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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
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
4.2 Shear stress versus shear rate in 40%-60% W/O emulsion in
(50%-50% oil blend with DEA Emulsifier
70
4.3 Shear stress versus shear rate in 30%-70% W/O emulsion in
(50%-50% oil blend with SDDS Emulsifier
71
4.4 Shear stress versus shear rate in 40%-60% W/O emulsion in
(50%-50% oil blend with Triton-X100 Emulsifier
71
4.5 Shear stress versus shear rate in 50%-50% W/O emulsion in
(70%-30% oil blend with SDDS Emulsifier
72
4.6 Shear stress versus shear rate in 30%-70% W/O emulsion in
(70%-30% oil blend with Triton-X100 Emulsifier
72
4.7 Shear stress versus shear rate in 40%-60% W/O emulsion in
(70%-30% oil blend with DEA Emulsifier
73
4.8 Shear stress versus shear rate in 50%-50% W/O emulsion in
(50%-50% oil blend with 0.5 vol. % DEA Emulsifier
74
4.9 Shear stress versus shear rate in 50%-50% W/O emulsion in
(50%-50% oil blend with 1.0 vol. % DEA Emulsifier
75
4.10 Shear stress versus shear rate in 50%-50% W/O emulsion in
(50%-50% oil blend with 1.5 vol. % DEA Emulsifier
75
4.11 Shear stress versus shear rate in 40%-60% W/O emulsion in
(50%-50% oil blend with 0.5 vol. % DEA Emulsifier
76
4.12 Shear stress versus shear rate in 40%-60% W/O emulsion in
(50%-50% oil blend with 1.0 vol. % SDDS Emulsifier
76
4.13 Shear stress versus shear rate in 50%-50% W/O emulsion in
(70%-30% oil blend with 0.5 vol. % Span 83 Emulsifier
77
4.14 Shear stress versus shear rate in 30%-70% W/O emulsion in
(70%-30% oil blend with 0.5 vol. % SDDS Emulsifier
77
4.15 Shear stress versus shear rate in 30%-70% W/O emulsion in
(70%-30% oil blend with 1.5 vol. % SDDS Emulsifier
78
4.16 Shear stress versus shear rate in 40%-60% W/O emulsion in
(70%-30% oil blend with 0.5 vol. % DEA Emulsifier
78
4.17 Shear stress versus shear rate in 40%-60% W/O emulsion in
(70%-30% oil blend with 1.5 vol. % Span 83 Emulsifier
79
4.18 Shear stress versus shear rate in 30%-70% W/O emulsion in
(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
4.20 Shear rate versus viscosity in 40%-60% W/O emulsion in (50%-
50% oil blend with 1.5 vol. % SDDS Emulsifier
82
4.21 Shear rate versus viscosity in 40%-60% W/O emulsion in (50%-
50% oil blend with 1.5 vol. % Triton-X100 Emulsifier
82
4.22 Shear rate versus viscosity in 30%-70% W/O emulsion in (50%-
50% oil blend with 1.5 vol. % DEA Emulsifier
83
xv
4.23 Shear rate versus viscosity in 50%-50% W/O emulsion in (50%-
50% oil blend with 0.5 vol. % Span 83 Emulsifier
83
4.24 Shear rate versus viscosity in 50%-50% W/O emulsion in (50%-
50% oil blend with 0.5 vol. % Span 83 Emulsifier at different
temperatures
84
4.25 Shear rate versus viscosity in 40%-60% W/O emulsion in (50%-
50% oil blend with 0.5 vol. % Span 83 Emulsifier at different
temperatures
84
4.26 Shear rate versus viscosity in 40%-60% W/O emulsion in (50%-
50% oil blend with 1.5 vol. % DEA Emulsifier at different
temperatures
85
4.27 Shear rate versus viscosity in 50%-50% W/O emulsion in (50%-
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
(50%-50% oil blend with 0.5 vol. % Triton-X100 Emulsifier
86
4.29 Temperature versus viscosity in 50%-50% W/O emulsion in
(50%-50% oil blend with 1.0 vol. % SDDS Emulsifier
87
4.30 Temperature versus viscosity in 30%-70% W/O emulsion in
(50%-50% oil blend with 1.5 vol. % SDDS Emulsifier
87
4.31 Temperature versus viscosity in 30%-70% W/O emulsion in
(50%-50% oil blend with 1.0 vol. % DEA Emulsifier
88
4.32 Temperature versus viscosity in 50%-50% W/O emulsion in
(50%-50% oil blend with 1.5 vol. % Span 83Emulsifier
88
4.33 Temperature versus viscosity in 30%-70% W/O emulsion in
(30%-70% oil blend with 1.5 vol. % Span 83Emulsifier
89
4.34 Temperature versus viscosity in 30%-70% W/O emulsion in
(30%-70% oil blend with 1.0 vol. % Triton-X100 Emulsifier
89
4.35 Temperature versus viscosity in 50%-50% W/O emulsion in
(30%-70% oil blend with 1.0 vol. % Triton-X100 Emulsifier
90
4.36 Effect of water content on emulsion viscosity in (30%-70% oil
blend) at T = 50 oC and RPM = 100
92
4.37 Effect of water content on emulsion viscosity in (50%-50% oil
blend) at T = 90 oC and RPM = 100
92
4.38 Effect of water content on emulsion viscosity in (50%-50% oil
blend) at T = 70 oC and RPM = 100
93
4.39 Effect of water content on emulsion viscosity in (30%-70% oil
blend) at T = 70 oC and RPM = 100
93
4.40 Effect of water content on emulsion viscosity in (30%-70% oil
blend) at T = 28 oC and RPM = 100
94
4.41 Effect of water content on emulsion viscosity in (30%-70% oil
blend) at T = 90 oC and RPM = 100
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
4.43 Shear rate versus shear stress for different water cuts at T=28 oC
and SDDS surfactant in (50%-50%) oil blend
96
4.44 Shear rate versus shear stress for different water cuts at T=28 oC
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
4.46 Shear rate versus shear stress for different water cuts at T=28 oC
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
4.48 Effect of emulsifier type on emulsion (40%-60% W/O) viscosity
in (50%-50% oil blend) at T = 50 oC
102
4.49 Effect of emulsifier type on emulsion (30%-70% W/O) viscosity
in (50%-50% oil blend) at T = 70 oC
102
4.50 Effect of emulsifier type on emulsion (30%-70% W/O) viscosity
in (30%-70% oil blend) at T = 28 oC
103
4.51 Effect of emulsifier type on emulsion (40%-60% W/O) viscosity
in (30%-70% oil blend) at T = 90 oC
103
4.52 Effect of emulsifier type on emulsion (50%-50% W/O) viscosity
in (30%-70% oil blend) at T = 70 oC
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
4.54 Shear rate versus Shear stress of Crude oil A and B with 0.5
vol.% Triton X-100 emulsifier in 50 vol.% water cut emulsion at
T =28 oC
107
4.55 Shear rate versus Shear stress of Crude oil A and B with 1.0
vol.% SDDS emulsifier in 40 vol.% water cut emulsion at T =28
oC
108
4.56 Shear rate versus Shear stress of Crude oil A and B with 0.5
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
4.58 Effect of additive concentration on droplet size and distribution
for emulsion formulated with crude oil B and 40 vol.% water cut
111
4.59 Effect of additive concentration on droplet size and distribution
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
4.61 Effect of temperature on the droplet size and emulsion viscosity
for Emulsions prepared with 1.5 vol. % DEA in crude oil A and
50 vol. % water
112
4.62 Effect of temperature on the droplet size and emulsion viscosity
for Emulsions prepared with 1.5 vol. % Triton X-100 in crude
oil B and 50 vol. % water
113
4.63 Effect of temperature on the droplet size and emulsion viscosity
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
separation) for (50 vol. %- 50 Vol. %) (water / crude oil B)
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
separation) for (40 vol. %- 60 Vol. %) (water / crude oil A)
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
separation) for (50 vol. %- 50 Vol. %) (water / crude oil B)
emulsion
125
4.72 Effect of additives type on the emulsion stability (water
separation) for (30 vol. %- 70 Vol. %) (water / crude oil B)
emulsion
125
4.73 Effect of additives type on the emulsion stability (water
separation) for (40 vol. %- 60 Vol. %) (water / crude oil B)
emulsion
126
4.74 Effect of additives type on the emulsion stability (water
separation) for (50 vol. %- 50 Vol. %) (water / crude oil A)
emulsion
126
4.75 Effect of additives type on the emulsion stability (water
separation) for (50 vol. %- 50 Vol. %) (water / crude oil A)
emulsion
127
4.76 Effect of additives type on the emulsion stability (water
separation) for (30 vol. %- 70 Vol. %) (water / crude oil A)
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
4.78 Effect of water content on the emulsion stability (water
separation) for SDDS emulsifier in emulsion formulated from
crude oil B
130
4.79 Effect of water content on the emulsion stability (water
separation) for DEA emulsifier in emulsion formulated from
crude oil B
130
4.80 Effect of water content on the emulsion stability (water
separation) for DEA emulsifier in emulsion formulated from
crude oil A
131
4.81 Effect of water content on the emulsion stability (water
separation) for Triton X-100 emulsifier in emulsion formulated
131
xviii
from crude oil A
4.82 Effect of water content on the emulsion stability (water
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
4.84 Effect of oil type on the emulsion stability (water separation) for
(30 vol. %- 70 Vol. %) (water / crude oil ) emulsion with 0.5%
SDDS
134
4.85 Effect of oil type on the emulsion stability (water separation) for
(40 vol. %- 60 Vol. %) (water / crude oil ) emulsion with 1.0%
DEA
135
4.86 Effect of oil type on the emulsion stability (water separation) for
(30 vol. %- 70 Vol. %) (water / crude oil ) emulsion with 0.5%
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
percentage for crude oil A emulsions stabilized with 1.5 vol.%
Cocamide DEA.
142
5.3 Effect of Dioctylamine concentration on the water separation
percentage for crude oil A emulsions stabilized with 1.5 vol.%
Cocamide DEA.
143
5.4 Effect of PEG 1000 concentration on the water separation
percentage for crude oil A emulsions stabilized with 1.5 vol.%
Cocamide DEA
143
5.5 Effect of PEG 600 concentration on the water separation
percentage for crude oil A emulsions stabilized with 1.5 vol.%
Cocamide DEA.
144
5.6 Effect of Cocamine concentration on the water separation
percentage for crude oil A emulsions stabilized with 1.5 vol.%
Span 83.
144
5.7 Effect of PEG-1000 concentration on the water separation
percentage for crude oil A emulsions stabilized with 1.5 vol.%
Span 83.
145
5.8 Effect of Hexylamine concentration on the water separation
percentage for crude oil A emulsions stabilized with 1.5 vol.%
Span 83.
145
5.9 Effect of Dioctylamine concentration on the water separation
percentage for crude oil A emulsions stabilized with 1.5 vol.%
Span 83.
146
5.10 Effect of PEG-600 concentration on the water separation
percentage for crude oil A emulsions stabilized with 1.5 vol.%
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.
5.12 Effect of Cocamine concentration on the water separation
percentage for crude oil B emulsions stabilized with 1.5 vol.%
Cocamide DEA.
147
5.13 Effect of Dioctylamine concentration on the water separation
percentage for crude oil B emulsions stabilized with 1.5 vol.%
Cocamide DEA.
148
5.14 Effect of PEG 1000 concentration on the water separation
percentage for crude oil B emulsions stabilized with 1.5 vol.%
Cocamide DEA.
148
5.15 Effect of PEG 600 concentration on the water separation
percentage for crude oil B emulsions stabilized with 1.5 vol.%
Cocamide DEA.
149
5.16 Effect of Cocamine concentration on the water separation
percentage for crude oil B emulsions stabilized with 1.5 vol.%
Span 83.
149
5.17 Effect of PEG-1000 concentration on the water separation
percentage for crude oil B emulsions stabilized with 1.5 vol.%
Span 83.
150
5.18 Effect of Hexylamine concentration on the water separation
percentage for crude oil B emulsions stabilized with 1.5 vol.%
Span 83.
150
5.19 Effect of Dioctylamine concentration on the water separation
percentage for crude oil B emulsions stabilized with 1.5 vol.%
Span 83.
151
5.20 Effect of PEG-600 concentration on the water separation
percentage for crude oil B emulsions stabilized with 1.5 vol.%
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
5.22 Comparing the effects of the Demulsifiers investigated (0.2
vol.%) with emulsion formed from crude oil A and DEA.
157
5.23 Comparing the effects of the Demulsifiers investigated (1.0
vol.%) with emulsion formed from crude oil A and DEA.
157
5.24 Comparing the effects of the Demulsifiers investigated (0.2
vol.%) with emulsion formed from crude oil A and Span 83.
158
5.25 Comparing the effects of the Demulsifiers investigated (0.5
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
5.27 Comparing the effects of the Demulsifiers investigated (0.2
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
5.29 Comparing the effects of the Demulsifiers investigated (1.0
vol.%) with emulsion formed from crude oil B and DEA.
160
5.30 Comparing the effects of the Demulsifiers investigated (0.2
vol.%) with emulsion formed from crude oil B and Span 83.
161
xx
5.31 Comparing the effects of the Demulsifiers investigated (0.5
vol.%) with emulsion formed from crude oil B and Span 83.
161
5.32 Comparing the effects of the Demulsifiers investigated (1.0
vol.%) with emulsion formed from crude oil B and Span 83.
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
5.34 Effect of ultrasonic forces on the water separation performance
for Crude oil A emulsion with DEA emulsifier and Cocamine as
demulsifier.
170
5.35 Effect of ultrasonic forces on the water separation performance
for Crude oil A emulsion with DEA emulsifier and PEG-600 as
demulsifier
171
5.36 Effect of ultrasonic forces on the water separation performance
for Crude oil A emulsion with Span 83 emulsifier and
Hexylamine as demulsifier
171
5.37 Effect of ultrasonic forces on the water separation performance
for Crude oil A emulsion with Span 83 emulsifier and Cocamine
as demulsifier.
172
5.38 Effect of ultrasonic forces on the water separation performance
for Crude oil A emulsion with Span 83 emulsifier and
Dioctylamine as demulsifier.
172
5.39 Effect of ultrasonic forces on the water separation performance
for Crude oil B emulsion with DEA emulsifier and Hexylamine
as demulsifier.
173
5.40 Effect of ultrasonic forces on the water separation performance
for Crude oil B emulsion with DEA emulsifier and Cocamine as
demulsifier.
173
5.41 Effect of ultrasonic forces on the water separation performance
for Crude oil B emulsion with DEA emulsifier and Dioctylamine
as demulsifier
174
5.42 Effect of ultrasonic forces on the water separation performance
for Crude oil B emulsion with Span 83 emulsifier and PEG1000
as demulsifier.
174
5.43 Effect of ultrasonic forces on the water separation performance
for Crude oil B emulsion with Span 83 emulsifier and PEG-600
as demulsifier.
175
5.44 Effect of ultrasonic forces on the water separation performance
for Crude oil A emulsion with DEA emulsifier and different
types of demulsifiers at 0.5 vol.%.
176
5.45 Effect of ultrasonic forces on the water separation performance
for Crude oil A emulsion with Span 83 emulsifier and different
types of demulsifiers at 0.5 vol.%.
176
5.46 Effect of ultrasonic forces on the water separation performance
for Crude oil B emulsion with DEA emulsifier and different
types of demulsifiers at 0.5 vol.%.
177
5.47 Effect of ultrasonic forces on the water separation performance
for Crude oil B emulsion with Span 83 emulsifier and different
types of demulsifiers at 0.2 vol.%.
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
5.51 Effect of PEG-1000 demulsifier concentration on the water
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
5.54 Effect of PEG-600 demulsifier concentration on the water
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
5.56 Predicted versus observed values for Crude oil A emulsion
stabilized with SDDS at 28 oC.
185
5.57 Predicted versus observed values for Crude oil A emulsion
stabilized with Span 83 at 28 oC.
186
5.58 Predicted versus observed values for Crude oil A emulsion
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
5.60 Predicted versus observed values for Crude oil B emulsion
stabilized with SDDS at 28 oC.
187
5.61 Predicted versus observed values for Crude oil B emulsion
stabilized with Cocaminde DEA at 28 oC.
188
5.62 Predicted versus observed values for Crude oil A emulsion
(stabilized with 1.5 vol.% Span 83) demulsified using
Hexylamine and ultrasonic power.
189
5.63 Predicted versus observed values for Crude oil A emulsion
(stabilized with 1.5 vol.% Span 83) demulsified using Cocamine
and ultrasonic power.
190
5.64 Predicted versus observed values for Crude oil A emulsion
(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
and ultrasonic power
193
5.67 predicted versus observed values for Crude oil B emulsion
(stabilized with 1.5 vol.% DEA) demulsified using Hexylamine
194
xxii
and ultrasonic power
5.68 predicted versus observed values for Crude oil B emulsion
(stabilized with 1.5 vol.% DEA) demulsified using Cocamine
and ultrasonic power
195
5.69 predicted versus observed values for Crude oil B emulsion
(stabilized with 1.5 vol.% DEA) demulsified using Dioctylamine
and ultrasonic power
196
5.70 predicted versus observed values for Crude oil B emulsion
(stabilized with 1.5 vol.% DEA) demulsified using PEG-1000
and ultrasonic power
197
5.71 predicted versus observed values for Crude oil B emulsion
(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
2
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
3
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
4
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.
5
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.
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