Numerical Study On Meso And Macro Migration Of Leaking Pollutant In Buried Oil Pipeline Leakage

With the development of the national economy,the consumption of petroleum energy is increasing.At the same time,the domestic underground pipeline network extends rapidly and now a huge oil pipeline network system has been formed with the adjustment of the national energy strategy.As a modern safe economical and convenient transportation equipment of oil,it is easily damaged by the soil corrosion and natural disaster with the passage of time.It leads to petroleum medium leak from oil pipelines,which not only affects the energy security,but also causes soil pollution and damages to the ecological environment.The study on migration regularity of leaking pollutant of buried oil pipeline in the soil plays an important role in the pipeline leak detection and the late soil remediation.Aiming at the migration regularity of buried oil pipeline leak pollutant,combining the lattice Boltzmann mesoscopic method(LBM)with the Fluent macro simulation method,this thesis has analysed the single phase fluid model,the multi phase flow model,the structure of the soil porous media,the soil resistance coefficient and the influencing factors of the pollutant migration of the pipeline leakage,and the migration regularity of pollutants in the soil porous media was obtained.The main research contains the following aspects:1.The validation of multiphase flow model and the determination of its parameters.Based on lattice Boltzmann method,the fluid model and boundary conditions of buried oil pipeline leak pollutant were analyzed.The migration characteristics of oil pipeline leak pollutant in single-phase and multi-phase were respectively investigated by the D2Q9 model,and the single-phase flow was solved by the Poiseuille flow model,and the multiphase flow was established by the pseudo potential SC(Shan-Chen)model.The parameters of the multi-phase model of buried oil pipeline leak pollutant were determined based on the Young-Laplace's law.2.The construction of porous soil media.The porous soil media was produced based on the lattice Boltzmann and the QSGS(Quartet Structure Generation Set)stochastic methods.The differences between the two methods were compared and finally the QSGS stochastic method was determined to produce the porous soil media.3.The calculation of the drag coefficient of the porous soil media.Based on the lattice Boltzmann method,the migration characteristics of oil pipeline leak pollutant in porous soil media containing gas were studied.The method of solving the drag coefficient of porousmedia was introduced and the conversion relation between the lattice unit and the physical unit was studied.The drag coefficient of oil pipeline leak pollutant migration under the soil porosity was obtained by numerical fitting.4.The analysis of the influencing factors of oil pipeline leak pollutant migration in the soil.The migration model of oil pipeline leak pollutant in the soil was built,and the effects on oil pipeline leak pollutant migration process caused by leakage aperture,leak rate,soil porosity and leakage location were simulated by Fluent.The controlling variable method was adopted to further analyze the migration regularity of oil and water phase pollutants.Through this study,the mesoscopic migration characteristics of oil pipeline leak pollutant are obtained,and the drag coefficient is achieved based on the numerical method.The macro migration regularity of oil pipeline leak pollutant is researched by Fluent.The research results provide a theoretical basis for the future research on the migration mechanism,detection method and late remediation technology of buried oil pipeline leak pollutant.