Page 100 - PVT Property Correlations

78 PVT Property Correlations

FIGURE 4.6 Phase diagram for Sample 2.

conditions is expected. The separator conditions in both samples are well
within the two-phase region, indicating condensation of liquid hydrocarbon
at surface.

Dew Point Pressure

In dry gas reservoirs, the assumption is that the gas does not exhibit a dew
point at reservoir temperature or at surface. In wet gases, it is assumed that
the vaporized liquid in the gas under reservoir conditions will condense on
surface. This means that the fluid will exhibit two-phase conditions at the
separator or on the way to the separator. The assumption is also that a dew
point pressure is not reached at reservoir temperature. Practically, however,
and for engineering purposes, we can approximate some gas condensate
reservoirs to follow the wet gas model for its simplicity. In this regard, we
would like to be able to estimate the dew point pressure and the liquid drop
out in the reservoir. Dew point pressure can be estimated at reservoir temper-
ature from the correlations given in the Gas Condensates Chapter, if not
available from a PVT report. If the liquid drop out at reservoir temperature
is not significant, the wet gas model assumption is usually sufficient.

Heat Content

In general, the heat content for wet gases is higher than the heat content for
dry gases due to the presence of greater amounts of higher molecular weight