Page 122 - PVT Property Correlations

100 PVT Property Correlations

Problem 1—Calculation of Dew Point Pressure for a
Gas Condensate

Calculate dew point pressure for the gas with the composition given in
Table 5.8. Use dew point correlations from Appendix B, Gas Correlations
Formulae (e.g., Elsharkawy, 2001; Al-Dhamen and Al-Marhoun, 2011)to
show the variation of the calculated dew point. Notice that Elsharkawy (2001)
requires the gas composition as input, while Al-Dhamen and Al-Marhoun
(2011) require gas specific gravity and basic field information. Compare your
calculated dew point pressure with the laboratory-measured value of

3245 psia. The reservoir temperature is 323 F, separator gas specific gravity

is 0.786, the separator-gas-to-separator-liquid ratio is 1910 scf/STB at 60 F,
separator liquid to stock-tank liquid ratio is 1.255 rbbl/STB and the conden-
sate specific gravity is 0.7823. Separator conditions are given as follows:
1st stage separator pressure 5 800 psi, 1st stage separator
temperature 5 110 F

2nd stage separator pressure 5 60 psi, 2nd stage separator
temperature 5 75 F

Solution of Problem 1
Calculating the dew point using the basic field data by Al-Dhamen and Al-
Marhoun (2011):
GOR 3 γ

ð
ln P d Þ 5 a 1 1 a 2 ln g 1 a 3 ln T R Þ 1 a 4 γ 1 a 5 1 a 6 e a 7 1a 8 ln GORÞ
ð
ð
γ 71 g γ cond:
ð5:5Þ
where the correlation parameters are given in Table 5.9.
TABLE 5.8 Gas Composition (in mole %) for Problem 1

N 2 CO 2 C1 C2 C3 i-C4 n-C4
3.16% 6.42% 50.26% 9.68% 6.20% 2.19% 3.73%
i-C5 n-C5 C6 C7 1 C7 1 Mw C7 1 SpGr.
1.88% 1.85% 3.04% 11.59% 146 0.782

TABLE 5.9 Dew Point Correlation Constants (Al-Dhamen and
Al-Marhoun, 2011)
a1 a2 a3 a4 a5 a6 a7 a8
18.60 2 0.15 2 0.17 0.07 2 5.90 2 0.06 8.50 2 0.75