| Title | High Resolution Gravity Data to Characterize Density Variations and Reduce Uncertainty in Geothermal Reservoirs in the Geneva Basin (GB) |
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| Authors | GUGLIELMETTI L., PEROZZI, L., DUPUY D., MARTIN F., MÉTRAUX V., MEYER M., MIJIC G., MOSCARIELLO A., NAWRATIL DE BONO C., RADOGNA P.V |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | gravity, high-resolution, uncertainty, inversion, geothermal reservoir, Geneva, GEothermie2020, sedimentary basin, GECOS |
| Abstract | This paper focuses on the acquisition, processing and interpretation of gravity data collected in the Canton of Geneva in the framework of the InnoSuisse funded project GECOS (Geothermal Energy Chance of Success). The goals of GECOS is to reduce the costs and the exploration risk for geothermal exploration by integrating high resolution data acquisitions such as gravity, S-waves reflection seismic and 3D DAS VSP (Distributed Acoustic Sensing Vertical Seismic Profiling). The main geological challenges in geothermal exploration in the Geneva area are the characterization of the lithological heterogeneities and the fault zones affecting potential geothermal targets in the Quaternary sediments, Tertiary Molasse sequence and the Mesozoic Units. The study area covers the central part of the Canton of Geneva and overlaps with the location of two geothermal exploration wells drilled by SIG in the framework of the Geothermie 2020 program. A total of 1714 new stations were collected in 71 days of field work thanks to the collaboration between the University of Geneva and GEO2X Sarl. The goal of the survey has been to constrain the lateral density variations associated to lithological anisotropies in the Quaternary, Tertiary Molasse and in the Mesozoic carbonate sequence. The results of the survey showed that the new stations produced a dramatic increase in resolution compared to the gravity data available at the regional scale. In particular Quaternary deposits are much better constrained than before, which is a crucial step forward as these sediments are known to be lithologically and geometrically heterogeneous and locally can host hydrocarbon gas pockets, which can represent an element of risk for drilling operations. Below the Quaterary deposits gravity data show that the Molasse sediments have a dipping geometry towards South-East and are in lateral contact with the Lower Cretaceous limestone which are most possibly uplifted by compressional structures. Finally, the Mesozoic Units are characterized by local density variations which are interpreted as associated to large strike slip zone crossing the study area. |