Depth modelling and imaging of the 4D seismic survey of the Basso Livenza area (NE Italy)

We apply a modelling and in-depth imaging procedure to the 4D high-resolution seismic data acquired in Basso Livenza (Friuli-Venezia Giulia, NE Italy), in order to characterize an important multilayered aquifer. The survey consists in four 3D seismic cubes, acquired in two different zones and periods (March and July). This system is made up of an unconfined layer and, at increasing depths, of several confined aquifers of variable thickness and hydraulic permeability, mainly consisting of sandy/gravel material. In particular, two saturated bodies, located at about a 30 m and a 180 m depth respectively, are known very well from the well stratigraphies of the aqueduct of Basso Livenza. The purpose of this work is to build a 3D image of the aquifer, in order to extend the well information to the surrounding area, and to investigate the difference in the P-wave velocity of the saturated layers between the two periods. In the 3D cubes, two high-velocity layers were identified at about 270 m and 480 m respectively, which correspond in the stratigraphy of a recent well to new, deeper aquifers. However, considering a velocity error of about 5%, the seismic method cannot detect any difference in the overpressure condition of the aquifers between the two periods.