elucidation of physio-chemical charachterization of ultrasonic

ELUCIDATION OF PHYSIO-CHEMICAL

CHARACHTERIZATION OF ULTRASONIC

CHEMICALLY DEMULSIFIED CRUDE OIL

WAFAA KAMIL MAHMOOD

Thesis submitted in fulfillment of the requirements

for the award of the degree of

Doctor of Philosophy (Chemical Engineering)

Faculty of Chemical and Natural Resources Engineering

UNIVERSITI MALAYSIA PAHANG

May 2014

vi

ABSTRACT

Formation of emulsions during oil production and processing is a costly problem, both

in terms of chemicals used and production losses. It is necessary to separate the water

completely from the crude oils before transporting to refinery. Traditional ways of

breaking emulsions using heat and chemicals are disadvantageous from both economic

and environmental perspectives. In this thesis, an alternative and multiple frequency

energy potential of ultrasonic-assisted chemicals (environmental friendly) in

demulsification of water-in-crude oil emulsions were utilized and investigated. Two

types of crude oils were used namely; (Tapis and Miri crude oils). The study begun with

some characterization studies to provide understanding of fundamental issues such as

formation, formulation and breaking of emulsions by both chemicals and ultrasonic

approaches. The aim was to obtain optimized operating conditions as well as

fundamental understanding of water-in-oil stability, upon which further development of

the demulsification process could be developed. The stability studies were carried out

by analyzing operating conditions such as surfactant concentration, surfactant type, oil

type, temperature and water-oil ratio (30-50%). For stability performance test, four

emulsifiers were used namely; Triton X-100, Span 83, Cocamide DEA and SDDS. It

was found that there exist a correlation between these factors and emulsion stability.

Among these, emulsion stabilized by cocamide DEA was the best and followed by Span

83, SDDS and Triton X-100 respectively. For chemical emulsification performance test,

five types of demulsifies with different functional groups were utilized; these are

Hexylamine, Dioctylamine, Cocamine, Polyethylene Glycol, PEG 1000 and PEG 600.

Among these; Hexylamine was found to be the best in separating water and oil from

emulsions (88%) and followed by cocamine (81%), Dioctylamine (79%), PEG 1000

(76%) and PEG 600 (70%). For ultrasonic forces (3, 5, 7 and 9) applied for emulsion

breaking, results were significantly enhanced the separation time and amount of water

separated. Results showed that, ultrasonic power, 9 and Hexylamine (1.0%) in

demulsifying the crude oil A stabilized by Span 83 with maximum water separation of

96% after 150 min. Also, and within the same operating conditions mentioned above, a

maximum water separation up to 99% was achieved with crude oil B. The other

investigated demulsifiers with ultrasonic force showed also high water separation

percentages such as cocamine (1.0%) emulsifier with 91% and 93% for crude oils A and

B emulsions respectively. The results obtained in this thesis have exposed the capability

of ultrasonic-assisted chemicals technology in demulsification of W/O emulsions.

Further works are nevertheless required to provide deeper understanding of the

mechanisms involved to facilitate the development of an optimum system applicable to

the industry.

vii

ABSTRAK

Pembentukan emulsi semasa pengeluaran dan pemprosesan minyak adalah isu yang

kritikal dari segi penggunaan bahan kimia dan masalah kerugian pengeluaran. Langkah

pemisahan air yang menyeluruh daripada minyak mentah adalah penting sebelum

dibawa ke kilang penapisan. Cara-cara tradisional untuk pengasingan emulsi

menggunakan haba dan bahan kimia tidak effisyen dari segi ekonomi dan alam sekitar.

Tesis ini mengandungi alternatif dan pelbagai frekuensi tenaga potensi daripada bantuan

bahan kimia ultrasonik (mesra alam sekitar) dalam proses pengasingan emulsi air

daripada minyak mentah yang telah dikaji dan diaplikasikan. Dua jenis minyak mentah

iaitu minyak mentah dari Tapis dan Miri telah digunakan. Kajian ini telah dimulakan

dengan penyelidikan ciri-ciri supaya isu-isu asas seperti pembentukan, fomulasi dan

pengasingan emulsi dapat difahami menggunakan kaedah bahan kimia dan ultrasonik.

Objektif kajian ini adalah untuk memperolehi kondisi optimum serta perfahaman yang

mendalam tentang kestabilan air dalam minyak agar kaijan proses pemisahan dapat

diperkembangkan lanjut. Penyelidikan stabiliti dijalankan dengan menganalisa keadaan

operasi seperti kepekatan surfaktan, jenis surfaktan, jenis minyak, suhu dan nisbah air-

minyak (30-50%). Pengemulsi seperti Triton X-100, Span 83, Cocamide DEA dan

SDDS telah digunakan bagi mengaji prestasi kestabilan. Kajian telah menunjukkan

hubung kait antara faktor-faktor ini dengan kestabilan emulsi. Cocamide DEA adalah

yang terbaik di antara emulsi-emulsi yang lain diikuti dengan Span 83, SDDS dan

Triton X-100. Terdapat 5 jenis pengasing emulsi yang digunakan untuk kajian

pengemulsian bahan kimia. Antaranya adalah Hexylamine, Dioctylamine, Cocamine,

Polyethylene Glycol, PEG 1000 dan PEG 600. Kajian ini juga megesahkan bahawa

Hexylamine adalah bahan kimia terbaik untuk mengasingkan air daripada minyak

(88%), diikuti dengan cocamine (81%), Dioctylamine (79%), PEG 1000 (76%) dan

PEG 600 (70%). Keputusan signifikan telah dipertingkatkan dari segi jarak masa dan

kuantiti air yang diasingkan dengan menggunakan tenaga ultrasonic (3, 5, 7 dan 9).

Selepas 150 min , penceraian maksimum sebanyak 96% telah dicapai dengan aplikasi

tenaga ultrasonik 9 dan Hexylamine (1.0%) di dalam proses pengasingan minyak

mentah A yang distabilkan oleh Span 83, manakala bagi minyak mentah B adalah

sebanyak 99%. Kajian juga menunjukkan peratusan tinggi pengasingan air seperti

cocamine (1.0%) dengan 91% dan 93% menggunakkan tenaga ultrasonik untuk emulsi

minyak mentah A dan B. Keputusan yang diperoleh daripada kajian ini telah membantu

untuk mendedahkan keupayaan teknologi bantuan kimia ultrasonik dalam pengasingan

air/minyak emulsi, lantaran memberi kefahaman yang mendalam atas mekanisme yang

terlibat untuk membantu dalam perkembangan optimum sistem dalam industri.

viii

TABLE OF CONTENTS

Page

SUPERVISOR’S DECLARATION ii

STUDENT’S DECLARATION iii

DEDICATION iv

ACKNOWLEDGEMENTS v

ABSTRACT vi

ABSTRAK vii

TABLE OF CONTENTS viii

LIST OF TABLES xii

LIST OF FIGURES xii

LIST OF SYMBOLS xxii

LIST OF ABBREVIATIONS xxiii

CHAPTER 1 INTRODUCTION

1.1 Background 1

1.2 Problem Statement 3

1.3 Objectives of Research 5

1.4 Scopes of Research 5

1.5 Study Contributions 6

1.6 Overview of the Thesis 7

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction 8

2.2 Emulsions 8

2.3 Emulsions Formation Techniques 9

2.4 Factors Influencing the Emulsion Formation, Stability and

Type

12

2.4.1 Emulsifying agents (Surfactants) 12

ix

2.4.2 Crude Oil Properties 17

2.5 Emulsification and Emulsion Stability 20

2.6 Demulsification 28

2.6.1 Chemical Demulsification 30

2.6.2 Thermal Demulsification 35

2.6.3 Microwave Demulsification 39

2.6.4 Membrane Demulsification 43

2.6.5 Ultrasonic Demulsification 46

CHAPTER 3 MATERIALS AND METHOD

3.1 Introduction 54

3.2 Materials

3.2.1 Emulsifiers 54

3.2.1.1 Cocamide DEA (Diethanolamide) 54

3.2.1.2 Span 83 (Sorbitan Sesquiester) 55

3.2.1.3 Triton X-100 55

3.2.1.4 Sodium Dodecyl Sulfate (SDDS) 56

3.2.2 Demulsifiers

3.2.2.1 Cocamine 58

3.2.2.2 Hexylamine 59

3.2.2.3 Dioctylamine 59

3.2.2.4 Polyethylene Glycol (600 and 1000) 60

3.2.3 Crude oils 60

3.3 Emulsion formation (Procedures and Equipment) 61

3.3.1 Rheology Test 61

3.3.2 Stability Test 62

3.4 Demulsification of crude oil emulsions 64

http://en.wikipedia.org/wiki/Diethanolamide

x

CHAPTER 4 CRUDE OIL EMULSIONS FORMATION AND STABILITY

4.1 Introduction 67

4.2 Rheological Behaviour of the Prepared Emulsions 67

4.2.1 Shear Stress versus Shear Rate (Effect of

Additive Concentration)

68

4.2.2 Shear Stress versus Shear Rate (Effect of

Temperature)

73

4.2.3 Emulsion Viscosity 80

4.2.3.1 Effect of Temperature 80

4.2.3.2 Effect of Rotation Speed (Shear rate) 86

4.2.3.3 Effect of Water Cut 90

4.2.3.4 Effect of Emulsifier Type 98

4.2.4 Effect of Oil Type on Emulsion Rheology 104

4.2.5 Emulsion droplets size effect 109

4.3 Emulsion Stability 114

4.3.1 Effect of emulsifier concentration on the

emulsion stability

115

4.3.2 Effect of emulsifier type on emulsion

stability

119

4.3.3 Effect of water content on the emulsion

stability

128

4.3.4 Effect of oil type on the emulsion stability 132

CHAPTER 5 CRUDE OIL EMULSION DEMULSIFICATION

5.1 Introduction 136

5.2 Chemically Assisted Demulsification 136

5.2.1 Effect of Demulsifier Concentration 136

5.2.2 Effect of Demulsifier Type 152

5.3 Ultrasonic-Chemically Assisted Demulsification 162

xi

5.3.1 Effect of Irradiation Power 163

5.3.2 Effect of Demulsifier type (with Ultrasonic

Irradiation)

175

5.3.3 Effect of Demulsifier Concentration (with

Ultrasonic Irradiation)

178

5.4 Correlation Equation 182

CHAPTER 6 CONCLUSIONS AND RECOMMENDATIONS

6.1 Conclusions 199

6.2 Recommendation of Future Work 201

REFERENCES 202

APPENDICES

A Apperent physical properties and water separation of

emulsions investigated

215

B Chemically-Assisted Demulsification Data 251

C Ultrasonic-Chemically-Assisted Demulsification Data 253

D Statistica Software example 263

E Accomplishments and publications 268

xii

LIST OF TABLES

Table No. Title Page

2.1 Classification of emulsion types 22

3.1 Properties of Cocamide 55

3.2 Properties of Span 38 55

3.3 Properties of Triton x-100 56

3.4 Properties of SDDS 57

3.5 Properties of Cocamine 58

3.6 Properties of Hexylamine. 59

3.7 Properties of Dioctylamine 59

3.8 Properties of Polyethylene Glycol (600 and 1000) 60

4.1 Crude oil blends characteristics 105

5.1 Separation percentage and time performance for demolsifiers

investigated

139

5.2 Water separation percentage and time enhancement for

chemically-assisted and ultrasonic-chemically assisted

demulsification

168

5.3 Correlation parameters for emulsification system at 28 oC 183

5.4 Correllation parameters for demulsification system at 28 oC 184

LIST OF FIGURES

Figure No. Title Page

2.1 Schematic diagram of membrane emulsification process. 11

2.2 Alkyl dimethyl benzyl ammonium chloride surfactant 15

2.3 Dodecyl methyl poly(ethylene oxide) ammonium chloride

surfactant

15

2.4 Alkoxylated alkyl phenol formaldehyde condensates 16

2.5 Structure of hypothetical asphatene molecule 19

2.6 Schematic drawing of the electric field cell 23

2.7 The relation HLB and even diameter to the emulsion of different

Brine/Kelamay atmospheric residue

26

2.8 TEM images of prepared samples. The effect of HLB of the 27

xiii

surfactant on the morphology of the samples was shown

2.9 Schematic representation of the various breakdown processes in

emulsions

29

2.10 The effect of dosage on demulsification of PAE82 at 45 °C 33

2.11 Demulsifying ability of the cells and demulsifying substances 35

2.12 Demulsification mechanism in freeze/thaw process of oily

sludge (1, oil; 2, water; 3, surfactant)

36

2.13 Micrographs of freeze/thaw process of #1-1 emulsion. (a) Before

freezing; (b) freezing; (c) after melted. The images represent a

time/temperature sequence for a single field of view

37

2.14 Micrograph of an O/W emulsion (using Mexican HCO) diluted

in water

39

2.15 Micrograph showing the effect of microwave dielectric heating

at 50 W (left) and oil bath heating (right) 10 min after creation of

the O/W emulsion

39

2.16 Separation of 50-50% water-oil emulsion using different

methods

41

2.17 Schematic diagram of demulsification by porous glass

membrane: (a) droplets in emulsion are adsorbed on the surface

of the porous glass membrane, (b) droplets entering into smaller

pore must deform (droplets are amplified), and (c) droplets in the

pore are broken and adsorbed on the pore wall (droplets are

amplified)

44

2.18 Schematic diagram of demulsification by hydrophilic

nitrocellulose membrane

45

2.19 Schematic of rotating disk modulus 46

2.20 proposed mechanism for demulsification of crude oil emulsion

with ultrasonic irradiation

50

2.21 Photo of water/oil emulsion after ultrasonic standing-wave

irradiation

50

2.22 Effects of ultrasound on oil content after oily sludge deoiling

(ultrasound frequency 28 kHz; sludge water ratio 1:16; acoustic

pressure amplitude 0.10 MPa; ultrasonic irradiation time 20 min;

air liquid volume ratio 0.27)

51

2.23 Effects of ultrasonic frequency on oil content after oily sludge

deoiling (ultrasound frequency 28 kHz; sludge water ratio 1:16;

temperature 40 °C; ultrasonic irradiation time 20 min; air liquid

volume ratio 0.27)

52

3.1 Chemical structure of Cocamide DEA 55

3.2 Chemical structure of Span 83 56

3.3 Triton X-100 structure 57

3.4 Chemical structure of SDDS surfactant 57

3.5 Molecular structure of Cocamine. 58

3.6 Chemical structure of Hexylamine 59

3.7 Chemical structure of Dioctylamine 60

3.8 Chemical structure of PEG-600 and PEG-1000 60

3.9 Flow diagram of the emulsification Process 63

3.10 Brookfield Rotational Digital Viscometer Model LV/DV- II 64

xiv

3.11 Powersonic® - tabletop ultrasonic generator (Type D) 65

3.12 Powersonic® - tabletop ultrasonic generator (Type D) setting

screen (from equipment manual).

65

3.13 Flow diagram of the Demulsification Process. 66

4.1 Shear stress versus shear rate in 50%-50% W/O emulsion in

(50%-50% oil blend with Span83 Emulsifier

70


(50%-50% oil blend with DEA Emulsifier

70


(50%-50% oil blend with SDDS Emulsifier

71


(50%-50% oil blend with Triton-X100 Emulsifier

71


(70%-30% oil blend with SDDS Emulsifier

72


(70%-30% oil blend with Triton-X100 Emulsifier

72


(70%-30% oil blend with DEA Emulsifier

73


(50%-50% oil blend with 0.5 vol. % DEA Emulsifier

74



75



75



76


(50%-50% oil blend with 1.0 vol. % SDDS Emulsifier

76


(70%-30% oil blend with 0.5 vol. % Span 83 Emulsifier

77



77



78



78


(70%-30% oil blend with 1.5 vol. % Span 83 Emulsifier

79


(70%-30% oil blend with 1.5 vol. % Triton-X100 Emulsifier

79

4.19 Shear rate versus viscosity in 40%-60% W/O emulsion in (50%-

50% oil blend with 0.5 vol. % SDDS Emulsifier

81


50% oil blend with 1.5 vol. % SDDS Emulsifier

82


50% oil blend with 1.5 vol. % Triton-X100 Emulsifier

82


50% oil blend with 1.5 vol. % DEA Emulsifier

83

xv


50% oil blend with 0.5 vol. % Span 83 Emulsifier

83


50% oil blend with 0.5 vol. % Span 83 Emulsifier at different

temperatures

84


50% oil blend with 0.5 vol. % Span 83 Emulsifier at different

temperatures

84


50% oil blend with 1.5 vol. % DEA Emulsifier at different

temperatures

85


50% oil blend with 1.5 vol. % SDDS Emulsifier at different

temperatures

85

4.28 Temperature versus viscosity in 50%-50% W/O emulsion in


86



87



87



88


(50%-50% oil blend with 1.5 vol. % Span 83Emulsifier

88


(30%-70% oil blend with 1.5 vol. % Span 83Emulsifier

89



89



90

4.36 Effect of water content on emulsion viscosity in (30%-70% oil

blend) at T = 50 oC and RPM = 100

92



92



93



93



94



94

4.42 Shear rate versus shear stress for different water cuts at T=28 oC

and Span83 surfactant in (50%-50%) oil blend

95


and SDDS surfactant in (50%-50%) oil blend

96


and Span 83 surfactant in (30%-70%) oil blend

96

4.45 Shear rate versus shear stress for different water cuts at T=28 oC 97

xvi

and SDDS surfactant in (30%-70%) oil blend


and Triton X-100 surfactant in (30%-70%) oil blend.

97

4.47 Effect of emulsifier type on emulsion (50%-50% W/O) viscosity

in (50%-50% oil blend) at T = 28 oC

101



102



102



103



103



104

4.53 Shear rate versus Shear stress of Crude oil A and B with 1.5

vol.% Span 83 emulsifier in 30 vol.% water cut emulsion at T

=28 oC

107


vol.% Triton X-100 emulsifier in 50 vol.% water cut emulsion at

T =28 oC

107


vol.% SDDS emulsifier in 40 vol.% water cut emulsion at T =28

oC

108


vol.% DEA emulsifier in 50 vol.% water cut emulsion at T =28

oC

108

4.57 Effect of additive concentration on droplet size and distribution

for emulsion formulated with crude oil A and 30 vol.% water cut

111


for emulsion formulated with crude oil B and 40 vol.% water cut

111


for emulsion formulated with crude oil A and 50 vol.% water cut

111

4.60 Effect of temperature on the droplet size and emulsion viscosity

for Emulsions prepared with 1.5 vol.% SDDS in crude oil A and

50 vol.% water

112


for Emulsions prepared with 1.5 vol. % DEA in crude oil A and

50 vol. % water

112


for Emulsions prepared with 1.5 vol. % Triton X-100 in crude

oil B and 50 vol. % water

113


for Emulsions prepared with 1.5 vol. % Span 83 in crude oil B

and 50 vol. % water

113

4.64 Effect of DEA concentration on the emulsion stability (water

separation) for (50 vol. %- 50 Vol. %) (water / crude oil B)

emulsion

116

xvii

4.65 Effect of SDDS concentration on the emulsion stability (water


emulsion

116

4.66 Effect of Triton X-100 concentration on the emulsion stability

(water separation) for (50 vol. %- 50 Vol. %) (Water / crude oil

B) emulsion

117

4.67 Effect of Span 83 concentration on the emulsion stability (water

separation) for (50 vol. %- 50 Vol. %) (water / crude oil A)

emulsion

117

4.68 Effect of DEA concentration on the emulsion stability (water


emulsion

118

4.69 Effect of SDDS concentration on the emulsion stability (water

separation) for (30 vol. %- 70 Vol. %) (Water / Crude oil A)

emulsion.

118

4.70 Emulsion separation performance with SDDS surfactant in crude

oil B

124

4.71 Effect of additives type on the emulsion stability (water


emulsion

125



emulsion

125



emulsion

126



emulsion

126



emulsion

127



emulsion

127

4.77 Effect of water content on the emulsion stability (water

separation) for DEA emulsifier in emulsion formulated from

crude oil B

129


separation) for SDDS emulsifier in emulsion formulated from

crude oil B

130



crude oil B

130



crude oil A

131


separation) for Triton X-100 emulsifier in emulsion formulated

131

xviii

from crude oil A


separation) for SDDS emulsifier in emulsion formulated from

crude oil A.

132

4.83 Effect of oil type on the emulsion stability (water separation) for

(50 vol. %- 50 Vol. %) (water / crude oil ) emulsion with 0.5%

DEA

134



SDDS

134



DEA

135



Triton X-100

135

5.1 Effect of Heylamine concentration on the water separation

percentage for crude oil A emulsions stabilized with 1.5 vol.%

Cocamide DEA.

142

5.2 Effect of Cocamine concentration on the water separation


Cocamide DEA.

142

5.3 Effect of Dioctylamine concentration on the water separation


Cocamide DEA.

143

5.4 Effect of PEG 1000 concentration on the water separation


Cocamide DEA

143



Cocamide DEA.

144



Span 83.

144

5.7 Effect of PEG-1000 concentration on the water separation


Span 83.

145

5.8 Effect of Hexylamine concentration on the water separation


Span 83.

145



Span 83.

146



Span 83.

146

5.11 Effect of Heylamine concentration on the water separation

percentage for crude oil B emulsions stabilized with 1.5 vol.%

147

xix

Cocamide DEA.



Cocamide DEA.

147



Cocamide DEA.

148



Cocamide DEA.

148



Cocamide DEA.

149



Span 83.

149



Span 83.

150

5.18 Effect of Hexylamine concentration on the water separation


Span 83.

150



Span 83.

151



Span 83.

151

5.21 Comparing the effects of the Demulsifiers investigated (0.5

vol.%) with emulsion formed from crude oil A and DEA.

156



157



157


vol.%) with emulsion formed from crude oil A and Span 83.

158


vol.%) with emulsion formed from crude oil A and Span 83.

158

5.26 comparing the effects of the Demulsifiers investigated (1.0

vol.%) with emulsion formed from crude oil A and Span 83

159


vol.%) with emulsion formed from crude oil B and DEA.

159

5.28 comparing the effects of the Demulsifiers investigated (0.5

vol.%) with emulsion formed from crude oil B and DEA

160


vol.%) with emulsion formed from crude oil B and DEA.

160


vol.%) with emulsion formed from crude oil B and Span 83.

161

xx



161



162

5.33 Effect of ultrasonic forces on the water separation performance

for Crude oil A emulsion with DEA emulsifier and Hexylamine

as demulsifier.

170


for Crude oil A emulsion with DEA emulsifier and Cocamine as

demulsifier.

170


for Crude oil A emulsion with DEA emulsifier and PEG-600 as

demulsifier

171


for Crude oil A emulsion with Span 83 emulsifier and

Hexylamine as demulsifier

171


for Crude oil A emulsion with Span 83 emulsifier and Cocamine

as demulsifier.

172


for Crude oil A emulsion with Span 83 emulsifier and

Dioctylamine as demulsifier.

172


for Crude oil B emulsion with DEA emulsifier and Hexylamine

as demulsifier.

173


for Crude oil B emulsion with DEA emulsifier and Cocamine as

demulsifier.

173


for Crude oil B emulsion with DEA emulsifier and Dioctylamine

as demulsifier

174


for Crude oil B emulsion with Span 83 emulsifier and PEG1000

as demulsifier.

174


for Crude oil B emulsion with Span 83 emulsifier and PEG-600

as demulsifier.

175


for Crude oil A emulsion with DEA emulsifier and different

types of demulsifiers at 0.5 vol.%.

176


for Crude oil A emulsion with Span 83 emulsifier and different


176


for Crude oil B emulsion with DEA emulsifier and different


177


for Crude oil B emulsion with Span 83 emulsifier and different


177

xxi

5.48 Effect of Cocamine demulsifier concentration on the water

separation of crude oil B-Span 83 emulsion with ultrasonic

power 3

178

5.49 Effect of PEG-1000 demulsifier concentration on the water

separation of crude oil B-Span 83 emulsion with ultrasonic

power 9

179

5.50 Effect of Hexylamine demulsifier concentration on the water

separation of crude oil A-DEA emulsion with ultrasonic power 3

179


separation of crude oil A-DEA emulsion with ultrasonic power 7

180

5.52 Effect of Dioctylamine demulsifier concentration on the water

separation of crude oil A-Span 83 emulsion with ultrasonic

power 7

180

5.53 Effect of Cocamine demulsifier concentration on the water

separation of crude oil A-Span 83 emulsion with ultrasonic

power 9

181


separation of crude oil B-DEA emulsion with ultrasonic power 5

181

5.55 Predicted versus observed values for Crude oil A emulsion

stabilized with Triton X-100 at 28 oC.

185


stabilized with SDDS at 28 oC.

185


stabilized with Span 83 at 28 oC.

186


stabilized with Cocamide DEA at 28 oC.

186

5.59 Predicted versus observed values for Crude oil B emulsion

stabilized with Triton X-100 at 28 oC.

187


stabilized with SDDS at 28 oC.

187


stabilized with Cocaminde DEA at 28 oC.

188


(stabilized with 1.5 vol.% Span 83) demulsified using

Hexylamine and ultrasonic power.

189


(stabilized with 1.5 vol.% Span 83) demulsified using Cocamine

and ultrasonic power.

190


(stabilized with 1.5 vol.% Span 83) demulsified using

Dioctylamine and ultrasonic power.

191

5.65 predicted versus observed values for Crude oil A emulsion

(stabilized with 1.5 vol.% Span 83) demulsified using PEG-1000

and ultrasonic power

192

5.66 predicted versus observed values for Crude oil A emulsion

(stabilized with 1.5 vol.% Span 83) demulsified using PEG-600


193

5.67 predicted versus observed values for Crude oil B emulsion

(stabilized with 1.5 vol.% DEA) demulsified using Hexylamine

194

xxii



(stabilized with 1.5 vol.% DEA) demulsified using Cocamine


195


(stabilized with 1.5 vol.% DEA) demulsified using Dioctylamine


196


(stabilized with 1.5 vol.% DEA) demulsified using PEG-1000


197


(stabilized with 1.5 vol.% DEA) demulsified using PEG-600 and

ultrasonic power

198

LIST OF SYMBOLS

M Meter

µr Emulsion relative viscosity

µe Emulsion viscosity

µo Continouse phase viscosity

Ø Disperesed phase volume fraction

K2 Disperesed phase concentration

K Ratio of dispersed to continouse phases

%Ws Percentage water separation

Vws Volume of watewr separated

Vi Initial water volume in emulsion

TE% Percentage of time enhancement

Tb Separation time for lower demulsifier concentration

Ta Separation time for higher demulsifier concentration

Wsb Maximum water separation at lower concentration

Wsa Maximum water separation at higher concentration

h Hours

LIST OF ABBREVIATIONS

W/O Water in oil emulsion

O/O Oil in oil emulsion

O/W Oil in water emulsion

ME Membrane emulsification

TAN Total acid number

IFT Interfacial tension

R/A Resine to asphaltenes ratio

HLB Hydrophil-Lipophil balance

CMC Critical micceler concentration

PPO Polypropylene –block-Polypropylene oxide

xxiii

PEO Polypropylene –block-Polyethylene oxide

SDS Sodium Dodecylesufate

DSC Differential Scanner Calorimeter

RSM Response surface Methodology

LSWR Low sulfer wax residue

DTAB Dodecyltrimethylammonium bromide

SPG Shirasa-porouse-glass

TOC Total organic carbon concentration

OI Operational index

TMP Trous membrane pressure

PVDF Hydrophilic polyvinyldene difluoride

PES Polyether sulfate

MWCO Molecular weight cut off

CHAPTER 1

INTRODUCTION

1.1 BACKGROUND

The emulsion can be defined as the dispersion (suspension) of one liquid into

another immiscible liquid in the form of droplets with the aid of surface active agents.

Crude oil is rarely produced alone in commercial oil wells because most of the time it is

combined with water in an emulsion form. Emulsions can be formed during almost all

stages of crude oil production, starting with the deep oil wells, wellbores, and

wellheads; at wet-crude handling facilities, during transportation through pipelines, and

petroleum processing. The separation of the water from the crude oil emulsions is an

initial step in any crude oil production and processing facility to control the quality of

the final product. A good understanding of petroleum emulsions is necessary in order to

control and enhance processes at all these stages.

Crude oil emulsions can be classified into three main categories, namely:

1- Week emulsions: where the water is separated within a few minutes of

production.

2- Medium emulsions: where the water requires more time than the week

emulsions to separate.

3- Tight emulsions: where the water is not separated completely even after a

few days.

Generally speaking, emulsions are kinetically stable (stable over a period of

time) because there is a natural driving force for the suspended droplets forming the

emulsion to colloid and separate in a single phase. The behaviour of emulsions is

mainly controlled by the properties of the adsorbed layers which stabilise the oil-water

surfaces. The complexity of petroleum emulsions stems from the oil composition in

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terms of surface-active molecules (surfactants) contained in the crude, such as low

molecular weight fatty acids, naphthenic acids and asphaltenes. These surfactants

suppress the mechanisms involved in sedimentation, aggregation, coalescence, and

phase inversion that would otherwise break down an emulsion.

The emulsion’s stability is controlled by a large number of factors such as the

solid’s content (asphaltenes, waxes, clays, etc.), operation temperature, droplet size and

distribution and the ph of the water. The surfactant type (anionic, cationic, amphoteric

or non-ionic) also plays a major role in the emulsion formation process and will

significantly control the stability of the emulsion and the tendency of the water layer to

separate. All of these factors must be taken under consideration in order to achieve an

efficient and effective water separation process (Demulsification).

Demulsification (emulsion breaking) is needed in many practical applications

such as the petroleum industry, environment technology, and waste-water treatment.

Demulsification is the process whereby water is separated from crude oil. Depending

on the crude oil emulsion type, a suitable demulsification process is needed so as to

ensure a highly efficient as well as low cost emulsion breaking process.

Currently, water-crude oil emulsions are typically destabilised through the use of

chemical demulsifiers. The chemical structure of these demulsifiers is usually based on

alkylphenol formaldehyde ethoxylated resins. These chemical demulsifiers are effective,

but, unfortunately, are now believed to be endocrine disrupters, and thus it is likely that

they may be banned by various national environmental protection agencies (Zaki, et al.,

1996, 1997, 1998).

Other means of destabilising asphaltene-stabilised W/O emulsions include

thermal pressurisation and rapid depressurisation (Ohsol et al., 1999), electrostatic

droplet shattering and coalescence. Both of these methods are established around efforts

at “cracking” or “disrupting” the rigid, viscoelastic film of asphaltenes which forms

around the water droplets. One problem with these methods is the reformation of

stabilised water droplets due to readsorption of displaced or “disrupted” asphaltenic film

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fragments in shear fields under solvent conditions at which the asphaltenes are capable

of reassembly (Hart, 1997; Mitchell, 1998).

The present work will present and evaluate a new demulsification technique

using ultrasonic force. Four different types of emulsifiers will be used in the formation

of crude oil emulsions, namely Triton-X, Span 83, SDDS and Cocoamide. The

Cocoamide is applied for the first time as an emulsifier in the crude oil emulsions. The

most stable emulsions will be selected and tested for the demulsification processes. Two

methods of demulsification process will be adopted, namely the chemically-assisted

demulsification process and the Ultrasonic-chemically-assisted demulsification process.

The chemically-assisted demulsification process will be adopted with different types of

demulsifiers, including Hexylamin, Octylamine, Polyethylene Glycole (600 and 1000),

and Cocamine. Cocamine is used for the first time as an alternative environmental

friendly demulsification agent. The Ultrasonic-chemically-assisted demulsification

process will be applied to the same emulsion and a comparison of the water separation

performances will be conducted.

1.2 PROBLEM STATEMENT

Most of the crude oils produced from the oil wells are in the form of emulsions.

Generally speaking, crude oil emulsions do exist in the form of oil-in-water (O/W) or

water-in-oil (W/O) formation whilst on other occasions it will be in a more complex

form such as water-in-oil-in-water (W/O/W) or oil-in-water-in-oil (O/W/O). Indeed, this

depends on the operation factors, including type of emulsifier and the mixing intensity.

Oilfield crude oil usually contains natural emulsifiers which stabilise the

emulsion and include surface active agents (surfactants) and fine solids. The value of

any crude oil is highly dependent on the type and the tightness of the emulsion formed,

which in turn depends on the type of natural emulsifier involved. This is why the price

of crude oil varies from country to country. Indeed, the natural emulsifiers usually exist

in the heavy fraction of the crude oil. The emulsification intensity of the natural

emulsifiers is significantly controlled by the type of crude oil, i.e. different crude oils

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will have different amounts of heavy components. At a glance, crude oil emulsions with

low amounts of natural emulsifier will result in a weak emulsion which can be separated

easily whilst other crudes which contain the right type and amount of emulsifier, will

result in a very stable emulsion. Artificial emulsifiers are more often used to maintain

the emulsion structure and stability during the production of crude oil from the oil wells

as well as during the transportation of these crude oils through pipelines. Crude oil

emulsions form when oil and water (brine) come into contact with each other, when

there is sufficient mixing, and when an emulsifying agent or emulsifier is present.

Different types of artificial emulsifying agent exist (mostly anionic and non-ionic

surfactants) and are applied commercially in different oil fields depending on the type

of crude oil produced. Most of these surfactants are not environmental friendly and their

emulsification efficiency can be controlled by operation conditions including pressure,

temperature and mixing intensity. Indeed, a more environmental friendly additive is

needed. In the present work, natural and environmental friendly emulsifying agents are

introduced for the first time in the form of Cocoamide emulsifiers.

One of the key factors controlling crude oil value in the market is the speed and

efficiency of water separation in the refining facility. This water separation process is

called “Demulsification”. Traditionally, the separation of water from crude oil emulsion

is achieved using any, or a combination, of different methods such as the addition of

chemical demulsifiers, increasing the temperature of the emulsion, applying

electrostatic fields which promote coalescence or lowering the crude oil speed to allow

for gravitational separation. Choosing one or more separation processes depends on the

type and tightness of the emulsion. Beside the advantages of these methods, several

disadvantages also emerge, including the high cost of the chemical demulsifiers

involved and the long period of time needed to complete the separation. In addition,

most of the demulsifiers used are artificial, chemical, and not environmental friendly.

This is why an environmental friendly demulsification agent together with a more

efficient and less time consuming demulsification technique are needed. In the present

work, ultrasonic force will be utilised to enhance the chemically-assisted

demulsification process. A comparison between the water separation performances will

be conducted with and without the use of the ultrasonic force to determine its effect in

terms of enhancing the water separation and demulsification time.

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1.3 OBJECTIVES OF RESEARCH

The objectives of this research are:

1. To evaluate the performance of ultrasonic-assisted chemicals as and alternative

and cost effective method for demulsification of crude oil emulsions.

2. To examine and evaluate the performance of a new environmental friendly

Cocamide DEA as stabilizer for crude oil emulsions.

3. To introduce Cocamine as a new and environmental friendly chemical for

separation of crude oil emulsions.

4. To optimize and analyze the overall potentials of ultrasonic-assisted chemicals

demulsification method as an alternative to the conventional chemical

demulsification method in demulsifying water-in-oil emulsions.

5. To evaluate the rheological characteristics and stability of W/O emulsions

formulated from two different crude oils.

SCOPES OF RESEARCH

1. Characterization of oil and aqueous phases:

Different emulsions are prepared using different operating and emulsification factors

such as:

a. Crude oil type; two types of crude oil are investigated (Tapis and Miri crude oils

blends) with two blending percentages (30%-70% and 50%-50%).

b. Water cut percentages; to form emulsions the water will be introduce to the

crude oil with three different percentages (30, 40 and 50 Vol.%).

c. Emulsifier type; four types of emulsifying agent will be investigated, namely

Triton-X100, SDDS, Span83 and Cocamide DEA.

elucidation of physio-chemical charachterization of ultrasonic

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