Abstract Oil reserves in Brazil are characterized by heavy and ultra heavy petroleum. This type of oil is relatively difficult to process. In fact, it is necessary to upgrade such kind of oil in order to increase productivity of light fractions, mainly diesel. An important step in the definition and set up of suitable process to deal with this is the oil characterization. This is made with the aid of the True Boiling Point (TBP) curve through ASTM standard test methods until 565°C and it extension obtained from molecular distillation for heavy oil and residues. In this work, it is proposed a refining evaluation making use of the extended TBP curves. The conceptual process was implemented in Hysys Process Simulator through a novel procedure for the generation of pseudocomponents for characterizing the feeding of distillation columns. It was developed a simulation methodology in order to evaluate the petroleum residues extended TBP curves in the process separation after the FCC (Fluid Catalytic Cracking) reactor, for producing liquefied petroleum gas, gasoline and diesel.