Swellable metal packer with porous external sleeve

1. A swell packer, comprising:

a tubular;

a swellable metal sealing element disposed about the tubular; and

a porous layer disposed about the swellable metal sealing element;

wherein the swellable metal sealing element is configured to react with a downhole fluid to produce particles; and

wherein the porous layer is configured to contain the particles in an annulus between the porous layer and the tubular.

2. The swell packer of claim 1 , wherein the porous layer is movable between a first configuration in which the porous layer defines an unexpanded diameter and a second configuration in which the porous layer defines an expanded diameter that is greater than the unexpanded diameter.

3. The swell packer of claim 2 , wherein, when in the first configuration, the porous layer forms multiple longitudinal folds such that the porous layer is pleated.

4. The swell packer of claim 1 ,

wherein the porous layer comprises a mesh comprising nestable longitudinally-extending frame segments;

wherein each nestable longitudinally-extending frame segment defines a pore size; and

wherein the nestable longitudinally-extending frame segments are movable circumferentially relative to the swellable metal sealing element while maintaining the pore size for each nestable longitudinally-extending frame segment.

5. The swell packer of claim 1 , wherein the porous layer comprises a frame defining a plurality of voids, and wherein each void is sized based on a material of which the swellable metal sealing element is at least partially composed.

6. The swell packer of claim 1 ,

wherein the porous layer comprises first portions having a first permeability and second portions having a second permeability that is less than the first portions; and

wherein the first and second portions are spaced longitudinally and/or circumferentially along the swellable metal sealing element.

7. The swell packer of claim 6 , wherein the first portions form a pattern relative to the second portions; and wherein the pattern is variable along a longitudinal direction of the swellable metal sealing element.

8. The swell packer of claim 6 , wherein the porous layer that is selected has a permeability that is based on the downhole fluid expected to contact the porous layer.

9. The swell packer of claim 1 , wherein the swellable metal sealing element comprises magnesium and/or aluminum.

10. The swell packer of claim 1 , wherein the porous layer has a permeability that is variable along a longitudinal direction of the well packer.

11. A method for forming a seal in a wellbore comprising:

positioning a swell packer comprising a swellable metal sealing element disposed about a tubular in the wellbore;

wherein a porous layer is disposed about the swellable metal sealing element;

exposing the swellable metal sealing element to a downhole fluid;

allowing or causing to allow the swellable metal sealing element to react with the downhole fluid to produce particles; and

accumulating the particles within a first annulus formed between the porous layer and the tubular.

12. The method of claim 11 , further comprising enlarging a diameter of the porous layer to sealingly engage a wall of the wellbore.

13. The method of claim 12 , wherein the accumulation of the particles results in the enlargement of the diameter of the porous layer.

14. The method of claim 12 , wherein the porous layer forms multiple longitudinal folds such that the porous layer is pleated.

15. The method of claim 11 , wherein the swell packer comprises magnesium and/or aluminum.

16. The method of claim 11 ,

wherein the porous layer comprises a mesh comprising nestable longitudinally-extending frame segments;

wherein each nestable longitudinally-extending frame segment defines a pore size; and

wherein enlarging the diameter of the porous layer comprises circumferentially moving the nestable longitudinally-extending frame segments while maintaining the pore size for each nestable longitudinally-extending frame segment.

17. The method of claim 11 , wherein the porous layer comprises a frame defining pores, and wherein the pores are sized based on a material forming the swellable metal sealing element.

18. The method of claim 11 , wherein the swellable metal sealing element comprises magnesium.

19. The method of claim 11 , further comprising selecting the porous layer having a permeability based on the downhole fluid expected to contact the porous layer.

20. The method of claim 11 , wherein the porous layer has a permeability that is variable along a longitudinal direction of the swell packer.