Page 123 - Fundamentals of Enhanced Oil and Gas Recovery

Miscible Gas Injection Processes 111

Solution: At the beginning, the modified critical temperature is computed by the
followings:
T cm 5 P w i 1 T ci 5 51:77 C, from Eq. (4.18)

Then, the effect of H 2 S impurity on MMP can be taken into account through
Eq. (4.17) as follows:

ð 1:935 3 87:8Þ

87:8 ð 1:8 3 T cm 132Þ
F impure 5 5 0:618;
1:8 3 T cm 132
from Eq. (4.17)
Multiplying this factor by the predicted value of Eq. (4.15),wehave
MMP 5 0:618 3 11:562 5 7:145 MPa, from Eq. (4.15)

4.3.2.7 Impurity Correction Factor by Sebastian et al. [38]
In addition to Alston et al. [37], Sebastian et al. [38] also applied a correction factor
(F impure )toAlstonet al. [37] MMP correlation, which is a function of modified impuri-
ties critical temperature (T cm ) and their mole fraction (x i ) by the following relationships:
22 24 2
F impure 5 1:0 2 2:13 3 10 ðT cM 2 304:2Þ 1 2:51 3 10 ðT cM 2304:2Þ (4.19)
3
2 2:35 3 10 ðT cM 2304:2Þ .. .
27
where
X
T cM 5 x i 3 T ci (4.20)
where T ci , T cM , F impure , and x i indicate the critical temperature of each component in
K, modified impurities critical temperature in K, impurity correction factor, and
mole fraction of each component, respectively. H 2 S critical temperature is modified to
51.67 C.

Example 4.9: In Example 4.7, calculate the MMP by Sebastian et al. [38] consider-
ing H 2 S mole fraction of 0.1 as an impure component.

Solution: At the beginning, the modified critical temperature is computed as follows:

X
T cM 5 x i 3 T ci 5 278:317 K
from Eq. (4.20)
The effect of H 2 S impurity on MMP can be taken into account through
Eq. (4.19) as follows:
22 24 2
F impure 5 1:0 2 2:13 3 10 ðT cM 2 304:2Þ 1 2:51 3 10 ðT cM 2304:2Þ
3
27
2 2:35 3 10 ðT cM 2304:2Þ 5 1:723
from Eq. (4.19)