Heterogeneity effects on pressure and CO2 saturation during core-scale multiphase flow tests

Carbon capture and storage (CCS) technologies can help manage current emission levels of greenhouse gases while enhancing energy security and diversifying energy economy. For a successful and effective CO2 geological storage, a comprehensive understanding of the multiphase flow properties of the CO2/water system in permeable rocks is crucial because they control the engineering design and management of industrial CO2 storage projects. In this study, we conducted multiphase flow tests at a core-scale to understand the migration behaviors of CO2 and water in a stratified geologic media (sandstone interbedded with silt). A core-flooding apparatus combined with an X-ray scanning system provided high-resolution experimental dataset of continuous data on the differential pressure (Delta P) across a core plug and CO( )saturation maps over time. During the multiphase flow tests, we captured dynamic fluctuation in Delta P as CO2 front advanced by displacing water through different geologic media. The spatio-temporal evolution of CO2 saturation in each geologic media revealed two increasing stages, implying that the capillary pressure of the downstream geologic media affects the upstream CO2 saturation. In addition, multiphase transport simulations were conducted to assess the sensitivity of model parameters. Permeability and porosity were respectively sensitive to pressure and CO2 saturation. Overall, the parameters of the silt layer were more sensitive to the pressure and CO2 saturation build-up compared to those of the sand layer. Additionally, history matching was conducted to validate the model by sequentially matching Delta P and CO2 saturation within the stratified system. Finally, we extended the core-scale modeling work further to field-scale and investigated the impact of boundary conditions and heterogeneity on both pressure and CO2 saturation distribution.