Visosifying Surfactant forChemical EOREOR Workshop“Mario Leschevich”, 3-5 Nov. 2010 Mikel Morvan, Guillaume Degré, RhodiaAlain Zaitoun, Jérôme Bouillot, Poweltec.
Rhodia/Poweltec
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Contents
•Introduction to viscosifying surfactants for EOR
•Rhodia and Poweltec methodology: application tosynthetic field cases
•Viscosity measurements
•Fluid propagation tests
•Core flood tests
•Viscosifying surfactant: application to field case
•Conclusion
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Introduction to viscosifying surfactants for EOR
•Introduction to surfactant mesophases in aqueous solutions
Packing Parameter (P) = VH/(lc.a0)
Spherical micelles P ~ 1/3
Cylindrical micelles P~ 1/3 to ½
(Wormlike micelles or Hexagonal phases)
Lamellar phase P ~ 1
Molecular dimension, concentration andenvironment determine (T, S)mesophases sequences
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•Rheological properties of surfactant micelles in aqueous solutions
Spherical Micelles
Cylindrical Micelles
Low viscosity
Newtonian fluid
Entanglements
Analogy with polymer
Typical surfactant flooding
(S, SP, ASP)
L 1 m
Viscosifying surfactant asan alternative approach toSP & ASP flooding
Breakage/recombination dynamic
= volume fraction
G0: Elastic modulus
: Relaxation time
Introduction to viscosifying surfactants for EOR
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Presence of giant micelles of ≈ 5nm in diameter. A structure is visible, since theyappear mostly in parallel configuration, with an inter particle distance 15 to 20nm.
Cryo-TEM image of wormlike micelles in aqueous solution
Introduction to viscosifying surfactants for EOR
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Contents
•Introduction to viscosifying surfactants for EOR
•Rhodia and Poweltec methodology: application tosynthetic field cases
•Viscosity measurements
•Fluid propagation tests
•Core flood tests
•Viscosifying surfactant: application to field case
•Conclusion
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Rhodia & Poweltec methodology: application to syntheticfield cases
Solubility
Rheology
Injectivity
Viscosifyingsurfactantformulation
Coreflood
RHODIA
POWELTEC
Injectivity
Adsorption
Oil Recovery
Chemistry selection
Millifluidicscreening tests
Petrophysicexperiments
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• Principle of high-throughput screening for viscosity measurementsdeveloped at Rhodia LOF
• Formulation composition (surfactant & salt concentrations) are imposed thanks tosyringe pumps
Viscosity
Shear rate
• Formulation viscosity is determined by pressure drop measurement
Capillary (length L,radius R)
Surfactant
solution
Saturated
salt sol
Water
viscosity (cP)
Map viscosity performance versus reservoir brine variations priorto full characterization using traditional rheometer
Rhodia & Poweltec methodology: application to syntheticfield cases
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Viscosity measurements
0
0.1
0.2
0.3
0.4
0.5
0
20
40
60
80
concentration (%
w/w
)
Abs. viscosity (cP)
0
0.1
0.2
0.3
0.4
0.5
0
20
40
60
80
concentration (%
w/w
)
Abs. viscosity (cP)
0.1
0.3
0.5
0.7
0.9
0
50
100
150
200
concentration (%
w/w
)
Abs. viscosity (cP)
0.1
0.3
0.5
0.7
0.9
0
100
200
300
400
500
concentration (%
w/w
)
Abs. viscosity (cP)
Our viscosifying surfactants are salt tolerant (including divalent ions) withfavorable impact of high brine concentration
Salinity
(g/L TDS)
T (°C)
0
32°C
51°C
200
80°C
96
90°C
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Field 3
Field 2
Field 1
Field 3
Shear rate: 4 s-1
Viscosity measurements appliedto various reservoir cases
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Flow curve measurements in one reservoir condition
Shear thinning behavior indicates that a decrease of shear rates lead to anincrease of viscosity. Required surfactant concentration is thus reduced
Viscosity measurements
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• Principle of miniaturized core flood test developed at Rhodia LOF
5 cm
Syringe pump
Capillary
viscometer
Pressure sensor
Pressure sensor
core
• A miniaturized core flood test has been developed to measure fluidpropagation in single-phase condition
• This miniaturized test can be used prior to full coreflood study topre-screen performances of new surfactant formulations.
Rhodia & Poweltec methodology: application tosynthetic field cases
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• An illustration of permeability measurement from (Q, P) curve
Syringe pump
Porous media
Injectivity in porous media
Pcore
Pcapillary
Imposed flow rate
Capillary
Adsorption
Q = 5 mL/min
Q = 4 mL/min
Q = 3 mL/min
Q = 2 mL/min
Q = 1 mL/min
k
Patmosph..
Millifluidic set-up used to measure mobility & permeability reduction
Rhodia & Poweltec methodology: application to syntheticfield cases
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Mobility Reduction is also called “Resistance Factor RF”
pressure drop during viscosifyingsurfactant slug injection at q cm3/h
pressure drop during initial brineinjection at q cm3/h
Mobility Reduction
Background on mobility & permeability reduction
Permeability Reduction “Residual Resistance Factor RRF”
Visco. Surf
P
P
Rm
=
pressure drop during brineinjection after viscosifyingsurfactant slug at q cm3/h
pressure drop during initialbrine injection at q cm3/h
Permeability Reduction
Initial brine
Brine - After visco surf.
P
P
Rk
=
Initial brine
Rhodia & Poweltec methodology: application to syntheticfield cases
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• Example of flow behavior in representative porous media (Clashachsandstone) using miniaturized core flood test
Rheometer Bulk viscosity
Viscosity in porous media injection in cores
impose Q and measure P
C2
C1
Miniaturized core data
Bulk rheology
Flow in porous media match bulk rheology
Good propagation of viscosifying surfactant in porous media
Fluid propagation tests
Mean pore radius
Darcy’s Law
Flow rate
Q
Shear rate
Pressure drop
viscosity
P
Capillary bundle model
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• Representative porous media: synthetic core
• Surfactants solution is injected in water saturated cores to evaluatepropagation properties in porous media
• Surfactants solution is injected in oil saturated cores to measure oilrecovery efficiency (additional oil after water flooding)
Core flood tests
Darcy’s law
1cm
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• Porous media: clashach sandstone core
• Kw = 1133 mD at 50°C – Injection brine: sea water
Mobility and permeability reduction measurements in monophasic conditions
Mobility Reduction values match bulk rheology: product has a good injectivity
Permeability Reduction is close to Rkw=1, showing no core damage
Core flood tests
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Core flood sequence
Core - Clashach sandstone:
•Porosity: = 0.18
•Pore radius (est.):Rp = 3.4 µm
•Water permeability:Kw = 1133 mD at 50°C
•Residual oil saturation: Sor = 0.49 (oil = 4.2 cp @50°C) (before injectingsurfactant)
Fluid formulation:
•Injection brine: sea water (39 g/L TDS)
•Surfactant concentration: 3 g/L
•Temperature: 50°C
Protocol
1.Saturation with oil until Swi
2.Water injection until Sor
3.Surfactant injection
4.Oil recovery measurement
Results
Sor reduction: 12%
Sor reduction: 12%
No Sor reduction withHPAM
No Sor reduction withHPAM
Core flood tests: oil recovery efficiency
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Contents
•Introduction to viscosifying surfactants for EOR
•Rhodia and Poweltec methodology: application tosynthetic field cases
•Viscosity measurements
•Fluid propagation tests
•Core flood tests
•Viscosifying surfactant: application to field case
•Conclusion
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Viscosifying surfactant: application to field case
• Temperature: T = 51°C
• Permeability: k ~ 1 – 2 D
• Oil viscosity @ 51°C : = 100 - 200 cP
• Brine concentration: 6.2 g/L TDS
Reservoir conditions
• Select best viscosifying surfactant that matchesreservoir characteristics
• Compare recovery performance with polymerflooding
Methodology
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Absolute viscosity measurements in reservoir conditions show thatsame viscosity (20 cP - 10 s-1) as selected for HPAM solution(0.09%w/w) is obtained at a concentration of 0.3%w/w.
Viscosifying surfactant: application to field case
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•Thermal stability of surfactant solution
Viscosity measured at 50°Cat low shear rate (10s-1)
Surfactant concentration 0.3% w/w
Temperature T = 51°C
Brine concentration: 6.2 g/L TDS
Oxygen content < 50 ppb
Fluid formulation
Anaerobic ageing of surfactant solution shows that no viscosityloss is observed over one month - On going ageing
Viscosifying surfactant: application to field case
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Regular polymer flooding (HPAM) experiment
No Sor reduction is observed after HPAM injection
Reservoir core plug
Viscosifying surfactant: application to field case
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Oil recovery experiments after polymer injection (HPAM)
Injection of a 0.3%w/w surfactant solution after HPAM has mobilized asignificant fraction of the residual oil saturation (+16% OOIP)
Reservoir core plug
Viscosifying surfactant: application to field case
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Simulation
• Five Spot Pattern (1 Injector 4 Producers)
• Multilayer Reservoir, Strong vertical heterogeneity
• Reservoir thickness = 10 m
• Comparison between
• Waterflood
• Polymer Flood
• Viscosifying Surfactant Flood
Evaluation of viscosifying surfactant insynthetic field case
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Simulation
Evaluation of viscosifying surfactant insynthetic field case
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Recovery Factor
RF @ 6 years
RF @ 11 years
Water flood
33 %
39 %
Polymer flood
40 %
46 %
Viscosifying surfactant
50 %
56 %
Simulation
Evaluation of viscosifying surfactant insynthetic field case
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Contents
•Introduction to viscosifying surfactants for EOR
•Rhodia and Poweltec methodology: application tosynthetic field cases
•Viscosity measurements
•Fluid propagation tests
•Core flood tests
•Simulation
•Viscosifying surfactant: application to field case
•Conclusion
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Conclusion
• Specific millifluidic tools have been developed to screenviscosifying surfactants from Rhodia
• Following performances have been measured for viscosifyingsurfactants in different conditions
• Viscosity at low concentration: 0.1 to 0.5% w/w
• Sor reduction in coreflood Sw = 10 to 20% (oil at least 100 cps)
• High temperature / high salinity tolerance
• Shear thinning / recombination dynamics (Unlike Polymer)
• Limited surface facility Capex required
• Perspectives
• Pursue experiment on field case reservoir: adsorption measurements,additional oil recovery tests, simulation and extrapolation at pilot scaleto evaluate economics