Improved Oil Recovery by Waterflooding - University of Wyoming

Improved Oil Recovery by Waterflooding
Nina Loahardjo
Petrophysics and Surface Chemistry Group
Chemical and Petroleum Engineering
University of Wyoming
18 January 2011
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Project Personal
• Norman Morrow
• Carol Robinson (administration)
• Winoto Winoto, Ph.D.
– Low salinity, removal of water blocks, rate effect, and core properties for screening cores
• Nina Loahardjo, Ph.D.
– Low salinity, sequential waterflooding, and interfacial properties
• Siluni Wickramatilaka, Ph.D.
– Spontaneous Imbibition – scaling of viscosity ratio etc., gravity dominated imbibition, MRI imaging
of an imbibition front, low salinity imbibition at Sor, surfactant enhanced imbibition
• Pu Hui, Ph.D.
– Low salinity flooding of reservoir cores including CBM water, chemical analysis and inline
monitoring of pH and conductivity of effluent brine
• Behrooz Raeesi, Ph.D. Student
– Drainage/imbibition capillary pressure data, theory and experiments on surface energy, wetting and
surface roughness
EORI staff
• Peugui Yin
– Petrophysics: thin section analysis and data acquisition: surface areas, clay analysis, cation
exchange capacities (Susan Schwapp)
• Shaochang Wo
– Data analysis, modelling, simulation
Machine shop
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E
• Ron Borgialli, George Twitchell, and Dean Twitchell

• Jill Buckley
Adjunct Professors
• Crude oil characterization, wetting, low salinity and sequential
waterflooding recovery mechanisms, adhesion, interfacial
tension, asphaltene phase behavior
• Koichi Takamura
• Recovery mechanisms, surfactants, emulsions, dispersions,
DLVO theory, fundamentals of interfacial tensions including
effect of pH and salinity for crude oils
• Geoff Mason
• Spontaneous imbibition, pressures at imbibition front and core
face, viscosity ratios – correlations and theory, bubble snap-off
and capillary back pressure for precise pore geometries, nuclear
tracer imaging and interpretation (with EU N H ABergen) N C E D O I L R E C O V E R Y I N S T I T U T E

•Australian National University
Collaborations
•Digital Core Consortium for Wettability : Mark Knackstedt, Andrew Fogden, Munish Kumar, Evgenia
Lebedevia and Tim Senden
Micro X-ray CT Imaging and Surface Chemical Techniques Related to Recovery Mechanisms for Crude Oil
and Core (Tensleep and Minnelusa) Which Complement UW Coreflood and Imbibition Studies
•University of Manitoba: Doug Ruth
Simulation and Theory of Imbibition
•University of Bergen: Arne Graue and Martin Fernø
Nuclear Tracer Imaging of Imbibition
•ConocoPhillips: James Howard and Jim Stevens
MRI Imaging of Sequential flooding, Spontaneous Imbibition, and Low Salinity Flooding
•University of Kyoto
Application of Molecular Simulation to Interpretation of the Interfacial and Surface Properties of Crude Oil
•University of Edmonton: David Potter
Tracking the Movement of Clay Particles Within Porous Media from Magnetic Properties
•Chevron: Guoqing Tang
Low Salinity Waterflooding – Industrial X-Ray Imaging
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

July 2010 onward
Presentations
• Morrow, N:” Interfacial Properties and Improved Oil Recovery by Waterflooding”, presented at Technical Advisory Board for
Enhanced Oil Recovery Institute, University of Wyoming, July 2010
• Loahardjo, N., Xie, X., Winoto, W., Buckley, J., and Morrow, N.R., “Improved Oil Recovery by Sequential Waterflooding”,
presented at the 14th Annual Gulf of Mexico Deepwater Technical Symposium, New Orleans, LA, Aug. 19-19, 2010.
• Xie, X., Pu, H., Buckley, J., Morrow, N.R., and Carlisle, C., “Low Salinity Waterflooding and Improved Oil Recovery”, presented
at the 14th Annual Gulf of Mexico Deepwater Technical Symposium, New Orleans, LA, Aug. 19-19, 2010.
• Morrow, N. and Mason, G:”Areas of Crude Oil/Rock Contact That Govern The Development of Mixed Wet Rocks”, presented at
11th International Symposium on Reservoir Wettability Calgary, AB, Canada, September 2010
• Loahardjo, N., Xie, X., Winoto, W., Buckley, J. and Morrow, N.:”Mechanism of Improved Oil Recovery by Sequential
Waterflooding”, ”, presented at 11th International Symposium on Reservoir Wettability Calgary, AB, Canada, September 2010
• Buckley, J. and Morrow, N.:”Improved Oil Recovery by Low Salinity Waterflooding: A Mechanistic Review”, presented at 11th International Symposium on Reservoir Wettability Calgary, AB, Canada, September 2010
• Morrow, N. and Mason, G:”Spontaneous Imbibition Into Cores with Different Boundary Conditions”, presented at 11th International Symposium on Reservoir Wettability Calgary, AB, Canada, September 2010
• Wickramatilaka, S., Mason, G., Morrow, N., Howard, J. and Stevens.:” Magnetic Resonance Imaging of Oil Recovery during
Spontaneous Imbibitions”, presented at 11th International Symposium on Reservoir Wettability Calgary, AB, Canada, September
2010
• Loahardjo, N.: “Mechanism of Improved Oil Recovery by Sequential Waterflooding” Chemical & Petroleum Engineering Graduate
seminar, Nov. 8, 2010.
• Takamura, K., Loahardjo, N., Buckley, J., Morrow, N, Kunieda, M., Liang, Y. and Matsuoka, T.:” Preferential Accumulation of
Light End Alkanes and Aromatics at The Crude Oil/Air and Crude Oil/Water Interfaces: Potential Mechanism of Accelerated Tar
Ball Formation from Spilled Crude Oil”, be presented at the Annual SME Meeting, Denver, February 27 – March 2, 2011
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

July 2010 onward
Publications
• Mason, G., Fisher, H., Morrow, N.R., and Ruth, D.W.: “Correlation for the Effect of Fluid Viscosities on Counter-Current
Spontaneous Imbibition”, JPSE. 72, (August) 2010, 195-205.
• Loahardjo, N., Xie, X., and Morrow, N.R., “Oil Recovery by Sequential Waterflooding of Mixed-Wet Sandstone and Limestone”,
Energy Fuels 24 (9) 5073-5080, Web published August 30, 2010.
• Pu, H., Xie, X., Yin, P. and Morrow, N.:”Low Salinity Waterflooding and Mineral Dissolution”, SPE 134042, SPE Annual Meeting
Technical Conference and Exhibition, Florence, Italy, September 2010
• Pu, H., “Recovery of Crude Oil from Outcrop and Reservoir Sandstone by Low Salinity Waterflooding”, PhD Defense, Sept. 27,
2010
• Wickramatilaka, S., G., Morrow, N. and Howard, J.:”Effect of Salinity on Oil Recovery by Spontaneous Imbibition”, 24
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E
th
International Symposium on the Core Analysts, Halifax, Nova Scotia, Canada, October 2010
• Kumar, K., Fodgen, A., Morrow N. and Buckley J.:”Mechanisms of Improved oil Recovery from sandstone by Low Salinity
Flooding”, 24th International Symposium on the Core Analysts, Halifax, Nova Scotia, Canada, October 2010
• Loahardjo, N., Morrow, N., Stevens, J. and Howard, J.:”Nuclear Magnetic Resonance Imaging: Application to Determination of
Saturation Changes in a Sandstone Core by Sequential Waterflooding”, 24th International Symposium on the Core Analysts,
Halifax, Nova Scotia, Canada, October 2010
• Morrow, N., and Buckley, J. ” Improved Oil Recovery by Low Salinity Waterflooding”, SPE Distinguished Author Series, October
2010
• Morrow, N.:” Low salinity Waterflooding”, EORI Newsletter, Wyoming, October 2010
• Fogden, A., Kumar, M., Morrow, N.R., Buckley, J.S.: “Mobilization of Fine Particles during Flooding of Sandstones, and Possible
Relations to Enhanced Oil Recovery”, Energy Fuels, submitted November, 2010.
• Li, Y., Mason, G., Morrow, N. and Ruth D.:” Capillary Pressure at A Saturation Front during Restricted Counter-Current
Spontaneous Imbibition with Liquid Displacing Air”, Transport in Porous Media, November, 2010
• Siluni Wickramathilaka, “Oil Recovery by Spontaneous Imbibition,” Dec. 1, 2010, PhD. Defense
15 Manuscripts in Preparation for 2011

TOPICS
• Screening outcrop cores for model rocks for low
salinity waterflooding
• Low salinity waterflooding with mineral dissolution
– Eolian sandstones containing dolomite and anhydrites
but without clays (Tensleep, Minnelusa, and Phosphoria)
• Sequential waterflooding
– Mechanisms of Sequential waterflooding
– Field test applications
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Oil Recovery: Waterflooding
Single 5-Spot Well Pattern
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Laboratory Measurement of
Oil Recovery by Waterflooding
brine
core
Oil Recovery, %OOIP
100
80
60
40
20
0
Target for Tertiary Recovery
Oil Recovery by Waterflood
0 2 4 6 8 10 12
Brine Injected, PV
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Definitions
• Low Salinity Waterflooding (LSW) at S or
– Low salinity waterflooding of watered-out reservoir, nominally at
residual oil saturation, S or, after High Salinity Waterflooding (HSW)
(common approach)
R wf (%OOIP)
100
80
60
40
20
0
Core U : R1/C1
LC Crude Oil
HSW
LSW
LSE
0 2 4 6 8 10 12
Brine Injected, PV
Loahardjo et al., 2007
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Definitions (cont’d)
• Low Salinity Waterflooding (LSW) at S wi
– secondary mode low salinity waterflooding that begins at initial water
saturation, S wi (growing interest)
Loahardjo et al., 2010
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

# # # of of of No. No. No. Papers Papers Papers of of of Published Published Published & & & Presentations
Presentations
Presentations Papers Papers Papers
Low Salinity Waterflooding
25
20
15
10
5
0
1996 1996 1996
UW
Other
1998 1998 1998
1999 1999 1999
2000 2000 2000
2001 2001 2001
2002 2002 2002
2003 2003 2003
2004 2004 2004
Year
Figure 3. Histogram of Low Salinity Papers and Presentations
EORI Newsletter Fall 2010
Mechanism of Low Salinity Waterflooding ?
SPE Distinguished Author article on LSE (Morrow and Buckley, 2010)
2005 2005 2005
2006 2006 2006
2007 2007 2007
2008 2008 2008
2009 2009 2009
2010 2010 2010
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Main Hindrances to Systematic
Investigation of Low Salinity Flooding
• The type of Berea sandstone which
responded to low salinity waterflooding is
no longer available
• Currently available Berea shows little
(< 2% OOIP increase) if there is any
response to low salinity flooding
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Solutions/work in progress
A. Work with reservoir crude oil/brine/rock
Reservoir cores are generally more responsive than outcrop
cores but :
• coring are expensive
• duplicate core plugs are not usually available because of heterogeneity
• core quality, history, cleaning and re-use of cores are problematic.
• quality of crude oil samples can be uncertain
Papers on reservoir sandstone and carbonate results are in
preparation, covering:
• Step changes in salinity
• Injection flow rate
• Intermissions in flow
• Effluent brine analysis
• Etc.
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Solutions/work in progress
B. Total has identified a responsive outcrop
Three groups have reported response (U. of Wyoming, U.
Bordeaux, and U. of Stavanger)
• Cost, heterogeneity, and logistics of supply are still a problem
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Solutions/work in progress
C. Screening Outcrop Cores
for Model Rocks for Low
Salinity Waterflooding
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Screening of commercially available outcrop
Klinkenberg Permeability, mD
Klinkenberg Permeability, mD
10000
1000
100
10
1
0.1
Berea Buff
Berea Stripe
Idaho Hard
Wisconsin
Silurian Dolomite
Bentheimer
Parker
Torrey Buff
Briar Hill
Boise
Leopard
Castle Gate
Sister Gray
Berea
Kirby
Edwards
0 5 10 15 20 E N25 25 H A N C E D 30 O I L R E C O35 35 V E R Y I N40 40 S T I T U T E 45
Porosity, %
Bandera Gray
Bandera Brown
Austin Chalk
Idaho Gray
Cordova Cream
Stephen Xtra
Georgetown
Edwards Brown

Berea Stripe,
K klink=382–457 mD, f=20.1–20.5%
Briar Hill,
K klink=5,500–5,900 mD, f=23.7–24.2%
Castle Gate,
K klink=1,140–1,300 mD, f=25.0–25.6%
Idaho Gray,
Kklink=5,600–7,200 mD, f=28.6–29.7%
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

R wf (% OOIP)
100
80
60
40
20
Berea Stripe (WP Crude Oil)
T a = 60 o C ; T d = 60 o C
k g = 463 mD ; k b = 282 mD
S wi = 23%
Seawater
20x Dilution of Seawater
2.3% OOIP
0
0 5 10 15 20 25 30 35 40 0
Injected Brine, PV
pH
P (psi)
Low Salinity Waterflooding for Berea Stripe Outcrop
14
12
10
8
6
4
2
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E
pH and P (psi)

R wf (% OOIP)
100
80
60
40
20
Idaho Gray (WP Crude Oil)
T a = 60 o C ; T d = 60 o C
k g = 7.2 D ; k b = 700 mD
S wi = 22%
Seawater
3.3% OOIP
P (psi)
0
0 5 10 15 20 25 30 0
Injected Brine, PV
Low Salinity Waterflooding for Idaho Gray Outcrop
p
20x Dilution of Seawater
16
14
12
10
8
6
4
2
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E
pH and P (psi)

R wf (% OOIP)
100
80
60
40
20
Briar Hill (WP Crude Oil)
T a = 60 o C ; T d = 60 o C
k g = 5.6 D ; k b = 700 mD
S wi = 27%
Seawater
20x Dilution of Seawater
3.7% OOIP
0
0 5 10 15 20 25 30 0
Injected Brine, PV
Low Salinity Waterflooding for Briar Hill Outcrop
pH
P (psi)
14
12
10
8
6
4
2
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E
pH and P (psi)

R wf (% OOIP)
100
80
60
40
20
Castle Gate (WP Crude Oil)
T a = 60 o C ; T d = 60 o C
k g = 1.3 D ; k b = 460 mD
S wi = 24%
Seawater
20x Dilution of Seawater
(psi)
10
P
8
and
pH
pH
6
P (psi)
4.6% OOIP
0
0 5 10 15 20 25 0
Injected Brine, PV
Low Salinity Waterflooding for Castle Gate Outcrop
14
12
4
2
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

enefit compare to
waterflood results (%)
40
35
30
25
20
15
10
5
0
1
2
Low salinity Effect
3
4
Reservoir cores
(Lager et al., 2006)
SorHSWSorLSW
SoiSorLSW
5
6
8
Endicott core
% benefit 100%
9
10
11
12
13
Endicott field average
(Seccombe et al., 2008)
14
15
16
17
18
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E
40
35
30
25
20
15
10
5
0
Outcrop
cores
Berea
Stripe
Idaho
Gray
Briar
Hill
Castle
gate

LSW from LC Reservoir Core
R wf (%OOIP)
100
80
60
40
20
0
Core U : R1/C1
LC Crude Oil
HSW
LSW
14% OOIP
P
pH
0
0 2 4 6 8
Brine Injected, PV
10 12
40
30
20
10
Pressure Drop (psi) and pH
Loahardjo et al., 2007
The result shows benefit to LSW compared to HSW is 43%
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Importance of Laboratory Coreflood
Tests on Reservoir for LSW
• For any positive LSW effect, tests on reservoir core show
substantial response (averaged at 14%) as opposed to low
response (0-9.6%) on tested outcrop core to date
• Single well chemical tracer tests showed 13% OOIP reduction
in residual oil, consistent with laboratory core test (McGuire et
al. 2005)
• A candidate North Sea field that met the necessary condition
for low salinity effect did not respond to LSW in either
laboratory or pilot test (Skrettingland et al. 2010)
• The correlation between laboratory coreflood test and field
test results confirms the need for individual laboratory tests for
screening low salinity candidate;
The variability in response demonstrates the value
of laboratory tests in screening candidate reservoirs
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

2. Low Salinity Waterflooding
with Mineral Dissolution
Studies on Wyoming Reservoirs using
Low Salinity - Coal Bed Methane Water
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Target Formations
• Minnelusa (Gibbs) and Tensleep (Teapot Dome) eolian
sandstones
One half of Wyoming’s oil production
Abundant dolomite & anhydrite cement
Formation water salinity: 3,300 – 38,650 ppm
Low salinity water: Coalbed Methane Water (1,316 ppm)
• Phosphoria (Cottonwood) dolomite formation
Recovery factor as low as 10%
Patchy anhydrite
Formation water salinity: 30,755 ppm
Low salinity water: Diluted formation water (1,537 ppm)
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Oil sample
Crude Oils
n-C 6 Asph
[%wt]
Acid #
[mg KOH/g oil]
Base #
[mg KOH/g oil]
Tensleep 3.2 0.16 0.96
Minnelusa 9.0 0.17 2.29
Phosphoria 2.9 0.56 1.83
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

100 mm
Minnelusa Rock from Oil Zone
Dolomite
Anhydrite
• Mineralogy: sandstone with abundance dolomite and anhydrites cements
• Porosity: 12.2 -18.1%
• Permeability: 63.7 – 174.2 mD
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E
Dolomite
Pu et al., 2010

Oil recovery, %OOIP
100
90
80
70
60
50
40
30
20
10
0
M1
K g = 78.4 md, f = 14.6%
S wi = 8.2%,
MW (38,651ppm)
0 2 4 6 8 10 12 14 16 18
Brine injected, PV
+5.8%
CBMW (1,316ppm)
Low Salinity Waterflooding for Minnelusa Rock from Oil Zone
25
20
15
10
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E
5
0
Pu et al., 2010
Pressure drop, psi

Phosphoria Rock from Cottonwood Creek Field
100 mm
Vug
Dolomite
Mineralogy: Crystallin dolomite and patchy anhydrites
Porosity: 9.5 -19.6%
Permeability: 0.25 – 294 md
Dolomite
Pu et al., 2010
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Oil recovery, %OOIP
100
90
80
70
60
50
40
30
20
10
0
P1
K g = 6.8 md, f = 9.5%
S wi = 22.7%
PW
30,755ppm
K we1 = 2.1 md
+8.1%
0 5 10 15 20 25 30 35 40 45 50
Brine injected, PV
5% PW dilute
1,537ppm
K we2 = 1.1 md
Low Salinity Waterflooding for Phosphoria Rock
30
25
20
15
10
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E
5
0
Pu et al., 2010
Pressure drop, psi

100 mm
Tensleep Rock from Oil Zone
Dolomite
quartz
dolomite
anhydrite
• Mineralogy: sandstone with dolomite and anhydrites cements
• Porosity: 8.6 -15.7%
• Permeability: 7.0 – 42.7 md
Pu et al., 2010
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Oil recovery, %OOIP
100
90
80
70
60
50
40
30
20
10
0
T4
K g = 22.9 md, f = 12.5%
S wi = 15.3%
MW
38,651ppm
K we1 = 0.53 md
CBMW
1,316ppm
0 10 20 30 40 50 60 70
Brine injected, PV
+5.2%
K we2 = 0.55 md
Low Salinity Waterflooding for Tensleep Rock from Oil Zone
90
80
70
60
50
40
30
20
10
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E
0
Pu et al., 2010
Pressure drop, psi

Anhydrates dissolution in Tensleep rock – the green regions show the region
of cement dissolutions after flooding with CBM water (Lebedeva et al., 2009)
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

100 mm
Tensleep Rock from Aquifer
Dolomite
Dolomite
Mineralogy: sandstone with interstitial dolomite crystals and minimal anhydrates
Porosity: 17 -18.7%
Permeability: 50.8 – 228.5 md
Pu et al., 2010
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Oil recovery, %OOIP
100
90
80
70
60
50
40
30
20
10
0
Core# K g (md) f S wi (%)
TA1 228.5 18.7 22.4
TA2 50.8 18.1 20.4
MW
38,651ppm
CBMW
1,316ppm
0 5 10 15 20 25 30
Brine injected, PV
R TA1
K we = 10.4 md
P TA1
K we = 1.1md
P TA2
R TA2
Low Salinity Waterflooding for Tensleep Rock from Aquifer
30
25
20
15
10
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E
5
0
Pu et al., 2010
Pressure drop, psi

Silurian Dolomite Outcrop
Mineralogy: interstitial dolomite and no anhydrates
Porosity: 17 – 20%
Permeability: 100 mD – 1,000 md
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

R wf (% OOIP)
100
80
60
40
20
Silurian Dolomite (WP Crude Oil)
T a = 60 o C ; T d = 60 o C
k g = 102 mD ; k b = 19 mD
S wi = 24%
Seawater
P (psi)
20x Dilution
of Seawater
0
0 5 10 15 20 25 30 35 0
Injected Brine, PV
Low Salinity Waterflooding for Silurian Dolomite Outcrop
pH
35
30
25
20
15
10
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E
5
pH and P (psi)

Summary
• Tensleep and Minnelusa sandstones, and
Phosphoria dolomite all contained
anhydrites and all responded to low
salinity waterflooding
• Tensleep sandstone from an aquifer and
Silurian dolomite outcrop did not contain
any noticeable anhydrites and did not
respond to low salinity waterflooding
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

3. Sequential Waterflooding
Morrow, Xie, and Loahardjo,
US Patent No. WO 2009/12663 A2, October 2009
Morrow, Xie, and Loahardjo,
Pending Provisional Patent No. 61/226,709, July 2009
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Effect aging at S or and/or S wi
on sequential waterflooding
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Recovery of Crude Oil
Medium Permeability Berea Sandstone
Aging at S or after 3 cycles
T a = 75 o C
T d = 60 o C
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

RR RR (%OOIP) (%OOIP) (%OOIP) (%OOIP)
wf wf wf wf
100
80
60
40
20
PH 2L H 02 (WP Crude Oil)
T = 75 a o T = 75 C ; t = 6 months
a a o T = 75 C ; t = 6 months
a a o T = 75 C ; t = 6 months
a a o C ; t = 6 months
a
T = 60 d o T = 60 C (m = 28.8 cP)
d o T = 60 C (m = 28.8 cP)
d o T = 60 C (m = 28.8 cP)
d o C (m = 28.8 cP)
R1/C1 : S = 26% : S = 44%
wi or
R1/C2 : S = 36% : S = 28%
wi or
R1/C3 : S = 46% : S = 19%
wi or
k = 604 mD
g
20 days at S or
R1/C4 : S = 42% : S = 15%
wi or
0
0 1 2 3 4 5 6 7
PV Brine Injected
Sequential waterflooding with wettability control
for medium permeability Berea sandstone
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Recovery of Crude Oil
Low Permeability Berea Sandstone
Aging at S wi after 4 cycles
followed by aging at S or
T a = 75 o C
T d = 60 o C
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

RR RR RR (%OOIP) (%OOIP) (%OOIP) (%OOIP) (%OOIP) (%OOIP)
wf wf wf wf wf wf
100
80
60
40
20
Ev 2L 2L 02 02 (WP (WP Crude Crude Oil)
Oil)
T = 75 a o T = 75 C ; t = 6 months
a a o T = 75 C ; t = 6 months
a a o T = 75 C ; t = 6 months
a a o T = 75 C ; t = 6 months
a a o T = 75 C ; t = 6 months
a a o C ; t = 6 months
a
T = 60 d o T = 60 C (m = 28.8 cP)
d o T = 60 C (m = 28.8 cP)
d o T = 60 C (m = 28.8 cP)
d o T = 60 C (m = 28.8 cP)
d o T = 60 C (m = 28.8 cP)
d o C (m = 28.8 cP)
k = = 84 84 mD
mD
g
30 days at S wi
20 days at S or
R1/C1 R1/C1 : : S S = 28% : S = 49%
wi or
R1/C2 : S = 28% : S = 43%
wi wi wi wi wi or
R1/C3 : S = 31% : S = 38%
wi wi wi wi or
R1/C4 : S = 38% : S = 29%
wi or
R1/C5 : S = 34% : S = 38%
wi or
R1/C6 : S wi = 37% : S or = 22%
0
0 1 2 3 4 5 6 7
PV Brine Brine Injected
Injected
Sequential waterflooding with wettability control
for low permeability Berea sandstone
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Recovery of Crude Oil
High Permeability Berea Sandstone – BS 4
Aging at S or after 4 cycles
followed by aging at S wi, S or , S or and S or
Restoration 2
T a = 75 o C; t a = 1 year
T d = 60 o C
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

21 3 months days at at Sor Sor 25 days at Swi 17 24 days days at at SorSor Sequential waterflooding with wettability control
for high permeability Berea sandstone – Restoration 2
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Summary
• Further investigation of oil recovery by sequential
waterflooding is needed, particularly for different types of
crude oil, because wettability, and changes in wettability,
depend on specific crude oil/brine/rock interactions
• Aging at high water saturation usually gave increase in
oil recovery, whereas aging at low water saturation
resulted in decreased oil recovery
• Sequential waterflooding without change in salinity and
without cleaning or re-aging between cycles usually
showed sequential reductions in residual oil saturation.
• Single-well field testing of sequential waterflooding is
justified
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Single-Well Tests of
Sequential Floods
Calculations are based on a simple
piston-like displacement model
f =20.9%, 30 ft reservoir oil-zone thickness
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Reservoir at residual oil saturation after waterflood
(WF1)
Day 0
0 10 20 30 40 50 ft
S OR (WF1)=36.2%
target zone radius = 45 ft
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Injection of oil into the target zone
Day 1
0 10 20 30 40 50 ft
S OR (WF1)=36.2%
target zone radius = 45 ft
S O=64.9%
oil injected = 100 bbl
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Displacement Radial length of of injected oil reaches oil by minimum injection before of brine
growing upon more (WF2) injection of brine
Day 12
0 10 20 30 40 50 ft
S OR (WF1)=36.2%
inner radial distance
START WATER INJECTION
oil bank radial length
oil bank minimum
radial length= 4.5 ft
oil bank volume = 406 bbl
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Continuation of oil bank displacement by
injection of brine (WF2)
Day 23
45
6
0 10 20 30 40 50 ft
S OR (WF1)=36.2%
S O=64.9%
S OR (WF2)=28.8%
oil bank radial length= 5.9 ft
oil bank volume = 1,149 bbl
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

The well is put on production and the oil bank
grows in volume and radial length
Day 68
910
0 10 20 30 40 50 ft
S OR (WF1)=36.2%
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

The well is put on production and the oil bank
grows in volume and radial length
Day 10 11 12 13 14
0 10 20 30 40 50 ft
S OR (WF1)=36.2%
S OR (WF2)=28.8%
S OR (WF3)=24.0%
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

100 bbl
oil
100 bbl
oil
Single Well Field Test
2,000 bbl
brine
10,000 bbl
brine
900 bbl oil in 14 days
(as high as 3200 bbl optimistically)
4,000 bbl oil in 62 days
(as high as 15,000 bbl optimistically)
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Single Well Field Tests
• Low cost: Injected brine and oil are directly
available: Required oil volume is small
• Test should first be applied to reservoirs
with flow conformance (responded well to
waterflooding), oil viscosity close to that of
the injected brine and low gas/oil ratio
• Single well tracer tests can be used to
determine residual oil saturations before
and after the process
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Field Test ? 2011 ?
Discussion of potential field test
with James Seccombe and Scott Digert (BP Alaska)
Laramie, Wyoming, October 13, 2010
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Further Application of Sequential Waterflood
Improved Recovery
by Injection of Small Volumes of Oil
1. Inject multiple oil banks
(single well or well to well)
2. Reversing production and injection well before breakthrough
to avoid sand production, especially for less consolidated
reservoir
3. Convert a tertiary mode low salinity flood into a more
favorable/effective secondary mode low salinity waterflood
by pre-injection of oil
4. Establishing initial oil bank for other recovery methods, e.g.
before flooding natural residual oil zone
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Ongoing Topics and Future Work
1. Low Salinity Waterflooding
a. Tests on reservoir rocks
b. Screening outcrop cores, at S wi and S or
c. Attempt to identify a mechanism for LSW
2. Sequential Waterflooding
a. Further laboratory tests
b. Field tests of Sequential Waterflooding
3. Waterblock Treatment
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Acknowledgments
• EORI, University of Wyoming
• Wold Chair
• Industry:
Saudi Aramco*, BP*,Chevron, ConocoPhillips, Shell,
StatoilHydro*, Total* (enquiries from Oxy, Kuwait, Maersk)
* includes provision of reservoir rock and/or crude oil
Thank You !
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

Improved Oil Recovery by Waterflooding
Nina Loahardjo
Petrophysics and Surface Chemistry Group
Chemical and Petroleum Engineering
University of Wyoming
18 January 2011
E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

E N H A N C E D O I L R E C O V E R Y I N S T I T U T E

E N H A N C E D O I L R E C O V E R Y I N S T I T U T E