Fluorescence Methods for Downhole Fluid Analysis of Heavy Oil Emulsions

• Published in: Journal of dispersion science and technology 2008-02, Vol.29 (2), p.171-183
• Main Authors: Andrews, A. Ballard, Schneider, Marc H., Cañas, Jesus, Freitas, Evie, Song, YiQiao, Mullins, Oliver C.
• Format: Article
• Language: English
• Subjects: Chemistry; Colloidal state and disperse state; downhole fluorescence measurements; Emulsions. Microemulsions. Foams; Exact sciences and technology; General and physical chemistry; hydrocarbon compositional grading; Reservoir compartmentalization; stable water-in-oil) emulsions
• ISSN: 0193-2691; 1532-2351
• DOI: 10.1080/01932690701706839

Acquisition of oil samples from the reservoir prior to oil production is essential in order to design production strategies and production facilities. In addition, reservoir compartmentalization and hydrocarbon compositional grading magnify the necessity to map fluid properties vertically and laterally in the reservoir prior to production. Downhole fluid analysis (DFA), performed in situ in the oil well, helps optimize this fluid mapping process. However, for heavy oil reservoirs drilled with water based muds, fluid mapping has been largely precluded due to the formation of stable water-in-oil (w/o) emulsions, which add significant complexity to sample acquisition and which can preclude standard DFA measurements. Here, fluorescence measurements are shown to be dependent on oil type but independent of the state of emulsion even at very high water fractions. Thus, downhole fluorescence measurements can be used to perform hydrocarbon fluid mapping in the reservoir. The sensitivities of fluorescence and optical absorption measurements are determined for different excitation wavelengths, oil type, and oil concentration.