5. 5 AK
5/5/2010
Improve Basic Oil Recovery Techniques
Improvement Classes of Basic Techniques
1 - Make Injectant fluid more effective in regions where an injectant contacts oil
2 - Try to Steer the Injectants from already drained regions to undrained (oil) areas
6. 6 AK
5/5/2010
Improve Basic Oil Recovery Techniques
Divertors/Agents for 2 classes of basic Techniques
Surfactant flooding
1- Make Injectant fluid more effective in regions where injectant contacts oil
Foams, along with WAG, gel, polymer
2 - Try to Steer the Injectants from already drained regions to undrained (oil) areas
7. 7 AK
5/5/2010
Improve Basic Oil Recovery Techniques
SubDivertors for class-2 of basic Techniques
Foams, along with WAG, gel, polymer
2 - Try to Steer the Injectants from already drained regions to undrained (oil) areas
Gel: is designed to steer the flow of water by reducing water mobility
Foam: is means to control the flow of gas in the reservoir by reducing gas mobility
8. 8 AK
5/5/2010
Near – Well Injectivity Control
Near – Well Production Well Treatment
Sand Control
Gas Blocking
Acid Diversion
Gas Diversion
Deep Treatments
Environmental Remediation
Foam Applications
9. 9 AK
5/5/2010
Foam Assisted Water Alternating Gas
Pilot candidate – Western Fault Block
FAWAG Pilot Objectives
to increase sweep efficiency during gas injection,
to increase the storage of gas in the reservoir
to reduce the producing GOR in production well P-39.
Deep Treatment Method
10. 10 AK
5/5/2010
Snorre WFB pilot - history
Pilot time: November 1999 – 2001
Wells involved:
P32 (inj)/P39 (prod), 1550 m
P32 (inj)/P42 (prod), 1450 m
2 FAWAG cycles after gas injection and
WAG operation for about 3 years
Total surfactant injected: ~140 tonn
Slug 1: 15262 SM3 (0.49 wt%) for 9,5
days followed by 100 days gas injection
Slug 2: 31733 SM3 (0.2 wt%) for 20.3
days followed by more gas injection
Ref: SPE 75157 by A. Skauge et.al.
11. 11 AK
5/5/2010
WFB – sector (Prototype)
WFB – Full Field (2005 – Statoil)
ECLIPSE
Snorre WFB Prototype Model
Prototype – EPS, upscaled Logs, Stochastic,
3Phase
Operator Model
12. 12 AK
5/5/2010
Foam Assisted Water Alternating Gas
Figure: P-32G, Gas injection Mode showing clear
Path of gas flow towards P-39 (Producer),
effecting P-42AP
Gas Breakthrough Path among Producer-Injector Pair (Streamline Based Simulation)
13. 13 AK
5/5/2010
Foam Assisted Water Alternating Gas
Figure : pilot Injector, P-32W, Effect on Surrounding Wells
Water Injector Effecting neighbouring well (Streamline Based Simulation)
18. 18 AK
5/5/2010
ECLIPSE Blackoil Foam Model
Foam Simulation Model
Note: Foam decay is
modeled as Oil
saturation vs foam
half-life. The concept
of half life simple
means that after a
certain amount of time
the concentration of
foam becomes half of
the original value.
19. 19 AK
5/5/2010
Mr > # , small size bubble, stable Foam
Mr > # x factors, more unstable Foam
Mr =The reference mobility reduction factor
is typically in the range of 5 to 100 and
corresponds to the normalized resistance
to flow for a minimum bubble size in the
absence of factors that increase bubble
size.
ECLIPSE Blackoil Foam Model
Foam Simulation Model
20. 20 AK
5/5/2010
ECLIPSE Blackoil NEW Foam Model
Foam Simulation Model
Foam can be modelled as transport in:
> Water (new mechnism) or
> Gas (old versions)
Foam material balance in a Reservoir
Oil accelerated
Effective foam is the one
that remains in the
solution form
21. 21 AA, JR
5/5/2010
Som = Max Oil sat. Above whic foam is not effective=0.3
So = Curent Block Oil Saturation @timestep =0.2
eo = is an exponent which controls the steepness of the transition
about the point = 1
Foam Simulation Model
Simple Calculation
22. 22 AA, JR
5/5/2010
Som = Max Oil sat. Above whic foam is not effective=0.3
So = Curent Block Oil Saturation @timestep =0.2
eo = is an exponent which controls the steepness of the transition
about the point = 1
Mr = 100
Fs, Fw, Fc =1
Foam Simulation Model
Simple Calculation
23. 23 AA, JR
5/5/2010
Som = Max Oil sat. Above whic foam is not effective=0.3
So = Curent Block Oil Saturation @timestep =0.2
eo = is an exponent which controls the steepness of the transition
about the point = 1
Mr = 100
Fs, Fw, Fc =1
Foam Simulation Model
Simple Calculation
24. 24 AA, JR
5/5/2010
Som = Max Oil sat. Above whic foam is not effective=0.3
So = Curent Block Oil Saturation @timestep =0.2
eo = is an exponent which controls the steepness of the transition
about the point = 1
Fo = ((0.3-0.2)/0.3)^1
=0.33
MRF = 1/ (1+MrxFo)
=1/(1+100x0.33)
=0.03 (Foam)
Mr = 100
Fs, Fw, Fc =1
Foam Simulation Model
Simple Calculation
25. 25 AA, JR
5/5/2010
Som = Max Oil sat. Above whic foam is not effective=0.3
So = Curent Block Oil Saturation @timestep =0.2
eo = is an exponent which controls the steepness of the transition
about the point = 1
Fo = ((0.3-0.2)/0.3)^1
=0.33
MRF = 1/ (1+MrxFo)
=1/(1+100x0.33)
=0.03 (Foam)
Mr = 100
Fs, Fw, Fc =1
Fo = ((0.3-0.3)/0.2)^1
=0.0
MRF = 1/ (1+MrxFo)
=1/(1+100x0.0)
= 1 (No Foam)
Foam Simulation Model
Simple Calculation
26. 26 AA, JR
5/5/2010
Som = Max Oil sat. Above whic foam is not effective=0.3
So = Curent Block Oil Saturation @timestep =0.2
eo = is an exponent which controls the steepness of the transition
about the point = 0.25
Fo = ((0.3-0.2)/0.3)^0.25
=0.76
MRF = 1/ (1+MrxFo)
=1/(1+100x0.76)
=0.01 ( VERY Good Foam)
Mr = 100
Fs, Fw, Fc =1
Fo = ((0.3-0.3)/0.2)^0.25
=0.0
MRF = 1/ (1+MrxFo)
=1/(1+100x0.0)
= 1 (No Foam)
Foam Simulation Model
Simple Calculation
27. 27 AK
5/5/2010
Foam Oil Saturation Function
Snorre Prototype- Homogenous Reservoir
Sensitivity analysis: Foam oil saturation function –
Comparison for Recovery factors and GORs between low,
medium and high oil affected, HIGH strength foams.es=1,
Csr=0.01
I
N
C
R
E
A
S
I
N
G
I
n
c
r
e
a
s
i
n
g
I
N
C
R
E
A
S
I
N
G
1/(1+MrxFo)
I
N
C
R
E
A
S
I
N
G
S
o
c
h
a
n
g
e
F
a
s
t
e
r
So change Slower
Unstable
Foam
stable
Foam
Shifting higher
Som improves
Foam and thus
more gas is
stored and less
GOR
Shifting higher eo
accelerate
unstability of
Foam and thus
less gas is stored
and more GOR
28. 28 AA, JR
5/5/2010
MRF = 70, FMOIL_EPOIL SENSTIVITY
Gas Oil Ratio SC P-39P RESTART_SECTOR_WFB_MRF_70_epoil_0.5_fmoil_0.2.irf
Gas Oil Ratio SC P-39P RESTART_SECTOR_WFB_MRF_70_epoil_1_fmoil_0.2.irf
Gas Oil Ratio SC P-39P RESTART_SECTOR_WFB_MRF_70_epoil_2_fmoil_0.2.irf
Gas Oil Ratio SC WGOR_HIST_P39P gor_p39p.fhf
Gas Oil Ratio SC P-39P SECTOR_WFB_No_Foam_11.irf
Gas Rate SC P-32G SECTOR_WFB_No_Foam_11.irf
Water Rate SC P-32W_ij SECTOR_WFB_No_Foam_11.irf
Time (Date)
Gas
Oil
Ratio
SC
(m3/m3)
Gas
Rate
SC
(m3/day)
Water
Rate
SC
(m3/day)
1999-10-1 1999-12-30 2000-3-29 2000-6-27 2000-9-25 2000-12-24
0
200
400
600
800
0.00e+0
5.00e+5
1.00e+6
1.50e+6
2.00e+6
0
2,000
4,000
6,000
8,000
I
N
C
R
E
A
S
I
N
G
1. Surf slug: 0.49 wt%, 9.5 days, 15262 SM3 2. Surf slug: 0.20 wt%, 20.3 days, 31733 SM3
Foam Oil Saturation Function
With lower Som, eo effect is large
29. 29 AA, JR
5/5/2010
MRF = 70, FMOIL_EPOIL SENSTIVITY
WGOR (other foam factors, switch off)
RESTART_SECTOR_WFB_MRF_70_epoil_0_fmoil_0.3.irf
RESTART_SECTOR_WFB_MRF_70_epoil_0.5_fmoil_0.3.irf
RESTART_SECTOR_WFB_MRF_70_epoil_1_fmoil_0.3.irf
RESTART_SECTOR_WFB_MRF_70_epoil_2_fmoil_0.3.irf
History
Eclipse-fullfield-no foam
WGIR, P-32G
WWIR, P-32W
No Foam
Time (Date)
Gas
Oil
Ratio
SC
(m3/m3)
Gas
Rate
SC
(m3/day)
Water
Rate
SC
(m3/day)
2000-1 2000-4 2000-7 2000-10
0
200
400
600
800
0.00e+0
5.00e+5
1.00e+6
1.50e+6
2.00e+6
0
2,000
4,000
6,000
8,000
I
N
C
R
E
A
S
I
N
G
Foam Oil Saturation Function
With higher Som, eo effect is narrow
31. 31 AK
5/5/2010
Foam Surf. Conc. Function
Snorre Prototype- Homogenous Reservoir
I
N
C
R
E
A
S
I
N
G
I
n
c
r
e
a
s
i
n
g
1/(1+MrxFs)
c
h
a
n
g
e
F
a
s
t
e
r
c
h
a
n
g
e
S
l
o
w
e
r
Unstable
Foam
s
t
a
b
l
e
F
o
a
m
Sensitivity analysis: Foam concentration function – Effect of
changing es on Recovery factor and Average Mrf
U
n
s
t
a
b
l
e
F
o
a
m
stable
Foam
optimum
32. es = 7
es = 1,2,3
Sensitivity analysis: Foam concentration function: Effect of foam
strength on Injector well BHP.
Foam Surf. Conc. Function
Effect of foam strength on Injector well BHP.
High stength Foam,
retards injectivity in
injector thus BHP
rises, good sign of
Foam strength – but
issues sometimes
with co-injection --
fracing wells
33. Summarized results from the sensitivity analysis of Foam concentration
Foam Surf. Conc. Function
Hetro-Horitz Hetro-Incl
Homog-Horitz
Homog-Incl
Gravity BT’s
Effect of Reservoir Type and Dip on Recovery in terms of Vol of Foam injected
Homog-Horitz
Due to stable front
arrival
Hetro-Horitz
Hetro-Incl
Overall hetrogenous res will have less recovery than the homogenous,
and inclination will impede foam formation
35. 35 AK
5/5/2010
f(Fs) f(Mr ) > Fo > Fc > Fw
The key parameters with ranges of effectiveness are:
es Range : 1 – 7
eo Range : 1 – 10
ec Range : 1 – 2
fw Range : 0.1 – 1000
Result of Foam properties sensitivity
Conclusions
37. 37 AA, JR
5/5/2010
Gravity affects foam flow behavior. This implies that short WAG cycles of 1 month or 2 months are
beneficial in foam injection rather than longer ones.
Run simple Scenarios to develop any pilot understanding
Parametric approach to do quick feasibility study with simple physical input
Key parameters affect foam performance in this case are: WAG ratio, Controlled foam injection
(Use of smart wells).
Foam can be effectively used to control gas front in layers of different permeability. This action
can be performed by changing two foam parameters es and Mr
Key parameters found affecting concentration performance are: Reservoir heterogeneity, Inclination
Conclusions
39. 39 AK
5/5/2010
Thank you
Questions please!
Arif Khan
PetroTechnical Expert (Reservoir/Production)
Engineering Services
Data & Consulting Services – NorthSea Geomarket
Schlumberger - Oilfield Services
Mobile # +47 45 22 1367
Direct line # +47 5194 6717
Risabergveien-3, 4068 Stavanger - Norway
http://hub.slb.com/services/reservoir_characterization.aspx
40. 40 AK
5/5/2010
ECLIPSE 100 models foam by an approximate but potentially accurate method that uses
foam flowing through the reservoir as a tracer that may be transported with either the gas
or the water phase with account taken of adsorption on to the rock surface and decay
over time . The model does not explain the non-newtonian foam flow behavior and the
physical processes associated with foam generation, flow and collapse. This model can
be used as good comparison tool.
The process can be explained by four simple steps:
Laboratory experiments on surfactants
Black oil simulation
History match to fit foam parameters
Predicting the future.
