Development and application of trenchless magnetic detector for oil and gas pipeline defect

Abstract

Trenchless detection technology for oil and gas pipeline defect is of great significance to remedy the shortcomings of in-pipeline detection and pipeline direct assessment technology. Pipeline defect detection technology can be expanded and the long-term service of the pipeline can be achieved due to the trenchless detection technology. According to the fluctuation range of ground magnetic field caused by typical pipeline defect, fluxgate sensor was selected as the sensitive element to detect the magnetic fluctuation of the pipeline in this paper. Excitation circuit, detection circuit and data processing circuit of fluxgate sensor were designed. Long-distance pipeline defect detection experiments under indoor and field conditions were carried out by using a self-made fluxgate detector. The indoor experimental results showed that the sensitivity of the magnetic detector is higher than that of the international advanced magnetic detector, and it can detect artificial pipe defects with a depth greater than 20% of the wall thickness at a distance of 1.6 ∼ 2.2 m (7 ∼ 10 times the pipe diameter). The field experimental results showed that the magnetic detector could detect corrosion thinning of pipeline with buried depth of 2.5 m (3.5 times diameter) effectively.