Method and apparatus for measuring the depth of local defects in ferromagnetic elements
US4704580A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 11, 1984 |
| Grant date | Nov 3, 1987 |
| Priority date | — |
| Expiry date | Apr 11, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/82
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for determining the extent of defects in ferrogmagnetic elements, such as tubing comprising a continuous string for use in an oil or gas well is disclosed. The tubing trip tool measures the depth of local defects, such as corrosion pitting, 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 is applied to the tubing and a comparison of two derivatives of flux leakage is made to quantify defects in the tubing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.