Method and apparatus for measuring defects in tubular members

摘要

A method and apparatus for determining the extent of defects in ferromagnetic tubular elements comprising a continuous string for use in an oil or gas well is disclosed. The tubing trip tool measures tubing average wall thickness, local defects, and axial defects, such as sucker rod wear during removal of the tubing from the well. Tubing velocity is also measured. A saturating magnetic field and a fluctuating magnetic field are applied to the tubing. Signals corresponding to changes in the induced fields are divided into channels for complete circumferential coverage. Phase shift is then determined by a zero crossing technique to quantify axial defects, such as sucker rod wear.