Page 35 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

Basic Principles, Definitions, and Data 23

..I
SLOPE AT 4500 psia
---- 0.22 -
-
nz
I .o AP 2000
LOPE AT 1000 psia

0.9

0.8

0.7

0.6 I I I I I I
0 1000 2000 3000 4000 5000 6000
PRESSURE , psia

Figure 5-18. Gas compressibility from the gas deviation factor vs. pressure [17].

c as a function of pseudo-reduced temperature and pressure, Tpr and ppr,
P"
respectlvely [27]:

(5-13)

where p,, is the pseudo-critical pressure (reduced and critical pressures have been
defined earlier). Gas compressibility is computed for the pseudo-reduced com-
pressibility from the appropriate figure:

(5-14)

Pseudo-critical pressures and temperatures can be calculated from the mole
fraction of each component present in hydrocarbon gas mixture or estimated
from Figure 5-20 [3].

Oil Compressibility. The compressibility of oil, co, can be obtained in the
laboratory from PVT data. In the absence of laboratory data, Trube's correlation