Page 239 - PVT Property Correlations

Selection of PVT Correlations Chapter | 9 209

indicate that reservoir temperature is 190 F. Separator information shows
that specific gravity of separator gas is 1.221. Use the worksheets of
Appendix F, Worksheets for Oil PVT Correlations Selection, to select PVT
correlations to calculate PVT properties for this oil. Calculate fluid properties
with the selected correlation(s) and compare results with laboratory data
using appropriate plots. Table 9.4 shows the laboratory-measured data for
this oil sample.

Solution of Problem 2
The workflow in Fig. 9.2 and worksheets of Appendix F, Worksheets for Oil
PVT Correlations Selection, are followed to select the best correlation for every
PVT property. Details of the procedure are given in the following sections.

Bubble Point Pressure
Fig. 9.3 shows the four basic inputs intersecting the different correlations.
Table 9.5 lists the calculated bubble point pressure and its related errors.
According to the applicability limits of the four inputs, two correlations can
be selected (Al-Shammasi, 2001; Lasater, 1958). The bubble point was esti-
mated for this fluid using all eight correlations. Comparison between the
results of all correlations reveals that Dindoruk and Christman (2004) have
the lowest error for this fluid. The two selected correlations (Al-Shammasi,
2001; Lasater, 1958) have the second and third-lowest errors.

Gas in Solution
Fig. 9.4 shows that three of the four solution GOR correlations are selected.
Fig. 9.5 shows the comparison between the different solution GOR correla-
tion results with the laboratory-measured values. The comparison shows that
all solution GOR correlations (including the selected three) produce values
that reasonably match the laboratory data. The Farshad et al. (1996) correla-
tion is selected for further work on the problem.

Oil Formation Volume Factor
Fig. 9.6 shows that the inputs for selection of oil formation volume factor
correlation intersect only two correlations (Kartoatmodjo and Schmidt, 1994;
Vasquez and Beggs, 1980). Fig. 9.7 shows the comparison plot for all corre-
lations with the laboratory-measured data. The Vasquez and Beggs (1980)
correlation is indeed the best correlation out of all.

Saturated Oil Density
The selection of the most appropriate correlation for saturated oil density is
shown in Fig. 9.8. By use of the intersections of the inputs with the applica-
bility ranges for all correlations, one correlation only is selected (Standing,