A Investigation Of Multiphase Transport Of Pollutants Leaked From Inner Pipe Of Submarine Double-layer Thermal Insulation Oil Pipeline

The exploitation area of submarine oil resources has gradually shifted from shallow sea to deep sea,and because of the extreme deterioration of deep-sea environment,the doublelayer thermal insulation pipeline has been widely used in the process of exploitation of submarine oil resources.However,due to the influence of many factors,pipeline leakage occurs from time to time,and has caused serious environmental pollution and huge economic losses.The safety maintenance of submarine double-layer thermal insulation pipeline has become a difficult problem to be solved in petroleum industry,and pipeline leakage detection is a necessary means for pipeline safety maintenance.At present,optical fiber,capacitance,biosensor,characteristic impedance leak detection techniques have potential application prospects in oil pipeline leakage detection because of their advantages of accurate and fast measurement.But manufacturing costs have been hampering the development of these technologies.Through the research on the pollutant migration of the inner pipe of the submarine oil pipeline,this paper provides some reference basis and advice for the layout of the leakage detection sensor and optical fiber,and which can solve the cost problem of the pipeline leakage detection to a certain extent.Therefore,it is of great value to study the multiphase transport of pollutants leaked from inner pipe of submarine double-layer thermal insulation pipeline.In this paper,the multiphase migration of leakage pollutants is studied through mesoscopic and macroscopic simulation by taking the pollutants leaked from the inner pipe of submarine double-layer thermal insulation pipeline as the research object.At the same time,the mesoscopic and macro migration law of the pollutant leaked from inner pipe of submarine oil pipeline under different influence factors are analyzed.The main research contents are as follows :(1)The porous structure model of insulation material is constructed.According to the pore structure characteristics of thermal insulation material in actual submarine double-layer oil pipeline,the porous structure model of ideal insulation material is constructed by QSGS method.And when the distribution probability is 0.01 and the growth rate is 0.01,the porous structure model with different porosity is ideal.(2)Mesoscopic simulation of oil and water migration in porous structure of thermal insulation material.The mesoscopic simulation of oil and water migration in porous structure of insulating materials was carried out,and then the mesoscopic migration law of oil and water under different control parameters was analyzed.Although the process of oil and water migration was affected by many factors,However,the porosity and fluid driving pressure of porous structure are the main influencing factors of oil and water migration in porous structure.(3)The resistance coefficient of oil and water migration in porous structure of insulating material is obtained.Using the above mesoscopic simulation data,the curves of resistancecoefficient of oil and water migration in porous structure of different porosity insulation materials are obtained.When the porosity of porous structure is smaller,the viscous resistance and inertia resistance of oil and water will be greater,and the viscous resistance of water is higher than that of oil,and the inertia resistance of oil and water is basically the same.(4)Macroscopical simulation of multiphase transport of pollutants leaked from inner pipe of submarine double-layer thermal insulation pipeline.Through macroscopic simulation,the multiphase migration law of different influencing factors on the leakage pollutants in the inner pipe of submarine oil pipeline is analyzed,such as leakage time,leak location,pipeline specification,leakage speed,leakage aperture,the porosity of insulating material has a significant effect on the multiphase migration of pollutants in the inner pipe of submarine oil pipeline,but the effect of fluid density is not obvious.Through the research of this subject,the mesoscopic and macroscopic migration law and the change curve of oil-water migration resistance coefficient with porosity in porous structure of thermal insulation material are obtained.It can provide some references and suggestions for the arrangement of sensors and optical fibers in leak detection technology.