Seismic Imaging of Fractured Reservoirs in the Scansano-Amiata area, Southern Tuscany

Fresh water availability has recently become a serious concern in the Italian Apennines as various activities rely on a predictable supply. In southern Tuscany along the Scansano-Amiata ridge the situation is further complicated because of the contamination of the nearby alluvial aquifers. Locally aquifers consist of thin fractured reservoirs, generally within low-permeability formations, and planning exploitation of resources, based on conventional techniques, could be complicated. An integrated investigation program, based on remote sensing, structural geology and geophysical exploration, was initiated in 2002 to associate tectonics and groundwater circulation and better define the hydrological model. After the regional identification of fault and fracture patterns a major structure has been investigated in detail to accurately map the spatial position, and understand the associated aquifer geometry and properties to assess exploitation potentials. The subsurface around the fault zone was clearly imaged with Ground Probing Radar, 2D and 3D resistivity tomography and more recently with 3D shallow seismic. The vertical and the horizontal contacts between the different geological units of the Ligurian and of the Tuscan Series were resolved with a high degree of spatial accuracy. 3D high-resolution geophysical imaging proved to be very effective in small-scale fractured reservoir characterisation.