Light beam reflectance measurement of droplets diameter distribution in crude oil emulsions

• Published in: Fuel (Guildford) 2013-07, Vol.109, p.542-550
• Main Authors: Less, Simone, Vilagines, Regis
• Format: Article
• Language: English
• Subjects: Applied sciences; Crude oil; Diameter; Distribution; Droplet; Droplets; Emulsion; Emulsions; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fuels; Liquids; Optical properties; Phases; Reflectance; Reflectivity
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2013.03.048

•FBRM was tuned with solid particles having refractive indexes as water and crude oil.•Several tests were conducted to provide a DDD data bank on Arabian crude oils.•A PCA conducted on the data bank showed that FBRM can provide meaningful DDD.•FBRM of PMMA particles in crude oil suspensions resulted in scattered and unreliable DDD.•FBRM is valuable to monitor cause–effect links in crude oil emulsion processes. Stable oil field emulsions create challenging conditions in the petroleum production industry. One important characteristic affecting the stability and rheology of emulsions is the Droplet Diameter Distribution (DDD). A few techniques are available to determine the DDD in clear and dark liquid/liquid mixtures. Most of them, like the traditional light scattering techniques, require sampling and dilution. Dilution can affect the droplets coalescence rate, and consequently, change the DDD by altering the solubility state of components responsible for emulsion interface properties. Moreover, the samples obtained may not be representative of the actual process conditions once depressurized to ambient for observation. Focused Beam Reflectance Measurements (FBRMs) were conducted on suspensions mimicking the optical properties of emulsion systems, with the goal of optimizing the instrumental settings. Then, the same technique was applied to water-in-crude oil and crude oil-in-water emulsions to evaluate its accuracy. An algorithm was developed to compute the diameter distribution in populations of spherical droplets from the chord length distributions measurement data. The greatest advantage of this technique is the ability to perform a real-time, in situ measurement of DDD at actual process conditions. The method is capable of repeatable measurements of droplet diameter distributions; however, the measurements are limited within a range of droplet sizes, and the results are sensitive to the relative optical properties of the continuous and dispersed phases, making the calibration step a fundamental phase of the measurement protocol.