Phase behavior of pseudoternary brine/alkane/alcohol-secondary alkanesulfonates systems.Surfactant ratio effects of salinity and alcohol

Dodecanesulfonates (isomer mixtures) have been synthesized by the process developed in our laboratory. First, pseudoternary phase diagrams of the water or (brine) decane/ dodecanesulfonates-butan-1-ol systems were drawn and compared with those of a commercial sample (Hostapur 60). In the presence of NaCl, a three-phase region (Winsor III) appears for the two systems, and is larger with the home-made surfactants. This region is interesting in enhanced oil recovery because it leads to very low interfacial tensions. Then, the behavior of the Winsor III region was investigated as a function of the alcohol/surfactant mass ratio (C/T). At a constant salinity (2.5 wt. % NaCl) a value of 2 for C/T gives the best compromise for a larger W III region with both systems. For this ratio, optimal salinity values of 1.55 and 1.65 mass % for our sample and Hostapur 60, were found, respectively