This paper presents a new empirical model to estimate the dewpoint pressures for gas condensate reservoirs as a function of routinely measured gas analysis and reservoir temperature. The proposed model was developed using experimentally measured and collected data of 340 gas condensate samples covering wide rage of gas properties and reservoir temperature. The new model has an average relative deviation of 0.44 % and average absolute of 7.68% or 346 psia. The accuracy of the model has been compared to SRK-EOS, PR-EOS, and other correlations. The model proved to be superior for most of the gas condensate samples used in this study. Gas condensate samples from this study as well as from literature have been used to check the validity of the proposed model against EOS simulation. These examples have shown that the model successfully captures the physical trend and that the model is reliable. This model is useful to provide an estimate of the dewpoint pressure when experimentally measured ones is not available.
The current study also shows that predicting the dewpoint pressure for gas condensates depends on the EOS(s), the number of pseudo-components, and the characterization of the plus fraction. For most of the gas condensate used in this study, a ten to twelve pseudo-component of the heptane plus fraction resulted in minimum error in calculation of dewpoint pressures using PR-EOS with Pedersen characterization of the plus fraction.
In gas condensate reservoirs, well productivity often declines rapidly when near-wellbore pressure drops below the dewpoint pressure. Radial compositional-reservoir simulation models often used to investigate this productivity decrease. These models clearly show that liquid dropout around well bore causes the productivity decreases. This ring of increased condensation saturation around the wellbore reduces effective permeability to gas and result in rapid well-productivity decline1. Therefore, it is very important to accurately determine the dewpoint pressure for gas condensate reservoirs.
Number of Pages
Looking for more?
Some of the OnePetro partner societies have developed subject- specific wikis that may help.