PROPERTIES OF BLACK OILS - Petroleum Reservoir Fluid Property Correlations - page 48

Table 3-9. Statistical summary of data set used to evaluate solution gas-oil ratio and oil formation
volume factor correlations at pressures equal to and below bubblepoint pressure (5,359 lines of
data from 718 reservoir fluid studies with worldwide origins). Data at pressures below 400 psia
were eliminated due to very large errors for some of the correlations at low pressures.
Laboratory measurement

Minimum Median Mean Maximum

Bubblepoint pressure, p b , psia 415 2,151 2,278 7,750

Reservoir temperature, T R , ºF 70 183 187 320

Stock-tank oil gravity, API , ºAPI 11.6 38.4 37.2 56.2

Separator gas specific gravity, γ gSP 0.5548 0.7835 0.7931 1.4720

Solution gas-oil ratio at p b , R sb , scf/STB 43.0 542 598 1,808

Oil formation volume factor at p b , B ob , res bbl/STB 1.012 1.333 1.358 2.042

The data described in table 3-9 cover the full range of conditions
and properties expected in black oil reservoirs. The samples for the
laboratory work that provided the data for table 3-9 had worldwide
origins. The results of calculations with various correlation equations
from the literature compared with these values of solution gas-oil ratios
are given in table 3-10.

Table 3-10. Evaluation of published solution gas-oil ratio correlation equations for reservoir
pressures equal to and below bubblepoint pressure reveals the more reliable correlations.

Predicted solution gas-oil ratios
ARE, % AARE, %
Velarde et al. (1999), p b from data 1.94 4.50
Velarde et al. (1999); p b from equation (3.7) 2.15 8.81
Casey-Cronquist (1992),* p b from data -6.54 9.51
Casey-Cronquist (1992),* p b from equation (3.7) -5.41 12.62
Kartoatmodjo-Schmidt (1994) -10.81 19.06
Levitan-Murtha (1999) a -16.22 19.44
Glaso (1980) † -11.99 19.47
Standing (1977)* -8.64 19.62
Vazquez-Beggs (1980) -17.78 22.31
Hanafy et al. (SPE 37439, 1997)* -16.51 29.20
Elsharkawy-Alikhan (1997) b -12.67 30.62
Carlson (1997); p b from equation (3.7) -19.17 32.62
a Levitan. L.L. and Murtha, M. “New Correlations Estimate P b , FVF.” Oil & Gas Journal. Vol. 97 (March 8, 1999) 70-76. b Elsharkawy, A.M.
and Alikhan, A.A. “Correlations for Predicting Solution Gas/Oil Ratio, Oil Formation Volume Factor, and Undersaturated Oil Compressibility.”
Journal of Petroleum Science and Engineering. Vol. 17 (1997) 291-302. * Author restricted correlation to a specific geographical area.

Correlation

† Rearrangement of bubblepoint pressure equation—not suggested by author.