Well barrier method and apparatus

1. A method off setting a barrier within a wellbore, comprising:

deploying a running string into a wellbore, wherein the running string comprises a first plug assembly connected to the running string and a second plug assembly connected to the running string above the first plug assembly, the first and second plug assemblies comprising respective extendable arrangements;

setting the first plug assembly within the wellbore by extending its respective extendable arrangement;

injecting a settable medium via the running string above the first plug assembly;

providing a displacement barrier or restriction on the running string, wherein the displacement barrier is acted upon by the settable medium during injection, to facilitate or assist with displacement of the running string along the wellbore;

displacing the running string by the injected settable medium; and

setting the second plug assembly within the wellbore by extending its respective extendable arrangement during or after injection of the settable medium.

2. The method according to claim 1 , wherein the settable medium is selected from the group consisting of: cement, an epoxy, and/or a gel.

3. The method according to claim 1 , wherein the first plug assembly comprises a respective first extendable arrangement which is configured to provide sealing with a wall of the wellbore, and a respective second extendable arrangement which is configured to provide an anchor within the wellbore.

4. The method according to claim 3 , wherein the respective extendable arrangements of the first and/or second plug assemblies comprise a radially extendable structure comprising a deformable structure configured to be deformed to become radially extended, and the method comprises radially extending the radially extendable structure by application of an axial actuation force.

5. The method according to claim 4 , wherein the radially extendable structure comprises a bellows construction.

6. The method according to claim 1 , wherein the extendable arrangement comprises a metal structure, and the method comprises engaging the extendable arrangement with a metal wellbore structure to create a metal-to-metal seal.

7. The method according to claim 1 , wherein the extendable arrangement comprises a hybrid metal and non-metal construction and the method comprises engaging the extendable arrangement with a wellbore structure to create a hybrid metal and non-metal seal.

8. The method according to claim 1 , wherein the displacement barrier comprises an extendable structure provided on or otherwise associated with the running string, and wherein the displacement barrier extendable structure is activated to be extended prior to or during injection of the settable medium.

9. The method according to claim 8 , wherein the displacement barrier extendable structure comprises or is defined by an extendable arrangement of the second plug assembly.

10. The method according to claim 1 , wherein the displacement barrier extends from the running string to engage a wall of the wellbore, and functions to wipe the wall of the wellbore during displacement of the running string.

11. The method according to claim 1 , further comprising releasing the running string and the second plug assembly from the first plug assembly, and moving the second plug assembly relative to the first plug assembly.

12. The method according to claim 1 , further comprising injecting the settable medium within an axial space between the first and second plug assemblies.

13. The method according to claim 1 , wherein the second plug assembly comprises a respective first extendable arrangement which is configured to seal with a wall of the wellbore, and a respective second extendable arrangement which is configured to provide an anchor within the wellbore.

14. The method according to claim 1 , wherein the second plug assembly comprises an extendable arrangement which slidingly contacts a wall of the wellbore.

15. The method according to claim 1 , wherein the second plug assembly comprises an extendable arrangement, and the method comprises at least partially extending the extendable arrangement of the second plug assembly to define the displacement barrier.

16. The method according to claim 15 , further comprising partially extending the extendable arrangement of the second plug assembly to define the displacement barrier and subsequently fully or more completely extending the extendable arrangement to set the second plug assembly within the wellbore.

17. The method according to claim 1 , wherein after setting the first plug assembly within the wellbore by extending its respective extendable arrangement, the method further comprises releasing the running string and the second plug assembly from the first plug assembly, and wherein after the running string and the second plug assembly have been released from the first plug assembly, injecting the settable medium via the running string above the first plug assembly causes the running string and the second plug assembly to move relative to the first plug assembly.

18. The method according to claim 1 , further comprising providing further plug assemblies.

19. The method according to claim 1 , comprising setting a barrier during a well abandonment operation.

20. The method according to claim 1 , comprising setting a barrier as part of a wellbore construction operation.