GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione 3.3 593 Modeling techniques for cross-hole seismic monitoring CO 2 injection in a deep saline aquifer F. Da Col, D. Gei, J. Carcione Istituto Nazionale di Oceanografia e Geofisica Sperimentale - OGS, Trieste, Italy Introduction. Geological storage of carbon dioxide has been proven to be a viable, yet partial, solution to the excessive carbon present in the atmosphere due to human activities. Deep saline aquifers appear to be the geological setting with the highest storage capacities, since the injected supercritical CO 2 dissolves in the brine. The presence of the gas in the bulk fluid changes the elastic properties of the medium, therefore it is possible to monitor the propagation of the CO 2 in the formation by means of an active seismic experiment. In this work, we present a synthetic, yet realistic, 2D anticlinal formation suitable for CO 2 injection, monitored with a cross-hole seismic experiment. Modeling consists of 4 steps: i) Propagation of the CO 2 plume via a 2-phase flow simulator ii) Computation of the p- and s-wave velocities via White’s model iii) Computation of the synthetic seismograms iv) Tomographic inversion of the synthetic seismograms using cat3d software. Geological setting and numerical discretization. We consider a 2D sandstone aquifer with shale intrusions, as in Carcione et al. (2012), with shale above and below such formation. The formation is located from 0.7 to 1.5 km depth and is 800 m long in the horizontal direction. The depth has been chosen so that carbon dioxide is in supercritical state and better dissolves in the Fig. 1 – Geological set-up of the synthetic formation considered (a), distribution of the porosity (b), permeability (c) and clay content (d).