Corrosion Failure Prediction And Repair Strategy Of In-service Oil And Gas Pipeline

Oil and gas pipelines,as a key tool for regional deployment of related energy in China,play an important role in Chinese industrialization.However,as Chinese oil and gas pipelines operate,accidents such as leaks,cracks,and perforations caused by corrosion are becoming increasingly frequent,resulting in many unnecessary casualties and economic losses.In order to prevent the occurrence of such incidents,to achieve the application of relevant technical methods on risk assessment of oil and gas pipeline corrosion failures,and to formulate appropriate countermeasures for pipeline inspection and maintenance so that pipelines can be safely and reliably operated,the following studies have been conducted in this paper:(1)According to the traditional grey system,a tail-segment residual GM(1,1)model was constructed to predict the service life of the pipeline.Firstly,using the detected corrosion data records,the data is screened according to the smoothness and quasiexponential regularity.Secondly,I calculate the parameter values for the required data according to albinism differential equation,and construct the traditional grey system.Then,the residual correction is performed to build the GM(1,1)model with residual correction of tail section.This model predicts the remaining service life of the pipeline.Finally,the relevance degree test is performed to the new model.The prediction accuracy is improved substantially.(2)By combining the gray system with Markov theory,an improved Grey-Markov model predicts tube corrosion trends.Firstly,analyze the collected inspection data and use the grey equation to fit the corrosion depth of oil and gas pipelines in service.Then,the state is divided according to the trend prediction value,and the slip transition probability matrix is established by Markov theory,converting the corrosion depth prediction to a probabilistic problem.Finally,the state of the pipeline can be predicted by the change probability of pipeline state,and the corrosion trend of the pipeline can be obtained.(3)Combine the detection interval of oil and gas pipelines in service with GreyMarkov theory,and predict the reasonable detection time according to the corrosion trend of oil and gas pipelines in service.According to the actual situation detected,the classification of corrosion damage to the pipe body is divided,different corrosion maintenance strategies are formulated,and maintenance plans such as continuous use,pressure reduction,maintenance,and scrap reconstruction are proposed to ensure the safe operation of the pipeline.(4)The model is further verified by examples to determine its accuracy.The detection and analysis of two different oil and gas pipeline test sections predicted the corrosion trend of the pipeline.When the API 5L X52 pipeline reached the limit state during the 72 nd normal detection,the average relative error of fitting decreased from 36.70% to 3.63%;From the relative value of corrosion depth of the pipeline in which the next 4a is located,the prediction accuracy of the pipeline corrosion depth is increased from 92.85% to 95.04%,and the 6th year is taken as the next inspection time of the pipeline.