Downhole flow control device

1. A downhole flow control device for controlling a flow of a fluid from a borehole into a well tubular structure and/or from the well tubular structure into the borehole, comprising:

a base tubular having an axial axis and adapted to be mounted as part of the well tubular structure, the base tubular having a first opening,

a first sleeve arranged within the base tubular, the first sleeve having a first sleeve part and a second sleeve part with a second opening, and the first sleeve being adapted to slide along the axial axis for at least partly aligning the first opening with the second opening,

wherein a second sleeve is arranged at least partly between the second sleeve part and the base tubular, and

an engagement element is arranged for engaging an indentation of the second sleeve part in a first position and for disengaging the indentation of the second sleeve part in a second position,

wherein the second sleeve is engaged with the second sleeve part in the first position and is disengaged from the second sleeve part in the second position.

2. The downhole flow control device according to claim 1 , wherein the second sleeve has a through-going bore in which the engagement element is arranged.

3. The downhole flow control device according to claim 1 , wherein the base tubular has a recess for receiving the engagement element at the second position.

4. The downhole flow control device according to claim 1 , wherein the downhole control device is configured to open the first opening by movement of the first sleeve and the second sleeve in a first direction along the axial axis and to close the first opening by movement of the first sleeve and the second sleeve in a second direction, the second direction being the opposite direction in relation to the first direction, along the axial axis.

5. The downhole flow control device according to claim 3 , wherein the recess has a first recess end and a second recess end, the second recess end being closest to the first opening, the first recess end having a first end face which is inclined and the second recess end having a second end face extending in a direction substantially perpendicular to the axial axis.

6. The downhole flow control device according to claim 5 , wherein the second sleeve is prevented from sliding past the first opening when the engagement element is in engagement in the recess and abuts the second end face.

7. The downhole flow control device according to claim 5 , wherein the inclined first end face of the recess is configured to disengage the engagement element from the recess by the engagement element sliding up from the recess during the movement of the second sleeve in the second direction.

8. The downhole flow control device according to claim 1 , wherein the engagement element is spring-loaded.

9. The downhole flow control device according to claim 1 , further comprising a first sealing element and a second sealing element, the first sealing element being arranged in a first circumferential groove in the base tubular on a first side of the first opening and the second sealing element being arranged in a second circumferential groove in the base tubular on a second side of the first opening, the second side being opposite the first side.

10. The downhole flow control device according to claim 9 , wherein the first sealing element is arranged between the first sleeve part and the base tubular, and the second sealing element is arranged between the first sleeve part and the base tubular in the first position and between the second sleeve and the base tubular in the second position.

11. The downhole flow control device according claim 1 , wherein the first sleeve part and the second sleeve part are produced as one sleeve.

12. The downhole flow control device according to claim 1 , wherein the first sleeve part is a third sleeve which is connected with the second sleeve part.

13. The downhole flow control device according to claim 1 , wherein the first sleeve part has a first end and a second end, and the second sleeve has a first end and a second end, the first end of the first sleeve part abutting the second end of the second sleeve in the first position.

14. The downhole flow control device according to claim 13 , wherein a gap is formed between the second end of the second sleeve and the first end of the first sleeve part when the second sleeve is prevented from movement in the first direction and the first sleeve part continues to move past the first opening, whereby fluid communication between the first opening and the second opening is provided via the gap.

15. The downhole flow control device according to claim 1 , wherein the second sleeve part has an inner face and a groove in the inner face for engagement with a key tool of a downhole tool.

16. The downhole flow control device according to claim 1 , wherein the flow control device is a frac port or an inflow control device or a valve.

17. A downhole system for controlling a flow of a fluid from a borehole into a well tubular structure and/or from the well tubular structure into the borehole, comprising:

a well tubular structure, and

the downhole flow control device according to claim 1 .

18. The downhole system according to claim 17 , further comprising an annular barrier, the annular barrier comprising:

a tubular part adapted to be mounted as part of the well tubular structure, the tubular part having an outer face,

an expandable sleeve surrounding the tubular part and having an inner sleeve face facing the tubular part and an outer sleeve face facing the wall of the borehole, each end of the expandable sleeve being connected with the tubular part, and

an annular space between the inner sleeve face of the expandable sleeve and the tubular part.

19. The downhole system according to claim 18 , wherein the annular barrier is a first annular barrier and the system further comprises a second annular barrier, both adapted to be expanded in an annulus between the well tubular structure and a wall of the borehole or another well tubular structure downhole for providing zone isolation of a production zone positioned between the first and second annular barriers, the downhole flow control device being arranged opposite the production zone.