Downhole expandable tubular

1. A downhole expandable tubular to be expanded in a well downhole from a first outer diameter (D 1 ) to a second outer diameter (D 2 ) to abut against an inner face of a casing or borehole, the downhole expandable tubular having an axial extension,

wherein the downhole expandable tubular is made of metal and is machined from one metal tubular blank, providing the downhole expandable tubular with at least one circumferential projection extending entirely around the expandable tubular along a plane substantially perpendicular to the axial extension, and

wherein the metal tubular blank is made by centrifugal or spin casting.

2. The downhole expandable tubular according to claim 1 , wherein the downhole expandable tubular is machined, providing the downhole expandable tubular with at least one groove.

3. The downhole expandable tubular according to claim 1 , wherein the machining is performed as milling, cutting or grinding or latheing.

4. The downhole expandable tubular according to claim 1 , wherein the tubular blank has an inner diameter (D i ) and an outer diameter (D o ), said blank being machined so as to increase the inner diameter (D i ) and/or decrease the outer diameter (D o ).

5. The downhole expandable tubular according to claim 1 , wherein the tubular blank is made from steel or stainless steel.

6. The downhole expandable tubular according to claim 1 , wherein the downhole expandable tubular has a length and the downhole expandable tubular is machined along the entire length.

7. The downhole expandable tubular according to claim 1 , wherein the downhole expandable tubular comprises several projections and/or at least one groove.

8. The downhole expandable tubular according to claim 7 , wherein a sealing element is arranged between two adjacent projections or in the groove.

9. The downhole expandable tubular according to claim 8 , wherein a ring-shaped retaining element is arranged between two adjacent projections or in the groove for pressing the sealing element in the axial extension towards an edge of the projection or groove.

10. The downhole expandable tubular according to claim 9 , wherein the ring-shaped retaining element is a split ring.

11. The downhole expandable tubular according to claim 9 , wherein an intermediate element is arranged between the ring-shaped retaining element and the sealing element.

12. The downhole expandable tubular according to claim 1 , wherein the downhole expandable tubular is a patch to be expanded within a casing or well tubular structure in a well, a liner hanger to be at least partly expanded within a casing or well tubular structure in a well, or a casing to be at least partly expanded within another casing.

13. An annular barrier to be expanded in an annulus between a well tubular structure and an inside face of a casing or borehole downhole for providing zone isolation between a first zone and a second zone of the casing or borehole, the annular barrier having an axial extension and comprising:

a tubular part, the tubular part being a separate tubular part or a casing part for mounting a part of the well tubular structure,

the downhole expandable tubular according to claim 1 , the expandable tubular surrounding the tubular part, each end of the expandable tubular being connected with the tubular part and extending along the axial extension,

an annular barrier space between the tubular part and the expandable tubular, and

an expansion opening in the tubular part through which fluid may enter the space in order to expand the expandable tubular.

14. The annular barrier according to claim 13 , further comprising at least one sealing element surrounding the downhole expandable tubular.

15. The annular barrier according to claim 13 , wherein the downhole expandable tubular has an opening providing fluid communication between the first or the second zone and one of the space sections.

16. The annular barrier according to claim 13 , wherein the projection is a ring-shaped projection of an increased thickness in relation to other parts of the downhole expandable tubular, the ring-shaped projection providing an enforcement of the annular barrier when the annular barrier is expanded.

17. A downhole completion comprising a well tubular structure and an annular barrier according to claim 13 , where the tubular part of the annular barriers is mounted as part of the well tubular structure.

18. A downhole completion comprising a downhole expandable tubular according to claim 1 , and a casing having an inner face against which at least part of the downhole expandable tubular is expanded.

19. A manufacturing method for the manufacture of the downhole expandable tubular according to claim 1 , comprising:

machining the metal tubular blank to a decreased inner and outer diameter, and

machining the metal tubular blank, providing it with at least one circumferential projection or groove.