Page 438 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

400 Production

Pre~~re: PSI0
Figure 6-22. Adjustment of oil relative volume curve to separator conditions [SI.

(text continued fim page 394)
yi - concentration of 'I i" component in vapor phase
Ki =-- (6-16)
xi concentration of 'I i" component in liquid phase
In bubble point calculations, x, is knows and either T or P is fiued. The vapor
phase composition (yi) and P or T of the system are unknown.

Yi = Qi (6-17)
Several different values of the dependent variable are assumed. The correct value
is the one that yields

$Kixi = eyi = 1.0 (6-18)
i=l i=l
An additional requirement when using composition dependent K values is

Iy:+' - yr I I i = 1 ton (6-19)
E,