www.sciencedirect.com/topics/...anetary-sciences/fluorescence
Reservoir Geochemistry
Harry Dembicki, Jr., in Practical Petroleum Geochemistry for Exploration and Production, 2017
Fluorescence and Cut
Fluorescence and cut are part of the visual inspection of the cuttings recovered from the potential reservoir interval. After the cuttings’ lithology and grain size have been described, a visual inspection of the cuttings is done for any visible indications of oil staining. At the same time, a check for any odor of hydrocarbons that may be present is usually made. Staining may not be obvious in the cuttings. To look for the more subtle forms of staining, the cuttings should be placed under an ultraviolet light (both long and short wavelengths) to determine if any fluorescence is present. Fluorescence present may be from traces of hydrocarbons in the sample, or it could be from minerals or some contaminant. To help distinguish between fluorescence from hydrocarbons versus minerals or contaminants, the color, intensity, and distribution of the fluorescing material is noted. Oil fluorescence ranges from blue-white to white to yellow to red-brown. Fluorescing minerals are usually intense and related to only specific grains in the cuttings sample. To help distinguish fluorescence of oil from minerals, a few drops of solvent are added to the cuttings while still under UV light to induce a cut or mobilization of the oil from the cuttings. The appearance of the cut, (uniform or streaming), color, intensity, and the rate at which it forms can provide information about the oil’s mobility and reservoir permeability. A more detailed discussion of fluorescence and cut can be found in Whittaker (1991).
While fluorescence and cut can provide very useful information about potential shows, there are a few obstacles to universally applying it. First, if the drilling mud has been formulated with diesel or crude oil, the technique cannot be used. In addition, pipe dope and some drilling mud additives may also fluoresce giving false positive indications. And finally cavings or recycled oil in the drilling mud can be observed and be misleading.
Also solche, wie oben abgebildete Fluoreszenz, kann auf eine höffige Bohrung deuten, wenn sauber gearbeitet wurde und die Proben nicht verunreingt sind.
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