Analysis Of Mechanical Behavior Of Pressure Pipeline And Its On-line Monitoring System

The pressure pipeline of high pressure gas well is an important part of oil and gas well production.With the continuous deterioration of oil and gas exploitation conditions and the application of some stimulation technologies such as sand inclusion fracturing and acidification,the high-pressure environment and fluid particle erosion will cause serious damage to the pressure pipeline,and even safety accidents such as puncture and blowout of the pipeline will occur.In order to find out the damage of the inner structure of pipeline in time and effectively,it is very important to monitor the pressure pipeline in real time.In this paper,the fluid mechanics simulation calculation is carried out for the erosion process of pressure pipeline,and the erosion damage of pressure pipeline is analyzed by using the liquid-solid fluid erosion model,and the mechanical behavior of pipeline under high pressure load is studied,so as to further build the online monitoring system of pressure pipeline.In this paper,the finite element model of elbow erosion was established,and FLUENT software was used to simulate the erosion behavior of liquid-solid fluid on elbow,and the influence rule of different fluid factors on erosion damage was analyzed.The results show that the erosion damage of the outer arch of the inner wall of the elbow is serious,ranging from the middle of the outer arch to the outlet of the elbow,and the erosion rate near the outlet is large.ANSYS finite element software was used to analyze the structural statics of damaged elbow with different defect depth.The results show that stress concentration occurs at the defect of the bend.The circumferential strain increases exponentially with the increase of defect depth,and starts to increase sharply when it reaches 0.5 wall thickness.The damage of the straight pipe was analyzed by using the liquid-solid erosion model.The results show that the erosion effect of straight pipe is not as obvious as that of bend pipe,which is mainly manifested by evenly distributed pits on the pipe wall.Further erosion simulation of some pits shows that the erosion rate is higher at the edge of the pits,which tends to form long gully defects.ANSYS structural statics module was used to analyze the local thinning damage model of straight pipe,and the effects of defect depth,length and width on the stress and strain field of the pipe wall were studied respectively.The results show that the defect depth and axial length have great influence on the circumferential strain of the pipe wall,and the width has little influence after reaching a certain value.When the defect depth reaches 0.5 wall thickness,the circumferential strain begins to increase sharply.In this paper,the method of neural network is introduced to identify the damage of pressure pipeline.The simulated data of different damage models are used to train the damage identification neural network.The on-line monitoring system processes the field data in real time,realizes the interface functions such as real-time strain,real-time temperature and realtime wall thickness,and can be used for damage location and safety warning of pipelines.