Influence of capillary pressure on CO2 storage and monitoring

equestration of CO2 in geological formations is one of the solutions to mitigate the greenhouse effect. We are interested in analyzing the influence of capillary pressure on CO2 injection, storage and monitoring in saline aquifers. To do so, we present a methodology integrating numerical simulation of CO2- brine flow and seismic wave propagation. Besides, we build a suitable geological model that includes mudstone layers and fractures. The simultaneous flow of CO2 and brine in porous media is described by the Black-Oil formulation, which applies a simplified thermodynamic model. Capillary pressure is represented as a potential function of CO2 saturation. The wave propagation is simulated using a viscoelastic model that includes attenuation and dispersion effects due to mesoscopic scale heterogeneities. The fluid simulator properly models the CO2 injection, obtaining accumulations below the mudstone layers as injection proceeds. We are able to identify the time-lapse distribution of CO2 from the synthetic seismograms, which show the typical pushdown effect. When capillary pressure is higher, CO2 upward migration is slower and thicker zones of CO2 accumulations are obtained. Numerical examples show the effectiveness of this methodology to detect the spatio-temporal distribution of CO2 and to make long term predictions.