The present study is aimed at attaining an approach of the crust structure at
Travale area (Tuscany, Italy) by 3D electrical resistivity modelling and forward
computing, and understanding the differences between the forward computed
results and measured magnetotelluric resistivity data. Pointing to these
targets, different 3D models were built including the resistivity of geological
units from a resistivity log, zones of high temperatures and productive fractures
from drillholes measurements, bright-spot type horizons identified in seismic
profiles and estimated resistivity values of the lower crust and mantle.
Responses from forward modelling were calculated and compared with
magnetotelluric data obtained in the field. The outcomes of the study point out
that low resistive bodies are present at the depth of the exploited geothermal
reservoirs, that cannot be explained only by means of the geological units.
A secondary scope of this study was to establish if MT method is capable to
distinguish between different porosity structures in geothermal reservoirs, as
fluids situated within rock pores or within spaced or dense fracture systems. 2D-
3D modelling and forward computing of models containing different porosity-
type reservoirs were developed to achieve this aim.
The study was supported by the IGET EU Project and partly carried out within
the framework of ICTP Programme for Training and Research in Italian
Laboratories, Trieste, Italy.