Numerical Simulation For Water Hammer Of Multi-phase Flow Of Oil-gas-water In Oil And Gas Pipelines

In oil and gas storage and transportation projects,oil and gas gathering and transporting media are mostly filled with multi-phase flow of oil-gas-water.Due to transmission pressure transients or switching valves,the multi-phase water hammer accidents of oil-gas-water caused by the pressure surge in the pipeline causing pipeline rupture occur.Endangering the safety of life and property.How to effectively solve the problem of multi-phase water hammer in oil-gas-water needs further research.The paper analyzes the research literature at home and abroad,and conducts in depth research on the multi-phase flow of oil-gas-water.Firstly,the theoretical analysis of the problems related to multi-phase flow of oil-gas-water is carried out,including the occurrence,damage and influencing factors of multi-phase flow of oil-gas-water,and the movement of fluid in the neutral pipe during multi-phase flow of oil-gas-water.Coupled vibration response of marine riser caused by multi-phase flow of water hammer;multi-phase flow water hammer protection device for oil-gas-water working principle of pressure relief valve and influencing factors of pressure accuracy.Secondly,based on multi-phase fluid mechanics theory,structural mechanics theory,dynamics theory and computational fluid dynamics theory,the above analysis problems are numerically simulated,and the coupled water hammer model and gas content change of multi-phase flow of oil-gas-water are constructed.The gas-liquid two-phase flow water hammer model,the water hammer model in the water-in-oil or oil-in-water state,the spool dynamics model,and the coupled vibration finite element model of the pipeline system.Then,the constructed mathematical model is solved by the characteristic line method,the vector flux decomposition method and the Galerkin method,and the water hammer model is applied to the pressure accuracy setting of the nitrogen water hammer relief valve and the dynamic response analysis of the riser structure.Finally,in order to verify whether the proposed mathematical model is in practical application,the paper designs and simulates the coupled vibration response experiment of three-phase flow of oil-gas-water riser,the simulation experiment of multi-phase flow and water-splitting discharge of oil-gas-water,and the simulation experiment of multi-phase flow of oil-gas-water.According to the scientific analysis of the experimental results and the simulation results,the study found that the water hammer wave velocity and the water hammer pressure in the multi-phase flow of the oil-gas-water water show periodic changes,and the marine riser coupled vibration caused by the water hammer responds to the bottom displacement of the neutral pipe.The pressure at the bottom of the tube is consistent with the change period of the water hammer wave velocity and the water hammer pressure.Due to the relationship of the time,Influence of discounted gas velocity and phase velocity difference on water hammer velocity and water hammer pressure,the external force and the internal force of the riser system have not been applied to the coupled vibration of the riser system.More discussion,this will also be a direction of later research.