Multicolor fluorescent silica nanoparticles as tracers for production and well monitoring

A method of fracturing multiple productive zones of a subterranean formation penetrated by a well, the method comprising:

• injecting a fracturing fluid into the multiple production zones at a pressure sufficient to enlarge or create fractures in the multiple productive zones, wherein the fracturing fluid comprises silica nanoparticles;
• recovering a fluid containing hydrocarbons from one or more of the multiple productive zones;
• detecting the silica nanoparticles in the recovered fluid;
• and
• identifying the zone from which the recovered fluid was produced or monitoring an amount of fluids produced from at least one of the multiple productive zones by identifying the silica nanoparticles in the recovered fluid,
• wherein the silica nanoparticles comprise a silica core, a donor chromophore, an acceptor chromophore, and an outer silica shell;
• the donor chromophore and the acceptor chromophore being selected such that an emission spectrum of the donor chromophore overlaps with an absorption spectrum of the acceptor chromophore.

A method of enhancing the production of hydrocarbon from a production well penetration a hydrocarbon bearing formation, wherein one or more of the injection well are associated with the production well, the method comprising:

• introducing into one or more of the injection wells a fluid comprising silica nanoparticles;
• flowing at least a portion of the fluid comprising the silica nanoparticles from the injection well to the production well;
• and
• recovering a production fluid from the production well,
• wherein the silica nanoparticles comprise a silica core, a donor chromophore, an acceptor chromophore, and an outer silica shell;
• the donor chromophore and the acceptor chromophore being selected such that an emission spectrum of the donor chromophore overlaps with an absorption spectrum of the acceptor chromophore.

A method of determining water breakthrough in a production well associated with one or more injection wells, the method comprising:

• introducing a fluid comprising silica nanoparticles into an injection well;
• flowing the fluid from the injection well into the production well;
• producing a production fluid from the production well;
• determining water breakthrough in the production well by qualitatively determining the presence or quantitatively measuring the amount of the silica nanoparticles in the production fluid,
• wherein the silica nanoparticles comprise a silica core, a donor chromophore, an acceptor chromophore, and an outer silica shell;
• the donor chromophore and the acceptor chromophore being selected such that an emission spectrum of the donor chromophore overlaps with an absorption spectrum of the acceptor chromophore.