Well tool

1. A well tool for removing metal debris from a well bore, comprising a magnet element, a rotation generation device, a debris removal unit and a debris container, wherein

the magnet element comprises a cylinder-shaped housing having a first end and a second end;

the debris removal unit comprises a first helix-shaped longitudinal guide element arranged around the cylinder-shaped housing;

the rotation generating device is operably connected to the cylinder-shaped housing or the first helix-shaped longitudinal guide element;

the debris container comprises a first opening arranged at the second end of the cylinder-shaped housing,

wherein

the cylinder-shaped housing, or the first helix-shaped longitudinal guide element, is rotatable around its centreline, and configured such that metal debris accumulating on the cylinder-shaped housing during use is guided by the first helix-shaped longitudinal guide element towards the first opening of the debris container when the rotation generating device is operated.

2. A well tool according to claim 1 , wherein the rotation generating device comprises a rotary nozzle assembly.

3. A well tool according to claim 2 , wherein the rotary nozzle assembly comprises nozzles directed at an angle in relation to a plane perpendicular to the centreline of the cylinder-shaped housing and inclined in the direction towards the debris container.

4. A well tool according to claim 1 comprising a connecting end distal from the debris container, the connecting end being suitable for connecting the well tool to a wireline, a power cable, an umbilical, a well string, a drill pipe or a coiled tubing.

5. A well tool according to claim 1 comprising a tube element aligned around the centreline of the cylinder-shaped housing and extending through the cylinder-shaped housing and the debris container.

6. A well tool according to claim 5 , wherein the rotation generating device comprises a rotary nozzle assembly, and the tube element comprises radial through-bores fluidly connected to nozzles of the rotary nozzle assembly.

7. A well tool according to claim 5 or 6 , wherein the tube element is connectable to a string, pipe or coiled tubing.

8. A well tool according to claim 1 comprising a second helix-shaped longitudinal guide element operably connected to the rotation generating device and arranged within the debris container, the handedness of the second helix-shaped longitudinal guide element is configured such that metal debris being guided by the first helix-shaped longitudinal guide element towards the first opening of the debris container is guided further into the debris container by the second helix-shaped longitudinal guide element when the rotation generating device is operated.

9. A well tool according to claim 1 , wherein the cylinder-shaped housing comprises an end section which is tapered towards the second end.

10. A well tool according to claim 1 , wherein the first opening of the debris container have an edge featuring a rounded recess at the intersection between the first helix-shaped longitudinal guide element and said edge.

11. A well tool according to claim 1 , wherein the debris container is cylinder-shaped, and wherein the centreline of the debris container is aligned with the centreline of the cylinder-shaped housing of the magnet element.

12. A well tool according to claim 1 , wherein the rotation generating device is arranged at the first end of the cylinder-shaped housing of the magnet element.