Study On Intelligent Magnetic Flux Leakage Inspection Of Subsea Pipeline

Pipeline which transports oil and gas plays an important role in oil and gas production.pigging to the pipeline at regular intervals can effectively remove the deposits and wax accumulated in the pipeline.Though the intelligent inspection of pipeline can help the operators to grasp the situations of pipeline,give necessary maintenance to the flaws can avoid occurrence of pipeline and extent the life of pipeline effectively.This paper studies the technology of pigging using at the field and finite element analysis of magnetic flux leakage of pipeline.The main content and conclusions are as follows:Design and implement an experiment about fragmentation and sealability of the pig.It was found that the foam pig is hard to broken in the pipeline,and when the pressure increased to a certain value,the fluid will bypass.It was also found that the sealability of the cup pig is better than the stright cup pig,and the sealability of the cup pig with the steel frame is better than the polyurethane cup pig.The baffle which are criss-cross and annular can obstruct the pig well and do not cause the broken of the pig.Pigging of an oil pipeline and a gas pipeline have some differences.we cosider wax most at the oil pipeline and hydrops most at the gas pipeline.There are lots of methods to predict the pigging time,the method using pressure differential and gas-flowrate summarized from the filed can achieve the goal.The type of the flaw on the pipe is varied, Corrosion pits are the key points which studied in this paper.The magnetic flux leakage models of different defects were established by ANSYS,and the conditions of defects were simulated.It was found that the magnetic flux leakage peak value increase with the increase of defect depth, and there is a linear relationship between depth and the peak value;The distance between magnetic flux leakage positive and negative peak values increase as the length increase,and the distance between magnetic flux leakage peak values equals to defect length;for the different three-dimension shapes of the defects, the axial magnetic flux leakage signal shows a similar shape.