A micromodel was applied to estimate the effects of geological conditions and injection methods on displacement of resident porewater by injecting scCO
2 in the pore scale. Binary images from image analysis were used to distinguish scCO
2-filled-pores from other pore structure. CO
2 flooding followed by porewater displacement, fingering migration, preferential flow and bypassing were observed during scCO
2 injection experiments. Effects of pressure, temperature, salinity, flow rate, and injection methods on storage efficiency in micromodels were represented and examined in terms of areal displacement efficiency. The measurements revealed that the areal displacement efficiency at equilibrium decreases as the salinity increases, whereas it increases as the pressure and temperature increases. It may result from that the overburden pressure and porewater salinity can affect the CO
2 solubility in water and the hydrophilicity of silica surfaces, while the neighboring temperature has a significant effect on viscosity of scCO
2. Increased flow rate could create more preferential flow paths and decrease the areal displacement efficiency. Compared to the continuous injection of scCO
2, the pulse-type injection reduced the probability for occurrence of fingering, subsequently preferential flow paths, and recorded higher areal displacement efficiency. More detailed explanation may need further studies based on closer experimental observations.
Keywords: Micromodel;Supercritical CO2;Areal displacement efficiency;Binary image;Injection methods;