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Optimum Formulation Relationship topredict a solution in micro/macroemulsions

applications in SOW systems

J.L. Salager, A.M. Forgiarini & J.Bullón

Lab FIRPUniversity of the Andes,

Mérida - Venezuela

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Emulsion persistance (stability)has been studied for more than 100 years

vs surfactants, polymers and particles

It was only ~ 40 years ago that ageneral rule was found

from the surfactant effects in relationto EOR Optimum formulation

What is the physicochemical formulation ?A concept based on interactions at O/W interface

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Winsor’s Ratio (1954)between molecular interaction energies

R =Aco

Acw

very pedagogicalbut qualitative!

R < 1, R = 1 or R > 1related to phase behavior

oil(O)

water(W)

Aco

Acw

surfactant(C)

Winsor P., Solvent Properties of Amphiphilic Compounds, Butterworth London (1954)

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Winsor researchshowed a relation between R

and the phase behavior

R < 1 R > 1

S1 micelle micelle S2 micelleS

OW

S

O W

2 2__

W IW I W IIW IIPhase behavior (in two-phase zone at )

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S

W Ocomplex phase behavior

liquid crystal microemulsion

W III S 2

S 1

R = 1

Winsor researchshowed a relation between R

and the phase behavior

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Formulation Scanchanges the phase behavior

Example: Formulation variable = Salinity of aqueous phase

R = Aco

Acw

If salinity increasesAcw decreases R increasestransition R < 1 R = 1 R > 1

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Formulation Scanphase behavior

1.0 1.4 2.0 2.8 4.0 5,6 % NaCl

R > 1R < 1 R = 1

Salinity

W I W IIW III

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Formulation Scan

W IIIW III

Optimum Formulation

W IW I2

W IIW II2

Shah D., Schechter R., Eds,. Improved Oil Recovery by Surfactant andPolymer Flooding, Academic Press New (1977)

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Same transition (R < 1 R >1)with all formulation variables able

to alter Axx interactions

Salinity (type and conc.) ACN and structure Surfactant (Hydroφ part) Surfactant (Lipoφ part) Temperature Alcohol (type and conc.)

R = Aco - 1 / 2 Aoo - 1 / 2 ALL

Acw - 1 / 2 Aww - 1 / 2 AHHoil(O)

water(W)

Aco

Acw

surfactant(C)

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two-dimensional scan =series of one-dimensional scans

formulationvariable #1(Salinity)

formulation variable # 2 (ACN)

2 φ (W I)

2 φ (W II)

3 φW III

OptimumFormulationS - ACN

Optimum Formulationsystematic studies

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Ln S

ACN

Relation:LnS = K ACN + ...or dLnS = K dACN

For all systemscontaining ionicsurfactants3φ

2

2

Optimum Formulationsystematic studies

Salager J. L. et al., Soc. Petroleum Eng. J., 19: 107 (1979) ANIONIC SYSTEMSBourrel M. et al., J. Colloid Interface Science, 75: 451 (1980) NONIONIC SYSTEMSAntón R. E. et al., J. Dispersion Science Technology, 18: 539 (1997) CATIONIC SYSTEMS

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OPTIMUM FORMULATION

lnS - K ACN - f(A) + σ - aT ∆T = 0

α - EON + b S - k ACN - φ(A) + cT ∆T = 0

Salinity Oil Alcohol Temperature

ionic

nonionic

empirical correlations(thousands of experiments)

Σ c X = 0i iWhich may be written as :

Surfactant

Surfactant

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Surfactant Affinity Difference(Affinity = - µ*)

µ = µ* + RT ln C = µ* + RT ln Cw w o o

SAD = µ* - µ* = RT ln C /Coow w

At optimum formulationCw = Cothus SAD = 0

(anionic systems)

Salager et al., Langmuir, 16: 5534 (2000)

Surfactant Partition Coefficient

CO

CW

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Conceptual SupportSurfactant Affinity Difference SAD

complex but quantitative

><HLD = SAD/RT = lnS - K ACN - f(A) + σ - aT ∆T = 0

HLD = SAD/RT = β + b S - k ACN - φ(A) + cT ∆T = 0

ionic

nonionic Salinity Oil Alcohol Temperature

Surfactant

HLD = Hydrophilic-Lipophilic Deviation

Surfactant

Salager J.L., in Pharmaceutical Emulsions and Suspensions,Nielloud F., Marti-Mestres G., Eds., Chap. 2, Dekker (2000)

<>

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Minimuminterfacial

tension

γ*minAt a very preciseformulation value in ascan (here salinity)

16 / 30 It is a general phenomenonlow interfacial tension in WIII system (HLD ~ 0)

in a narrow zone of any formulation scan

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∆P Poiseuille∆P Laplace

Capillary Number NCav η γ

= = 10 - 6

should be x 100 or 1000 to produce displacement

Capillary Number =

EOR Displacement criterion

Value in Sor

vusual = 1 ft/dayηwater = 1 cP, ηpolymers 100 cPγwater/crude = 10 mN/m

General phenomenon

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Correlation NCa Recovery

Stegemeir G. L., Mechanism of entrapment and mobilization of oil in porous materials.In Improved Oil Recovery by Surfactant and Polymer Flooding,Shah D. O., Schechter R. S., Eds. Academic Press (1977)

NCa = v η γ

Res

idua

l Sat

urat

ion

S or

10 - 4 10 - 210 - 6 10 - 4 10 - 210 - 6

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STA

BIL

ITY

(sec

)

Emulsion stability vs formulation Experimental Results

Salager et al., JDST (1982)

Another general phenomenon

O / W W / O

Hydrophilic LipophilicSurfactant Behavior

at optimum: 3 phases, emulsion inversion and instability

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Emulsion stability vs formulation Experimental Results

Another general phenomenon

Bourrel et al. JCIS (1979) Salager et al. JCIS (1980)

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Milos & Wasan COLS (1982) Anton & Salager JCIS (1986)

Stability - Formulation Experimental Results

22 / 30 Same instability whatever thesurfactant concentration : At HLD = 0surfactant does not seem to be at O-W interfaceto stabilize emulsion

Anton & Salager JCIS (1986)

23 / 30 Why are emulsions very unstable at HLD=0?Various explanations

Surfactant is trapped in a microemulsion Surfactant forms liquid crystal bridges Holes in interdrop films are unstable Tension ~ 0 and thus tension gradient ~ 0 (no Gibbs-Marangoni effect) Fast transfer to interface and quick apparent equilibration Zero curvature is inconsistent with spherical drops etc...

Bourrel M. et al., J. Colloid Interface Sci., 72: 161 (1979)Salager J.L. et al., J. Colloid Interface Sci., 77: 288 (1980)Anton R., Salager J.L., J. Colloid Interface Sci., 111: 54 (1986)Hazlett R. D., Schechter R. S. Colloids Surfaces, 29: 53 (1988)Kabalnov A. et al., Langmuir, 12: 8 & 12: 276 (1996)Ivanov I. et al., Colloids Surfaces A, 128: 155 (1997)Fillous L. et al. J, Surfactants & Detergents 2: 303 (1999)Salager JL et al. Langmuir, 18: 607 (2002)

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Principle of Desestabilization is basedon a mixture to attain HLD = 0

natural surfactant (asphaltene) is lipophilic demulsifier surfactant should be hydrophilic so

that the mixture of both is balanced (HLD = 0).

natural surfactant(asphaltenes …)

propermixturedemulsifier

surfactant

unstableemulsion

- HLD = 0 +Salager J. L., Int. Chem. Eng., 30: 103 (1990)

Emul

sion

Stab

ility

25 / 30Precise Asphaltene (A) – Demulsifier (D)

Mixture

for a given reservoir ... S, EACN and T are fixed,thus the Surfactant Characteristic Parameter Cp(σ or β) for the mixture must satisfy:

lnS - K ACN + σ - aT ∆T = 0

CpSYS = K ACN – lnS + aT ∆T = Constant

Optimum at HLD = 0

CpMix = xD CpD + xA CpA = CpSYS

Simple A-D surfactants mixture condition (Linear rule)

CpMix = xD CpD + (1-xD) CpA = CpSYS

Salager J. L., SPE J., 19: 271 (1979)

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"Bottle test"in practice

originalW/ O

emulsion

Add CD (hence xD)ppm of demulsifier

Homogenize

Pour inbottle

Wait some time

Measure water separation

crude

water

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Aspect of test bottles(changing formulation, i.e. type or concentration of demulsifier)

naturalsurfactant(asphaltenes)

Propermixturedemulsifier

surfactant

unstableemulsion

- HLD = 0 +

Emul

sion

Stab

ility

28 / 30Other applications at HLD = 0

Formation dammage > microemulsions to breakdrilling fluid emulsion plugging the posousmedium close to well bottom

High solubilization in microemulsion with non-alkane oils and extended surfactants forcosmetics and pharmaceutical

Phase inversion by transitional/catastrophicmechanisms to make or destroy emulsions

Special detergency mechanisms and differenttypes of cleaning of soils, lathers …

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Applications away from HLD = 0 High stability of simple emulsions W/O and O/W

with HLD ≠ 0 … at ± 2 to 4 units (any kind)

Minimum drop size at HLD ≠ 0 but close to it (± 0.5 units) in many applications (paints,cosmetics, pharmaceuticals)

Multiple emulsions by changing WOR with twosurfactants at HLD ± 2-3 units in food, medicine ...

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JL.SALAGER@GMAIL.COM