Improving SNR of MFL detecting defect signal of drill pipe by using pole piece

Abstract

MFLThe magnetic flux leakage (MFL) technique is generally considered to be an efficient and effective non-destructive testing (NDT) method and has been widely used in the oil field inspection industry for the examination of drill pipe. This paper studies the resistance distribution in the magnetic circuit of magnetic flux leakage detection probes and proposes the method of adding a pole piece to reduce magnetic resistance. The magnetic circuit model is simulated by using finite element analysis and the results show that the detection probe with a pole piece can strengthen the magnetic leakage signal for a drill pipe defect, and pole pieces with different thicknesses have little influence on the defect magnetic leakage signal in the circuit. Practical testing confirms that the probe with a pole piece can clearly improve the SNR of the MFL signal. The analysis results are of great value for improving defect identification rates and for the precise detection of defects.This book will provide guidance on the subject of Infrared Thermography (IRT), namely heat transfer theory, equipment selection, applications and operational factors; and as such can be used as an information source to support IRT operations. Volume 2: Applications by A N NowickiThis book is aimed at thermographers who have attained at least Level 1 accreditation in IRT. It is recommended that the reader also has some operational experience in order to have the required level of knowledge to understand the terminology and diagnostic descriptions included.

A Lift-Off-Tolerant Magnetic Flux Leakage Testing Method for Drill Pipes at Wellhead

“…Therefore, to avoid accidents and economic losses, according to the API (American Petroleum Institute) standard, drill pipes should be inspected by NDT (nondestructive testing) technologies before use [ 2 ]. MFL (magnetic flux leakage) technology is one of the most commonly used and powerful NDT methods and has been applied for the highly efficient inspection of defects in various kinds of ferromagnetic materials [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ], particularly in elongated ferromagnetic objects, such as steel pipes [ 12 , 13 , 14 , 15 , 16 , 17 ] and wire ropes [ 18 , 19 , 20 , 21 ]. There are three types of MFL methods, namely, DC MFL, AC MFL, and pulsed MFL [ 22 , 23 ].…”

“…In this paper, to realize lift-off-tolerant MFL testing for drill pipes at wellheads, a novel MFL testing method that includes the Helmholtz coil magnetization method, the lift-off-tolerant MFL sensor, and the whole MFL inspection apparatus is proposed and developed here for the first time. Compared with the magnetization method based on permanent magnets, alternative currents, and pulsed currents [ 16 , 17 , 22 , 23 ], the Helmholtz coil method can generate a strong and uniform magnetizing field to meet the requirements of hard-magnetization drill pipes. The proposed MFL sensor is an active method that can guide more magnetic flux to leak out.…”

A Method for Improving SNR of Drill Pipe Leakage Flux Testing Signals by Means of Magnetic Concentrating Effect

“…China University of Petroleum, therefore, has developed wellhead online testing technique based on permanent magnet excitation principle [1], and to a certain extent, solved the difficulties for drill pipe to test defects in time during ultradeep well drilling, offshore drilling, and so on. Defect-recognizing is the key point of the wellhead online testing.…”

Research on internal and external defect identification of drill pipe based on weak magnetic inspection

“…Very little work has been reported on the ability of MFL machines to distinguish between internal and external defects in drill pipe. After years of research into this problem [1][2] , a method based on the weak magnetic field has been proposed. This paper discusses the defect identification problem of the inside and outside walls of the drill pipe from both theoretical and applied aspects and provides a technical foundation for the integrity assessment of pipeline defect detection.…”