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PGE 312 - FALL 2009
Physical and Chemical Behavior of Petroleum Fluids I
Test #2, 50 Minutes
Solution Key
Problem 1 (25 points)
In the space provided on the next page, sketch the Pressure-Temperature phase diagrams
for the following hydrocarbon systems:
a.
Retrograde gas condensate
b.
Undersaturated black oil
c.
Wet gas
d.
Dry gas
Mark the following features on your sketch using the symbols enclosed in the brackets.
1. Initial reservoir pressure and temperature (P
Ri
, T
R
)
2. The critical point (C)
3. The bubble point curve (BP)
4. The dew point curve (DP)
5. Separator pressure and temperature (P
sep
, T
sep
)
6. A few iso-volume lines

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Problem 2 (25 points)
A binary mixture of 45 lb moles
of methane and 80 lb moles of normal decane is
confined in a sealed vessel at T = 361 ºF and P = 1600 psia. The equilibrium ratios (k-
values) for the methane and normal decane at the given conditions are as follows:
k
1
= 2.6360
k
2
= 0.0708
a.
Calculate the lb moles of liquid in the vessel if any.
Subscripts: 1 = methane, 2 = normal decane
First determine the state of the system.
n
1
= 45 lb moles
n
2
= 80 lb moles
n = n
1
+n
2
= 45+80 = 125 lb moles
z
1
= n
1
/n = 45/125 = 0.36

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