Page 125 - PVT Property Correlations

Gas Condensates Chapter | 5 103

FIGURE 5.9 Net heating value for produced separator gas from a gas condensate reservoir.

Chapter 4, Wet Gases). However, the estimation of original gas in place
(OGIP) in gas condensates from MB calculations is different from calcula-
tions for dry and wet gases. In dry gases, the MB uses single-phase z-factor
in the p/z versus cumulative gas production (Gp) plot. In gas condensates,
two modifications must be considered: (1) Two-phase z-factor is used instead
of single-phase z-factor and (2) surface condensate production should be
added to the cumulative gas production (because the condensate produced on
surface is associated with the gas phase in the reservoir). The following
equations are used to convert the surface condensate and water production to
their equivalent gas (Craft et al., 1991).
γ
GE 5 133; 000 o ð5:7Þ
M o
Molecular weight can be estimated from the following correlation, if not
measured in the laboratory.
5954
M o 5 ð5:8Þ
API 2 8:811
42:43γ
M o 5 o ð5:9Þ
1:008 2 γ o
GE w 5 7390 scf=surface bbl ð5:10Þ
In a three-stage separation system; and if gas produced from primary separa-
tor, secondary separator, and the stock-tank is measured, the following equa-
tion is used to estimate total reservoir gas production