A geomechanical transversely isotropic model of the Po River basin using
PSInSAR derived horizontal displacement
C. Janna, N. Castelletto, M. Ferronato, G. Gambolati, P. Teatini
Dept. Mathematical Methods and Models for Scientific
Applications, University of Padova, Padova, Italy
ABSTRACT
Hydrocarbon production, CO2 subsurface sequestration, and gas storage in exhausted reservoirs are a
few anthropogenic activities involving the extraction or injection of fluids underground. As a
consequence,the withdrawn/injected formation undergoes an effective stress change that may induce
deep deformations propagating to the ground level with possible fault re-activations. The geomechanical
parameters needed to simulate and predict the above processes can also be indirectly inferred by
Interferometric Synthetic Apertur Radar (InSAR)-based techniques that are used to monitor the land
surface displacements. In the present study, the InSAR measurements above two exhausted fields of the
Po River plain, Italy, presently employed for seasonal gas storage, are used to develop, setup, and
calibrate a transversely isotropic geomechanical model of the porous medium. It is shown that only
assuming transverse isotropy allows for a satisfactory reproduction of both the vertical and horizontal
displacements that cannot be simultaneously matched by a simpler isotropic model. Moreover, similar
parameters prove correct for both the reservoirs, located about 30 km apart, providing evidence of the
regional range of the above model applicability.
