Research On Subsea Production System Modeling And Visual Simulation Of Production Flow Characteristics

The subsea production system is an important part of deep-water oil and gas development,and the change of flow characteristics in the pipeline of subsea production is an important factor affecting the underwater production and accident.On the basis of intensive study on the visual simulation technology of subsea production,this paper studies and develops the visual simulation of subsea production system based on virtual reality technology,so as to solve the problems of process prediction evaluation and preview during subsea production.Based on the Vega Prime virtual engine,the visualization requirements of virtual roaming system design,distributed interactive simulation and the flow characteristics of scene and pipeline are deeply analyzed.The models of seabed topography,water and seaweed are established using the high efficient 3D modeling techniques,such as LOD and DOF,to develop and design immersed ocean scenes.The subsea equipment model is established to build the underwater production scene.The visual simulation window interface is designed to achieve interface button function.The user roaming mode is developed to complete the virtual roaming scene design of subsea production simulation system.Based on the HLA framework,a data transmission mechanism is established between MATLAB numerical simulation and Vega Prime visual simulation.In order to keep the efficiency and real time of data transmission,the judgment criterions of the view constraint and the dynamic image change rate constraint in the LOD high efficient hierarchical modeling are adopted based on the simplified algorithm of progressive grid model,which is used to eliminate the equipment model which is not in the view window,and then reduce the complexity of the simplified algorithm.Meanwhile,the user interest degree is introduced,and a multi-constraint model simplification algorithm is proposed to simplify the model while meeting the requirements of the system.The mechanism of hydrate formation is analyzed to choose the suitable prediction model of hydrate formation condition.The contribution degree constant of mixture to water activity in natural gas hydrate is introduced,thus the mixture concentration is corrected,and then the prediction model of hydrate production condition is improved.The diagram of hydrate formation prediction with working condition data is studied based on the principle of image simplification to analysis the 4 types of hydrate formation prediction models,and there threedimensional models are established respectively.The formation conditions of two-phase flow patterns in vertical and horizontal pipelines are studied,and the flow patterns in the production pipelines of target oil and gas fields are predicted in combination with the working condition data,and then the suitable flow pattern conversion model is chosen.The two-phase flow pattern distribution image is obtained by experiment,meanwhile,by simplifying the image,the mathematical model of the state transition of two-phase flow in the pipeline is calculated,and their three-dimensional model is established respectively.The model base is established to store all the models in the scene.Finally,the visualization of the flow characteristics in the subsea production pipeline is realized through the real-time invocation of the model.