The conventional fluorescence reaction by UV light is a very popular and simple method for oil show detection of cuttings or core samples at oil field. This method is, however, unreliable because of detection with naked eye and it is impossible to distinguish between crude oil and mud materials, especially derived from petroleum products having strong fluorescence.
In this report, a new synchronous spectrofluorimetric method for making a discrimination between crude oils and the mud materials is described.
Although synchronous fluorescence spectra of the mud materials are similar to those of crude oils, it is possible to distinguish clearly between the mud materials and crude oils having density more than 0.8g/cm3 by comparing fluorescence strengths of monoaromatic (MA), diaromatic (DA) and triaromatic (TA) compounds in the spectra.
The crude oils investigated have relatively high TA/DA and low MA/DA ratios, whereas the mud materials have high MA/DA and low TA/DA. When the data are plotted, with TA/DA as ordinate and MA/DA as abscissa, the location of the plot indicates whether the sample is crude oil or the mud materials.
This method can be applied to oil show detection of core samples as the more reliable method than the fluorescence reaction method.