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SPE DISTINGUISHED LECTURER SERIESis funded principally
through a grant of the
SPE FOUNDATIONThe Society gratefully acknowledges
those companies that support the programby allowing their professionals
to participate as Lecturers.
And special thanks to The American Institute of Mining, Metallurgical,and Petroleum Engineers (AIME) for their contribution to the program.
SPE Distinguished Lecturer Series
Viscous Oil EOR by Viscosity Viscous Oil EOR by Viscosity Reducing Immiscible (VRI) WAG Reducing Immiscible (VRI) WAG
ProcessProcess
Bharat S JhaveriBharat S Jhaveri
BP Exploration (Alaska) Inc.BP Exploration (Alaska) Inc.
Acknowledgements• SPE
• BP, Exxon Mobil, ConocoPhillips
• Alan Clark
• Frank Paskvan
• Jonathan Williams
• Katrina Yancey
• Pat McGuire †
• Rydell Reints
† SPE 93914Viscosity Reduction WAG: An Effective EOR Process for North Slope Viscous OilsP. L. McGuire, BP Exploration (Alaska) Inc., R. S. Redman, ConocoPhillips Alaska Inc., B. S. Jhaveri, K. E. Yancey, S. X. Ning, BP Exploration (Alaska) Inc.
• Motivation
• Miscible WAG* EOR
• Viscosity Reducing Immiscible WAG
• North Slope Situation
• Closing Remarks
* Water-Alternating Gas
Outline
Motivation For Gas EOR in Viscous Oil
• Conventional technology* not applicable⎯ Too deep
⎯ Offshore
⎯ Arctic
• Big projects with many high rate wells
• Available gas resource* e.g. Steam, Hot water flooding
• Motivation
• Miscible WAG EOR– Enriched Gas Drive
– Vaporizing Gas Drive
• Viscosity Reducing Immiscible WAG
• North Slope Situation
• Closing Remarks
Outline
Pseudo-Ternary Diagram
CH CI
CL
Critical point
Single Phase
C
PR = 2000 PSIA
Dew point
Bubble point
Two Phase
Enrichment Process
CH CI
CL
Critical point
Single Phase
C
PR = 2000 PSIA
Dew point
Bubble point
Two Phase
Oil
MI
MI - Oil Miscibility
CH CI
CL
Critical Composition
Single Phase
C
PR = 2000 PSIA
Dew point
Bubble point
Two Phase
Oil
MI
Pressure Dependence
CH CI
CL
Critical pointSingle Phase
C
PR = 1500 PSIA
Bubble point
Two Phase
Dew point
COil
MI
Minimum Miscibility Pressure (MMP)
CH CI
CL
Critical Composition
Single Phase
C
PR = 2000 PSIA
Dew point
Bubble point
Two Phase
Oil
MI
Slimtube Recovery: Miscible
Pressure, PSIA
Rec
over
y @
1.2
PV
2000 3500
1.0
MMP (Minimum Miscibility Pressure)
Phase Viscosities in Slimtube
0.01
0.1
1
10
100
0 200 400 600 800 1000
Oil ViscosityGas Viscosity
Inj. ---->Distance along slimtube (Grid-block no.) Prod.
Oil,
Gas
Vis
cosi
ty, c
p
Miscible WAG EOR Summary• Injection gas rich in (C2-C4)
hydrocarbons
• Fluid properties change by mass transfer
• MI composition a key design parameter
• WAG process to optimize gas sweep
• Motivation
• Miscible WAG EOR
• Viscosity Reducing Immiscible WAG
• North Slope Situation
• Closing Remarks
Outline
VRI Mechanism
CHCI
CL
Oil
VRI
(Viscosity Reducing Injectant)
Critical point
1 Phase
2 Phase
PR = 2000 PSIA
0.01
0.1
1
10
100
0 0.2 0.4 0.6 0.8 1
Oil ViscosityGas Viscosity
Viscosity Reduction in Slimtube
Inj. ---->Distance along slimtube (Grid-block no.) Prod.
Oil,
Gas
Vis
cosi
ty, c
p
VRI Reservoir Process (2D)I1 InjectorP1 Producer
Kx scale
• Vertical injector, horizontal producer
• Waterflood, WAG simulations
• Low and Moderate Viscosity Oils
• 1:1 WAG ratio, 30% HCPV Gas Injection
Injectant Description
• Low viscosity (10 cp) oil miscible with injected gas (MI)
• The same MI immiscible with moderate viscosity (57 & 117 cp) oils
• Injectant referred to as VRI for moderate viscosity oils
Slimtube Recoveries for 2 Oils
Pressure, PSIA
Rec
over
y @
1.2
PV
2000 3500
10 cp 57 cp
1.0
Injected Gas
Miscible for 10 cp
VRI for 50 cp
EOR Recoveries for MI & VRI (2D)
0
4
8
12
16
20
0 5 10 15 20 25 30Years
EO
R, %
OO
IP
10cp L-117 OBd
57cp Z-39 OBd
117cp Z-39 OBa
Miscible
VRI WAG
VRI WAG
EOR recovery similar for MI & VRI
Oil Rate for MI & VRI (2D)
0
200
400
600
800
1000
1200
0 2 4 6 8 10Years
Oil
Rat
e, S
TB/D
10cp_MI
10cp_wf
57cp_MI
57 cp_wf
117cp_MI
117cp_wf
Miscible
VRI WAG VRI WAG
Earlier EOR response for lower viscosity oils
117cp oil
45 cp oil
13 cp oil
117cp oil
45 cp oil
13 cp oil
Oil Viscosity Map (after 30 years)
117 cp oil
10 cp oil
57 cp oil
Miscible
VRI
VRI
VRI WAG Process
• Injectant not rich enough in (C2-C4) hydrocarbons
• Oil viscosity reduction and swelling by mass transfer
• Improved displacement by subsequent water injection
• WAG process to optimize gas sweep
• Motivation
• Miscible WAG EOR
• Viscosity Reducing Immiscible WAG
• North Slope Situation
• Closing Remarks
Outline
North Slope Viscous Oil Resource
KUPARUK RIVER UNIT
PRUDHOE BAY UNIT
West Sak (non-core)W S/Schrader Bluff (core)
S-Pad
Polaris
Orion
West Sak 1J
W-203
NS Viscous Oil Opportunity• Huge Resource (Tens of BSTB)
• Current development targets ~5 BSTB in W. Sak/Schrader Bluff Formation
• Low primary & waterflood recovery
• Available Gas Resource
• Prudhoe MI not miscible with moderate to high viscous oil (>15 cp)
Schrader Bluff Oil Quality Variation
-
2
4
6
8
10
5 7 9 11 13 15 17 19 21 23 25 27 29Carbon Number
Mol
e %
40 cp W-203 Polaris
87 cp WS 1-01 D-Sand
61 cp WSP 8i D-Sand
10 cp Orion L117 OBd
57 cp Orion Z-39 OBd
117 cp Orion Z-39 OBa
52 cp Polaris W205 OBc
11 cp Milne S-12
C5+ fraction normalized to 100%
Miscible Target
VR-WAG Target
EOR Prediction Methodology
Reservoir Simulation- Type patterns
(based on reservoir description)
- EOR Type Curves (Oil, MI, RMI)
Reservoir Simulation- Type patterns
(based on reservoir description)
- EOR Type Curves (Oil, MI, RMI)
Liq
VapAdd MI
0%
5%
10%
15%
20%
0% 10% 20% 30% 40%MI INJECTED (TPV)
REC
OVE
RY
(%O
IIP)
Field Scaleup- Project area segments
(segment PV, well allocations)
- Tank model scaleup
Field Scaleup- Project area segments
(segment PV, well allocations)
- Tank model scaleup
Phase Behavior Model- PVT, Slimtube Data- EOS
Phase Behavior Model- PVT, Slimtube Data- EOS
Reservoir Simulation- Type patterns
(based on reservoir description)
- EOR Type Curves (Oil, MI, RMI)
Reservoir Simulation- Type patterns
(based on reservoir description)
- EOR Type Curves (Oil, MI, RMI)
Liq
VapAdd MI
Liq
VapAdd MI
Liq
VapAdd MI
Liq
VapAdd MI
0%
5%
10%
15%
20%
0% 10% 20% 30% 40%MI INJECTED (TPV)
REC
OVE
RY
(%O
IIP)
0%
5%
10%
15%
20%
0% 10% 20% 30% 40%MI INJECTED (TPV)
REC
OVE
RY
(%O
IIP)
Field Scaleup- Project area segments
(segment PV, well allocations)
- Tank model scaleup
Field Scaleup- Project area segments
(segment PV, well allocations)
- Tank model scaleup
Phase Behavior Model- PVT, Slimtube Data- EOS
Phase Behavior Model- PVT, Slimtube Data- EOS
KUPARUK RIVER UNIT
PRUDHOE BAY UNIT
West Sak (non-core)W S/Schrader Bluff (core)
S-Pad
Polaris
Orion
West Sak 1J
W-203
SPE 99569, “A New Scaleup Approach for Nonpattern Field Development Under Water or WAG Injection”, B. S. Jhaveri, BP Exploration (Alaska) Inc
NS Field Scaleup Example
0102030405060708090
100
Jan-06 Jan-11 Jan-16 Dec-20 Jan-26 Jan-31 Jan-36
MI I
nj m
msc
f/
0
5000
10000
15000
20000
25000
30000
35000
EOR
Rat
e B
PD
MI Inj WROM_BSJ_Update
EOR Oil Rate WROM_BSJ_Update
• Huge Development Target • 50 mmscf/d of VRI injection• 12 MBD EOR rate, 6% (OOIP) EOR• MI efficiency close to classical miscible
• Huge Development Target • 50 mmscf/d of VRI injection• 12 MBD EOR rate, 6% (OOIP) EOR• MI efficiency close to classical miscible
EOR
Rat
e
MI I
njec
tion
Rat
e
North Slope VRI Status• VRI project designed for Polaris & Orion fields
• IRS ruled VRI process as a qualified recovery method for EOR tax credit
• Alaska State approval to commence VRI injection in Polaris reservoir.– Injecting 2 mmscf/d MI in W-215
– 6% EOR recovery from 350 MSTB OOIP
• Application for Orion VRI injection approved– 1,000 MSTB OOIP target with similar EOR recovery
expected
Key Project Design Components• (Lean Gas, NGls, MI Capture)
• Surveillance (Gas Analysis, Well Intervention)
• Injectivity (Water/MI, Gas Trapping)
• Conformance (Zonal, Volumetric)
• Flood Management MI Resource (Voidage Replacement, Pressure Maintenance, WAG Ratio, MI Slug ,MI Allocation)
• Asphaltenes Dropout (Reservoir & Facility)
Closing Remarks• When conventional technology not applicable
• VRI technology can dramatically increase primary and waterflood recovery in viscous oil reservoirs
• Recovery enhancement by viscosity reduction and swelling
• Developed approach for the design, engineering, and evaluation of viscous oil gas EOR projects