Numerical Simulation Research On Erosion Problem Of Deepwater Subsea Multiphase Pipeline

With rapid development of offshore oil industry,our country's offshore oil&gas resourece has continued being developed successfully and stepped into deepwater field gradually,which leads to the heavier responsibilities for subsea pipelines who plays the role of airtight offshore engineering structure.Compared with onshore pipeline,subsea pipeline system has wider area and more complicated subsea suuroundings,and the application of detection equipment is inconvenient which cause to higher examination costs.So in the offshore oil&gas industry,the erosion problem caused by the motion of fluid with sand has been concerned widely.Erosion phenomenon is very complicated,and has kinds of factors influence on the severity of erosion to varying degrees,for example,fluid flow rate,fluid property,sand mass rete,sand property,wall material,pipe geometry,etc.In conclusion,some professional engineering software needs to be applied to analyze the erosion rules of subsea pipeline and predict the weakest position of the whole pipeline system,which has profound significance to pipeline system's management of safety,reliability,operability and integrity.The thesis uses ANSYS 16.2 Fluent to simulate the subsea multiphase pipeline of certain Brazil deepwater oil&gas field in different erosion conditions,which aims to reliaze the fluid flow condition and erosion rules of pipeline more clearly.Software simulation mainly consists of three procedures: fluid flow characteristic(Turbulent Model & Multiphase Model),solid particle traces(DPM Model)and erosion rate calculation.After simulation,erosion rate and the weakest position can be found through erosion countor output,and the thesis also analyses the detail erosion influence factors of operation condition,particle character and fluid property,then includes the sensitivity analysis.In the end,the thesis also compares the output of CFD with the five most widely used erosion prediction model in the world through self-programming software on the various conditions of fluid GOR,pipeline outlet pressure,sand mass flow rate and sand diameter,which lies the solid foundation and technical support for future engineering operating and subsea multiphase pipeline design of deepwater.