Abstract
To meet the great needs for MFL (magnetic flux leakage) inspection of drill pipes at wellheads, a lift-off-tolerant MFL testing method is proposed and investigated in this paper. Firstly, a Helmholtz coil magnetization method and the whole MFL testing scheme are proposed. Then, based on the magnetic field focusing effect of ferrite cores, a lift-off-tolerant MFL sensor is developed and tested. It shows high sensitivity at a lift-off distance of 5.0 mm. Further, the follow-up high repeatability MFL probing system is designed and manufactured, which was embedded with the developed sensors. It can track the swing movement of drill pipes and allow the pipe ends to pass smoothly. Finally, the developed system is employed in a drilling field for drill pipe inspection. Test results show that the proposed method can fulfill the requirements for drill pipe inspection at wellheads, which is of great importance in drill pipe safety.
Highlights
As critical components of drill strings, drill pipes are used to transmit torque and transport drilling fluids
ToTo meet thethe great needs wellheads,aanovel novellift-off-tolerant lift-off-tolerant meet great needsfor forMFL
Testing method has been proposed this which paper,has which high sensitivity and good. This novel method can be used for other ferromagnetic material inspections at wellheads, suchatas repeatability
Summary
Jianbo Wu 1 , Hui Fang 1, *, Long Li 2 , Jie Wang 1 , Xiaoming Huang 1 , Yihua Kang 2 , Yanhua Sun 2 and Chaoqing Tang 3.
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