Page 141 - Fundamentals of Enhanced Oil and Gas Recovery

Miscible Gas Injection Processes 129

Therefore, X 52 lnR 2 1 2 5:615=R 1 ln5:615. Taking the limit as R reaches
to infinity lead to the followings:
X 52 lnR 1 0:725 (4.42)
0 0
Hence, E R 5 m lnRð Þ 1 n
For example, if oil recovery versus GOR is plotted on a semilog scale, a straight
line should be obtained.

4.12 CO 2 PROPERTIES AND REQUIRED VOLUMES
4.12.1 Correlation of CO 2 /Heavy Oil Properties
The following correlations are introduced to determine the solubility of CO 2 , swell-
ing factor, and viscosity of the CO 2 /heavy oil mixture. For this purpose, temperature,
pressure, specific gravity of oil, and oil viscosity at any temperature and pressure con-
dition are required to be specified. The temperature dependence of heavy oil viscosity
can be correlated as follows [67]:
μ 1 1

log 2 5 5707 2 (4.43)
μ
1 1 atm T 2 T 1
where μ and μ are the viscosities of heavy oil at temperatures of T 2 and T 1 (in R),

2 1
respectively. This equation is a modified version of proposed correlation by Reid
et al. [119]. The pressure dependency of the heavy oil viscosity could be estimated as
follows [67]:
μ p

log 2 5 A T 2 1 (4.44)
μ 14:7
1
in which, p shows pressure in psia and A T is a function of temperature. It should be
noticed that Eq. (4.44) is valid for pressures less than 3000 psia. It is notable that Eq. (4.44)
is not applicable for a highly viscous oil. μ and μ are the oil viscosities at temperature T
2 1
and pressures of p and 14.7 psi, respectively. The proportionality constant, A T , can be cor-
related as a function of temperature and the specific gravity of oil as follows [67]:
13:877exp 4:633γÞ
ð
A T 5 (4.45)
T 2:17

In Eq. (4.45), T and γ denote the temperature (in R) and oil specific gravity, respec-
tively. The solubility of CO 2 in a crude oil is defined as the volume of CO 2 in the CO 2 -
saturated oil per barrel of dead oil at the temperature in which solubility is measured.