Drag reduction with cationics

Gas hydrate inhibitors. Gas hydrates, solid water clathrates containing small hydrocarbons, are problematic for oil and gas production because they can precipitate and cause line blockage. Simple cationic surfactants containing at least two butyl groups were previously developed to inhibit formation of gas hydrate precipitates in gas production lines [87]. However, similar to the situation with cationic drag reduction additives, poor toxicity profiles prevent widespread commercial acceptance. Ester quaternaries with structures somewhat similar to those used in fabric care have been claimed as hydrate inhibitors [88 ]. Additionally, certain alkylether quaternary compounds, e.g. C12-C14 alkyl polyethoxy oxypropyl tributyl ammonium bromide, were shown to have hydrate inhibition properties [89]. 

Fig. 8 shows DR vs. of a typical DR cationic surfactant with counterion solution, Ci7H35N(CH3)3Cl/ 3,4-Cl-benzoate (5mM/12.5mM). Drag reduction reaches a maximum of 65%. In the effective temperature range (15-85°C), DR first increases with Arc until a critical Arc (critical wall shear stress) is reached above which it begins to lose its DR ability because of the... 

Lin, Z. Chou, L-C. Lu, B. Zheng, Y. Davis, H.T. Scriven, L.E. Talmon, Y. Zakin, J.L. Experimental studies on drag reduction and rheology of mixed cationic surfactants with different alkyl chain lengths. Rheol. Acta 2000, 39, 354-359. 

Lin, Z., Mateo, A., Zheng, Y, Kesselman, E., Pancallo, E., Hart, D. J., Talmon, Y., Davis, H. T., Scriven, L. E., and Zakin, J. L., Comparison of drag reduction, rheology, microstructure and stress-induced precipitation of dilute cationic surfactant solutions with odd and even alkyl chains, Rheol. Acta, 41, 483 92 (2002). 

The simfactant drag reducers may exhibit strong viscoelasticity and high extensional viscosity. Excess coimterions in cationic surfactant may make the solution still nonviscoelastic with distinct extensional viscosity. This suggests the correlation between drag reduction and extensional viscosity. 

Smith, G. L. and C. L. McCormick (2001). Water-soluble polymers. 79. Interaction of microblocky twin-tailed acrylamido terpolymers with anionic, cationic, and nonionic surfactants. Langmuir 17(5) 1719—1725. Sreenivasan, K. R. and C. M. White (2000). The onset of drag reduetion by dilute polymer additives, and the maximum drag reduction asymptote. Journal of Fluid Mechanics 409 149—164. 

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