Research On Cathodic Protection Of Underground Metallic Pipe Of The Contacting Pipeline In Yanchang Oil Field

Due to its characters of long transmission distance, complicated environments and detection difficulty, the corrosion of long distance underground oil & gas metallic pipeline has great effects on the safe and stable running in a long time, and serious damage will be done to the environments on occurring of leakage from the pipeline. Cathodic protection is widely applicated in the oil field for its effectiveness in corrosion control, so great effort are necessary to be done to the study of the mechanism and application under the particular condition.In order to improve the effect of cathodic protection on underground metallic pipe, and to prolong the service life of pipeline, investigate, survey and test are performed on breakage point location and the anticorrosive coating of the contacting line in Yanchang oil fields on the basis of research of the the corrosion characteristics and corrosion mechanism of soil. Then, systematical analysis is carried on the test results, and the corresponding processing method is achieved.Firstly, researches are carried out on the resistivity, hydrogen ion concentration and corrosion current density of the soil around the contacting line in Yanchang oil fields, first-hand data of the local soil corrosion characteristics is obtained, which provides powerful basis for the study of the corrosion characteristics under particular condition.Secondly, pipe and coating damage of the contacting line in Yanchang oil fields are tested through alternating current grading method, detail data of soil corrosion is acquired for the achievement of the on-site condition.Thirdly, the corrosion resistance coating of the pipelines is detected through PCM detector, and the data of the current is analyzed through the CDFFW software, then the insulation resistance of the coating outside of the pipe is acquired.Finally, stray current in the running pipeline is detected through pipeline current detection method,and the generation principle, influencing factors, current sources and drainage scheme of stray current is analyzed.Auxiliary anodic protection and other protection solutions are proposed for the addition to the cathodic protection on the detecting and analysis of the results from the pipeline, especially the pipeline in the river crossing section and undulating terrain, all these can provide a useful reference and support for the running of pipeline in Yanchang oil field.