ABSTRACT
To perform phase equilibrium calculations on a reservoir fluid composition using a cubic equation of state, the critical temperature (T
), the critical pressure (P
), and the acentric factor (
ω
), are required for each component contained in the mixture. In addition, a binary interaction parameter (k
) is needed for each pair of components. If an equation of state with volume correction is used (e.g., Peneloux et al., 1982), a volume shift parameter must further be assigned to each component. Naturally occurring oil or gas condensate mixtures may contain thousands of different components. Such high numbers are impractical in flash calculations. Some components must be lumped together and represented as pseudocomponents. C
characterization consists of representing the hydrocarbons with seven and more carbon atoms (the heptane plus or C
fraction) as a convenient number of pseudocomponents and to find the needed equation of state parameters (T
, P
, and
ω
) for each of these pseudocomponents. The characterization (or lumping) problem is illustrated in Figure 5.1.
