Page 85 - PVT Property Correlations

Dry Gases Chapter | 3 63

3.2 For the gas composition given below, calculate critical pressure and
temperature from both gas-specific gravity and gas composition using
the following methods:
Sutton (2007) from the gas-specific gravity.
Kay’s rules (Kay, 1936) and Elsharkawy (2000) from the gas
composition.

Component Mole %
H 2 S 0
7.65
CO 2
0.27
N 2
C1 84.11
C2 5.79
C3 1.19
i-C4 0.18
n-C4 0.26
i-C5 0.09
n-C5 0.07
C6 0.07
C7 1 0.32

C7 1 molecular weight and specific gravity are estimated in the lab-
oratory to be 157.7 lb/lb mol and 0.693, respectively.
3.3 For the gas in the above problem, estimate the z-factor at 230 F and for

a pressure range from 100 to 5000 psia using Dranchuk and Abou-
Kassem (1975), Gopal (1977), and Hall and Yarborough (1973) correla-
tions. Compare between the calculated z-factors. Use the pseudocritical
properties estimated by Kay’s rules and by Piper et al. (1993).
3.4 For the above gas (Problem 3) and using the estimated z-factor with any
of the correlations, calculate the gas formation volume factor, gas den-
sity, and gas compressibility. Also estimate gas viscosity using Lee
et al. (1966) and Londono et al. (2005) correlations. Compare between
the two calculated viscosity curves.