataset includes both public data, from the ViDEPI project database and literature, and private data provided by Pentex Italia Ltd. The seismic profiles were recorded from different acquisition surveys carried out in the 1980s and 1990s for hydrocarbons exploration by AGIP, Sovereign and Pentex. The seismic dataset was both a stack and migrated version. Furthermore, public data were in raster format, so seg-y files were produced for each available raster seismic line in order to import all the dataset into the interpretation software. This was achieved using Kogeo© 2.7, free and open software for 2D/3D seismic data analysis that allows to create a geo-referenced seg-y file from a scanned seismic image ( http://www.kogeo.de/index.htm ) . Main results. The outcomes suggest the occurrence of four main areas characterized by high temperatures values at shallow depth, that are: the Bolsena, Vico and Bracciano lakes and Campi Flegrei area. In these areas the magmatic heat influence is present in between the first 4 Kms of depth and the heat flux encompasses a large part of the perythirrenian sedimentary carbonatic and siliciclastic sequence. A downtrend of temperature values is evident in the coastal part of the Latina valley where such high temperatures are expected only in its deeper portion (at about 9Km of depth). On the contrary, toward to the south-eastern part of the Apennines, a temperature uptrend occurs, and the highest values are recorded in correspondence of the Campi Flegrei area that is, in fact, a very well-known magmatic province. In the preliminary seismic interpretation for the Valle Latina study area, the most evident reflectors are the unconformities at the top of the upper Cretaceous carbonates. For the interpretation of the seismic profiles, the top of the limestone succession - the main target for the geothermal goal - was considered as the key reflector with an observed high acoustic impedance contrast throughout the Valle Latina. Miocene and Cretaceous near-top reflectors were interpreted thanks to their geometry and energy picks, higher than the above and below reflectors reflectors (Fig. 2), confirmed by the HC well ties in the area. In particular, the top of marly/carbonate layers reflect most of the seismic energy, making the interpretation under these reflectors more difficult, also due to the almost total lack of very deep wells in this area, below the identified Cretaceous carbonates. The above siliciclastic succession showed transparent seismic facies, representing the Miocene flysch units. In order to time-to-depth convert the seismic interpretation, an average velocity for each lithology was considered, using the TD charts from wells, and the velocity values reported from literature and technical reports. The interpreted seismic profiles highlight a complex structural setting, mainly dominated by compressional structures (thrust and backthrust) related to the ongoing emplacement of the Apennines fold-and-thrust-belt, affecting the Meso-Cenozoic sedimentary succession of the Latium-Abruzzi paleogeographic domain.