Performance Evaluation of Empirical Correlations to Estimate the Properties of Gas Condensate Reservoirs in South of Iran

Measurement and modelling of phasic behaviour and fluid properties of gas condensate reservoir fluids are challengnig tasks. Therefore, many researchers have proposed empirical correlations that make use of either the field data such as Gas to Condensate Ratio (GCR) or laboratory data such as compositions and plus fraction characteristics to estimate PVT properties.
In this study, several valid empirical correlations for estimating gas condensate fluid properties have been selected to be benchmarked against fields data. Laboratory data from 30 lean gas condensate samples taken from 9 gas condensate fields in south of iran have been collected to examine reliablity of the emprical correlations. The estimated results from empirical correlations have been compared with measured laboratory data. The accuracy of empirical correlations have been evalauted via error analysis.
In this study, a wide range of data are used for evaluation: reservoir temperature 159-235° F, gas molecular weight 17.4-21.13 gr/grmole, dew point pressure 3100-5170 psia, gas deviation factor in dew point pressure 0.84-1.059, maximum retrograde condensation 0.09%-2.91% and gas to condensate ratio 33487.86 - 617721 SCF/STB.
Parameters evaluated with empirical correlations include C₇₊mole%, gas molecular weight, maximum retragrade condensate, gas to condensate ratio, dew point pressure and gas deviation factor in dew point pressure.
The results indicate that dew point pressure correlations and maximum retrograde condensation have minimum and maximum error, respectively. In cases where gas to condensate ratio is high, C7+ mole% correlations are not suitable. Estimation of gas deviation factor (in dew point pressure) with empirical correlations is not recomended.