Modeling of gas condensates properties using continuous distribution functions for the characterisation of the heavy fraction

The modeling of thermodynamic behaviour for gas condensates is not yet satisfactory and it involves an adjustment of thermodynamic models. We propose here a fitting based on the characterisation of the plus fraction using three continuous distribution functions associated to the following families: n-alkanes, n-alkylbenzenes and polyaromatics. No continuous thermodynamic model is used and PVT calculations are made with the PR-EOS. For polyaromatics, a simple correlation of Tc, Pc, w with carbon number is given. The parameters of the distributions are fitted in order to improve the accuracy of the constant composition liquid deposit curve calculation at the reservoir temperature. Good results on fitting PVT properties have been obtained with 20 gas condensates from different areas. Moreover, the prediction of tank liquid and heavy-plus fraction densities are given with average deviations of 1.2% and 3.1%, respectively. Tests on temperature extrapolation show that our model yields a good representation of pressure and temperature influence on gas condensate behaviour.