In Situ Downhole Fluid Analysis Systems Using LED, Laser-Induced Fluorescence, and Uranine-Traced Drilling Water.

The paper discusses a novel three-channel method to distinguish the formation oils, water, and uranine-based drilling mud and to monitor the clean-up process in the downhole fluid analysis systems. The proposed method is based on the study of the fluorescence spectra of the formation fluid or drilling mud samples. The experiment for different excitation sources (365 nm, 395 nm LEDs, and 405 nm, 460 nm laser sources) was carried out; the spectra were recorded with a VISION2GO VIS spectrometer. The characteristic features in fluorescence spectra of the crude oil sample and various concentrations of the uranine solution in pH-neutral water (5 mg/l, 10 mg/l, 25 mg/l, 50 mg/l, 100 mg/l) were observed. The sufficient unambiguous criterion for differentiating the type of fluid and clean-up process analysis is presented.