Controlling a wellbore pressure

1. A method comprising:

installing a tubing-packer sealing assembly at a downhole location within a casing of a wellbore formed from a surface to a subsurface reservoir through a subterranean zone, the tubing-packer sealing assembly sealing a downhole portion of the wellbore downhole of the downhole location from an uphole portion of the wellbore uphole of the downhole location;

disposing a tubing within the casing of a wellbore formed from a surface to a subsurface reservoir through a subterranean zone, the tubing and the casing forming a tubing casing annulus in the uphole portion uphole from the tubing-packer sealing assembly;

installing a tubing-packer sealing assembly at a downhole location within the casing, wherein the tubing-packer sealing assembly seals a downhole portion of the wellbore downhole of the downhole location from an uphole portion of the wellbore uphole of the downhole location, wherein the tubing is disposed in the uphole portion;

flowing an annulus fluid through a wellhead assembly coupled to the wellbore into the tubing casing annulus uphole from the tubing-packer sealing assembly;

responsive to flowing the annulus fluid through the wellhead assembly into the tubing casing annulus uphole from the tubing-packer sealing assembly, filling the tubing casing annulus in the uphole portion with the annulus fluid;

after filling the tubing casing annulus in the uphole portion with the annulus fluid, injecting a volume of inert gas into the tubing casing annulus in the uphole portion causing an equal volume of the tubing casing annulus fluid to be flowed out of the wellbore;

after injecting the volume of inert gas, stinging-in the tubing into a tubing-packer sealing assembly to seal the tubing to a packer of the tubing-packer sealing assembly; and

responsive to stinging-in the tubing into the tubing-packer sealing assembly, i) sealing the annulus fluid and the inert gas in the tubing casing annulus ii) fluidly coupling a downhole end of the tubing with the downhole portion of the wellbore.

2. The method of claim 1 , wherein flowing the annulus fluid through the wellhead assembly into the tubing casing annulus comprises flowing the annulus fluid though the tubing into the tubing casing annulus.

3. The method of claim 1 , wherein injecting the inert gas into the tubing casing annulus comprises displacing a portion of the annulus fluid from the tubing casing annulus.

4. The method of claim 1 , wherein injecting the inert gas into the tubing casing annulus comprises flowing the inert gas through a tubing casing annulus valve into the tubing casing annulus.

5. The method of claim 1 , further comprising flowing a fluid from the subsurface reservoir in the wellbore through the tubing.

6. The method of claim 5 , wherein flowing the fluid from the subsurface reservoir through the tubing increases a pressure in the tubing casing annulus below a first threshold pressure.

7. The method of claim 1 , wherein:

the inert gas is a helium gas; and

the annulus fluid comprises at least one of an inhibited diesel fluid or a brine.

8. The method of claim 1 , further comprising:

flowing a fluid from the subsurface reservoir fluidly coupled to the wellbore through the tubing to the surface of the Earth;

responsive to flowing the fluid from the subsurface reservoir through the tubing, heating the annulus fluid and the inert gas;

responsive to heating the inert gas, increasing a pressure in the tubing casing annulus; and

responsive to increasing the pressure in the tubing casing annulus, compressing the inert gas at a higher rate than the annulus fluid to maintain the pressure of the tubing casing annulus below a first threshold pressure.

9. The method of claim 1 , further comprising before installing the tubing-packer sealing assembly at the downhole location, installing a plug in the wellbore downhole from the downhole location.

10. The method of claim 1 , further comprising after stinging-in the tubing into the tubing-packer sealing assembly, removing the plug from the wellbore.

11. The method of claim 6 , further comprising bleeding excess pressure from the tubing casing annulus.

12. The method of claim 11 , further comprising operating a tubing casing annulus valve of the wellhead assembly to bleed excess pressure from the tubing casing annulus.

13. The method of claim 6 , further comprising:

increasing the volume of inert gas in the tubing casing annulus; and

responsive to increasing the volume of inert gas in the tubing casing annulus, maintaining the pressure of the tubing casing annulus above a second threshold pressure, wherein the second pressure threshold is lower than the first threshold pressure.