Effect of molar ratio of counter-ions to cationic surfactants on drag reduction characteristics of trimethylolethane hydrate slurries

An experimental study on flow characteristics of trimethylolethane (TME) hydrate slurries treated with drag-reducing surfactants has been performed in order to investigate the effect of molar ratio of counter-ions to surfactants. As drag-reducing surfactants, oleylbishydroxyethylmethylammonium chloride was used. The molar ratio of counter-ions of sodium salicylate to surfactants ranged from 0 to 100 and surfactant concentration was changed in two steps; 1000 ppm and 2.000 ppm while the concentration of TME in water was set constant at 25 wt%. From the results, it was found that the drag reduction limitation becomes larger when the molar ratio of the counter-ions to surfactants is set around 20 for each surfactant concentration. From the detailed discussions, the drag reduction characteristics in a higher range of the molar ratio of counter-ions to surfactants were found to relate to the molar ratio of counter-ions to TME more significantly. Under the present conditions, it was concluded that 0.05 of the molar ratio of counter-ions to TME shows the most effective drag reduction.