Measurement And Correlation Of The Viscosity And Density Of Crude Oil At High Temperatures And High Pressures

With the development of science and technology,injecting CO2 to enhance oil recovery(CO2-EOR)has become an important technology to the petroleum industry.During the process,the viscosity and density data of petroleum fluids versus temperatures and pressures are needed for the study of heat transfer and mass transfer and other thermodynamic properties.In this work,n-tridecane and n-hexadecane were chosen as a model compound of paraffin;methyl-cyclohexane and ethyl-cyclohexane can be regarded as the naphthenic model compounds;tert-butylbenzene was chosen as the aromatic model compounds.The density and viscosity data of five pure compounds and mixture systems n-hexadecane + methyl-cyclohexane,n-hexadecane + tert-butylbenzene,n-hexadecane + methyl-cyclohexane + tert-butylbenzene,n-tridecane + n-hexadecane + methyl-cyclohexane + tert-butylbenzene have been measured in the temperature range from 318.15 K to 378.15 K and pressure range from 2.00 MPa to 20.00 MPa.PR-BM、SRK、PR-BM-t、SRK-t and Tait equation were used to correlate the densities of pure compounds.The Tait equation gave the best results and the maximum average relative deviation was 0.049%.The transfer volume method was introduced to the PR-BM and SRK equation and the calculation results were obviously improved.The densities of binary systems were calculated by the Tait equation and parameters correlated from pure compounds,the ARD were around 0.7%.The ternary and quaternary systems were assumed as pure compound and their density data at different compositions were successfully correlated by Tait equation,the maximum ARD was 0.0466%.The viscosity data of pure compounds and mixtures were correlated by the classical mixing rules GN and KC,the self-referencing model,the free-volume model,the LBC model,the hard-sphere viscosity scheme model and the K-R model.The self-referencing model gave the better results than other models and the maximum ARD was 4.21%.The RK mixing rules were used to calculate the critical temperature and critical pressure in the LBC model and the calculated results were improved obviously.The K-R model with the parameters correlated from data of binary systems were used to calculate the viscosity of the ternary and quaternary systems.The results were relatively satisfactory with ARD of 8.149% for ternary system and 4.589% for quaternary system.The experimental viscosity and density data,the models and the relevant parameters in the research are of great significance for controlling the flow of oil in the pipeline,calculating the reserves of oil field,planning EOR process and design of the production equipment.