Heavy organic deposition is a common problem in oil industry, especially in oil production, transportation, and processing equipments. One of the most important deposits is asphaltene deposition, which causes major difficulties in petroleum mixtures, such as reservoir fluids. In this paper, the deposits are assumed to be a mass of pure hydrocarbon components that contain mutually immiscible precipitating components. Association term has been incorporated in equation of state (EOS) by a simple and theoretical method. This model is also able to predict pressure and composition effects (solvents injection, such as CO2, methane, propane, etc.) on asphaltene deposition. In this model, Peng-Rebinson EOS was used to describe vapor, liquid and pure liquid phase behavior. All the obtained results were in good agreement with experimental data and the results of other works.