Mathematical Modeling of Electrokinetic Transport and Enhanced Oil Recovery In Porous Geo-Media - Electrokinetics for Petroleum and Environmental Engineers - page 208

1

Core A
Core B
Core C
Core D

0.1
0.08
0.06
0.04
0.02
0

0.8

0.6

0 0.5 1

0.4

Water Saturation (S w )

0.2

0 0

0.2 0.4 0.6 0.8 1

Water Saturation (S w )

Figure 5.6 Experimentally evaluated k er,ow coefficient for the core samples (After
Ghazanfari, 2013a)

computed at a specific water saturation of the core. In these tests a fresh
core was used for each measurement to establish the next water saturation
level. Figure 5.6 shows the distribution of the evaluated coefficients for the
core specimens in two different scales for clarity.
As observed in figure 5.6, the coupling coefficient k er,ow varied from 0.02
to 0.09, on the dimensionless scale of 0 to 1. This coefficient essentially
describes the contribution of viscous drag of water on the oil phase, which
results in the production of oil by EK. At low water saturations, the drag-
ging capacity of the water is low because there is less water available in
the pore space. As the water saturation increases the water mass that cre-
ates the momentum to drag oil increases, hence increased oil production.
Beyond a critical level of water saturation, the oil production drops despite
the increase in the dragging capacity of the water, because there is now less
oil available in the pore space.
he k er,ow coefficient, reflecting the contribution of oil to water produc-
tion, was set to zero since EO body force in the oil phase was assumed to
be insignificant, hence no viscous drag by oil exists at the interface to cause
water flow.

5.8.4.4 Analytical evaluation of coupling coefficients

It is also possible to evaluate relative EO permeability coefficients analyti-
cally, as it may become difficult and tedious to evaluate them experimen-
tally. The analytical representation of coupling coefficients is based on the
principles of EO viscous pumps which use conductive liquids (e.g., water)