Magnetic Flux Leakage Data Processing for Casing Inspection: An Inversion Approach

Abstract

Measurements of magnetic flux leakage are used extensively to map and monitor defects and corrosion in pipelines, well casings, and storage tanks. The application of this method enables locating defects and determining metal loss. The measurements have complex response characteristics, which must be understood to optimize measurement design and data processing choices. Until recently, the industry lacked an adequate first principles description of sensitivity to defect penetration and size, including the foundational cases of circular and elliptical defects. An inversion method has been developed and validated with independent synthetic and lab data. The data was obtained using an analytical forward model, finite element modeling, and laboratory data from different thickness and diameter pipes with known machined defects of different sizes and penetrations. The approach enables inverting field data to reconstruct 3D defect profiles, which helps to assess casing health and offers valuable information to the decision-maker for well integrity.