Finite Element Analysis of 3D Defect Characterization in Coiled Tubing in Weak Magnetic Field.

In this paper, signal characterization of arbitrary three-dimensional (3D) defects with weak magnetic field signals from coiled tubing inspections is investigated. A detection model based on weak magnetic fields using the geomagnetic field is established using the finite element method, with different-shape 3D defects on the surface of coiled tubing, typically cylindrical, conical, spherical, rectangular, and crack-like defects. The weak magnetic signal characteristic response from each of these defects has been simulated in this research. This paper acquires the characteristics of the three components of self-leakage magnetic signal and illustrates the characteristics of five typical 3D defects using self-leakage magnetic signal, and the shapes and sizes of different defects are presented as 3D images. The focus of the investigation is to identify and estimate the size and shape of surface 3D defects on the basis of their weak magnetic signal features. [ABSTRACT FROM AUTHOR]