Carbon dioxide geological sequestration is considered to be one of the feasible options for reducing greenhouse gas emissions. The density of aqueous CO2 solution is a key parameter for CO2 geological sequestration. Magnetic suspension balance was applied to obtain the densities of CO2 solutions accurately under reservoir conditions. In the experiments the temperature is between 30°C and 60°C and the pressure is between 10 Mpa and 20Mpa when CO2 mass fraction is equal to 0, 0.5% and 2% respectively. From the experimental data it is found that the density of aqueous solutions increases linearly with the increase of pressure at a constant CO2 mass fraction and the rate of the increase at different pressures is almost the same. The density of CO2 aqueous solutions also shows an increasing trend with the increase of CO2 mass fraction. In the pressure range of 10 to 20Mpa, the ratio of CO2-bearing water density with respect to CO2-free water density is independent of the pressure. The proposed model for CO2 aqueous solution density was therefore based on the CO2 mass fraction and temperature, without including the pressure term. Compared with the experimental data, it is found that the average relative error is 0.021%. The results demonstrate that the model can work well for CO2 geological sequestration.
China is heavily dependent on fossil fuels such as coal, petroleum and natural gas in recent years. The burning of fossil fuel has increased the atmospheric concentration of CO2 in the earth, which lead to a significant climate change. Therefore the greenhouse effect and greenhouse gas reduction has attracted the world's attention increasingly and China is also investing huge resources to protect the environment. Geological storage is one of potentially effective means of reducing anthropogenic emission of CO2 to atmosphere.
