Thermo-poro-elastic effects in the anthropogenic uplift of Venice by deep seawater injection
N. Castelletto, M. Ferronato, G. Gambolati, C. Janna, P. Teatini
Dept. Mathematical Methods and Models for Scientific
Applications, University of Padova, Padova, Italy
ABSTRACT
To mitigate the flooding that periodically plagues Venice, a project of anthropogenic uplift of the
city by deep seawater injection has been recently advanced. A pilot programme has been designed to test the
feasibility of the proposal, improve the knowledge of the subsurface below the Venice Lagoon and help the
calibration of the full-scale prediction models. The present communication aims at supplementing the
proposal with the investigation of the role played by a temperature variation should the injection take place
in non-isothermal conditions. A three-dimensional (3-D) nonlinear hydro-thermo-mechanical model is
developed making use of lowest order Mixed Hybrid Finite Elements (MHFEs) and shock capturing Finite
Volumes (FVs) for the coupled subsurface fluid flow and heat transfer, and Finite Elements (FEs) for the
structural equilibrium. A set of computer simulations is performed using realistic information on the
hydrogeological, geothermal, and geomechanical properties of the Northern Adriatic basin. A representative
750-m deep brackish aquifer is selected with the seawater injection programme planned with an overpressure
of 1 MPa over a 3-year time period. Different scenarios are simulated depending on the temperature
difference ΔT between formation water and injected seawater that is assumed to be taken from the Adriatic.
Basically a ΔT according to season is addressed. The numerical results show that the ΔT impact on the
pressure field is negligibly small relative to the isothermal case, while some influence is exerted by a thermal
gradient on the predicted uplift, which can vary at the most by nearly 10% for an injection in ambient
conditions.
