Modeling geomechanical effects of the well case on radioactive marker measurements in the Northern Adriatic, Italy

The present communication describes a multidisciplinary approach to evaluate the sustainability of the underground gas storage (UGS) programs in a Po Plain gas field, northern Italy. Long-time records of injected/removed gas volume and fluid pore pressure together with multi-year measurements of vertical and horizontal land displacements by an advanced PSInSAR technique allow for the development of representative 3D fluid-dynamic and transversally isotropic geomechanical models. The latter is successfully implemented to simulate both the vertical and horizontal cyclic motions, on the range of 8-10 mm and 6-8 mm, respectively, measured between 2003 and 2007 over the field. The calibrated models are then used to predict the ground displacements in connection with two UGS future scenarios where the injected gas is increased from the original in-situ value pi to 107%pi and 120%pi. These programs are of the greatest importance as they allow for an increase of the stored gas volume by more than 240% relative to the current storage value at pi. The results show that the planned UGS developments have a small impact as they generate very modest ground movements, with displacement gradients well below the most severe bounds recommended to preserve the overland structure and infrastructure integrity.