Seal apparatus and methods of use

1. A seal apparatus comprising:

a seal assembly comprising a plurality of seal elements assembled together to form a ring structure around a longitudinal axis;

wherein the ring structure is operable to be moved between an expanded condition and a collapsed condition by movement of the plurality of seal elements;

and wherein the plurality of seal elements is operable to be moved between the expanded and collapsed conditions by sliding with respect to one another along respective contact surfaces;

wherein each of the plurality of seal elements is each formed from a compliant, compressible or resilient material;

wherein at least some of the plurality of seal elements are formed from different materials, or formed with different material characteristics; and

wherein sequential seal elements in the ring structure are alternately formed from different materials and/or different material characteristics.

2. The seal apparatus according to claim 1 , wherein the plurality of seal elements are formed from a plastic, rubber, or elastomeric material.

3. The seal apparatus according to claim 1 , wherein the plurality of seal elements are fully formed from the compliant, compressible or resilient material.

4. The seal apparatus according to claim 1 , wherein at least a part of one or more of the plurality of seal elements is coated with a low friction material.

5. The seal apparatus of claim 1 , wherein the ring structure is operable to be expanded to a seal diameter, at which the plurality of elements are presented to a surface in use, wherein the seal diameter is an outer diameter of the ring structure.

6. The seal apparatus of claim 5 , wherein the surface is an inner surface of a tubular, tool or borehole.

7. The seal apparatus according to claim 1 , comprising one or more anti-extrusion and/or support rings for the seal assembly.

8. The seal apparatus according to claim 7 , comprising one or more additional expanding and collapsing ring structures, which function as anti-extrusion and/or support rings for the seal assembly.

9. The seal apparatus of claim 1 , wherein each seal element comprises a first contact surface and second contact surface respectively in abutment with first and second adjacent seal elements.

10. The seal apparatus of claim 9 , wherein the first contact surface and/or the second contact surface converge towards one another in a direction towards an inner surface of the ring structure.

11. The seal apparatus of claim 1 , wherein the seal elements are provided with interlocking profiles for interlocking with an adjacent seal element.

12. The seal apparatus of claim 1 , wherein the ring structure is a solid ring structure in its expanded condition.

13. A seal apparatus comprising:

a seal assembly comprising a plurality of seal elements assembled together to form a ring structure around a longitudinal axis;

wherein the ring structure is operable to be moved between an expanded condition and a collapsed condition;

wherein in the expanded condition, the plurality of elements combine to form a solid seal ring structure having a surface;

wherein each of the plurality of seal elements is formed from a compliant, compressible or resilient material;

wherein each element comprises a first contact surface and second contact surface respectively in abutment with first and second adjacent seal elements; and

wherein the first contact surface and/or the second contact surface converge towards one another in a direction towards an inner surface of the ring structure.

14. The seal apparatus of claim 13 , wherein the surface comprises a first surface portion configured for sealing with an external surface to the seal assembly.

15. The seal apparatus of claim 14 , wherein the surface comprises a second surface portion configured for sealing with an internal surface to the seal assembly.

16. The seal apparatus of claim 15 , wherein the surface comprises a third surface portion, axially separated from the second surface portion, configured for sealing with an internal surface to the seal assembly.

17. A seal apparatus comprising:

a seal assembly comprising a plurality of seal elements assembled together to form a ring structure around a longitudinal axis;

wherein the ring structure is operable to be moved between an expanded condition and a collapsed condition by movement of the plurality of seal elements;

and wherein the plurality of seal elements is operable to be moved between the expanded and collapsed conditions by sliding with respect to one another along respective contact surfaces;

wherein each of the plurality of seal elements is each formed from a compliant, compressible or resilient material;

wherein each element comprises a first contact surface and second contact surface respectively in abutment with first and second adjacent elements; and

wherein the first contact surface and/or the second contact surface converge towards one another in a direction towards an inner surface of the ring structure.

18. The seal apparatus of claim 13 , wherein the surface is a smooth surface.