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Polymer Rheology/Transport Reseach
Do Hoon Kim
Gary A. Pope, Chun HuhSeungjun Lee, David Levitt, Will Slaughter
Role of Polymers in Chemical EOR Processes
Chemical EOR Research Program Annual WorkshopThe University of Texas at Austin ● April 23-24, 2009
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Topics of Presentation
• Rheology of EOR polymers- Structure-property relationship- Effects of different salinity with hardness
• Role of EOR polymers in chemical floods: Case Studies.- ASP/SP/Polymer Flood- Different reservoir conditions- Different salinity with hardness
• Motivation for development of comprehensive polymer rheology database
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Rheological Study of EOR Polymers• Provide polymer-solution bulk viscosity in terms
of polymer conc’n, M.W., degree of hydrolysis, salinity, pH and shear rate
• Convert the bulk viscosity to apparent viscosity in reservoir rock, for both shear-thinning and shear-thickening regimes
• More efficient polymer screening for chemical EOR applications to particular reservoirs
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Rheological Characterization of Polymers
* Synthetic brine at 30 C** 2000ppm polymer in Synthetic brine at 30 C*** Mole % of AMPS
Polymer MW Degree of Hydrolysis |η|* λ** Ωp, μm**** Description
Floppam 3630S 20M 25-30% 2046 0.063 0.58 HPAM
Hengfloc 63026 26M 30-40% 2115 0.07 HPAM, Post-hydrolyzed
Hengfloc 63020 20M 30-40% 1859 0.043 0.56 HPAM, Post-hydrolyzed
AN-125 8 M 20-30%*** 1913 0.059 0.42 AMPS/ Acrylamide
AN-125 VLM 2 M 20-30%*** AMPS/ Acrylamide
****
CPGE 10-3 10-2 10-1 100 101 102 103101
102
103
104
105Steady Shear Viscosity of EOR Polymers
5000 ppm Polymer at 0.1% NaCl (25°C)
FP 3630S (20M)
AN125 VLM (2M)FP 3230S (5M)AN125 (8M)
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Effect of Divalent Ions on Steady shear Viscosity
FP 3630S(20 MM, τ = 25-30%)
Hengfloc 63026(26 MM, τ =30-40%)Hengfloc 63020
(20 MM, τ =30-40%)
2000 ppm polymer in Synthetic brine at 30 oC
Visc
osity
(cP
@ 1
0 s-
1 )
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Oil and Reservoir dataBrine Reservoir
Hardness [ppm]#Oil
viscosity [cP]
Salinity [TDS,ppm]
EOR
Ca++ Mg++
Perm. [mD]
Temp [oC]
1 1.5 1,100 330 7 2000 85 ASP2 1.78 35,000 - - 1203 3.4 2800 60 5 2000 85 ASP4 4 200 - - 5000 100 SP5 5 200,000 16,000 2000 5~ 10 69 ASP/ AS6 7.8 65000 2700 1000 50~ 300 28 SP7 8.6 20,000 80 40 500~1000 85 ASP8 9 11,000 - - 54 ASP9 11 60,000 1200 - 50~500 36 SP
10 30 6000 300 200 1000 62 ASP
11 82 60,000 640 2605000 ~ 10000 30.6 SP/ASP
12 100 5,000 - - 2000 46 ASP13 100 38000 1700 570 500~1000 55 ASP14 5000 20,000 - - 500~1000 < 25 ASP
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Oil and Reservoir dataBrine Reservoir
Hardness [ppm]#Oil
viscosity [cP]
Salinity [TDS,ppm]
EOR
Ca++ Mg++
Perm. [mD]
Temp [oC]
1 1.5 1,100 330 7 2000 85 ASP2 1.78 35,000 - - 1203 3.4 2800 60 5 2000 85 ASP4 4 200 - - 100 SP5 5 200,000 16,000 2000 5~ 10 69 ASP/ AS6 7.8 65000 2700 1000 50~ 300 28 SP7 8.6 20,000 80 40 500~1000 85 ASP8 9 11,000 - 54 ASP9 11 60,000 1200 50~500 36 SP
10 30 6000 300 200 1000 62 ASP
11 82 60,000 640 2605000 ~ 10000 30.6 SP/ASP
12 100 5,000 - 2000 46 ASP13 100 38000 1700 570 500~1000 55 ASP14 5000 20,000 - 500~1000 <25 ASP
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Polymer Selection Criteria for Chemical Flood
• Viscosity of polymer solutions
• Salinity tolerance
• Chemical and thermal stability at reservoir temperature
• Transport characteristics in reservoir
• Sorption and retention characteristics
• Availability and cost
• Compatibility with surfactant
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Case #1. ASP flood• 100 cP Oil, 1500 mD, 46 oC• Same surfactant formulation with good solubilization ratio• Selection of adequate polymer viscosity improve the oil recovery
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0Pore Volumes
Oil
Cut
or C
umul
ativ
e O
il R
ecov
ered
(%)
μPolymer = 85 cP
μPolymer = 46 cP
Oil cut
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Comparison of Injection & Effluent Polymer viscosity in ASP flood
1
10
100
1000
0.1 1 10 100 1000
Injected Polymer
Effluent(2.02 PV)
Vis
cosi
ty, c
P
Shear Rate, s-1
2700 ppm FP 3630S1.2 um FilterF.R. = 1.11 (15psi)
• Adequate viscosity with good filterability of Polymer greatly improves oil recovery and transport in the porous media.
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Case #2. High MW Polymer in Low Permeability Rock
• 8 MM M.W. polymer causes plugging in very low permeability rock (5~ 10 mD).
0
2
4
6
8
10
12
14
0 1 2 3 4PV
Pres
sure
Dro
p (p
si)
K brine = 3.1 mD
μPolymer = 4.76 cP @ 500 s-1
1500 ppm AN-125
1.96 ft/D, 69 oCWhole
Inlet
Outlet
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Case #2. Low MW Polymer in Low Permeability Rock
0
1
2
3
4
5
6
7
8
9
10
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0Pore volume
Pres
sure
Dro
p (p
si)
• 2 MM M.W. polymer can be transported through very low permeability rock ( 5 ~ 10 mD).
K brine = 3.1 mD
μPolymer = 3.73 cP @ 500 s-1
2500 ppm AN-125 VLM
1.96 ft/D, 69 oC
Inlet
Outlet
Whole
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M.W. measurements by GPC does not show any significant degradation/chromatograph separation
Injected
Effluent
M.W.
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Case #3. Apparent Viscosity from Core Flood
K brine = 6.6 D
μPolymer = 60 cP @ 10 s-1
3000 ppm FP 3630S
1,2,4,8 ft/D, 30 oC
• High M.W. polymer (20 M) need to propagate into high permeability sand (~ 6.6 D).
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Apparent viscosity can be predicted from bulk viscosity
Calculated from core flood
Apparent shear rate:
Carreau-Model :( 1)/22( ) 1 ( )n
oη η η η λγ−
∞ ∞ ⎡ ⎤− = − +⎣ ⎦
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Summary
• Selection of adequate polymer viscosity improve the oil recovery in chemical flood.
• Low M.W. polymer can be transported through very low permeability rock (3mD).
• Apparent viscosity can be predicted from bulk viscosity in both shear-thinning and shear-thickening regimes.
• For a wide range of reservoir conditions, optimum polymer can be selected from rheologydata and corefloods.
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For a wide range of reservoir conditions, optimum polymer can be selected from rheology data and
corefloods
• Salinity (TDS, ppm) : 200 ~ 200,000 ppm• Hardness (Ca++, ppm) : 0 ~ 16,000 ppm• Temperature (oC) : 25 ~ 120 oC• Oil viscosity (cP) : 3 ~ 100 cP, 5000 ~ Million cP
for Heavy oil• Reservoir type: unconsolidated sandstone,
Dolomite, High-k sand• Permeability (mD) : few mD ~ thousands mD
CPGEReservoir simulation input (UTCHEM)
Limited Corefloods for Rheology correlation in porous media (γeff , τ
Motivation for Development of Polymer Rheology Database
Comprehensive bulk Rheology database
• Comprehensive rheology database for currently employed polymers is not available.
• Database for comprehensive rheology model parameters for process simulations are needed.
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Variables Studiedfor Database Development
Planned : up to 10%
Rheological properties
Viscosity
Relaxation timeVarious EOR
polymers
