Coiled tubing magnetic detection method

Abstract

The invention discloses a magnetic detection method for coiled tubings. The magnetic detection method comprises the steps of finding a position of a magnetic abnormal point through magnetic field intensity gradients, obtaining a two-dimensional matrix of the magnetic abnormal point through an interpolation algorithm, fitting an amplitude relationship expression between defect burial depth and the magnetic abnormal point, and reflecting defect size, position, shape and burial depth of the coiled tubings by size, position, shape and contour line value of abnormal area in color contour line images of the defect burial depth. The magnetic detection method calculates the two-dimensional matrix of the coiled tubings according to the magnetic signals acquired by the magnetic detection and obtains information such as the defect size, position, shape and burial depth of the detected coiled tubings from the matrix.

Description

technical field [0001] The invention relates to a coiled tubing detection method, in particular to a magnetic detection method for coiled tubing to measure the geomagnetic field based on a fluxgate sensor, which is mainly used for detecting the size, position, shape, buried depth and other information of coiled tubing defects. Background technique [0002] Coiled tubing technology has been widely used in workover, logging and drilling. Coiled tubing (CT) is the core component of the coiled tubing operation device, and the annual domestic usage of coiled tubing is about 30*10 4 m, the global annual consumption is about 500*10 4 m. Coiled tubing is subjected to axial load, internal pressure and complex bending stress during operation, and the main failure modes are corrosion, mechanical damage and manufacturing defects. The main problems encountered by coiled tubing in field use are severe corrosion or rust, blisters, pits and scratches on the surface, leakage, snapping...

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Problems solved by technology

[0004] However, the current online ultrasonic detector can only detect the wall thickness and ellipticity of the tubing, but cannot detect defects. Ultrasonic testing also requires a coupling agent, which makes it difficult to detect oil-stained pipes on site; the magnetic flux leakage detection method can only detect surface defects. It cannot detect the depth of defects, and most of them can only detect transverse defects, but cannot detect small longitudinal defects in the depths. At the same time, magnetic flux leakage detection requires strong magnetism for magnetization, and the equipment is heavy

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