Water-based fluids for drilling wells are an environmentally friendly alternative to oil-based formulations typically used in the oil industry. Aqueous mixtures of nonionic monoglyceride surfactants (C6, C8, C10, C12, and C18 carbon chains) and xanthan gum (XG) were investigated with that purpose, correlating their lubricity and solubility in water, as well as using surface tension and contact angle measurements. The results showed that monoglycerides behave as excellent lubricants in water, with a steady decrease of the friction coefficient as the hydrocarbon chain length increased. Monoglycerides were able to reduce the friction coefficient even further when used in XG suspensions, suggesting that they are probably forming a complex with the polysaccharide that shows a synergy toward their performance as lubricants. Experiments of adsorption onto iron oxide nanoparticles also produced evidence of the interaction between these molecules, which favors their adsorption on the metal surface. These results indicate that interactions occurring in solution between the surfactants and the polysaccharide are crucial in the mechanism of action of these mixtures as lubricants in water-based drilling fluids.
Amphiphilic polymers have found many applications, so many types of these copolymers have been prepared. Specifically, sulfonated polystyrene acts, for example, as a flocullant or dispersant of petroleum asphaltenes as a function of its hydrophilic-hydrophobic balance. However, when changing the sulfonation degree, looking for the best performance, the solubility also changes, and sometimes it is responsible for making the polymer unsuitable for any application. Therefor, this work investigates in detail the changes in the solubility range of copolymers based on styrene-stearyl methacrylate and styrene-stearyl cinnamate with different molar compositions and different sulfonation degrees. The copolymers were synthesized and characterized by 1 H-NMR, Fourier transform infrared spectroscopy, and elemental analysis. In the range of compositions analyzed, with increasing content of long hydrocarbon chains, not only the displacement of the solubility in solvents with lower solubility parameter (d), but also the broadening of the solubility range was observed. In general, the solubility was directly related to the sulfonic group content, but there appeared to be an influence of the randomness of the sulfonation reactions along the chains. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43112.
Some oil fields produce from different reservoirs, which may be incompatible generating precipitates. These precipitates are often asphaltenes, which can be an emulsion stabilizing agent negatively affecting the oil treatment processes. In this work, the influence of oil incompatibility on the stabilization of water-in-oil emulsions was studied. Emulsions were evaluated from three different oils (A, B and C) and their mixtures (AB, AC, BC and ABC). The results showed that there is a relationship between separation kinetics of emulsions and asphaltene precipitation. The separation kinetics of the emulsions was faster for more compatible oils. We observed that oil A, which was the less stable regarding asphaltenes, and the ABC mixture, which was the most incompatible mixture, both presented the slowest kinetics of emulsion separation. On the other hand, mixture BC which had the highest compatibility among the other mixtures presented a faster kinetic of emulsion separation.
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