Mass Transfer Research Of CO₂ Storage In Deep Saline Aquifers

The greenhouse effect has become today's serious ecological problems,the main cause of greenhouse gas CO₂,so the study method of CO₂ emission reduction has become the research focus in the governments and research departments.CO₂ storage is the most effective way to reduce CO₂ emissions,and also to prevent climate change.Main choice of underground storage is depleted reservoirs,deep brine reservoir,inability to mining of coal seam and the way the deep-sea storage,etc.Combining with the characteristics of deep layer of salt water,it is the most effective way of storage.In order to study the mass transfer in the process of CO₂ storage,in this paper,based on the mathematic model of the diffusion coefficient of the design and construction of the calculation of CO₂ in saline layer diffusion coefficient in the experiment.Combined with the experimental results was obtained under the condition of different diffusion coefficient of CO₂ in salt water layer.Results show that the injection pressure in a certain range,the diffusion coefficients increased with the increase of the pressure increase.In a certain temperature range,as the temperature increases.Filling clay can influence the diffusion coefficient,the higher the clay content of diffusion coefficient is smaller.For circulating quality are analyzed in theory,analyzes the necessary conditions for began circulating quality,analyzes the convection start time at the top of the pressure,temperature,salinity and the influence law of the analysis to get to a certain pressure range,convection time lengthened with the increase of pressure.In a certain temperature range,convection began with the increase of temperature and time delay.The higher the storage layer brine salinity convection start time is delayed.CMG component model is adopted to establish the storage model of CO₂ in salt water layer,to simulate the process of mass transfer in the whole process of storage,diffusion and mass transfer in the cover layer simulation,simulated the reservoir of the molecular diffusion and spread of the process,the permeability ratio,horizontal permeability and salt water caused by CO₂ dissolved the density difference,the greater the formation porosity and viscosity of brine,and CO₂ diffusion coefficient is smaller,the shorter the critical time of salt water convection,the smaller the critical width of high-density brine flow and convection phenomenon is more obvious.Factor analysis results show that the primary and secondary salinity is the main factor affecting CO₂ dissolved,convection can make the CO₂ in the formation water dissolved salt water volume increased by 0.53%⁵5.45%.