Research Of Point Corrosion Of Gfrp Oil Pipelinein In The Crude Oil Liquid With O₂

GFRP oil pipeline have light,corrosion resistance,long life and other advantages make non-metallic pipeline in the field of oil field applications become increasingly widespread.In the late stage of oil extraction,with the large amount of water and CO₂ injecting,CO₂ corrosion of the pipeline has become the main form of pipeline corrosion.In this paper,the corrosion of the initial surface of the pipeline is the analysis of the key points.The experiment choose four GFRP oil pipes,and to study the corrosion mechanism of GFRP pipe by comparing the influencing factors of pipeline corrosion behavior.In the simulated oil environment,The experiment analysis of the role of CO₂-containing crude oil for the pipeline corrosion,and study the effect of the size and depth of the point on the mechanical properties of the material.The experiment selected the four kinds of oilfields widely used in different components of the GFRP oil pipeline to analysis.In the three kinds of media and two kinds of temperature,the GFRP oil pipelines are corrosed four cycles,compared with the corrosion behavior of GFRP oil pipelines,The morpHology of the surface was observed by scanning electron microscopy（SEM）,and the morpHology of the corrosion was analyzed.The molecular structure of four GFRP was analyzed by infrared spectroscopy（IR）and X-ray pHotoelectron spectroscopy（XPS）.The types and quantity of surface resin groups in the process of corrosion were studied.Thermal Stability of GFRP pipelines was analysised by Differential Thermal Analysis（DTA）.According to the above experimental results,the amine-cured epoxy resin GFRP pipeline was selected as the material of the oil-environment simulation experiment,and the corrosion behavior of the crude oil medium was studied by comparing the change of pipelines’ performance before and after corrosion.The loss of the surface resin before and after the corrosion of the pipeline was characterized by the Baust hardness test,the resin content test and the density test.The corrosion mechanism of the pipeline in the crude oil medium was deduced by XPS and IR.In contrast to the moisture absorption curves of GFRP pipeline at different temperatures,The experiment study effects of crude oil composition on the corrosion behavior of the pipeline during the corrosion process were investigated.In the early stages of the corrosion of the oil pipeline,the degree of corrosion is not very severely.The corrosion site mainly occurs in the pipe surface—resin layer,the form of local corrosion,is especially the main point of corrosion.The surface morpHology of the pipe under different corrosion cycles was analyzed by scanning electron microscopy（SEM）.The size and quantity of the corrosion point were compared;The three-dimensional scanning of the corrosion point of the resin layer was carried out by the super-depth microscope.The corrosion depth of the fiber layer was observed and the corrosion of the fiber layer was observed;The effect of point corrosion on the mechanical strength of the material was studied by axial tensile strength and circumferential stiffness test.Through the above test analysis can be drawn,containing CO₂ crude oil on the GFRP pipeline in the initial stage of local corrosion is mainly the form of corrosion.The reason is due to the combination of pHysical and chemical corrosion caused by the loss of the surface of the pipe resin,the formation of micron-level point defects,so that the pipeline performance has declined.This process has a correlation with the corrosion cycle,the longer the test time,the more serious the degree of corrosion,and by the corrosion temperature,medium acidity,pressure and other factors.