Study On Velocity Prediction And Corrosion Mechanism Of Buried Long Distance Pipeline In Oilfield

Metal pipeline transportation is the most reliable and economical way of transporting oil and gas at present.It is widely used in the production of oil and natural gas,such as drilling,mining,gathering,location and transportation.At the same time,the environmental,security,economic and other problems caused by pipeline corrosion are becoming more and more serious this paper,a systematic study on the problems of failure(corrosion)in the transportation of buried pipelines in an oil field in Gansu is systematically studied,and the following research results are obtained.(1)In view of the characteristics of transmission medium in the pipeline of Gansu oilfield,a set of reasonable detection methods is explored.The method can quickly and accurately complete the qualitative and quantitative detection of the conveying medium and related impurities in the tube.It provides reliable data for the study of actual production and subsequent pipeline corrosion.(2)The OLGA software is used to simulate the running parameters of the pipeline,and the results show that:The pressure drop of the upper slope is larger,and the pressure change of the lower slope is small.Inverse ratio of flow velocity to pipeline elevation in pipe.The flow patterns of the medium in the tube are divided into stratified flow,segmental flow and a small amount of bubble flow.The slug flow mainly occurs in the upper slope pipe section,and the stratified flow is mainly distributed in the lower slope pipe section.The bubble flow is small in the presence of the abrupt mutation of the pipeline elevation.(3)We designed and built oil and gas water three phase corrosion simulation device independently,and made corrosion simulation test for pipeline steel.The experimental results were analyzed by single factor analysis and variance analysis.The results show that Cl-,Fe2+ and Fe3+ are the main ions that affect the corrosion of the pipeline,and the degree of influence increases with the increase of temperature.The order of the effect of medium operating parameters on pipeline corrosion is flow rate > temperature >p H value > pressure.(4)The corrosion mechanism of pipeline was studied by SEM and XRD.The research shows that the corrosion of buried pipelines in oil field can be divided into two aspects,namely,the dynamic gas liquid equilibrium of the oxygen in the gas sample and the dissolved oxygen in the water sample,causing the oxygen corrosion of the pipeline,and the erosion of pipeline caused by the medium transportation.(5)According to the fractal geometry principle,the gray histogram of the corrosion image and the fractal dimension of the calculation pipeline are drawn,and the relationship between the corrosion rate and the corrosion rate is studied.The results show that the gray mean value,gray mean value,gray variance and fractal dimension of the corroded image increase with the increase of corrosion rate.(6)According to the principle of neural network,the advantages and disadvantages of the BP neural network,which take the medium detection data and the characteristic data of the corroded image as samples,are compared.The results show that the latter is more suitable for the prediction of corrosion rate of buried pipeline in an oil field.Genetic algorithm is applied to optimize the model,so that it can predict the internal corrosion rate of pipelines quickly and accurately,and provide reliable basis for pipeline management and safe operation in daily production.