Deploying an expandable downhole seat assembly

1. A method comprising:

deploying a seat assembly into a tubing string within well;

releasing the seat assembly inside the tubing string, wherein releasing the seat assembly radially expands and axially contracts the seat assembly;

pumping the seat assembly to a restriction in the tubing string at downhole location; and

receiving an untethered object on the seat assembly to form an obstruction in the tubing string.

2. The method of claim 1 , further comprising:

deploying the untethered object in the tubing string, wherein pumping the seat assembly comprises pumping the seat assembly with the landed untethered object.

3. The method of claim 1 , further comprising:

deploying the untethered object in the tubing string; and

landing the untethered object in the tubing string,

wherein the deploying and landing are performed after the pumping of the seat assembly.

4. The method of claim 1 , wherein deploying the seat assembly comprises running the seat assembly on a conveyance line.

5. The method of claim 1 , wherein deploying the seat assembly comprises running the seat assembly with a downhole tool.

6. The method of claim 1 , wherein releasing the seat assembly comprises the seat assembly frictionally engaging a wall of the tubing string.

7. The method of claim 1 , wherein releasing the seat assembly comprises using another restriction in the tubing string that contacts the seat assembly.

8. The method of claim 1 , wherein releasing the seat assembly comprises using a go-no-go ring installed uphole of the restriction in the tubing string.

9. The method of claim 1 , further comprising dissolving at least one of the untethered object and the seat assembly.

10. The method of claim 9 , further comprising flowing the untethered object or the seat assembly in a flowback operation to complete removal of the untethered object or seat assembly.

11. The method of claim 1 , further comprising using the obstruction to perform a downhole operation.

12. An apparatus comprising:

a tubing string installable in a well, the tubing string having a passageway and a restriction in the passageway;

a seat assembly having a radially contracted state corresponding to an axially expanded state, and a radially expanded state corresponding to an axially contracted state, the radially contracted state having a smaller diameter than the radially expanded state; and

a setting tool adapted to deploy the seat assembly in the passageway in the radially contracted state and release the seat assembly in the radially expanded state at a downhole location, wherein the seat assembly is adapted to be pumped from the downhole location to the restriction.

13. The apparatus of claim 12 , wherein the setting tool is adapted to transition the seat assembly to the expanded state and the seat assembly is adapted to receive an untethered object in the expanded state.

14. The apparatus of claim 12 , wherein the seat assembly is adapted to be pumped to the restriction and receive an untethered object.

15. The apparatus of claim 12 , wherein the setting tool is adapted to be deployed in the passageway and retrieved therefrom on a conveyance line.

16. The apparatus of claim 12 , wherein the setting tool is adapted to release the seat assembly using frictional contact between the seat assembly and a wall of the tubing string due to transition of the seat assembly to an expanded state, and upward motion of the setting tool exerted by a conveyance line attached to the setting tool.

17. The apparatus of claim 12 , wherein the setting tool is adapted to release the seat assembly in response to upward movement of the setting tool and engagement of the seat assembly against another restriction in the passageway of the tubing string.

18. The apparatus of claim 12 , wherein at least part of the seat assembly or at least part of the untethered object comprises a dissolvable material.

19. The apparatus of claim 12 , wherein the tubing string comprises a go-no-go ring disposed uphole of the restriction in the tubing string.

20. A method comprising:

deploying a seat assembly downhole in a radially contracted and axially expanded state in a tubing string on a conveyance mechanism;

releasing the seat assembly in a radially expanded and axially contracted state from the conveyance mechanism inside the tubing string at a downhole location uphole of a feature of the tubing string using a tool attached to the conveyance mechanism;

communicating fluid into the tubing string to move the seat assembly inside the tubing string until the seat assembly engages the feature of the tubing string;

deploying an untethered object in the tubing string to land in the seat assembly and form a fluid barrier in the tubing string; and

using the fluid barrier to perform a downhole operation.