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In the practice of carbon dioxide capture, utilization and storage, the storage of CO2 in salt water layer has gradually become an effective way to deal with global warming, achieving the goal of net zero in 2050 and reducing CO2 emissions due to its multiple advantages such as wide distribution area and large storage potential. TOUGHREACT/ECO2N module in the Petrasim software was adopted to improve the storage efficiency of CO2 in brine reservoirs. Based on the existing data of relevant geological storage projects in China and other countries, the numerical simulation method was used to evaluate the CO2 dissolution quality and gaseous CO2 saturation. The influence mechanism of five geological parameters of formation brine salinity, composition of formation brine, formation pressure, formation temperature and permeability on CO2 sequestration was revealed, and the effect of CO2 sequestration was quantitatively evaluated. The results show that: ① the geological parameters control the solubility, fluidity and mass transfer of formation fluids by changing the density and viscosity of CO2, formation brine, CO2 solubility and the chemical reaction of CO2-brine and rock. ② The solubility of CO2 and the density of formation brine decrease and increase with the increase of salinity respectively, with the former being mostly affected. The salinity has an inhibitory effect on the dissolution of CO2. Therefore, the brine layer with low salinity is more conducive to increasing the storage capacity of CO2 and improving the storage safety. ③ Among the four salt solution components obtained according to the Sulin classification method, the CO2 dissolution quality corresponding to CaCl2 water type is slightly lower than that of the other three water types. Overall, different salt solution components have little influence on the effect of CO2 storage. ④ Under the combined effect of CO2 solubility and gas-liquid two-phase viscosity ratio, the dissolved mass of CO2 decreases with the increase of pressure and temperature, while the gaseous CO2 saturation changes inversely. Permeability plays a direct role in controlling the gas mobility and migration distance. Therefore, with the lower formation pressure and temperature, the brine layer with higher permeability is more conducive to CO2 storage. |
