| 摘要 |
The invention relates to a positioning tool for determining the position in a casing downhole. The positioning tool has a longitudinal tool axis (A) and comprises a detecting unit (2) comprising a first magnet (4) for generating a magnetic field (14), a first sensor (6) arranged in a first plane and at a first distance from the first magnet, for detecting changes in the magnetic field, and a second (5) sensor arranged in the first plane and at a second distance from the first sensor along (6) the axis, also for detecting changes in the magnetic field. |
