Reservoir Fluid Properties - Cased-Hole Log Analysis and Reservoir Performance Monitoring - page 30

4. finding the pseudo-reduced temperature ( T pr ), and
5. using the latter two to find Z .

Figure 3.13 may be used to find p pc and T pc as a function of gas gravity to air and
gas type. Using this Fig. 3.13 to find T pc and p pc is straightforward. For example if
ʳ g = 0.75 then enter the abscissa at 0.75 and go up to read (on the “Miscellaneous
gases” line) that T pc = 406° R and p pc = 664 psia. T pc and P pc may be converted to
pseudo-reduced values depending on the flowing-well conditions:

ppp = / and T TT = /

pr wf pc pr wf pc

Fig. 3.13 Pseudo-critical natural gas parameters. Courtesy Schlumberger; after Brown and Katz
1948