Method for modeling the flocculation conditions of hydrocarbon-containing fluids under pressure, related to a reference fluid. The asphaltenic properties are modeled from the results of an experimental study of a single asphaltenic reference fluid and by means of homothetic transformation laws. These reduced data allow to deal with asphaltenes flocculation in an industrial simulator working according to a simplified model. It is then possible to predict the amounts of asphaltenes that will flocculate in a reservoir or in a reactor during development, considering the variable pressure and composition conditions. Application: optimization of the development conditions of reservoirs or of an industrial reactor in which asphaltenic fluids undergo expansions.