PROPERTIES OF BLACK OILS - Petroleum Reservoir Fluid Property Correlations - page 46

Recommended correlation equations for estimation of bubblepoint
pressure at reservoir temperature
The recommended equation for estimating bubblepoint pressures is
given as equation (3.7). 13

(3.7a)

where

(3.7b)

and

(3.7c)

n VAR n C0 n C1 n C2 n C3 n

1 ln R sb -5.48 -0.0378 0.281 -0.0206

2 API 1.27 -0.0449 4.36 x 10 -4 -4.76 x 10 -6

3 γ gSP 4.51 -10.84 8.39 -2.34

4 T R -0.7835 6.23 x 10 -3 -1.22 x 10 -5 1.03 x 10 -8

Necessity of having correlations specific to a particular
geographical area
There have been many discussions about the necessity of having
fluid property correlations specific to particular geographical regions.
This question has not been fully answered. However, some of the data
described in table 3-6 could be identified by sampling location. Table 3-8
shows a comparison of calculations using equation (3.7) with subsets of
the data that could be referenced to particular geographical areas.
The average absolute relative errors are approximately the same for
each of the geographical subsets of data as well as for the entire data
set. This indicates that, at least for bubblepoint pressures, regional
correlations are not necessary.