Manipulating hydrophilicity and hydrophobicity of conventional dye molecules for tracer applications

A method of making a functionalized fluorescent dye, comprising:

• dissolving a water-soluble isothiocyanate-containing fluorescent dye in an aqueous solvent to yield an aqueous dye solution, wherein the water-soluble isothiocyanate-containing fluorescent dye is selected from the group consisting of fluorescein isothiocyanate, Rhodamine B isothiocyanate, or tetramethylrhodamine isothiocyanate, or any isoform thereof;
• dissolving a functional group in an organic solvent to yield an organic functional group solution, wherein the functional group comprises an aromatic compound with a primary amine and is selected from the group consisting of 1-naphthylamine, 2-aminoanthracene, 1-aminopyrene, 6-chrysenamine, 9-aminophenanthrene, 2-aminofluorene, 9-aminoacridine, 1,10-phenanthrolin-5-amine, 9H-carbazol-2-amine, or 3-amino-9-ethylcarbazole;
• mixing the aqueous dye solution and the organic functional group solution to form an emulsion;
• separating the emulsion into an aqueous phase and an organic phase;
• and
• extracting the functionalized fluorescent dye from the organic phase, wherein the functionalized fluorescent dye is a reaction product of the water-soluble isothiocyanate-containing dye and the functional group.

A method of tracing fluid flow in a subterranean formation, comprising:

• mixing a functionalized fluorescent tracer and a fluid to form a tracer fluid, wherein the functionalized fluorescent tracer comprises an isothiocyanate-containing dye functionalized with a functional group comprising an aromatic compound with a primary amine, wherein:
• the isothiocyanate-containing dye is selected from the group consisting of fluorescein isothiocyanate, Rhodamine B isothiocyanate, or tetramethylrhodamine isothiocyanate, or any isoform thereof;
• and
• the functional group is selected from the group consisting of 1-naphthylamine, 2-aminoanthracene, 1-aminopyrene, 6-chrysenamine, 9-aminophenanthrene, 2-aminofluorene, 9-aminoacridine, 1,10-phenanthrolin-5-amine, 9H-carbazol-2-amine, or 3-amino-9-ethylcarbazole;
• flowing the tracer fluid into a first subterranean formation;
• recovering a sample from the first subterranean formation or a second subterranean formation connected to the first subterranean formation;
• and
• analyzing the sample for a fluorescent signal.