Salinity-Alkane Carbon Number (ACN) Relationship of Some Anionic Nonionic Surfactant Mixtures

Salinity scans were performed for petroleum sulphonate/eugenol ethoxyate mixtures having the same composition (0.75 mole fraction of witco TRS 10-80 petroleum sulphonate + 0.25 mole fraction of any of the prepared eugenol ethoxylates). Widths of the obtained three-phase (3?) microemulsion regions, were determined and the optimum salinity (S*) values of these anionic/nonionic systems, were calculated at different oil phase alkane carbon numbers (ACN). Phase behaviour diagrams, of the investigated systems, were constructed by plotting the width of the 3? region against oil phase ACN. From the obtained phase maps, the areas of the 3? regions, bounded between the upper and lower phase boundaries (UPB & LPB), were located. Also, the areas bounded between the UPB and LPB fitted curves for the whole ACN range (from hexane to hexadecane, 3?6-16) and that for the preferred ACN (from hexane to nonane, 3?6-9), were determined through computational approach. Linear and polynomial equations were developed to describe the S*-ACN relationship of the investigated systems.Results obtained reveal that more pronounced shift, in the 3? region, to higher ACN was observed when nonionic having longer polyoxyethylene chain was employed. Sulphonate/eugenol ethoxylate mixtures gave 3 ?6-9 regions at a relatively higher salinity ranges if compared with that of sulphonate alone. Such mixtures are more beneficial in surfactant flooding for high salinity reservoirs. Keywords : Eugenol ethoxylates, Petroleum sulphonates, Phase behaviour, Phase map, Surfactant flooding formulation systems.