Top plug with transitionable seal

1. A method of well completion comprising:

floating a casing in a wellbore;

engaging a first plug with a landing collar of the casing;

pumping cement downhole through the casing and the first plug to supply cement between the casing and the wellbore;

engaging a second plug with the first plug, wherein the second plug includes a transitionable seal sealing a bore of the second plug;

increasing a pressure in the casing to pressure test the casing; and

decreasing the pressure in the casing to cause the transitionable seal to unseal the bore of the second plug.

2. The method of claim 1 , wherein the transitionable seal includes at least one of a cap and a sleeve.

3. The method of claim 1 , wherein the transitionable seal seals the bore of the second plug at least until completion of the pressure testing.

4. The method of claim 1 , wherein pressure testing includes the decrease in the pressure.

5. The method of claim 1 , wherein a pressure-drop signal includes the pressure decrease to cause the transitionable seal to unseal the bore of the second plug.

6. The method of claim 1 , wherein:

the increasing the pressure shears at least one shearable member holding the transitionable seal in a position to block the bore of the second plug.

7. The method of claim 1 , wherein the casing includes a pre-load collar located uphole from the landing collar, the method further comprising:

releasing the first plug from the pre-load collar.

8. The method of claim 1 , further comprising:

after pumping the cement and before engaging the second plug to the first plug, pumping a third plug downhole through the casing.

9. The method of claim 7 , further comprising:

perforating the casing between the pre-load collar and the landing collar.

10. The method of claim 7 , further comprising, after releasing the first plug and before pumping the cement and engaging the second plug with the first plug, pumping a third plug downhole through the casing.

11. A method of well completion comprising:

causing a casing to be floated in a wellbore;

causing cement to be pumped downhole through the casing to supply cement between the casing and the wellbore;

sequentially engaging a first plug with an uphole end of a second plug in the casing, wherein the first plug includes:

a housing;

a flow path; and

a transitionable seal moveable from a first position to a second position, wherein the flow path is blocked by the transitionable seal in the first position and unblocked by the transitionable seal in the second position; and

decreasing pressure of a wellbore fluid above the transitionable seal to move the transitionable seal from the first position to the second position.

12. The method of claim 11 , wherein the transitionable seal includes at least one of a cap and a sleeve.

13. The method of claim 11 , wherein the transitionable seal blocks the flow path until the completion of a pressure test.

14. The method of 11 , wherein the second plug is engaged with an uphole end of a third plug.

15. The method of claim 11 , further comprising:

increasing pressure of the wellbore fluid above the transitionable seal to move the transitionable seal from a third position to the first position, wherein the flow path is blocked when the transitionable seal is in the third position.

16. A method of well completion comprising:

landing a plug in a casing, the plug including a transitionable seal partially disposed outside a housing, the housing including a flow path, the transitionable seal blocking the flow path;

increasing a fluid pressure uphole of the landed plug to perform a pressure test; and

decreasing the fluid pressure to move the transitionable seal to open the flow path to allow fluid uphole of the landed plug to flow through the open flow path.

17. The method of claim 16 , wherein increasing the fluid pressure causes the transitionable seal to move from a first position to a second position, wherein the flow path is blocked when the transitionable seal is in the first position and second position.

18. The method of claim 17 , wherein decreasing the fluid pressure causes the transitionable seal to move from the second position to a third position.

19. The method of claim 16 , wherein the landed plug is a first plug, and wherein a second plug is landed in the casing prior to landing the first plug.

20. The method of claim 16 , wherein increasing the fluid pressure includes increasing the fluid pressure to a level above a biasing force applied to the transitionable seal.

21. The method of claim 20 , wherein decreasing the fluid pressure includes decreasing the fluid pressure to a level below the biasing force applied to the transitionable seal.

22. A method of well completion comprising:

landing a plug in a casing, the landed plug including:

a transitionable seal partially disposed outside a housing and blocking a flow path;

increasing a fluid pressure uphole of the landed plug to perform a pressure test, wherein increasing the fluid pressure causes the transitionable seal to move from a first position to a second position, wherein the flow path is blocked when the transitionable seal is in the first position and second position; and

decreasing the fluid pressure to move the transitionable seal to open the flow path.

23. The method of claim 22 , wherein decreasing the fluid pressure causes the transitionable seal to move from the second position to a third position.

24. A method of well completion comprising:

landing a plug in a casing, the landed plug including a biasing member and a transitionable seal blocking a flow path, wherein the transitionable seal includes a first portion and a second portion, and wherein second portion is at least partially disposed within the biasing member;

increasing a fluid pressure uphole of the landed plug to perform a pressure test, wherein increasing the fluid pressure includes increasing the fluid pressure to a level above a biasing force applied to the transitionable seal by the biasing member; and

decreasing the fluid pressure below the biasing force such that the biasing member moves the transitionable seal to open the flow path.

25. The method of claim 16 , wherein the flow path is a bore formed in the housing and at least one port formed the housing.

26. The method of claim 22 , wherein the transitionable seal is a cap having a lid portion and a stopper portion, wherein the stopper portion blocks the flow path in the first and second positions.