Numerical Study on the Effects of Contact Angle Change on Capillary Trapping

Low permeability and high capillary pressure are the major trapping mechanisms, while from Tertiary to Quaternary sedimentary basins with moderate permeability and capillary pressure are also the target sites of CO2 geological storage in Japan. In such a site, it would be a problem that geochemical reactions caused by dissolved CO2 may result in the reduction of capillary trapping. In this study, we conducted numerical simulations on the reduction of capillary trapping due to contact angle change and its effects on the long-term behavior of injected CO2. Also investigated is the effect of methane present in the storage formation or mixed in the injected CO2. Simulation results showed that i) changes in contact angle significantly influence the capillary trapping of CO2; and ii) the presence of methane retains higher gaseous mobility and affects the long-term behavior of injected CO2; and iii) the contributions of dissolution trapping and residual gas trapping are significant to the CO2 storage.