MICRO-EMULSION PHASE-BEHAVIOR - OBSERVATIONS, THERMODYNAMIC ESSENTIALS, MATHEMATICAL SIMULATION

A mathematical framework is presented for modeling phase behavior in a manner consistent with the thermodynamically required critical tie lines and plait point progressions from the critical endpoints. D. B. Hand's scheme for modeling binodals and G. A. Pope and R. C. Nelson's approach to modeling the evolution of the surfactant-rich third phase are extended to satisfy these requirements. An examination of model-generated progressions of ternary phase diagrams enhances understanding of the experimental data and reveals correlations of relative phase volumes (volume uptakes) with location of the mixing point (overall composition) relative to the height of the three-phase region and the locations of the critical tie lines (critical endpoints and conjugate phases). The correlations account, on thermodynamic grounds, for cases in which the surfactant is present in more than one phase or the phase volumes change discontinuously, both cases being observed in the study. This work is pertinent to oil well flooding.