Anchor tool

1. Anchor tool for anchoring a downhole tool within a casing, a well, or any other downhole cavity, comprising:

a longitudinal tool body with a centre axis extending through the tool body in the centre of the body,

a first recess, a second recess, a third recess, and a fourth recess in the tool body, and

a first anchor, a second anchor, a third anchor, and a fourth anchor, where the first anchor is provided in the first recess, and so forth, and the anchors are outwards movable in the recesses for anchoring the tool,

wherein each anchor provided in the recesses extends through the tool body transverse to and across the centre axis, and is mounted with the tool body in a non-rotational engagement, and

wherein the anchors and the corresponding recesses are situated in the tool body for providing a symmetrical anchoring of the anchor tool as follows:

the first anchor is positioned in the first recess and so as to move across the centre axis and out in one direction orthogonal to the centre axis,

the second anchor is positioned in the second recess next to the first recess and so as to move across the centre axis and out in a second direction opposite and parallel to the first direction,

the third anchor is positioned in the third recess next to the second recess and so as to move in the second direction, and

the fourth anchor is positioned in the fourth recess next to the third recess and so as to move in the first direction.

2. The anchor tool according to claim 1 , wherein the anchor is movable by means of hydraulic.

3. The anchor tool according to claim 2 , wherein hydraulic fluid is pumped into the recess for forcing the anchor to move out of the recess for anchoring the tool to its surroundings.

4. The anchor tool according to claim 3 , wherein each anchor has a cavity with an opening and a retaining means fastened in the recess outside the anchor and extending through the opening into the cavity, and wherein a resilient means is provided within the cavity between an inside of the opening of the cavity and the retaining means and is compressed during movement of the anchor out of the recess.

5. The anchor tool according to claim 4 , wherein the resilient means is positioned around the retaining means.

6. The anchor tool according to claim 4 , wherein the retaining means has a rod extending though the resilient means, the rod at its one end being fastened to the recess and, at its other end, having a plate-shaped means for abutting against the resilient means.

7. The anchor tool according to claim 4 , wherein the resilient means is a helically spring.

8. The anchor tool according to claim 1 , wherein the recess on its inside is provided with a circumferential groove and at least one sealing means in the groove.

9. The anchor tool according to claim 1 , wherein the anchor has an oval or elliptic cross-section.

10. The anchor tool according to claim 1 , further comprising a pump system with a piston movable within a piston housing for pumping fluid into the recess.