Page 90 - Fundamentals of Enhanced Oil and Gas Recovery

78 Ramin Moghadasi et al.

3.2.2.2.2 Simon and Graue [37]
In 1965, Simon and Graue [37] postulated that the swelling factor is not only a
function of the amount of dissolved CO 2 , but also of the size of the oil molecules
(M/ρ cc/g mol). They presented a graphical tool for predicting the swelling factor,
which is based on the relationship between swelling factor, mole fraction of CO 2 dis-
solved, and molecular size. Obviously, the swelling effect for heavy oil is not as drastic
as for light oil.
Simon and Graue [37] have reported an average deviation of 0.5% from experi-
mental data.

3.2.2.2.3 Mulliken and Sadler [38]
Mulliken and Sadler have tried to find a theoretical correlation for swelling factor pre-
diction. They applied the PR [44] EOS once to the CO 2 -saturated crude oil at satu-
ration conditions, and then again to the crude oil at 1 atm and the same temperature.
The swelling factor was defined as the ratio of the volume of the oil CO 2 mixture at
saturation pressure and temperature to the oil volume at the saturation temperature
and atmospheric pressure.

3.2.2.2.4 Emera and Sarma [41]
Based on Emera and Sarma [41] correlation, oil swelling factor can be predicted as
follows:
a. For oils with MW $ 300:
3
4
2
5
SF 5 1 1 0:3302y 2 0:8417y 1 1:5804y 2 1:074y 1 0:0318y 2 0:21755y 6 (3.13)
b. For oils with MW , 300:
3
2
4
5
SF 5 1 1 0:48411y 2 0:9928y 1 1:6019y 2 1:2773y 1 0:48267y 2 0:06671y 6
(3.14)
γ
γ 2 expðÞ

where y 5 1000 3 Sol MW . γ is the oil-specific gravity (oil density at
MW
15.6 C), SF is the oil swelling factor, Sol is the CO 2 solubility in oil in mole fraction,

and MW is the oil molecular weight in g/mol.
The experimental data ranges used for developing and testing of the model for
dead and live oil are given in the work of Emera and Sarma [41]. Emera and Sarma
[41] also examined their model over that of Simon and Graue [37].
3.2.2.2.5 Viscosity Reduction
By definition, viscosity is the resistance of a fluid to flow on a solid surface. Therefore
any flow equation accounts fluid viscosity for calculations. In a reservoir being flooded
immiscibly with gas, there is system of two-phase fluid flow. It is therefore very
important to accurately predict and model flow behavior of each fluid. Viscosity is a