Optimum Formulation of Surfactant/Water/Oil Systems for Minimum Interfacial Tension or Phase Behavior

A screening test used to help select surfactant systems potentially effective for oil recovery is to identify those formulations that yield middle-phase microemulsions when mixed with sufficient quantities of oil and brine. A correlation is presented to link these variables regarding their contributions to middle-phase formation: structure of the sulfonated surfactant, alkane carbon number (ACN), and alcohol type and concentration. WOR and temperature effects are introduced as correction terms added to the empirical correlation. Sets of variables that give middle-phase microemulsions are shown as identical to those defining the low tension state without observable middle phases. This generally occurs for low surfactant concentrations