Compositions of matter comprising suspended nanoparticles and related methods

1. A composition of matter, comprising:

a liquid; and

nanoparticles suspended in the liquid, the nanoparticles each comprising:

silica;

alumina;

organosilicon functional groups bonded to silicon atoms of the silica, none of the organosilicon functional groups of the nanoparticles being bonded to aluminum atoms of the alumina; and

hydroxyl (—OH) groups bonded to the aluminum atoms of the alumina.

2. The composition of claim 1 , wherein the liquid comprises aqueous brine.

3. The composition of claim 2 , wherein the liquid comprises dissolved multivalent ions.

4. The composition of claim 3 , wherein the dissolved multivalent ions are selected from the group consisting of Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , Fe 2+ , Fe 3+ , Cu 2+ , CO 3 2− , SO 3 2− , SO 4 2− , S 2− , and PO 4 3− .

5. The composition of claim 1 , wherein the liquid comprises a glycol.

6. The composition of claim 1 , wherein at least 90% of the nanoparticles remain suspended in the liquid over a time period of 30 days at 30° C.

7. The composition of claim 1 , wherein at least 90% of the nanoparticles remain suspended in the liquid over a time period of 10 days at 70° C.

8. The composition of claim 1 , wherein at least 90% of the nanoparticles remain suspended in the liquid over a time period of 24 hours at 90° C.

9. The composition of claim 1 , wherein an organosilicon functional group of the organosilicon functional groups exhibits a molecular weight of at least 200.

10. A composition of matter, comprising:

a liquid; and

nanoparticles suspended in the liquid, the nanoparticles each comprising silica, alumina, and an organosilicon functional group, the organosilicon functional group comprising (3-glycidyloxypropyl)trimethoxysilane.

11. A method, comprising:

functionalizing nanoparticles with an organosilicon functional group, the nanoparticles each comprising:

silica;

alumina;

organosilicon functional groups bonded to silicon atoms of the silica, none of the organosilicon functional groups of the nanoparticles being bonded to aluminum atoms of the alumina; and

hydroxyl (—OH) groups bonded to the aluminum atoms of the alumina; and

forming a suspension of the nanoparticles in a liquid.

12. The method of claim 11 , wherein functionalizing nanoparticles with an organosilicon functional group comprises functionalizing the nanoparticles with (3-glycidyloxypropyl)trimethoxysilane (GLYMO).

13. The method of claim 11 , wherein forming a suspension of the nanoparticles in a liquid comprises dispersing the nanoparticles in an aqueous medium.

14. The method of claim 11 , further comprising modifying an exposed surface of silica nanoparticles to form the nanoparticles comprising the silica and the alumina.

15. The method of claim 14 , wherein modifying an exposed surface of silica nanoparticles comprises replacing a silanol group with Al—OH.

16. The method of claim 11 , wherein functionalizing nanoparticles with an organosilicon functional group comprises reacting the nanoparticles with the organosilicon functional group in the presence of ethanol and water.

17. The method of claim 11 , wherein functionalizing nanoparticles with an organosilicon functional group comprises reacting the nanoparticles with the organosilicon functional group at a temperature of at least 50° C.

18. The method of claim 11 , wherein functionalizing nanoparticles with an organosilicon functional group comprises bonding the organosilicon functional group with the silicon atoms of the silica of the nanoparticles.

19. The method of claim 11 , further comprising injecting the suspension into a subterranean well.

20. The method of claim 11 , further comprising maintaining the suspension at a temperature of at least 30° C. for a time period of at least 30 days while maintaining at least 90% of the nanoparticles in the suspension.