Abstract: A tubing trip tool for use in determining the extent of defects in tubular sections of a continuous tubing string used in subterranean oil and gas wells is disclosed. The tubing trip tool is mounted on a surface rig surrounding the tubing string and defects are magnetically detected during tubing removal from the well bore. The tool comprises a segmented expandable detector head containing elements for measuring average wall thickness and local and axially extending defects. The expandable head is spring loaded and pneumatically actuated. Coupling detectors are located on the ends of the head to count tubing sections and to detect the presence of obstructions on the tubing to prevent damage to the detector head.

Abstract: 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, such as corrosion pitting, and axial defects, such as sucker rod wear during removal of the tubing from the well. Tubing velocity is also measured, and couplings between tubing sections are detected and counted, in order to specify the axial location of defects on each tube, and also provide a profile of the condition of the overall string. A saturating magnetic field and a fluctuating magnetic field are applied to the tubing and the magnitude of the induced fields and the changes are measured to quantify defects in the tubing.

Abstract: 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, such as corrosion pitting, and axial defects, such as sucker rod wear during removal of the tubing from the well. Tubing velocity is also measured, and couplings between tubing sections are detected and counted, in order to specify the axial location of defects on each tube, and also provide a profile of the condition of the overall string. A saturating magnetic field and a fluctuating magnetic field are applied to the tubing and the magnitude of the induced fields and the changes are measured to quantify defects in the tubing.