WE CLAIM:
1. A downhole tubing cutter tool (1) for submerging into a casing (2) or a drill pipe
(2) in a wellbore (3) and separating an upper part (4) of the casing from a lower part (5)
of the casing by cutting the casing from within, the tool extending in a longitudinal
direction, comprising:
- a tool housing (6) having a first (7) and a second (8) housing part,
- a cutting arm (9) which is pivotably connected with the first housing part and has a cutting edge (10) in a first end (10), said arm being movable between a retracted position and a projected position in relation to the tool housing,

- an arm activation assembly (11) for moving the cutting arm between the retracted position and the projected position, and
- a rotatable shaft (12) arranged in the second housing part and rotatably connected with the first housing part for rotating the cutting arm,
characterized in that the arm activation assembly comprises:
- a piston housing (13) arranged in the first housing part and comprising a piston chamber (14), and
- a piston member (15) arranged inside the piston chamber and engaged with the cutting arm to move the cutting arm between the retracted position and the projected position, the piston member being movable in the longitudinal direction of the downhole tool and having a first piston face (16) and a second piston face (17), the piston member being capable of applying a projecting force on the cutting arm by applying hydraulic pressure on the first piston face and moving the piston in a first direction (18).
2. The downhole tubing cutter tool as claimed in claim 1, wherein the piston
chamber is divided into a first chamber section (25) and a second chamber section (26),
and the hydraulic pressure on the first piston face, moving the piston in a first direction, is
applied into the first chamber section.
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3. The downhole tubing cutter tool as claimed in claim 2, wherein a hydraulic pressure is applied into the second chamber section, thereby moving the piston member in a second direction opposite the first direction.
4. The downhole tubing cutter tool as claimed in claim 2 or 3, wherein the chamber is divided by the piston.
5. The downhole tubing cutter tool as claimed in claim 2 or 3, wherein the chamber is divided by a partitioning wall (46) of the piston housing through which the piston member extend.
6. The downhole tubing cutter tool as claimed in any one of the preceding claims, wherein a spring member (40) is arranged in the first housing part, applying a spring force to move the piston member in a second direction opposite the first direction.
7. The downhole tubing cutter tool as claimed in claim 6, wherein the spring member is arranged in the second chamber section.
8. The downhole tubing cutter tool as claimed in any one of the preceding claims, wherein the piston member has a groove (31) cooperating with a second end (32) of the cutting arm.
9. The downhole tubing cutter tool as claimed in any one of the preceding claims, wherein the downhole tubing cutter tool comprising an anchor section (22) for anchoring the second housing part in the casing.
10. The downhole tubing cutter tool as claimed in any one of the preceding claims, wherein the cutting arm in cross-section has an edge (38) forming an outermost point of the arm when the arm is in its projected position, and the cutting edge is arranged at that edge forming the edge.
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11. The downhole tubing cutter tool as claimed in any one of the preceding claims, wherein the downhole tubing cutter tool comprising a gear section (23).
12. The downhole tubing cutter tool as claimed in any one of the preceding claims, wherein the downhole tubing cutter tool comprising a rotation unit (20), such as an electrical motor or a hydraulically driven impellor.
13. The downhole tubing cutter tool as claimed in any one of the preceding claims, wherein the cutting arm is L-shaped, creating a heel part (50), and pivotably connected around a pivot point (33) arranged in the heel part.
14. The downhole tubing cutter tool as claimed in any one of the preceding claims, wherein the downhole tubing cutter tool comprising a pump (21) for supplying the hydraulic pressure.
15. A downhole system, comprising:

- a downhole tubing cutter tool as claimed in any one of claims 1 to 14, and
- a driving unit (51) for moving the downhole tubing cutter tool forward in the casing.
Dated this 04 day of October 2013
DIGITALLY SIGNED
( Arindam Paul ) REG. No: IN/PA-324 of De Penning & De Penning Agent for the Applicants
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