Oilfield Fluids: Tales of Mud and Worms

1

Oilfield Fluids:

Tales of Mud and Worms

Geoffrey Maitland

Department of Chemical Engineering

Rideal Lecture Wednesday 28th March 2012

Collaborators

Schlumberger: Louise Bailey, Isabelle Couillet,

Trevor Hughes

Imperial College: Edo Boek, John Crawshaw

Utrecht University: Henk Lekkerkerker, Annemieke ten Brinke,

Marcel Vogel, Dzina Kleshchanok

Strasbourg ICS, CNRS Francoise Candau, Jean Candau

Twente University: Wim Briels, Johan Padding (Eindhoven)

Bristol University: Terence Cosgrove, Vania Croce

Cecile Dreiss (KCL) 2

Lecture Outline

• Design of Fluids and Materials

• Advanced Formulation and (More) Systematic Design of Fluids

• The Worm’s Tale

• Smarter Fracturing Fluids

• The Potter’s Tale

• Clays for Drilling Fluids – enhancing performance

• Some Conclusions

3

From Understanding to Designing Fluids

4

Composition – molecules and molecular assemblies

Forces Bulk Properties

Structure -molecular, nano, micro


5




Process


6




Process

Cost Material availability

Market acceptability

Environmental Compliance


7




Process

Cost Material availability

Market acceptability

Environmental Compliance

Which Components? How much of each?

8

From Empirical Formulation to Systematic

Fluid/Materials Design

Editorial:

G.C. Maitland

Transforming 'formulation':

systematic soft materials design

Soft Matter, 2005, 1(2), 93 - 94

Systematic Fluid Formulation

Experiment Simulation

Theory

Macroscopic

Molecular

Mesoscopic

k, lp, bT… *

1. Understand mechanisms

2. Design new/improved fluids/materials

Cp, G, Sol, h(T,P,x…)

Coarse Graining

*Including High-Throughput and

Combinatorial Methods

Product

Main building blocks for (oilfield)

functional fluids

• Hydrocarbons

– Aliphatics, aromatics, polar…

• Polymers

• Surfactants

• Colloids

– Mineral colloids

– Anisotropic clays…

11

The Worm’s Tale Stimulating an oil-gas reservoir

by Hydraulic Fracturing

12

Hydraulic Fracturing

Flow restricted by radial geometry

Increased productivity through fractures

Before Treatment

After Treatment

13

Aqueous Solutions of Guar – the

Standard Fracturing Fluid

Guar: Galactomannose, M ~ 105-106

14

The Problem - Polymer vs Surfactant Fluids:

Fracture Permeability

100

75

50

25

0

XL GUAR

HEC

Retained

Permeability (%)

Surfactant

15

Problem: Guar Polymer Fracturing Fluids give

<50% Theoretical Production from

Fractures

Solution: Shower Gels for Deep Hot Wells -

Wormlike Surfactant Micelles at >150oC

Low Production…Worms to the rescue!

16

Oil-responsive Viscoelastic Surfactants

Worm-like Micelles Network of Worm-like

Micelles Spherical Micelles

1.00E-02

1.00E-01

1.00E+00

1.00E+01

1.00E+02

1.00E-02 1.00E-01 1.00E+00 1.00E+01 1.00E+02 1.00E+03

Shear Rate (s-1)

Vis

co

sity (

Pa

.s)

40 oC (104 oF)

70 oC (158 oF)

90 oC (194 oF)

130 oC (266 oF)

150 oC (302 oF)

Hydraulic Fracturing

+oil +salt

1-4wt%

One Source of Worms...

17

18

Viscoelastic Surfactant Fracturing Fluids

• • Hydrophobic

tail

• C22 chain

• cis double bond at C13

• Hydrophilic head group

• quaternary ammonium with 2 hydroxyethyl groups

• Derived from rape seed oil

• Blended with iso-propanol

CH3–(CH2)7

C C

HH

(CH2)11–CH2–N–CH3

CH2–CH2–OH

CH2–CH2–OH

+

—Cl

Erucyl bis (2-hydroxyethyl) methyl ammonium chloride

EHAC

19

Typical Lengthscales

S.R. Raghavan and E.W. Kaler

Univ of Delaware

Bulk Properties

Simulation

Theory Phenomenological

Parameters

Simulation

Theory

Experiment Macroscopic

Molecular

Mesoscopic

Experiment

Coarse

Graining

Type of Study

Bulk Rheology

Continuous Shear Flow

22

VES Shear Viscosity

10 -4

10 -3

10 -2

10 -1

10 0

10 1

10 2

10 3

10 -2

10 -1

10 0

10 1

10 2

10 3

25 o C

68 o C

90 o C

38oC

55 o C

80 o C

Shear Rate (s-1)

Vis

cosity (

Pa

.s)

2.5% Surfactant 5% KCl

• Zero-shear viscosity, h0 decreases as T

• Relaxation time, tR (= 1/gc) decreases as T

• Viscosity at high shear-rates is nearly

independent of T

100s-1

50 cP

23

Origin of Viscoelasticity and High Viscosity

Spherical Micelles

Increasing salt,

concentration

Micelles are very long, 1-5 mm

Since tR ~ h ~ L3

micelles relax slowly

high viscosity

Transient Network of Wormlike Micelles

After E.W. Kaler , Univ of Delaware

Bulk Rheology

Oscillatory Shear Flow

27

Display Simple Linear

Viscoelastic Behaviour

1

10

100

0.001 0.01 0.1 1

Elastic Modulus

Viscous Modulus

G'

or

G"

/ P

a

/ Hz

VES Surfactant Solution

Maxwell Model for Linear

Viscoelasticity

28

G’ = G 2 t2 G” = G t

1 + 2t2 1 + 2t2

G t

Relaxation Time t = h/G

1

2

G’

G”

t + h dt = h dg

G dt dt

//upload.wikimedia.org/wikipedia/commons/d/db/Maxwell_diagram.svg

29

Dynamic shear rheology master curve

10-1

101

103

10-2

10-1

100

40C

15C2

1

G'

G'' G

' (P

a)

G''

(Pa)

.TR

Rheological master curves for dynamic shear for a sample at 14.4 mM active EHAC concentration with 400mM KCl, obtained by scaling the data generated at various temperatures (15,20,25,30,35 and 40C).

I Couillet, T Hughes, G Maitland F Candau and S J Candau, Langmuir, 20, 9541-9550, 2004

30

Linear Viscoelastic Regime

0.1

1

10

100

1000

0.01 0.1 1 10 100Frequency (rad/s)

3 wt% EHAC surfactant, 3 wt% potassium chloride solution at 40 C.

Data fitted to a 2 element Maxwell model.

η* Pa s G’ Pa G” Pa

Rachel Cooke and Malcolm Mackley, Cambridge University

31

Bulk Rheology of VES Fluids

1

10

100

0.001 0.01 0.1 1

Elastic Modulus

Viscous Modulus

G'

or G

" /

Pa

/ Hz

tr-1

1

10

100

100

101

102

103

104

0.001 0.01 0.1 1 10

Shear Rate / (1/s)

tr-1

Both types of behaviour in line with the ‘Reptation-Reaction’ model

of Cates, later adapted to h(g) by Spenley, Cates and McLeish.

tr = (tR tb)1/2

Bulk Properties

Simulation


Parameters

Simulation

Theory


Molecular

Mesoscopic

Experiment

Coarse

Graining

Type of Study

33

Chain Constraints –

Reptation in a Tube

Chain reptates down the tube which is continually renewed as other chains move

Repulsive interchain forces

Entanglements - moving obstacles

Obstacle course for a given chain represented by a tube

h ~ tR ~ L3

Reptation time tR

34

Cates-type models • Assume two main processes:

– Reptation, trep

– Chain scission-rehealing, tbr = (KL)-1

• Slow scission limit, tbr >> trep

– Terminal relaxation time tR = trep

h0 = L3c15/4

• Fast breaking limit, tbr << trep

tR = (tbrtrep)1/2

Maxwell behaviour for G’, G’’ with t = tR

h0 ~ Lc3

• Rouse modes at higher frequency if tRouse < tbr

Effect of Headgroup on Relaxation Time

1

10

100

0.001 0.01 0.1 1

Elastic Modulus

Viscous Modulus

G'

or G

" /

Pa

/ Hz

tr=700s

0.01

0.1

1

10

100

1000

104

105

106

0.001 0.01 0.1 1 10

Kesbos at 1 Hz 0.05 strain

Elastix Modulus / PaViscous Modulus / Pa

Ela

stix

Mod

ulu

s /

Pa

Frequency / Hz

0.6 Hz

t = 1.7s

C18 - Oleyl C22 - Erucyl

36

Screening salt: grows wormlike

micelles

NaCl Concentration (mM)

10 100 1000

h (Pa.s)

10-2

100

101

104

40 mM EHAC

77oF

Micellar surface

+

+ +

S.R. Raghavan and E.W. Kaler, University of Delaware

37

Spherical to wormlike micelles observed by SANS

Spheres

Cylinders Increasing salt

V.Croce, T. Cosgrove, G.C. Maitland, T.L. Hughes and

G. Karlsson, Langmuir 19 8536-41 (2003)

40

SANS study of micelle growth – no salt

Spherical micelles, R = 33.3 A

Data by Vania Croce, University of Bristol

V.Croce, T. Cosgrove, G.C. Maitland, T.L. Hughes and G. Karlsson, Langmuir 19 8536-41 (2003)

41

4.5 wt% EHAC…no salt

Spherical Micelles, R ~ 33A

Cryo-TEM by Goran Karlsson, Uppsala University

and Vania Croce, University of Bristol


42

Rodlike micelles, R = 21 A

Data by Vania Croce, University of Bristol

SANS study of micelle growth – added salt

Low Q:

I~Q-1 =

rods

High Q: R salt

independent


43

Add 2% KCl…peak viscosity

Entangled Wormlike Micelles



44

Maxwell behaviour…plus Rouse internal

modes at high frequency

Data: Vania Croce, Univ of Bristol

45

6% KCl …viscosity falling...

…branched micelles

Branched Wormlike Micelles



46

6% KCl - approaching Maxwell

behaviour…


47

12% KCl – essentially Maxwell

behaviour…


Bulk Properties

Simulation


Parameters

Simulation

Theory


Molecular

Mesoscopic

Experiment

Coarse

Graining

Type of Study

Probing the Microstructure

Rheology and Light Scattering

Sch

lum

berg

er P

rivate

VES – onset of entanglement regime

0.01 0.1 1

1

10

100

1000

10000

100000

1000000

Zero

shear

vis

cosity

[wt% J508]

c*=0.08wt%

c* is temperature

dependant:

@ 25 C, c*=0.08wt%

@ 40 C, c*=0.1wt%

@ 60 C, c*=0.15wt%

CryoTEM measurements by Goran Karlsson, Uppsala

University, and Vania Croce, University of Bristol

13.06.06 51

Concentration Regimes • Dilute

• Semi-Dilute

• Concentrated

Rg

Hydrodynamic volume Vh = 4/3pRg3

R >> Rg

V/n = M/C >>Vh

Concentration C=nM / V

Volume per molecule = V/n = M/C

R << Rg

V/n = M/C << Vh

C > C*

R = Rg

V/n = M/C = Vh

C = C*

Critical Overlap Concentration

C* = M / Vh

52

Critical Overlap Concentration c*

versus Temperature, Salt

100 200 300 400 500 600 7001.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

C* (

mM

)

KCl concentration (mM)

Crossover concentration C* of EHAC solutions versus KCl concentration at 25C ( ), 40C ( ) and 50C ( ).

Data: Isabelle Couillet


Note: IPA solvent reduces c* by about 30%

54

Correlation length from static light

scattering

0.1 1 1010

100

Corr

ela

tion lenght (n

m)

EHAC Concentration (mM)

Variation of the correlation length versus active EHAC concentration With 400mM KCl at 25C.

Correlation Length from Ornstein-Zernicke Equation: I(q)-1 = I(0)-1[1 + q22]


C*

55

Estimation of = tbreak/tR

0 1 2 30

1

2

3

= 0.3

G''/

G''m

ax

G'/G''max


Normalized Cole-Cole plot for a solution of EHAC at an active concentration 14.4 mM with T=15C, [KCl]=400mM. The dotted lines are the calculated Cole-Cole plots for different values of the parameter (0.1, 0.13 and 0.3).


Direct Determination of Esciss

3.2 3.3 3.4 3.5

10-1

100

101

G''/G

'in

f

1000/T (K-1)

m

in (

rad

/s)

Semi-log variation of G”min/G’inf ( ) and m (o) as a function of 103/T for a

solution with an active EHAC concentration of 14.1 mM, and 400 mM KCl

Esciss = 28kT

G”min/G’inf ~ le/<L>

~exp[-Esciss/2kT]



57

Activation Energy for Micelle Breaking

3.2 3.3 3.4 3.5

101

102

t b

reak (

s)

1000/T (K-1)

Arrhenius plot of the breaking time tbreak versus 103/T for active EHAC concentration of 14.1 mM and 400 mM KCl

Ebreak = 25.5kT

ER = 0.5(Ebreak + Erep)

= 0.5(Ebreak + 1.5 Esciss)

= 34kT

Esciss = 28kT

Bulk Properties

Simulation


Parameters

Simulation

Theory


Molecular

Mesoscopic

Experiment

Coarse

Graining

Type of Study

59

Simulation: from Micro to Meso to Macro

1. Micro-scale

• Atomistic Molecular Dynamics simulation of micelles

• Coarse-grained micelle MD

• Output: persistence length, compressibility, scission/end cap/branching energies, …

2. Mesoscopic simulation of wormlike micellar VES fluids

• Coarse-grained micelle MD

• Output: rheology of bulk VES fluid

3. Macro-scale: fluid dynamics

• flow in porous media: leak-off and clean up of frac fluid

• particle laden flow: proppant transport, shear banding,…

61

MD simulation of surfactant packing

Erucate (ordered)

Same tail, different heads: different packing behaviour

EHAC (less ordered)

Erucate EHAC Si,jsi.sj/N

2 0.93 0.62 ES Boek, A Jusufi, H Loewen and GC Maitland, J Phys Condens Matter, 14, 9413-9439, 2002

62

Density distributions

Penetration of water into membrane core

- similar to cylindrical micelles

(Watanabe & Klein, 1991)

ES Boek, A Jusufi, H Loewen and GC Maitland, J Phys Condens Matter, 14, 9413-9439, 2002

63

Intra-chain separations

Peaks at large r are due to fully extended chains –

at smaller distances show tendency to “fold back”

Sharper C=C peaks show that first part of chain is less flexible

ES Boek, A Jusufi, H Loewen and GC Maitland, J Phys Condens Matter, 14, 9413-9439, 2002

64

Control of Fluid Properties through

Design of Chemical Structure

Moving from Formulation towards

Molecular Engineering

Alternative VES Structures

Tune headgroup and tail interactions to increase packing

parameter, P = Vs /la, and so stabilise wormlike phase to

higher temperatures

R - X - Y - COO- Hydrophobic

Tail Spacer

group Spacer

group Charged

group

66

Improving Temperature Performance

1

10

100

1000

25 50 75 125 150 175

Temperature (oC)

Vis

co

sity (

cP

) @

100

s-1

System A

System B

System C

System D

100

Rheology

Specification

>50cP @ 100 s-1

Data: T L Hughes et al, Schlumberger

The major block for using new

molecules in the oilfield:

££££££££££££

Must leverage on other non-

oilfield applications

Bulk Properties

Simulation


Parameters

Simulation

Theory


Molecular

Mesoscopic

Experiment

Coarse

Graining

Type of Study

Tuning Properties by Blends

(a) Surfactant Blends

73

SANS for EHAC-C18E18 mixed micelles

vs [salt]

25C

4.5wt% EHAC,

4.0wt% C18E18

[KCl] wt%

6.0 4.0

2.0

1.0

0.5

0.0

2.0

wt

%

6.0 wt% EHAC

only

V Croce, T Cosgrove, C Dreiss, G Maitland, T Hughes and G Karlsson, Langmuir, 20, 7984-7990, 2004

EHAC = 4.5 wt%

C18E18 = 0

C18E18 = 1.0%

Low shear viscosity for EHAC-

C18E18 mixed micelles


Microstructure associated with rheology

changes in mixed worm-micelle fluids


Tuning Properties by Blends

(b) Polymer-Surfactant Blends

79

Polymer-surfactant mixtures Visco-elastic surfactant (VES) - EHAC

Hm-polymer

x mol% hydrophobe

• VES/hm-polymer blend

– visco-elastic physical gel

– selective response to oil

– lower concentrations of

both polymer and

surfactant

blended with

Hm-HPG: Mw ~ 1.8x106, <DP> ~ 3000, C22 side groups 10 per chain

R = [CEHAC]/[CEHAC + CHmHPG]

Hm-Polymer:Surfactant Mixtures -

Enhanced linear viscoelasticity

I Couillet, T Hughes, G

Maitland and F Candau,

Macromolecules, 38, 5271-

5282, 2005

81

Hm-HPG:EHAC mixtures – shear

viscosity enhancement

I. Couillet, T.L. Hughes, G.C. Maitland, F. Candau

Macromolecules, 38, 5271-5282 (2005)

Hm-HPG:EHAC mixtures – shear viscosity

Hm-HPG: Mw ~ 1.8x106, <DP> ~ 3000, C22 side groups 10 per chain R = [CEHAC]/[CEHAC + CHmHPG]

I. Couillet, T.L. Hughes, G.C. Maitland, F. Candau, Macromolecules, 38, 5271-5282 (2005)

Shear rate = 100 s-1

Shear rate = 0 s-1

Interpenetrating network of wormlike

micelles and hm chains of hm-HPG

85

Sticky Reptation Model for

hm-polymer:wormlike micelle coupling

D ~ average

mutual

entanglement

length

Needs quantitative model for worm-hm polymer coupled flow

86

The Potter’s Tale

• Or…Mud, Glorious Mud

– Tubular conduit for fluids…out and in

• Macro Tubes

– Clay colloidal particles are everywhere

– Smectite montmorillonite or Bentonite

• Clay water-based muds

• Low permeability filtercakes

• Soft, swellable shales

…compacted clay rocks

The Industrial Driver – Drilling Fluids

87

88

Drilling an oilwell...

• Colloidal clay oilfield drilling fluid

• Rheological behaviour critical – Minimize pumping energy

– Keep cuttings suspended, even when pumps stop

Gelation of mixed colloid drilling fluids on

cessation of flow

Concept: Designer Gels or Dial-a-Yield Stress

89

Base Clay: Montmorillonite or Bentonite

0

50

100

150

200

0 100 200 300 400 500 600 700

Shear rate (sec-1)

Shear

str

ess (

Pa/2

)

T = 25C

T = 125C, 16hrs

T = 125C, 32hrs

T = 150C, 16hrs

T = 190C, 16 hrs

90

Montmorillonite Clay Platelets - Bentonite

91

Visplex/Drillplex: Mixed Metal Hydroxide Cationic Colloid

hexagonal plates, aspect ratio ~10

plate diameter ~100nm, Mg/Al ~ 1.0

+

+

+

+

-

- -

-

- + - + + - + +

-

-

- -

- -

-

-

-

- -

+

+ +

+ +

+

1 micron

Bentonite platelet with negative faces.

Edge charges are pH-dependent.

VISPLEX crystals:

positive charge due to

electron-deficient lattice

100

1000

10000

100000

0.1 1 10 100

Shear rate (sec-1)

Appare

nt V

iscosity (

mP

a s

)

Clay-based WBM

MMH Fluid

92

Mixed metal oxide: TEM image

500 nm

93

But...problems -

• Loss of viscosity with salt, brines...seawater

• Gel degrades at temperatures higher than 115 oC

Visplex was renamed Drillplex but still these

issues persisted.

94

Henk Lekkerkerker to the rescue...

Flow curves for mixtures of bentonite and various

colloidal thickeners

Boehmite

Gibbsite

96

Felixplex Patents

97

Gelation of mixed colloid drilling fluids on

cessation of flow

Concept: Designer Gels or Dial-a-Yield Stress

98

Bulk Properties

Simulation


Parameters

Simulation

Theory


Molecular

Mesoscopic

Experiment

Coarse

Graining

Type of Study

Shaplex: Objectives of Study

• To determine the rheology over a wide range of

stress/strain-rates (using oscillatory, transient and

continuous shear) of well-characterised gelling

suspensions of colloids of varying shape:

rods (boehmite), laths (hectorite), plates (gibbsite)

• To explore the rheological synergies in mixed-shape

colloidal suspensions:

2.5% w/w laths (hectorite)

+ 0.25% w/w rods (boehmite)

or plates (gibbsite)

or spheres (alumina-coated silica)

100

Acknowledgements

Thanks to

• Henk, Annemieke, Marcel and Louise for many years

of fruitful collaboration

• Nederlandse Organisatie voor Wetenschappelijk

Onderzoek (NWO) and

• Schlumberger Cambridge Research,

for financial support to Annemieke ten Brinke

• SoftComp EU 6th Framework Network of Excellence

• Edo Boek of Imperial College London (formerly

Schlumberger Cambridge Research) for helpful

discussions

• Dzina Kleshchanok, University of Utrecht, for

producing the TEM images 101

Key messages

• General complex rheological behaviour of clay and

clay-colloid mixtures as they transform from gels

(elastoviscous solids) to weakly elastic shear-thinning

liquids

• The significant enhancements to gel rheological

properties caused by minor (~ 1:10 w/w) additions of

a second colloidal component of varying shape

• Contrasts between hectorite and montmorillonite as

the base clay

• The contrasting effect of one particular additive (silica

spheres) depending on charge and clay concentration

102

103

Tuning gel behaviour by shape and charge

• Understand structure/performance relationships

in mixed systems using model colloids

Hectorite Gibbsite Boehmite

Henk Lekkerkerker, Annemieke ten Brinke, Marcel Vogel (Utrecht), Louise Bailey Schlumberger

Characteristics of Particles Particle

Property Hectorite Gibbsite Boehmite Ludox CL

Shape Lath Plate Rod Sphere

L1 [nm] 288 81 200 12

L2 [nm] 43 81 10 12

d [nm] 6 6 10 12

Density [g/cm3] 2.39 1.96 2.06 2.2

160 6.8 200 1.0

C* [g/100 cm3] 1.5 28.8 1.1 220

pH 8.9 7.8 6.2 4.5

Sign of face charge – + + +

Conductivity [mS/cm] 38.1 80.2 46.0

@ 1336 ppm @ 1154 ppm @ 1045 ppm

Mobility [10-8m2/Vs] -1.2 2.8 3.9

Zeta potential mV -9.8 +24.0 +44.2 +42

is the ratio of hydrodynamic volume Vh (4p (L1/2)3/3) to real particle volume (~L1L2d)

C* is the ‘overlap concentration’ at which the hydrodynamic volumes swept out by the particle’s largest dimension start to overlap = (100 L1 L2 24d r)/4pL1

3

105




L1 [nm] 288 81 200 12

L2 [nm] 43 81 10 12

d [nm] 6 6 10 12

Density [g/cm3] 2.39 1.96 2.06 2.2

160 6.8 200 1.0

C* [g/100 cm3] 1.5 28.8 1.1 220

pH 8.9 7.8 6.2 4.5



@ 1336 ppm @ 1154 ppm @ 1045 ppm

Mobility [10-8m2/Vs] -1.2 2.8 3.9




3

106




L1 [nm] 288 81 200 12

L2 [nm] 43 81 10 12

d [nm] 6 6 10 12

Density [g/cm3] 2.39 1.96 2.06 2.2

160 6.8 200 1.0

C* [g/100 cm3] 1.5 28.8 1.1 220

pH 8.9 7.8 6.2 4.5



@ 1336 ppm @ 1154 ppm @ 1045 ppm

Mobility [10-8m2/Vs] -1.2 2.8 3.9




3

107




L1 [nm] 288 81 200 12

L2 [nm] 43 81 10 12

d [nm] 6 6 10 12

Density [g/cm3] 2.39 1.96 2.06 2.2

160 6.8 200 1.0

C* [g/100 cm3] 1.5 28.8 1.1 220

pH 8.9 7.8 6.2 4.5



@ 1336 ppm @ 1154 ppm @ 1045 ppm

Mobility [10-8m2/Vs] -1.2 2.8 3.9




3

108

Concentration Regimes

Dilute

Semi-Dilute

Concentrated

R << L

V/n = M/C << Vh

C >> C*

R = L

V/n = M/C = Vh

C = C*

Critical Overlap Concentration

C* = Mp / Vh

L/2

Hydrodynamic volume Vh = pL3/6

R >> L

V/n = M/C >>Vh

Concentration C=nMp / V

Volume per molecule = V/n = Mp/C

“Hydrodynamic close-packing”

109

Multi-technique study

• Oscillatory Shear

• Creep

• Steady Shear

• Controlled Stress

• Controlled Shear Rate

• Measurement Systems

• 1o, 2o and 4o cone & plate

• Micro-roughened and smooth

• Controlled sample pre-shearing

preparation protocols

110

Pure Components

A few remarks...

111

Hectorite – Oscillatory Shear Flow

1E-3 0.01 0.1 1 10

0

20

40

60

80

100

1E-3 0.01 0.1 1 10

0

20

40

60

80

100

120A

1.5 wt.% G'

1.5 wt.% G"

2.5 wt.% G'

2.5 wt.% G"

G-m

odulu

s [

Pa]

strain

1.5 wt.% G'

1.5 wt.% G"

2.5 wt.% G'

2.5 wt.% G"

B

G-m

odulu

s [

Pa]

strain

0.01 0.1 1 10

1

10

100

0.01 0.1 1 10

1

10

100

A

1.5 wt.% G'

1.5 wt.% G"

2.5 wt.% G'

2.5 wt.% G"

G-m

odulu

s [

Pa]

Frequency [Hz]

1.5 wt.% G'

1.5 wt.% G"

2.5 wt.% G'

2.5 wt.% G"

B

G-m

odulu

s [

Pa]

Frequency [Hz]

C* ~ 1.5 wt%

Hectorite – Gel State 112

Hectorite – Creep

0 50 100 150 200 250 300 350 400

0.000

0.005

0.010

0.015

0.020

0.10

0.15

0.20

0.25

stress off

recoverable elastic

strain ~ ge

ge

creep(1,

2)

0.5 Pa

4.5 Pa

5 Pa

Str

ain

Time [s]

0 2 4 6 8 10

1E-3

0.01

0.1

1

10

100

1000

10000

100000

vis

co

sity

[Pa

s]

Applied stress [Pa]

C = 2.5 wt% = 1.7C*

Hectorite – Transition from Gel to Sol

113

Hectorite – Continuous Shear

Recovered Gel C* ~ 1.5 wt%

Controlled Shear Rate Controlled Shear Stress

Hectorite Gel – From Cradle to Grave and Back Again 114


Recovered Gel C* ~ 1.5 wt%


Hectorite Gel – From Cradle to Grave and Back Again 115

Fann Flow Curves Probe only the Liquid Region

Bingham Model t = ty + hg

Herschel Bulkley Model t = ty + Kgn are only the tip of the iceberg!

116


Controlled Shear Stress – Recovered Gel

C* ~ 1.5 wt%

1E-3 0.01 0.1 1 10 100 1000

1

10

1E-5 1E-4 1E-3 0.01 0.1 1 10 100 1000

0.1

1

10

0.1 1 1010

-3

10-2

10-1

100

101

102

103

104

105

106

107

1.5 wt.% up

2.5 wt.% up

shear

str

ess [

Pa]

shear rate [s-1]

1.5 wt.% down

2.5 wt.% down

1.5 wt.% up

2.5 wt.% up

shear

str

ess [

Pa]

shear rate [s-1]

1.5 wt.% down

2.5 wt.% down

B

C

A

1.5 wt.% up

2.5 wt.% up

vis

cosity

[Pas]

shear stress [Pa]

1.5 wt.% down

2.5 wt.% down

118

Boehmite Rods – Continuous Shear


C* ~ 1.1 wt%

0.01 0.1 1 10 100

1

10

1E-6 1E-5 1E-4 1E-3 0.01 0.1 1 10 100 1000

1

10

1 10

10-2

10-1

100

101

102

103

104

105

106

1E-5 1E-4 1E-3 0.01 0.1 1 10 100 100010000

1

10

1.2 wt.% up

2.5 wt.% up

A

shear

str

ess [

Pa]

shear rate [s-1]

1.2 wt.% down

2.5 wt.% down

1.2 wt.% up

2.5 wt.% up

B

shear

str

ess [

Pa]

shear rate [s-1]

1.2 wt.% down

2.5 wt.% down

1.2 wt.% up

2.5 wt.% up

vis

cosity

[Pas]

shear stress [Pa]

1.2 wt.% down

2.5 wt.% down

C

1.2 wt.% up

2.5 wt.% up

D

shear

str

ess [

Pa]

shear rate [s-1]

1.2 wt.% down

2.5 wt.% down119

Continuous Shear – Generic Flow Curves

A

BP

M

L

K J

H

G

F

E

D

C

D’

J’

GIV

GIII

GII

GI

SIII

SII

SI

1E-3 0.01 0.1 1 10 100 1000

1

1E-3 0.01 0.1 1 10 100 1000

0.1

1

shear

str

ess [P

a]

shear rate [s ]-1

N

GV

L’

A

BP

M

L

K J

H

G

F

E

D

C

D’

J’

GIVGIV

GIIIGIII

GIIGII

GIGI

SIIISIII

SIISII

SISI

1E-3 0.01 0.1 1 10 100 1000

1

1E-3 0.01 0.1 1 10 100 1000

0.1

1

shear

str

ess [P

a]

shear rate [s ]-1

N

GVGV

L’

GI = Disordered Gel GII = Ordered Gel GIII = Breaking Gel

GIV = Partially-ordered Gel GV = Ordered Gel (not same as GII)

SI = Structured Sol SII = Breaking Fluid SIII = Dispersed, Partially-ordered Sol

120

Common critical factor – yield strain

• Consistent values of G, h, ‘ty’, gy etc from oscillatory, transient and continuous shear experiments

• gy essentially independent of concentration

gy for

• Gibbsite plates 0.1 + 0.05 (L1 = 81nm)

• Hectorite laths 0.3 + 0.05 (L1 = 200 nm)

• Boehmite rods 0.45 + 0.05 (L1 = 288 nm)

• Same ordering as L1 or parameter

122

Mixed Shape Dispersions

Replacement of 10 wt% of the Hectorite

(@ 2.5 wt%) by a second component

123

Mixed-shape Suspensions –

Oscillatory Flow

1E-3 0.01 0.1 1 10

0

100

200

300

400

500

600

1E-3 0.01 0.1 1 10

0

100

200

300

400

500

600A B

Hectorite/Boehmite G'

Hectorite/Boehmite G"

Hectorite/Gibbsite G'

Hectorite/Gibbsite G"

Hectorite

G-m

od

ulu

s [

Pa

]

strain

Hectorite/Boehmite G'

Hectorite/Boehmite G"

Hectorite/Gibbsite G'

Hectorite/Gibbsite G"

Hectorite

G

-mo

du

lus [

Pa

]

strain

Hectorite 2.5 wt% (1.7c*), Minor Component 0.25 wt%

Boehmite = 200

Hectorite = 160

Gibbsite = 6.8

124

Creep viscosity h(t) and plateau modulus Ge

10

100

1000

104

105

0 2 4 6 8 10 12

hG

e

Vis

co

sity

[P

as],

Mo

du

lus

[Pa

]

Stress [Pa]

Hectorite-boehmite 10:1 mixture

Hectorite ‘ty’

Chectorite = 2.5 wt% = 1.7C* 125

Controlled shear stress flow curves

- effect of 10 wt% minor colloid

10-5

10-4

10-3

10-2

10-1

100

101

102

103

1

10

100

1 10 10010

-2

10-1

100

101

102

103

104

105

106

Hectorite/Boehmite

Hectorite/Gibbsite

Hectorite

sh

ea

r str

ess [

Pa

]

shear rate [s-1]

Hectorite/Boehmite

Hectorite/Gibbsite

Hectorite

vis

co

sity

[Pa

s]

shear stress [Pa]

Chectorite = 2.5 wt% = 1.7C*

126

Post-creep viscosities –

added silica spheres and the effect of charge

0.1

1

10

100

1000

104

105

106

107

0 20 40 60 80 100

H + CL

H + AS40

Vis

co

sit

y [

Pa

s]

Stress [Pa]

Ludox CL cationic

Ludox AS40 anionic

D = 12 nm for both

Chectorite = 2.8 wt% = 1.9C*

Pure Hectorite ‘ty’ = 8 Pa

127

Early-time creep behaviour near ‘ty’

0

10

20

30

40

50

0 10 20 30 40 50

70 Pa75 Pa80 Pa

Cre

ep

Co

mp

lian

ce [

1/P

a]

Creep Time [s]

Hectorite (-ve)-Ludox CL (+ve)

128

130

Comparative anionic mixtures

10

100

10-5

0.0001 0.001 0.01 0.1 1 10 100 1000

Hectorite

Hectorite + AS40

Hectorite + Laponite

Shear

Str

ess / P

a

Shear Rate / s-1

1

10

100

1000

0.001 0.01 0.1 1 10

G' HectoriteG' Hectorite + AS40G' Hectorite + Laponite

Mo

du

lus /

Pa

Strain

Again enhancement of rheology laths + plates < spheres

Enhancement by adding minor colloid 1:10 to 2.5 wt% Hectorite

Property

Colloids

Hectorite Hectorite-

Boehmite

Hectorite-

Gibbsite

Hectorite-

Ludox CL

G” 1 2 5 30

ty 1 1 2 6

G’y 1 1 2 20

G’ (1Hz) 1 1.4 4 20

Ge (peak) 1 1 - 1500

h(t0) (Creep) 1 0.5 - 14

ty (Creep) 1 >1.2 - 8

h(t0) (Steady Shear) 1 3 10 20

ty (Steady Shear) 1 1.5 4.5 6

Yield Strain (Oscillatory) 1 0.6 0.3 0.25

Yield Strain (Cont Shear) 1 0.5 0.2 0.06

Relative particle concentration, np 2 1 280

Packing ratio per hectorite lath 0.8 4.5 200 131

Mixed Colloid Conclusions

• Complexity of hectorite and hectorite-aluminasol gel

rheology

• Elastoviscous solid weakly elastic, shear-thinning liquid

• ‘Yield Space’ rather than single Yield Stress

• Rheological behaviour and parameters by different

techniques consistent if uniform sample pre-

treatment used

• Major enhancements of rheology for small additions

of second component (~0.1cinitial w/w)

132

Mixed Colloid Conclusions

• Enhancements depend on second colloid shape, size, charge

and number concentration

• G’, h (t0) and ‘tyeff’ all increase rods < platelets < spheres,

• Enhancements for nanospheres being typically x20 and up to x500

• Critical parameter is gy, determined by size of minor component

• For a given shape, size and charge have a significant effect

• Most dramatic effects are with silica, a relativel cheap and

widely available material

• So cost-effective rheology enhancement and tuning of gelation

characteristics looks feasible

• Qualitative physicochemical models can rationalise the

observed behaviour – heteroflocculation

– depletion or dispersion effects

• More microstructural flow studies and quantitative models are

needed 133

Bulk Properties

Simulation


Parameters

Simulation

Theory


Molecular

Mesoscopic • Understand mechanisms

• Design new/improved fluids and

soft materials

Product

Experiment

Lengthscale

decreasing

Including High-Throughput

and Combinatorial Methods

Coarse

Graining

Transforming Soft Materials Formulation

135

Thank you all for your attention,

thanks to all my collaborators, in

Schlumberger, other companies,

many universities...

and many thanks to the SCI and

RSC Joint Colloid Groups for the

2012 Rideal Lecture Award.

Documents

Oilfield Fluids: Tales of Mud and Worms