The Equilibrium ratios (K-values) depend on temperature, pressure and the overall composition of the reservoir fluid. Several correlations are being used and are considered accurate enough. But on close examining these correlations provide accurate results only at lower pressures. This is because at lower pressure the K-values are primarily dependent on pressure and temperature. The compositional dependence which is more complicated to model happens at higher pressures. The compositional dependence is believed to be only a function of convergence pressure. When we consider that predicting convergence pressure in itself is dependent on the correlations, we can fathom the cause of inaccurate prediction of K-values. We believe that there is not enough data available to generate accurate correlations. The inaccuracy of correlations in prediction of the K-values will be shown in this paper by comparison with the experimental data.

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