1

Effect of Surfactant Synergism on Foam Rheology

Lauryl Sultaine: AOS 14-16 blends

Lauryl Betaine: AOS 14-16 blends

Rice University :Aarthi MuthuswamyMaura PuertoRafael VerduzcoClarence MillerGeorge Hirasaki

TU Delft, Shell RijswijkRouhi FarajzadehSebastien Bonnieu

2

Outline

• Foam experimental set up• Lauryl Sultaine & AOS14-16 blends, Lauryl Betaine &

AOS14-16 blends-N2 Foam flow in Bentheimer sandstone, 45°C.

-Regular solution theory interpretation of foam rheology.-Foam Presence of crude oil

• Interfacial rheology comparison of surfactants• Observations and conclusions

N2

GAS

MFC

Liquid Pump P1

P4

P3

P2

1.7”

2.46 ”

2.46

”

CORE

INLET

BPR

N2

GAS

OUTLET

TRAN

SDU

CERS

TO EFFLUENT

CHECK VALVE

CON

FIN

ING

PRE

SSU

RE

CON

FIN

ING

PRE

SSU

RE

OVEN 45 ⁰C

FOAM EXPERIMENTAL SET UP

4

Lauryl Sultaine –AOS 14-16 blends

5

Aqueous stability test - Sultaine AOS blends at 45⁰C

(S) 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 (AOS) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Clear ClearUnclear

6

Foam Quality scan- 45 °C, ~ 2.5 Darcy, ~ 20 ft/day interstitial velocity

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%10

100

1000

10000

S:AOS 8:2S:AOS 1:9

AOS

Sultaine

sultaine aos sultaine aos 1:9sultaine aos 8:2

Foam Quality (%)

App

aren

t vis

cosi

ty (c

P)

Ove

rall

IN

OUT

Internal tap

N2 foamBPR ~ 25 bar=362psi

𝚪=𝒒𝒈

𝒒𝒈+𝒒𝒍

= gas flow rate = liquid flow rate

7

Regular solution theory

Assumptions:• The entropy of mixing is ideal• However the change in the Gibbs free energy (ΔGmix= ΔHmix- TΔSmix)

arising due to the interactions between the two surfactants is taken into account using an activity coefficient f in the chemical potential equation. The activity coefficient signifies the deviations from the ideal solution.

• The regular solution approximation for the activity coefficient is given as (Rubingh, 1979)

Rosen, M. J. (1991). Synergism in mixtures containing zwitterionic surfactants. Langmuir, 885-888.

Rubingh, D. N. (1979). Mixed Micelle Solutions (Vol. 1). Springer New York.

Zhou, Q., & Rosen, M. (2003). Molecular Interactions of Surfactants in Mixed Monolayers at the Air/Aqueous Solution Interface and in Mixed Micelles in Aqueous Media:  The Regular Solution Approach. Langmuir, 4555-4562.

8

Calculation of β parameters- Regular solution theory

𝒙𝒎𝟏𝟐 𝐥𝐧 (

𝜶𝟏𝑪𝒎𝟏𝟐

𝒙𝒎𝟏𝑪𝒎𝟏

)

(𝟏−𝒙𝒎𝟏 )𝟐𝒍𝒏((𝟏−𝜶𝟏 )𝑪𝒎𝟏𝟐

(𝟏− 𝒙𝒎𝟏 )𝑪𝒎𝟐

)

=𝟏

𝜷𝑴=𝐥𝐧 (

𝜶𝟏𝑪𝒎𝟏𝟐

𝒙𝒎𝟏𝑪𝒎𝟏)

(𝟏− 𝒙𝒎𝟏)𝟐

α1- mole fraction of surfactant 1 in the prepared bulk solution (LB)xm1 – the mole fraction of surfactant 1 (LB) in the mixed micelleCm1, Cm2- cmc of the individual surfactants LB and AOS respectivelyCm12- cmc of the surfactant mixtureγ – surface tension X1= mole fraction of surfactant 1 (LB in this case) in the total mixed monolayer C12, C1

0, C20 are the molar concentrations of LB: AOS mixture,

LB, AOS respectively chosen to give a particular surface tension value

𝒙𝟏𝟐 𝒍𝒏(

𝜶𝟏𝑪𝟏𝟐

𝒙𝟏𝑪𝟏𝟎 )

(𝟏−𝒙𝟏 )𝟐𝒍𝒏((𝟏−𝜶𝟏 )𝑪𝟏𝟐

(𝟏− 𝒙𝟏 )𝑪𝟐𝟎 )

=𝟏

?

𝜷𝝈=𝒍𝒏(

𝜶𝟏𝑪𝟏𝟐

𝒙𝟏𝑪𝟏𝟎 )

(𝟏−𝒙𝟏𝟐)

?

?

?

9

Surface tension measurements for Sultaine-AOS blends mad in sea water Air-water interface, 20 °C

Surfactant CMC (wt%) CMC (M) Surface tension (mN/m)

LS 0.017 0.000983 33.52

8LS+2AOS 0.0073 0.00044 28.35

1LS+9AOS 0.00404 0.000313 29.74

AOS 0.00508 0.000407 28.76

0.000001 0.00001 0.0001 0.001 0.01 0.10

10

20

30

40

50

60

70

80

SultaineS:AOS 8:2S:AOS 1:9AOS

conc M

Surf

ace

tens

ion

(mN

/m)

CMC

C01

C02

C012

Du-Nuoy Padday method used

10

Interfacial tension between octane and sultaine-AOS blends, 20°C

0.000001 0.00001 0.0001 0.001 0.01 0.10

5

10

15

20

25

30

35

40

45

50

LSS:AOS 8:2S:AOS 1:9AOS

conc M

Inte

rfac

ial

tens

ion

(mN

/m)

Characterization of synergism by parameter for Sultaine AOS blends

Surfactant Bulk mole fraction LS

Interfacial mole fraction X1 LS

Sultaine8 Sultaine + 2 AOS 0.73 0.50 -1.56

1 Sultaine+ 9 AOS 0.072 0.18 +0.24AOS

Air-liquid interface

Surfactant LS X1 LS

Sultaine

8 Sultaine + 2 AOS 0.73 0.50 -1.01

1 Sultaine+ 9 AOS 0.072 Cannot solve perhaps mole fraction of LS is too low.

AOS

Octane-liquid interface

11Zhou, Q., & Rosen, M. (2003). Molecular Interactions of Surfactants in Mixed Monolayers at the Air/Aqueous Solution Interface and in Mixed Micelles in Aqueous Media:  The Regular Solution Approach. Langmuir, 4555-4562

12

Foam Quality scan- 45 °C, ~ 2.5 Darcy, ~ 20 ft/day interstitial velocity

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%10

100

1000

10000

S:AOS 8:2S:AOS 1:9

AOS

Sultaine

sultaine aos sultaine aos 1:9sultaine aos 8:2

Foam Quality (%)

App

aren

t vis

cosi

ty (c

P)

Ove

rall

IN

OUT

Internal tap

N2 foamBPR ~ 25 bar=362psi

13

1 10 1001

10

100f(x) = 96.6093893646772 x^-0.237982393289041R² = 0.777445235597079

f(x) = NaN x^NaNR² = NaN Sultaine, 2.7 Darcy, 30% foam

Interstitial velocity (ft/day)

App

aren

t vis

cosi

ty (c

P)

0.1 1 10 10010

100

1000

10000

f(x) = 122.054132090756 x^-0.597475390298641R² = 0.853871131799467

f(x) = 1877.30141528283 x^-0.2828916267485R² = 0.668106872069439

S:AOS 8:2 , 2.4 Darcy, 82% foam

Interstitial velocity (ft/day)

App

aren

t vis

cosi

ty (c

P)

S:AOS Foam with crude oil, 45⁰ C, ~ 40% residual oil

Ove

rall

IN

OUT

Internal tap (foam no oil)

IN

Foam presence of crude oil

Oil ~ 60 cP

14

0.1 1 10 10010

100

1000

10000

f(x) = 2147.56279369965 x^-0.615602675867607R² = 0.977176205400423

f(x) = NaN x^NaNR² = NaN AOS, 2.6 Darcy ~ 82% foam

Interstitial velocity (ft/day)

App

aren

t vis

cosi

ty (c

P)

0.1 1 10 100100

1000

10000

f(x) = 2999.38510470392 x^-0.702109198975358R² = 0.972126937163002f(x) = 1776.54021084261 x^-0.225091738612957R² = 0.820357766680693

S:AOS 1:9, 2.4 Darcy, ~82% foam

Interstitial velocity (ft/day)

App

aren

t vis

cosi

ty (c

P)

Ove

rall

IN

OUT

Internal tap (foam)

IN

Foam presence of crude oil

S:AOS Foam with crude oil, 45⁰ C, ~ 40% residual oil

15

Lauryl Betaine –AOS 14-16 blends

16

(LB) 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0(AOS) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Blend Scan (45 ⁰C)

Clear ClearNot Clear

17

Betaine- AOS foam quality scan- 45°CCompared at shear rate 28.3 1/s

20% 30% 40% 50% 60% 70% 80% 90% 100%100

1000

10000 LB LB:AOS 7:3 LB:AOS 1:9 AOS

Foam Quality

App

aren

t vis

cosi

ty (c

P)

2.5 Darcy

1.2 Darcy

2.6 Darcy

0.9 Darcy

Ove

rall

IN

OUT

Internal tap

N2 foamBPR ~ 5 bar=72.5psi

18

0.000001 0.00001 0.0001 0.001 0.01 0.10

10

20

30

40

50

60

70

80

LBLB:AOS 7:3LB:AOS 1:9AOS

Conc (M)

Surf

ace

Tens

ion

(mN

/m)

Surfactant CMC (wt%) CMC (M) Surface tension (mN/m)

LB 0.0136 0.00157 33.79

7LB+3AOS 0.0057 0.00034 27.9

1LB+9AOS 0.00415 0.000348 28.65

AOS 0.00508 0.000407 28.76

Surface tension measurements for Betaine-AOS blends made in sea water Air-water interface, 20 °C

19

Interfacial tension between octane and betaine-AOS blends- 20°C

0.000001 0.00001 0.0001 0.001 0.01 0.10

5

10

15

20

25

30

35

40

45

50

LBLB:AOS 7:3LB:AOS 1:9AOS

Conc (M)

Inte

rfac

ial T

ensi

on (m

N/m

)

20

Characterization of synergism by parameter- Betaine AOS blends

Surfactant Bulk mole fraction LB

Interfacial mole fraction X1 LB

Betaine

7 Betaine +3AOS 0.77 0.49 -7.08

1 Betaine+ 9 AOS 0.14 0.31 -2.72

AOS

Surfactant X1 LB

Betaine

7 Betaine +3AOS 0.37 -3.24

1 Betaine+ 9 AOS 0.30 -2.19

AOS

Octane-liquid interface

Air-liquid interface

21

1 10 10010

100

1000

LB , 2.5 Darcy, at ~60% quality, 20° C

Interstitial velocity (ft/day)

App

aren

t vis

cosi

ty (c

P)LB:AOS Foam with crude oil, ~ 30% residual oil

1 10 10010

100

1000

f(x) = 1345.7599091273 x^-0.609359540082445R² = 0.981064621291352

LB:AOS 7:3 , 1.2 Darcy at ~80%, 45° C

Interstitial velocity (ft/day)

App

aren

t vis

cosi

ty (c

P)

Ove

rall

IN

OUT

Internal tap (foam)

IN

Foam presence of crude oil

22

Ove

rall

IN

OUT

Internal tap (foam)

IN

Foam presence of crude oil

LB:AOS Foam with crude oil , ~30% residual oil (contd.)

1 10 10010

100

1000

f(x) = 750.1635990962 x^-0.627272535219658R² = 0.992071333842097

f(x) = 748.719136465846 x^-0.315929296669471R² = 0.976456200004859

LB:AOS 1:9 , 0.7 Darcy at ~90% , 45°C

Interstitial velocity(ft/day)

Appa

rent

vis

cosit

y (c

P)

0.1 1 10 10010

100

1000

10000

f(x) = 2147.56279369965 x^-0.615602675867607R² = 0.977176205400423

f(x) = NaN x^NaNR² = NaN AOS, 2.6 Darcy ~ 82% foam

Interstitial velocity (ft/day)

App

aren

t vis

cosi

ty (c

P)

Comparison of interfacial complex viscosity- Interfacial stress rheometer magnetic needle method

0.1 1 10 1001E-04

1E-03

1E-02

1E-01

LBLSAOSLS:AOS 1:9LB:AOS 1:9

Frequency (rad/s)

Com

plex

vis

cosi

ty h

*(m

Pa.s

.m)

DI water= ~0.01 mPa.s.m

All surfactant solutions made in sea water

Observations and Conclusions• Absence of crude oil: In a blend of zwitterionic Lauryl betaine and

Anionic AOS 14-16 (AOS) , betaine does not boost the foam of the blends to any better value than pure AOS itself. The same goes for blends of Lauryl sultaine and AOS where sultaine does not boost the foam of blend to any better value than AOS.

• Presence of crude oil : AOS foam performs well in the presence of crude oil that a blend is not required for the test conditions in this study.

• None of the surfactants have measurable interfacial rheology.• Regular solution theory predicts there is more synergism in Betaine

& AOS blends than in Sultaine & AOS blends. However this does not have correlation to foam strength for the test conditions. ( Rosen et.al , Journal of the American Oil Chemists’ Society, April 1988, Volume 65, Issue 4, pp 663-668)

• Pure Lauryl Betaine and Pure Lauryl Sultaine surfactants are not good foamers in interests of EOR.

Acknowledgements• Foam Experimental set up– Michiel Slob- TU Delft– Dr. Ali Akbar Eftekhari- TU Delft

• Interfacial Rheology – Dr. Gerard Fuller’s lab – Stanford University

• Surface/Interfacial tension measurements– Hakim Hamouche- Kibron

• Processes in Porous Media Consortium, Solvay, Shell Rijswijk.

Back up slides

27

Procedure to determine concentration to estimate parameter at interfaces

1E-06 1E-05 1E-04 1E-03 1E-020

10

20

30

40

50

60

70

80

f(x) = − 13.4079299801969 ln(x) − 85.0595667502185R² = 0.969775950106801f(x) = − 10.6320995010589 ln(x) − 59.1753417612303

R² = 0.950714095608722

f(x) = − 14.0942782895045 ln(x) − 80.062552908297R² = 0.962006673466344f(x) = − 10.5046045830633 ln(x) − 32.3740021495709

R² = 0.929662064381792

betaineLogarithmic (betaine)AOSLogarithmic (AOS)LB:AOS 7:3Logarithmic (LB:AOS 7:3)LB:AOS 1:9Logarithmic (LB:AOS 1:9)

concentration (M)

Surf

ace

tens

ion

(mN

/m)

Here example case of betaine AOS blends are shown

28

Du-Nuoy method- Kibron EZ-Pi Plus

Rate of pulling= 0.2 mm/s

F = 2 π r

29

Characterization of synergism by parameter for Sultaine AOS blends

Surfactant Bulk mole fraction LS

Interfacial mole fraction X1

Micellar mole fraction Xm

M

Sultaine8 Sultaine + 2 AOS 0.73 0.50 0.52 -1.56 -1.92

1 Sultaine+ 9 AOS 0.072 0.18 0.19 +0.24 +0.29AOS

Air-liquid interface(linear fit)

Surfactant LS X1 Xm M

Sultaine

8 Sultaine + 2 AOS 0.73 0.50 -1.01

1 Sultaine+ 9 AOS 0.072 Cannot solve perhaps mole fraction of LS is too low.

AOS

Octane-liquid interface (polynomial fit)

30

Characterization of synergism by parameter- Betaine AOS blends

Surfactant Bulk mole fraction LS

Interfacial mole fraction X1

Micellar mole fraction Xm

Surfactant

Betaine

7 Betaine +3AOS 0.77 0.49 0.48 -7.08 -2.84

1 Betaine+ 9 AOS 0.14 0.31 0.26 -2.72 -1.40

AOS

Surfactant X1 Xm M

Betaine

7 Betaine +3AOS 0.37 -3.24

1 Betaine+ 9 AOS 0.30 0.27 -2.19 -0.77

AOS

Octane-liquid interface

Air-liquid interface

31

Pressure History and Oil recovery LS:AOS 1:9

0 5 10 15 20 25 30 350

102030405060708090

100Oil recovery

Total injected PV

Cum

mul

ative

Oil

reco

very

(%

)

0 5 10 15 20 25 30 350

1020304050607080

0

5

10

15

20

25

30internal tap overall Interstitial velocity

Total injected PV

Pres

sure

dro

p (p

si)

Inte

rstiti

al v

eloc

ity (ft

/day

)