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Associative Polymers for EOR: towards a better understanding and control of their adsorption in porous media. D. Rousseau, R. Tabary, Z. Xu, G. Dupuis (IFP) S. Paillet, B. Grassl, J. Desbrières (EPCP/IPREM). Outline. Introduction Associative polymers chemistry Adsorption in porous media - PowerPoint PPT Presentation
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Controlled CO2 | Diversified fuels | Fuel-efficient vehicles | Clean refining | Extended reserves
IEA Collaborative Project on EOR – 30th Annual Workshop and Symposium – 21-23 September 2009, Canberra, Australia
Associative Polymers for EOR: towards a better understanding
and control of their adsorption in porous media
D. Rousseau, R. Tabary, Z. Xu, G. Dupuis (IFP)S. Paillet, B. Grassl, J. Desbrières (EPCP/IPREM)
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia2
Outline
Introduction
Associative polymers chemistry
Adsorption in porous media
Conclusion
Additional results
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia3
Introduction 1/3Polymers in IOR/EOR : polymer flooding and well treatments
Polymer flooding: aqueous polymer solutions aqueous phase viscosity reduction of mobility ratio R = (kw/w)/(koil/oil)
areal sweep efficiency improvement
vertical sweep efficiency improvement
(k2 > k3
> k1)minimum adsorption is required
Well treatments: aqueous polymeric gels or microgels
producing wells: water shutoff
injecting wells: profile/conformance control
kW
controlled adsorptionselective permeability reduction
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia4
Introduction 2/3Advantages of (hydrophobically) associative polymers for IOR/EOR
(Hydrophobically) Associative Polymers
polymers with hydrophilic backbone bearing hydrophobic groups along the chains, capable of creating physical links between each other
=
Strong adsorption on surfaces
associative polymers likely adsorb as multilayers
high permeability reductions (well treatments)
b) Mechanical stability
high viscosities with short chains (e.g. 1.106 g/mol)(≠ standard polyacrylamides: 18.106 g/mol)
less sensitivity to shear degradation (surface facilities + near wellbores)
"Super" thickeners
visc
osi
ty (
Pa.
s)
concentration (g/mL)
non- associative
associative
a) Higher viscosities above cac
less polymer needed to achieve a given viscosity
c) Salt tolerance
salinity hydrophobic bonds viscosity(≠standard polyacrylamides)
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia5
Introduction 3/3Associative polymers for IOR/EOR: literature review
Associative polymers flooding suggested in the 1980's
patents: Evani et al. (1984), Landoll (1985), Bock et al. (1987), Ball et al. (1987)
review by Taylor & Nasr-el-Din (1998, updated 2007 – Can. Int. Petr. Conf. paper 2007-016)
renewed interest in the 2000's CNOOC's offshore polymer flooding pilot in Bohai bay: Zhou et al. (IPTC 11635 - 2007, paper B7 - 2008 IEA/EOR, Beijing)
Associative polymers static adsorption
Li -- Oilfield Chemistry, Vol. 23, No. 4, 349-351 (2006)
Volpert et al. -- Langmuir, 14, 1870-1879 (1998)
Associative polymers for well treatments Eoff, Dalrymple & Reddy (2000's) Halliburton's "Waterweb" process
Injectivity? Adsorption? What makes a associative polymer more suitable
for polymer flooding or well treatment operations ?
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia6
Outline
Introduction
Associative polymers chemistry
Adsorption in porous media
Conclusion
Additional results
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia7
Associative polymers chemistry
Synthesis methods Post-modification = grafting hydrophobic groups on a pre-existing hydrophilic backbone
Micellar copolymerization = simultaneous polymerization in aqueous solutions of the hydrophilic monomers and of the hydrophobic monomers, solubilized in micelles
Present study Polymers type 1: sulfonated polyacrylamides with alkyl hydrophobic groups; (micellar copolymerization)
Polymers type 2: polyacrylic acids with alkyl hydrophobic groups ; (post-modification)
AP + equivalent non-AP
AP + equivalent non-AP
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia8
Outline
Introduction
Associative polymers chemistry
Adsorption in porous media
Conclusion
Additional results
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia9
Adsorption in porous media 1/6Experimental set-up (cont'd) & experimental procedure
Model granular packs SiC (silicon carbide) sharp-edged grains, 50µm in size k = 1000±50 10-15 m² ; = 40±1% hydrodynamic pore throats diameter
dh ≈ 10 µm/8215.115.1 kdd ch
Polymer solutions
Experimental procedure
adsorption study injection of diluted polymer solutions all solutions filtered on 3 µm calibrated membranes prior to injection
adsorption study monophasic flow conditions polymer solution injection mobility reduction (Rm) i.e. resistance factor (RF) brine injection permeability reduction (Rk) i.e. residual resistance factor (RRF)
estimation of hydrodynamic adsorbed layers thicknesses h :
)1()2/( 4/1 Rkdhh
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia10
Adsorption in porous media 2/6Polymers type 1: mobility reduction with equivalent non-AP
Polymer solution injected:
C = 0.84 g/L
r = 4.3 ; = 3.5 cP
0
1
2
3
4
5
6
7
8
9
10
0 0.5 1 1.5
# Pore volumes injected
Rm
= D
P(p
oly
mer
) / D
P(b
rin
e)
2-5 cm0-2 cm
5-10 cm
flow direction
close to piston-like in-depth propagation stabilized mobility reduction
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia11
Adsorption in porous media 3/6Polymers type 1: mobility reduction with AP
0
1
2
3
4
5
6
7
8
9
10
0 0.5 1 1.5
# Pore volumes injected
Rm
= D
P(p
oly
mer
) / D
P(b
rin
e)
2-5 cm
flow direction
0-2 cm
5-10 cm
Polymer solution injected :
C = 0.45 g/L
r = 2.6 ; = 2.1 cP
entry-face & internal plugging trend (?) strong polymer adsorption
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia12
Adsorption in porous media 4/6Polymers type 1: adsorbed layers thicknesses estimations
0.0
0.5
1.0
1.5
2.0
10 100Wall shear rate, g• (s-1)
Ad
sorb
ed l
ayer
th
ickn
ess,
h
(µm
)
Associative polymers
Equivalent non-associative polymers
equivalent non-APh does not depend on the amount of
polymer solution injectedh ≈ 0.2 µm ~ single-chain size in solution
APh depends on the amount of polymer
solution injectedh ≈ 1.4-1.5 µm after only 1.3 PV injected
likely multilayer adsorption
internal section 2-5 cm only
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia13
Adsorption in porous media 5/6Polymers type 2: mobility reductions with equivalent non-AP and AP
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
# Pore volumes injected
Rm
= D
P(p
oly
mer
) / D
P(b
rin
e)
Associating polymers
Equivalent non-associating polymers - 20 g/L NaCl
20 g/L NaCl 58.4 g/L NaCl
flow direction
2-5 cm section only Polymer solutions injected :
equivalent non-AP (20g/L NaCl):
C = 1.5 g/L ; r = 2.0
AP 20 g/L NaCl:
C = 1.6 g/L ; r = 2.2
AP 58.4 g/L NaCl:
C = 3.2 g/L ; r = 4.1
internal section 2-5 cm only
same volume fraction = 0.3
good in-depth propagation of both equivalent non-AP and AP
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia14
Adsorption in porous media 6/6Polymers type 2: adsorbed layer thicknesses estimation
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0 1 2 3 4 5# Experimental phase
Ad
sorb
ed l
ayer
th
ickn
ess,
h
(µ
m)
Associative polymersEquivalent non-associative polymers
20 g/L NaCl
Porous medium #1
Porous medium #2
injection 1: polymers20 g/L NaCl
injection 2: brine58.4 g/L NaCl
injection 3: polymers58.4 g/L NaCl
internal section 2-5 cm only
AP adsorbed layer collapse when exposed to higher salinity brine over-adsorption occurs when AP are injected in higher salinity brine
likely salinity-controlled multilayer adsorption
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia15
Outline
Introduction
Associative polymers chemistry
Adsorption in porous media
Conclusion
Additional results
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia16
Adsorption behavior in porous media of 2 types of associative polymers (AP) has been investigated
adsorption appears as a key parameter governing AP propagation in porous media
adsorption is a key parameter to address for EOR AP applications
A control of the adsorption is and must be possible (hydrophobic bonds = low-energy bonds)
control through salinity is possible
control through shear-rate ?
Ongoing work on this topic @ IFP
various injections conditions
various polymer chemistries
modeling AP adsorption in porous media
Conclusion
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia17
Outline
Introduction
Associative polymers chemistry
Adsorption in porous media
Conclusion
Additional results
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia18
Adsorption in porous media: additional results 1/3Polymers type 1 (micellar copolymerization): impact of molecular structure
Set of associative sulfonated polyacrylamides (G. Dupuis work) same backbones: 20 mol-% AMPS ; Mw = 106 g/mol C8, C12 and C18 hydrophobic side groups 0.1, 0.2 and 0.5 mol-% hydrophobic monomers (+ equivalent non-associative polymers)
vs. polymer concentration vs. salt concentration
Thickening ability
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia19
Adsorption in porous media: additional results 2/3Polymers type 1: long-term injections (0.5 mol-% C12)
Coreflood experiments: SiC granular packs (50 µm grains) ; k = 1D ; = 0.4 ; PV ≈ 8 cm3 low flow rate: Q = 2 cc/h (vD ≈ 1 foot/day) ; gwall = 15 s-1
diluted polymer solution: C = 0.9 g/L ; effective = 0.2 ; rbulk = 1.7
•
Pressure taps layout
flowflow
1-5 cm
5-9 cm0-1 cm
viscous front propagation + polymer adsorption (Rm > r
bulk)
breakthrough, with C/C0 = 1 entry-face plugging trend ?
3 Injected PV
"secondary adsorption" front propagation entry + internal stabilization trends (?) stable effluent concentration origin of the secondary adsorption ?
130 Injected PV
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IEA Collaborative Project on EOR - 30th Annual Workshop and Symposium - 21-23 September 2009, Canberra, Australia20
Adsorption in porous media: additional results 3/3Polymers type 1: re-injection test (0.5 mol-% C18)
Assumption: 2 components in the polymer solutions (chemical structure heterogeneity?) vast majority of low-adsorption (weakly damaging) polymers
quick effluent breakthrough, C/C0=1 minority of strong-adsorption (strongly damaging) polymers
slow propagation of the "secondary front"
Experimental testing: effluent collection until the secondary frontreaches half of the core
"cleaned" solution effluent re-injection in a fresh core
Practical outcomes for polymer flooding with associative polymers:
towards specific in-depth filtration procedures? improvement in chemical synthesis methods? controlling the injectivity of associative polymers seems possible
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