Three magnet casing collar locator
US4808925A · kind A · utility
242Cited by
2References
6Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Nov 19, 1987 |
| Grant date | Feb 28, 1989 |
| Priority date | — |
| Expiry date | Nov 19, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/26
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
For use with casing having flush joint collars, a detection system is set forth which comprises a tool body made of nonmagnetic material and enclosing abutted first, second and third permanent magnets. The magnets are axially aligned, abutted so that opposing poles are in contact with one another, thereby forming a magnetic field from the center magnet which is focused out into the metal of the casing. Separate detection coils spaced along the tool body detect signals induced by variations in magnetic reluctance as the tool traverses the cased well.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.