PHASE-BEHAVIOR IN A MODEL SURFACTANT ALCOHOL OIL BRINE SYSTEM OVER WIDE RANGES OF CONDITIONS

The phase behavior of the sodium stearate/isobutyl alcohol/n-hexadecane/NaCl brine system was studied at unit water/oil volume ratio over all ranges of surfactant/alcohol/salt compositions and from room temperature and pressure up to 50 degree C and 70 bar. Though turbidity and viscous phases were found at some conditions, from one to four isotropic phases were found. Sensitivity to state conditions of properties and phase amounts existed, and behavior characteristic of multiple critical regions was observed. The complex phase behavior and properties such as density, electrical resistivity, and interfacial tensions are illustrated. Application of critical scaling relationships yields linear correlations of interfacial tensions, which may be of practical use for systems with ultralow values.