PROPERTIES OF RESERVOIR GASES - Petroleum Reservoir Fluid Property Correlations - page 21

used all of these data plus some data from pure component and binary
mixtures. 31 Sutton also used some “laboratory measured gas/condensate
viscosity” data that apparently are not in the petroleum literature.

Table 2-4. Description of the data set used to evaluate gas viscosity correlations (243 data points
for eight naturally occurring petroleum gases)
Variable Minimum Median Mean Maximum

Pressure, psia 200 1,500 2,169 8,000

Temperature, ºF 100 220 227 340

Gas specific gravity 0.572 0.658 0.656 0.769

Hydrogen sulfide, mole fraction 0.000 0.000 0.000 0.000

Carbon dioxide, mole fraction 0.002 0.009 0.012 0.032

Nitrogen, mole fraction 0.000 0.005 0.016 0.052

Gas viscosity, cp 0.0125 0.0169 0.0193 0.0510

The Carr et al. gas viscosity correlation equations require values
of pseudocritical temperature and pseudocritical pressure. 32 For
this analysis, these were calculated from gas specific gravity and
nonhydrocarbon content with the Piper et al. correlations. 33
The Jossi et al. equations and the Dean and Stiel equations
were not evaluated because each procedure has a discontinuity at
a pseudoreduced temperature of 1.5. This is near the middle of the
pseudoreduced temperatures expected for petroleum reservoirs at
moderate to higher pressures. 34
Both of the Lee et al. gas viscosity correlation equations and the
Sutton correlation equations require values of gas density and gas
molecular weight. Gas densities were calculated using z-factors from the
Piper et al. and DAK equations. Gas molecular weight was calculated
using equation (2.10).
The Londono et al. gas viscosity correlation equations require values
of gas densities. These were calculated with z-factors from the Piper et
al. and DAK correlations for this evaluation.
The Piper et al. and DAK equations were used in this evaluation
because they gave the best results in the evaluation of the z-factor
correlation equations/procedures.
The gas samples of the set of gas viscosity data did not have sufficient
nonhydrocarbon or heptanes plus composition to allow evaluation of
the Elsharkawy equations. 35
The average relative errors for the gas viscosity correlations described
above are given in table 2-5.