American Oil and Gas Reporter - February 2016 - 65

SpecialReport: Improved Oil Recovery
FIGURE 1A

FIGURE 1B
Pilot 1 3-D Grid

10-acre area
Vertically has six zones
Model dimension 17 x 16 x 30
DX = DY = 40.79 ft
DZ is approximately 5 ft

Pilot 2 3-D Grid

Prod-1
Inj-1

Depth (ft)
1,323

25-acre area
Vertically has six zones
Model dimension 17 x 17 x 20 x 36
DX = 76.47 ft
DX = 80 ft
DZ is approximately 4 ft

Depth (ft)
Prod-1

1,296

1,296
1,271

Inj-1

Prod-2

Prod-5
1,248

1,270

Prod-2

1,221

1,243

ability channels (thief zones) between
pairs of injection and producing wells.
These high-permeability channels create
a path of least-resistance volume (PLRV),
or a short-circuit of injected fluids that
leaves residual oil in the channels and
renders a large volume of other parts of
the reservoir unswept.
As with the preceding injected water,
the additive should follow similar pathways
in the reservoir. Unlike water, however,
the nanofluid should mobilize residual
oil in the high-permeability channels to
the waterflood. Because the PLRV is a
smaller fraction of the total hydrocarbon
pore volume (HCPV) of the thief zone,
pilot testing in the reservoir PLRV minimizes economic risks by enabling smaller-sized treatment designs. It also allows
the mobilized oil to be produced quicker,
resulting in more attractive economics.
Economics are further derisked through
being able to circumvent some of the
steps in the lengthy laboratory/model/field

1,170

1,162

1,145

1,136

1,120

1,109

1,095

1,092

1,070

1,055

1,045

workflow associated with traditional
chemical EOR projects. In addition, minimal preparation or facility/injection infrastructure changes are required in existing waterfloods to deliver additive to
the reservoir.
Once the field trial is completed, the
data acquired can then be evaluated to
decide whether to expand treatment on a
fieldwide basis, perform conformance
treatments at the end of the trial, or add
the nanofluid additive in the subsequent
chase water injection.

show that a 1.0 pore volume slug of one
gallon per 1,000 gallons of the nanofluid
additive would recover 9-12 percent of
original oil in place, with a 1-12 percent
increase in oil cut. The lab results were
scaled up to test two pilot configurations
where the remaining oil in the channels
was the primary target.
As noted, treatment volumes were
based on the HCPV of the thief zones in
each pilot. Both pilot areas had been
under waterflood for more than 15 years,
and the water injection data showed that
the majority of the injected water circulated
through the thief zones. The thief zones
are believed to be at residual oil saturation
(Sor). The first pilot is a quarter nine-spot
with one injector and three producers.
The second pilot has a central injector
updip of the structure with five producers.
Figures 1A and 1B show the 3-D simulation grids for both pilots. Results show
significant peak oil production related to

Test Results
The nanofluid-based process works
on the principle that an increase in capillary
number increases oil recovery. Since the
capillary number is a function of viscosity,
velocity and IFT, any positive alteration
of these parameters leads to an increase
in the capillary number and increased oil
recovery.
Laboratory core flood experiments
FIGURE 2B

Increased Oil Cuts (Pilot 1)

Increased Oil Cuts (Pilot 2)

10
Oil Cut (%)

1,196

1,189

FIGURE 2A

8
6

8
6
4

2
0

Prod-4

Prod-3

1,216

Prod-3

MES

Chase Water
3

4
Time (Years)

2
6

Chase Water

MES
0

4
Time (Years)

FEBRUARY 2016 65

American Oil and Gas Reporter - February 2016

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