The Establish And Application Of Database For CO₂ Mixtures Density In Geological Storage

CO₂-mixture is the most common fluid in CO₂ geological storage.Density is one of the basic physical properties which effects the heat and flow transfer.A large number of accurate and reliable data are required and the influence of the density must be fully understood to ensure the long-term operation safety.In this paper,the density of the CO₂-mixture of CO₂ geological storage was systematic reviewed including more than 300 literatures and 100,000 data points.We found that most of the components and situations have sufficient data.Some experimental data were too old that the reliability can't be ensured.Some systems are lack of the reservoir conditions.There were few studies on CO₂-saline ternary and CO₂-gas systems which lack of numerical especially theory model.Basic on that,two database query systems were established.The database used Java language can be used on-line through Lan.By contrast,the database used C#is simpler and more convenient.After that,two models were established by fitting experimental data in the review.Both of models can predict the density of CO₂-mixture under 298.15-478.15 K,5-18 MPa,0.8-1_CO2 for gas and NaCl-H₂O multicomponent systems.The model based on Gradient Boost Regression Tree?GBRT?can accurately predict the density of CO₂-mixture and a wide applicability which AARD is 0.25%.The model based on Random Decision Forests?RF?was slightly weaker than GBRT which AARD is 0.89%.But the accuracy of RF was still good.It is necessary to strengthen the ability for the impurity concentration exceed 20%.The wellbore injection–saline aquifer storage model was established with the optimized density by GBRT.The sensitivity of the injection conditions was analyzed.The JTC and the temperature difference effect temperature variation for the shallow well.The temperature depends on the thermal resistance and formation for depth over 600m.The fluid temperature effect the cooling zone and the location of T_min.High temperature and lower pressure suppress the JTC.The injection conditions have few influence on the thermal properties for the long-term saline aquifer storage under the storage condition.