A lot of hydrocarbon and nonhydrocarbon components such as N
2, CO
2, and H
2S comprise reservoir fluid. Laboratory fluid properties reports usually describe the components as heavier than hexane as a pseudo component by molecular weight and specific gravity. This pseudo component is called the heptane plus fraction. In general, there are two techniques to the characterization of the plus fraction: the pseudocomponent approach and the continuous approach. The pseudocomponent approach refers to an approach in which the plus fraction splits into a number of pseudocomponents with a known mole fraction, molecular weight, specific gravity, and boiling point (
Ahmed, 1989;
Benmekki and Mansoori, 1989;
Riazi, 1989,
1997).