The influence of the oil composition on the phase behavior and properties of surfactant/brine/crude oil-systems

For the better understanding of crude oil mobilization process with surfactant flooding, the effects of ethoxylated sulfonates and salinity on some crude oil/- surfactantlbrine systems were investigated. The results clearly show that for fixed temperature salinity and surfactant are mainly responsible for the formation of three-phase-systems and for the distribution of the different components of the crude oil in the different phases of these systems. When aqueous solutions of ethoxylated sulfonates with a distinct degree of ethoxylation are equilibrated with an equal volume of crude oil, a middle-phase microemulsion (ME phase) will be formed in aspecific salinity range. It could be shown that the solubilized crude oil in the middle phase consists of a wide range of components, such as alkanes, alkylated cyclohexanes, alkylated benzenes, isoprenoids, alkylated phenanthrenes, and aromatic steroids.