EEOR in Carbonate Reservoirs - Electrokinetics for Petroleum and Environmental Engineers - page 165

100

RF WF = 62.6% RF ECXF = 86.5%

90

Ultimate RF EXSIM

80

Ultimate RF EXSEQ

70

EEOR

60

Simultaneous (EK+
Surfactant) flooding
Sequential WF

50

40

30

Sequential surfactant
flooding
Sequential
(EK+surfactant) flooding

20

RF WF = 60.4%

RF SF = 68.1%

RF EXSF = 76.4%

10

0

0 1 2 3 4 5 6 7 8 9

Number of injected pore volumes

Figure 4.7 An example of different stages in SMART EOR (After Ansari et al., 2012)

4.4.1 Electrokinetic-Assisted Surfactant Flooding (SMART
EOR) on Mixed to Oil-Wet Core Plugs
Simultaneous surfactant flooding produced 2.7% higher displacement
efficiency or 20% more displacement efficiency related to original recov-
ery when compared to sequential surfactant flooding. This was accom-
plished while reducing the surfactant/water consumption by 55%. EK
sequential surfactant flooding produces almost the same displacement
efficiency while providing up to 25% reduced water consumption when
EK is initiated after waterflooding at the 50% water cut instead of after
waterflooding at the 100% water cut. Therefore, if EK is applied in a
mature reservoir early enough, the efficiency of the EK process would
be further enhanced due to a significant reduction in water footprint.
Furthermore, sequential surfactant flooding requires a lower current
density and power consumption when compared to the simultaneous
surfactant flooding (figure 4.8).
It was found that oil-wet core plugs require approximately 10 times more
water consumption than water-wet core plugs at room temperature. In
addition, SMART EOR resulted in a higher yield in mixed to oil-wet res-
ervoirs as EK-assisted sequential surfactant EOR produced 56% of the