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