The characterization of the end fraction in reservoir fluids plays an important role in predicting the fluids properties and its phase behavior using equations of state. The reservoir fluid samples analyzed by the laboratory consist of an end fraction (Cn+) which is a mixture with unknown properties. The characterization on the end fraction is to use a group of pseudo-components to represent it by estimating the physical properties (critical temperature, Tc, critical pressure Pc and acentric factor, ω), so that the cubic equations of state may perform the calculations.
The certain rules have to be followed in the characterization of the end fraction in reservoir fluids including selection of a number of pseudo-components and appropriate correlations for the critical properties. There are three aspects in the fluid characterization:
- To determine a distribution function for the reservoir fluid components
- To define a number of pseudo-components and group lumping technic
- To select the appropriate correlations for the critical properties of the pseudo-component
Please note the results of the characterization for the same fluid sample could be significantly altered by the choice of the distribution functions and the correlations of the critical properties.
In this module, the multiple distribution functions and a group of correlations for critical properties are provided for selection as well as a default setting.