This report studies the application of carbon nanomaterials as a novel type of tracer in detection of residual oil. The carbon nanomaterials studied include oxidized carbon black (OCB) coated with different molecular weight polyvinyl alcohols(PVAs). Transport studies are conducted using columns packed with ground core materials, with synthetic seawater as the carrying fluid. Compared to lower molecular weight PVA-functionalized OCBs, the breakthrough of PVA(50K)-OCBs is less sensitive to aging and temperature; therefore, PVA(50K)-OCBs are chosen as nanoreporters to sequester chemical tags. Two different tags, 14 C labeled 2,2',5,5'-tetrachlorobiphenyl(PCB) and triphenylamine, are tested in the experiments. Efficient transport of tags through oil-field rocks and selective release when rocks contain oil are demonstrated. The kinetics of PCB adsorption is studied to better understand correlation between PCB release and oil content. A linear relationship between residual oil content and PCB release is found in flow-through experiments.