ABSTRACT
This chapter is concerned mainly with systems made of water or brine, oil, surfactant, and cosurfactant. The practical interest of three-phase states need no more be emphasized. The chemical potentials of every compound only depend, within a pseudophase, upon the composition of this pseudophase and in no way upon the geometrical structure. The experiment gives the evolution of chemical shifts for the hydroxylic proton of alcohol when the molar fraction of alcohol is varied within the organic phase of water, alcohol, oil system. The water pseudophase is mainly constituted of water and some alcohol. The pseudophase model allows us to calculate the composition of the water, oil, and interfacial phases or pseudophases coexisting in equilibrium in micellar systems. The pseudophase model, however, has so far considered the brine as a pseudocomponent, an approximation not always justified, which has led to some difficulties.
