Downhole vapor-transition control valve for fluid injection

1. An apparatus comprising:

a flow control valve configured to be positioned downhole in a wellbore and to control a flow of an injection fluid from a fluid conduit into a subterranean formation, the injection fluid comprising elemental hydrogen (H 2 );

wherein the flow control valve comprises a chamber having a variable volume and filled with a fill fluid comprising elemental hydrogen (H 2 ) or an azeotrope of elemental hydrogen, and

wherein the flow control valve is configured to actuate to an open configuration to provide a fluid passageway for the injection fluid to flow from the fluid conduit into the subterranean formation when a phase state of the elemental hydrogen (H 2 ) provided as the injection fluid to the flow control valve is in a predetermined phase state.

2. The apparatus of claim 1 , wherein the predetermined phase state is a high density fluid phase.

3. The apparatus of claim 1 , wherein the subterranean formation comprises an open cavity located within the subterranean formation.

4. The apparatus of claim 1 , wherein the chamber includes a biasing device configured to apply a biasing force on one or more portions of the chamber to reduce a pressure level present in the fill fluid.

5. The apparatus of claim 4 , wherein the biasing device is a bellows that encloses at least some portion of the chamber and the fill fluid.

6. The apparatus of claim 4 , wherein the biasing device is a spring positioned within the chamber.

7. The apparatus of claim 1 , wherein the flow control valve comprises an end cap configured to form a fluid seal with and to block an opening when the flow control valve is actuated to a closed position, the opening included as a portion of the fluid passageway between the fluid conduit and the subterranean formation.

8. The apparatus of claim 1 , further comprising:

a movable piston coupled to the chamber,

wherein the movable piston is configured to actuate to the open configuration and to open the fluid passageway through an interior space of the flow control valve when a phase state of hydrogen provided as the injection fluid to the flow control valve is in the predetermined phase state, and

wherein the movable piston is configured to actuate to a closed configuration and to block the fluid passageway through the interior space of the flow control valve when the phase state of hydrogen provided to as the injection fluid to the flow control valve is not in the predetermined phase state.

9. A method comprising:

providing an injection fluid to a fluid conduit extending downhole into a wellbore, the injection fluid comprising elemental hydrogen (H 2 );

controlling a flow of the injection fluid between the fluid conduit and a subterranean formation surrounding or coupled to the wellbore using one or more flow control valves;

wherein each of the one or more flow control valves comprises a chamber having a variable volume and filled with a fill fluid, wherein the fill fluid comprises elemental hydrogen (H 2 ) or an azeotrope of elemental hydrogen, and

wherein each of the one or more flow control valves is configured to actuate to an open configuration to provide a fluid passageway for the injection fluid to flow from the fluid conduit into the subterranean formation when a phase state of the injection fluid is provided to the flow control valve is in a predetermined phase state.

10. The method of claim 9 , wherein the subterranean formation comprises an open cavity located within the subterranean formation.

11. The method of claim 9 , wherein the predetermined phase state is a high density fluid phase of elemental hydrogen (H 2 ).

12. The method of claim 9 , wherein the one or more flow control valves comprise a plurality of flow control valves, wherein each of the plurality of flow control valves are spaced apart from one another along the wellbore and are surrounded by a respective portion of an annulus which is separated into isolated sections of the annulus by packers.