Analysis Of Vibration And Erosion Induced By Multiphase Flow In Hanging Jumper

With the development of petroleum exploitation,the use frequency of deep-sea risers is increasing.In order to ensure economic benefits,gas-liquid multiphase mixed transportation is mainly adopted in the process of oil and gas transportation.This kind of multiphase mixed transportation will cause pipeline vibration,and its vibration process is particularly complex.Vigorous vibration will lead to fatigue damage of pipelines;at the same time,the oil extracted from the seabed will be damaged.There is a certain amount of sand in the gas.The movement of sand particles in oil and gas along the pipeline will inevitably cause certain erosion damage to the pipeline.However,the understanding of the erosion degree and its erosion law under different conditions of multi-phase flow is insufficient.Aiming at the above problems,a set of non-interference gas-liquid two-phase flow vibration device was designed in this paper.The vibration law of multi-phase pipeline is analyzed by high-speed video camera and related equipment.At the same time,the erosion situation of gas-liquid-solid three-phase flow of real-sized pipeline under static and vibration conditions is simulated and predicted by ANSYS software,and different gas-liquid velocity,sand particle diameter,sand particle velocity and sand particle quality are obtained.The erosion situation of pipeline under flow rate is analyzed,and the main erosion location and rule are explored.Based on Reynolds similarity and pipeline vibration similarity,a set of non-interference experimental device was designed to capture the flow pattern,vibration displacement and pressure changes at the inlet and outlet of the pipeline.It is found that with the change of experimental conditions,the main flow pattern in the pipeline is hydrodynamic slug flow.When the gas flow rate is low,it is steady-state hydrodynamic slug flow.When the gas flow rate is high,it presents transient hydrodynamic slug flow.When the liquid flow rate is constant,with the increase of gas flow rate,the pressure fluctuation in the pipeline becomes larger and larger,and the vibration of the pipeline becomes more and more intense.In the process of fluid flowing through the pipeline,there are two obvious vibration parts.The vibration of the jump nozzle in X and Z directions are second-order modes,which are located near the middle of the downstream section of the pipeline and in the front part of the downstream section of the pipeline during the upstream process of the fluid.The-vibration amplitude in the direction of the suspended span tube varies along the direction of the instantaneous wing,and two amplitude peaks appear in the changing process,respectively at point 6 and 18.When the pipeline is in a stationary state,the erosion rate increases with the increase of the liquid velocity when the gas velocity is constant.The erosion location is mainly located at the bottom of the suspended pipeline,and diffuses along the bottom of the pipeline to both ends of the pipeline.The erosion morphology of the pipeline is continuous "cloud".The factors affecting pipeline erosion(sand flow rate,sand mass flow rate,sand diameter)are directly proportional to the pipeline erosion rate.In the case of pipeline vibration,the pipeline erosion rate is proportional to the gas phase velocity and liquid phase velocity,and the maximum erosion area is located in the range of pipeline amplitude wave peak.Compared with the pipeline erosion without vibration,the vibration pipeline erosion is more serious and the particle erosion is more dispersed,which is no longer a continuous "cloud" but a disordered "spot".