Reducing energy consumption and enhancing trapping and capacity of CO2 sequestration: The effects of pore heterogeneity and fluid properties

Sequestrating the CO2 into deep geological formations is a profound approach to reduce green-house gas and thus mitigate climate change. In this context, ceiling the energy consumption, enhancing the CO2 trapping to facilitate further dissolution and mineralization, and expanding the CO2 sequestration capacity have gained extensive interests. Here, we explore the roles of pore heterogeneity and fluid properties in optimizing energy consumption and maximizing CO2 sequestration effectiveness by computational modeling. We validate the modeling results through microfluidic experiments. We discover that placing the low Pore-Throat-Ratio layer at the middle fosters 7 % reductions of energy consumptions per pore volume, and a Ca<4.0 × 10−5 saves 8 % energy consumption per kgCO2. The High-Median-Low heterogeneous pores optimally perform not only in residual CO2 generation (22%PV) and conservation (7%PV) but also in CO2 sequestration capacity (67%PV). Regarding fluid properties, the enlarged hydrophilicity and viscosity ratio with reduced density difference and interfacial tension increase the residual CO2 and energy consumption while suppress the sequestration capacity. The presence of gravity especially when Bo > 6 × 10−5 promotes the residual CO2 generation and conservation yet burdens the energy consumptions. This work bridges the gap between energy consumption and CO2 sequestration effectiveness by uncovering the significant roles of pore heterogeneity and fluid properties.