Research On The Migration Law Of Carbon Dioxide Geological Sequestration

At present,CO₂ storage technology is the most intuitive and effective method for reducing CO2 content in the atmosphere.Compared with the oil and gas reservoirs,waste coal bed methane reservoirs,CO2 storage in deep saline aquifer is one of the most potential way of storage.The CO2 which injected into the deep saline aquifers is usually in a supercritical state.Supercritical CO2 has the characteristics of high density,low viscosity,large diffusion coefficient and high mass transfer ability.The difference of the pore structure between the salt water and the supercritical CO2,the chemical interaction between the CO2 and the salt-rock interaction seriously affect the migration capacity and distribution characteristics of the CO2 in the saline aquifers.To clarify the injection capacity of supercritical CO2 in the saline aquifers and the main factors affecting the migration,this paper takes the deep saline injection aquifer of the pilot demonstration area as the research object,and carried out the CO2-salt system flooding experiment and macroscopic Reservoir scale numerical simulation study,so as to provide a theoretical basis for the efficient injection and safe geological storage of CO2 in the deep saline aquifers of the demonstration area.Thus,the specific work of this paper and the contents are as follows:?1?The mechanism of transport and diffusion of CO2 in porous media were analyzed by combining the physical properties of supercritical CO2,the porous media characteristics of deep saline aquifers and the physical properties of brine.The differences and links of different storage mechanisms were discussed.?2?Based on the core of the Liujiagou formation in the CO2 geologic enclosure of the demonstration area of Ordos Basin,the supercritical CO2-salt system flooding experiment with different permeability,temperature,displacement pressure and confining pressure was carried out by unsteady method.The effects of permeability,temperature,displacement pressure and confining pressure on the relative permeability curves of supercritical CO2-brine were analyzed and discussed?3?Based on the experimental results of relative permeability of supercritical CO2-saline system,the EC02M module in the Tough commercial software was used to carry out the large-scale calculation of the reservoir parameters of the Liujiagou formation in the demonstration area of the Ordos Basin.CO2 geological storage numerical simulation study,The effects of formation permeability,injection volume,temperature and cap rock on formation pressure and CO2 mole fraction distribution were discussed and discussed.The results of this study have some theoretical significance for the CO2 injection capacity and storage safety assessment of CO2 geological storage,and can also provide reference for other similar CO2 geological storage area analysis and evaluation.