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1. (WO2019027462) METHODS FOR SUPPORTING WELLBORE FORMATIONS WITH EXPANDABLE STRUCTURES
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CLAIMS

What is claimed is:

1. A method to provide support within a wellbore, comprising:

underreaming a section of the wellbore at a depth spanning a layer of an unstable formation; deploying a bistable structure within the wellbore at the depth of the layer of the unstable formation; and

actuating an expandable packer within the bistable structure to expand the bistable structure in a radially outward direction from a longitudinal axis of the bistable structure, wherein the bistable structure is in contact with walls of the underreamed section of the wellbore upon expanding in the radially outward direction.

2. The method of claim 1 , wherein underreaming the section of the wellbore is performed by an underreamer while a downhole portion of the wellbore is drilled by a drill bit.

3. The method of claim 1 , comprising:

drilling the wellbore with a drill bit to a location downhole from the depth of the layer of the unstable formation; and

replacing the drill bit with an underreamer to underream the section of the wellbore spanning the depth of the layer of the unstable formation.

4. The method of claim 1 , wherein actuating the expandable packer comprises actuating a hydraulic pump to expand the expandable packer within the bistable structure.

5. The method of claim 1 , wherein the bistable structure comprises a sealing layer as an outer surface of the bistable structure, and, upon expansion of the bistable structure, the sealing layer is in contact with the walls of the underreamed section of the wellbore.

6. The method of claim 5, wherein the sealing layer comprises a mesh material or an elastomeric material.

7. The method of claim 1 , comprising drilling the wellbore downhole from the bistable structure upon expansion of the bistable structure within the underreamed section of the wellbore.

8. The method of claim 1 , comprising:

underreaming a second section of the wellbore at a second depth spanning a second layer of the unstable formation;

deploying a second bistable structure within the wellbore at the second depth; and actuating a second expandable packer within the second bistable structure to expand the second bistable structure in the radially outward direction from a second longitudinal axis of the second bistable structure, wherein the second bistable structure is in contact with walls of the second section of the wellbore upon expanding in the radially outward direction.

9. The method of claim 1, wherein the bistable structure comprises at least two independent sections, and a combined length of the at least two independent sections is substantially equal to a length of the underreamed section of the wellbore.

10. The method of claim 1 , wherein underreaming the section of the wellbore comprises cutting into a wall of the wellbore to expand a diameter of the wellbore by an amount equal to two times a thickness of a wall of the bistable structure.

1 1. A method comprising:

drilling a wellbore through a layer of an unstable formation;

underreaming a section of the wellbore at the layer of the unstable formation;

positioning a bistable structure in a collapsed state at a depth of the underreamed section of the wellbore;

expanding the bistable structure to an expanded state, wherein the bistable structure is in contact with the underreamed section of the wellbore upon expansion of the bistable structure; and

drilling downhole from the layer of the unstable formation.

12. The method of claim 11, comprising:

underreaming a second section of the wellbore at a second layer of the unstable formation; positioning a second bistable structure in the collapsed state at a second depth of the second underreamed section of the wellbore; and

expanding the second bistable structure to the expanded state, wherein the second bistable structure is in contact with the second underreamed section of the wellbore upon expansion of the second bistable structure.

13. The method of claim 11, wherein expanding the bistable structure to the expanded state comprises actuating an expandable packer positioned within the bistable structure.

14. The method of claim 11, wherein the bistable structure comprises a sealing layer configured to prevent portions of the unstable formation from entering the wellbore.

15. The method of claim 14, wherein the sealing layer comprises a mesh material or an elastomeric material that is compatible with wellbore fluids.

16. The method of claim 11, wherein underreaming the section of the wellbore is performed simultaneously with drilling the wellbore.

17. The method of claim 11, wherein positioning the bistable structure in the collapsed state at the depth of the underreamed section of the wellbore is accomplished using a wireline.

18. A system to support an unstable formation in a wellbore, comprising:

a bistable structure, wherein the bistable structure is configured to expand within an underreamed portion the wellbore from a collapsed state to an expanded state, and the bistable structure is stable in both the collapsed state and the expanded state; and

a sealing layer positioned around the bistable structure, the sealing layer configured to prevent debris from the unstable formation from entering the wellbore.

19. The system of claim 18, wherein the sealing layer comprises a mesh that prevents passage of solids from the unstable formation into the wellbore.

20. The system of claim 18, wherein the sealing layer comprises an elastomeric material that prevents contact between wellbore fluids and the unstable formation.