Study On Flow Characteristics And Vibration Mechanism Of Multi-Undulating Riser System

In offshore oilfield exploitation,the flow medium in the pipeline is mostly gas-liquid miscible flow,and the pipeline for oil and gas transportation usually consists of undercover pipeline and riser section.Due to the influence of the topography of the seabed,the undercover pipeline is usually undulating structure,and the existence of the undulating section will have a certain influence on the gas-liquid two-phase flow in the transportation process.Under some harmful flow patterns,the fluid pressure and momentum in the pipeline will fluctuate violently,which will lead to pipeline vibration and harm the pipeline system and downstream separation equipment.Therefore,it is of great engineering significance to further study the characteristics of pipeline pressure fluctuation and vibration.In this paper,the multi-undulating horizontal pipe-riser system is taken as the research object,and the gas-liquid two-phase flow characteristics and pipeline vibration characteristics are studied through the combination of laboratory test and numerical simulation.The main work and conclusions are as follows:Change combination of riser system in rolling tube position and the number of experiments,by measuring the differential pressure of the ups and downs up dip period and at the bottom of the stand pipe pressure signal,the combination of various ups and downs of the Go Pro form the flow state inside the pipeline,considering the mutual coupling effect between the rolling line,in the local flow pattern as the research object,studied the many ups and downs two-phase flow in vertical pipe system,explores the relief effect under different conditions,the impact on the downstream flow property of vertical section.Installation accelerometer measurement at the bottom of the riser and the top of the vibration acceleration,the analysis of different gas and liquid ratio on the gas liquid two phase flow pipeline vibration,summarized the vibration signal under different flow pattern change law and mechanism of mechanism,compared to the bottom of the riser and the separator imported the vibration signals of the two points difference,study its internal mechanism,analyzed the influence of gravity separator inlet side pressure and the effects of mutations.The acceleration signals were decomposed by using the empirical mode decomposition algorithm.The extracted IMF energy values were taken as the input parameters of the probabilistic neural network,and the flow pattern was taken as the output parameters.A noninsertion flow pattern identification model was established.