Seismic Imaging for Geothermal Exploration in Southern Tuscany, Italy

Abstract:

The Mt. Amiata area in southern Tuscany is well known for its geothermal power generation which at present provides about 26% of the region's total energy needs. The exploration of new potential reservoirs is a challenging process that requires integrated geological and geophysical investigations for finding the best location of a future production well.
In this study, we perform seismic depth imaging on reflection seismic profiles, which provides the starting point for geological interpretation and three-dimensional model building. For this purpose, we start with first-arrival traveltime tomography for resolving the near-surface velocity model, and then proceed with analyzing the migration velocities for deeper layers using Kirchhoff pre-stack depth migration. Finally, we apply Fresnel volume migration which increases the resolution of the reflectivity images and enables a better characterization of the predominant geological structures in this area. At that point, we are particularly interested in a strong reflective marker, the so-called “K-horizon”, which is associated with the regional heat sources. We image this important reflector and quantify its depth uncertainty in relation to the velocity model.
The seismic imaging results provide the base for geologic modeling and a hydrothermal assessment of the potential reservoir area which contribute to optimizing the geothermal exploration in that region.