In this paper, we use a phenomenological continuum theory of the Ginzburg-Landau type to address emulsion formation in water/light hydrocarbon/asphaltene systems. On the basis of the results of recent molecular dynamics simulations, we first calibrate the model parameters and show that the theory produces a reasonable equation of state. Next, the coalescence of oil droplets is studied by convection diffusion dynamics as a function of both the surface coverage and the viscosity contrast between the asphaltene and the bulk liquids. We show that, besides the traditional thermodynamic interpretation of emulsion formation, the time scale of drop coalescence can be controlled independently from the interfacial tension drop, which offers an alternative, solely kinetic driven mechanism of emulsion formation.