middot~

0

0

0

24551

bull

f

A Study of the Formation of Water-ln-01 EITlUslons by

Mar1lt Bobra ConsUchem

POBox 4472 Station E Ottawa Ontario

Introduction The formation of stable water-In-Oil emulsions (mousse) has long been a source of

problems for the ol Industry In the ol field emulsions cause dllflcultles In productionstorage and transportation When ol Is spilled In the marine environment Its emulsificationbehaviour wll play a cruclal role In determining the ultimate fate of the ol and theeffectiveness of countenneasure techniques

Canevari (1982) pointed out that there are two posslble mechanisms that are responsiblefor the formation of stable water-ln-01 emulsions The first mechanism Is due to the actionof naturally occurring surface active agents (surfactants) In petroleum and the second Is dueto the presence of solid particles The mechanism by which surfactants stabilize emulsionsIs fairly well understood Briefly surfactants are amphlpathlc molampcUes which means that onesection of the molecule is soluble In ol Qlpophlllc) and the other section Is soluble In water(hydrophHlc) Because of this molecular structure surfactants tend to concentrate at the olshywater Interface where they form lnterfaclal films This film reduces the lnterfaclal tensionbetween ol and water thereby decreasing the amount of work required to Introduce onephase Into the other and this film forms a barrier around droplets thus Inhibitingcoalescence A general rule of thumb In surfactant chemistry is that surfactants with mainlylipophRic character (that Is predornlnanUy ol soluble) form water-irHgtI emulsions Whereassurfactants with mainly hydrophRlc character (predornlnanUy water soluble) produce oR-lnshywater emulsions Examples of the latter are ol spill dispersanls (Rosen 1978 Becher 1983)

In the second mechanism of emulsion stabilization the emulslfylng agents are solidparticles which in only a specialized sense can be considered to be surface active (Becher1977) For solids to act as emulsifying agents the particles must possess certain propertiesThe particles must be very small relative to the droplet size The particles must collect at theInterface and they must be wetted by both the ol and water phases Figure 1 shows threeways that particles may distribute themselves between an ol-water Interface If the particle

is preferentially wetted by the oU the contact angle between the ol-water-solid boundary eis greater than 00deg and a water-In-oil emulsion wm form If the particle Is preferentially wetted

by water e is less than 90deg and an oil-In-water emulsion will form If the contact angle ismuch greater or lesser than 00deg the emulsion wll be unstable Stable emulslons form whenthe contact angle is near 00deg

It has long been recognized that Indigenous petroleum emulsifying agents areconcentrated In the higher bolling fractions (boUing point gt 370degC) and particularly In theresiduum (Lawrence and Killner 1948) Likewise It is generally accepted that asphaltenes andwaxes play key roles In the emulsion process (Birdie et al 1980 Mackay 1987 Thesecompounds are believed to be the main constituents of lnterfaclal films which encapsulatewater droplets within mousse These films have been shown to have high mechanical strengthand thus act as physical barriers which prevent droplet coalescence (Blair 1960 Haslba andJessen 1967) This In turn gives rise to the extreme stability cA mousse The phenomena o

88

0

0

0

filrn formation has yet to be fully understood Although the role of solid particles In petroleum emulsllicatlon has been recognized for

some time (van der Waarden 1958) the Importance of this mechanism to mousse formation has not been completely appreciated Eley et al (1976) examined the lnterlaclal surfaces of water-In-oil emulsions using an electron microscope Their mlcrographs dearly showed particulate formations on the oil side of the Interlace They Isolated structures which they conduded to be asphaltene granules (dimensions 10-30 nm) and plates of wax (lt 100nm) Thompson et al (1984) showed that wax particles and associated solids exert considerable influence upon the emulsion stability of a waxy North Sea crude They found that removal of partides reduced emulsion stability They also showed that the emulsion behaviour of an oil can be changed dramatically by altering the size of the wax particles The Importance of this finding Is that whether or not the oil formed a stable emulsion was dependent upon the physical form of the emulsifying agent (small versus large wax crystals) and not upon any changes In the oils chemical composition or bulk properties Similarly Eley et al (1988) demonstrated that by varying the aromaticaliphatic ratio of a synthetic oil they could control the precipitation of asphaltenes and in tum the extent of emulsification

The aim of the work described in this paper was to elucidate the role that physiochemical factors play In determining an oUs susceptibility to emulsify This was done by using model oils of known composition to examine the importance of oil chemistry in the emulsification process

Oil Chemistry The main constituents of any oD can be grouped Into lour broad classes of chemicals

These being Alkanes (also sometimes called saturates or allphatlcs) Aromatics Resins and Asphaltenes Previous studies have Identified that asphaltenes resins and waxes (which are part of the alkane group) play a role in emulsification It Is Important to realize how these components are defined and to have an understanding of their basic chemistry Different methods of separating these fractions from oft are likely to produce different materials

~ Simple definitions of petroleum wax are the material In an asphalteneresin-free oil which

are Insoluble In the solvent methyl ethyl ketone or Insoluble In dlchlorornethane at 32degC Another definition for petroleum wax is the high molecular weight parafllnlc substances which crystallize out from an oil when cooled below the pour point Petroleum wax Is nonnaJly divided Into two sub-categories paraffin wax and mlcrocrystalllne wax Paraffin waxes are normal alkanes with 20 to 40 carbon atoms and melting points from 32 to 71degC Mlcrocrystalllne wax mainly consists of lso-alkanes with 35 to 75 carbon atoms and has a melting point from 54 to 93degC (Oarllt 1988)

Bnm Resins are complex high molecular weight compounds containing oxygen nitrogen and

sulphur atoms They are polar and have strong adsorption tendencies The term resins has been defined In various ways but it is generally considered to be the material that remains In solution after the asphaltenes have been removed by precipitation and which will adsorb onto surlacamp-actlve material (such as Fullers earth)

Petroleum resins are often considered to be low molecular weight asphaltenes but usuaJIY contain a higher percentage of saturated aliphatic and naphthenlc structures In their molecules Molecular weights of resins are assumed to range from about 800 to 1500

0

c

0

0

i

_

bull gt

i~-

89

Asphaltenes

Asphaltenes are defined by their solubility behaviour asphaltenes are soluble In aromatic solvents and Insoluble In alkane solvents Asphaltenes are generally considered to consist of condensed aromatic nuclei which carry alkyl and allcydlc systems with heteroatoms (nitrogen oxygen sulphur metals salts) scattered throughout In various locations Asphaltene molecules can have carbon numbers from 30 to over 40 and molecular weights from 500 to 10000 have been cited In the literature Asphaltenes are characterized by a CH ratio of dose to one and a specific gravity near one Relatively little Is known about asphaltene structures and much of the data Is inferred Figure 2 shows a hypothetical structure of an asphaltene (Speight 1981 l

The physical nature of asphaltenes as they exist in petroleum Is still speculative But It Is now generally accepted that petroleum should be viewed as a colloidal system Asphaltene molecules agglomerate to form dusters simDar to micelles These asphaltene micelles interact with the resins which In tum peptize the asphaltenes and enables a stable colloidal dispersion to exist Since these colloids contain most of the polar material found in the oD they essentially determine the interfacial properties (Oark 1988 Long 1979 Speight 1981 Neumann et al 1981)

Solubility Theory Griffith and Siegmund (1985) used the concept of solubility to describe the precipitation

behaviour of asphaltenes from fuel oils In this context oU is viewed as being comprised of a solute and a solvent the solute being the asphaltenes and the solvent being the rest of the oil The Hildebrand-Scatchard equation (Barton 1983) Is the basic equation that can be used to describe the solubility behaviour of asphaltenes in petroleum

RT In (A8XJ =

Pa

where A = activity coefficient of asphaltenes8

X = mole fraction of asphaltenes8

M = molecular weight of asphaltenes8

bull = volume fraction of solvent

08

= Hildebrand solubility parameter of the asphaltenes

o1

= Hildebrand solubUity parameter of the solvent

Pa = density of asphaltenes R = gas constant T = temperature

It Is assumed that asphaltenes can be treated as homogeneous material and that A = 1 The equation can be written In terms of the maximum amount of asphaltenes soluble In ol XL If the amount of asphaltenes present In the ol exceeds X8 the excess asphaltenes wDI precipitate

In X =

8

I middot~

0

0

90

Figure 1 Three ways solid particles may be distributed Jn an oilwater Interface The particle on the left is more wetted by the water than the oil thus being situated primariry in the aqueous phase whereas the particle 1o the right egttlsts primarily In the oil phase The center situation illostrates a soiid particle equally wetted by both the oil and water phase

__ __

_ - __

__

_ _ _

middot_ middotmiddot _ -bull bull

middotmiddot __ --v _ v v - _ - shy_ __ _ _ __ --- _ middotmiddot-v _

WATER

Figure 2 Hypothetical structure of a CaJifornia crude oil asphaltene

middot middot middot

~1 -~ bull ~

$ 1117

0 ~y

f

- f

~ ~middot

ff ~

E

alalTmppRwuC

TwpsfoFimcFefral

R(frofa

middot V

middot si

o to 025 025 to 075 075 to 1

91

xperimental The model offs us0d In these experiments consisted ol three main compotients 1 an

kane component 2 an aromatic component and 3 the potential emulsifying agent(s) The kanes tested were n-octane n-tetradecane a light paraffin oil and a heavy paraffin on he aromatics used were p-xylene phenyl octane dimethyl naphthalene and diphenyl ethane Asphaltenes were precipitated from a California crude oQ (API gravity 11) using nshyentane at a pentane to oil ratio of 401 (Speight 1981) Asphaltenes and resins were recipitated together from the California crude using ethyl acetate (Neumann et al 1981) esins were precipitated from de-asphaltized oil using ethyl acetate Precipitated materials ere collected on a 045 micron filter dried by a nitrogen purge and stored in the dark nder a nitrogen headspace Other materials used were paraffin wax (Aldrich Chemical ompany melting point SltHgt1degC) and graphite powder (Aldrich Chemical Company)

Model oUs were prepared by adding the emulsifying agent to the aromatic component he miXture was vigorously shaken for one hour on a shaker table The alkane component as then added and the mixture was again shaken for one hour 30 ml of the oK was oured into a 500 ml Fieaker containing 300 ml of artificial seawater The Fieaker was ealed and allowed to stand for approximately 20 hours before undergoing the emulsion rmation and stability test described by Bobra (1989) Briefly the test involves rotating the eaker at 65 rpm for one hour and then allowing the mixture to rest for one-half hour before easuring the size of the emulsion and the fraction of oU that emulsifies F The rotationrest

ycle Is repeated three more times An indiction of an ois tendency to emulsify is given by the fraction of oil that emulsifies when F Is extrapolated to time zero The stability of the0 mulsion is obtained by allowing the emulsion to rest for 24 hours and then measuring the action of oQ that remains in the emulsion F1 The water content of stable emulsions were so measured The following criteria set by Mackay et al(1982) classify emulsion behaviour

o to 025 025 to 075

Emulsion formation tendency

not likely fairly likely

very likely

Emulsion stabRity

unstable fairly stable very stable

The rheol

o75 to 1

ogical properties of stable emulsions were measured using a Haake RV20 otovlscometer equipped with a MSSV1 senSOf The programmed shear rate was o to 100 81

) In 10 minutes and 100 too (s-1) In 10 minutes The yield point values were detennlned om the Increasing shear rate curves The yield point can be considered to be an indlctlon the solid character of the emulsion It Is the force required to change the emulsion from solid to a flowing llquid For the sake of comparison under these same shear conditions

mayonnaise has a yield point of 114 Pa and two samples of 18 day-old mousse from the aldez spRI had values of 17 and 121 Pa

The size distribution ol water droplets were determined using a lab-Tee 1000 particle ze analyser and a Zeiss Axloskop lightfluorescence microscope

AR experiments were conducted at 15degC

92

Results and Discussion Effect ofmiddotAsohaltenes

Figures 3 to 6 show the Influence of the alkanearomatlc ratio and the Influence of increasing asphaltene content upon F

0 F1 water content and yield point The alkane

component Is heavy paraffin oil and the aromatic component Is xylene At an asphaltene concentration of 001 gml (1 ) no stable emulsions are formed At an asphaltene concentration of 0025 gml (25) the model oil has a tendency to emulsify (F =1) when

0

the oil Is 50 alkane and 50 aromatic and this emulsion Is only marginally stable (F=05) When the asphaltene content is Increased to 005 gml (5) stable emulsions are readily produced for oils containing 50 to 95 alkane component Likewise at an asphaltene concentration of 01 gml stable emulsions form for oUs containing 35 to a0 alkane Figure 5 shows that the water content of stable emulsions are between 80 to 90 The change in yield point as a function of alkane composition Figure 6 clearly shows that there Is a maximum value for each concentration of asphaltenes For oDs containing 5 asphaltenes this maxima occurs at 80 alkane and for oils containing 10 asphaltenes this occurs at 70

The results illustrate several important points concerning the influence of the alkanearomatic ratio upon an oils emulsification behaviour The amount of asphaltenes precipitated out of solution is determined by the alkane concentration Figure 7 shows the percent of asphaltenes precipitated as a function of alkane concentration for an oU containing 5 asphaltenes Clearly the amount precipitated Is important in determining the emulsification of the oil But it would also appear that the alkanearornatlc ratio controls other factors which are involved In emulsification The size of the asphaltene particles are determined by the alkanearornatlc ratio and this Is particularly true given the method by which these model oils were prepared Asphaltenes were first dissolved In the appropriate quantity of xylene and then the paraffin oil was added which causes the asphaltenes to precipitate out of solution When the model on Is predominantly composed of paraffin oil this precipitation mechanism does not occur and the asphaltene particles maintain their original dimensions ( gt 1 microns) These particles are too large to effectively stabilize water droplets This was confirmed by microscopic examination of the oils When model oils which were prone to emulsification were examined under the microscope Individual particle sizes could not be accurately determined because the particles were at the limit of resolution (lt05 microns) But it could be seen that collectively the particles formed a continuous layer of finely dispersed particulates which are closely packed together As the alkane content of the oU Increased the particles became more tightly packed and Increased In size An Interesting phenomenon was observed when model oils with high aromatic content were viewed under the microscope The actual precipitation of asphaltenes could be observed as the oil evaporated Particles would precipitate out In a uniform distribution covering the slide with a IDm of subshymicron particles

Figure 8 shows the lnterfaclal tension as measured by the duNuoy ring method decreases as the aromatic content of the oil Increases It would appear that changes In lnterfaclal tension have little to do with the emulslflcatlon behaviour of the model oils

It would be expected that the alkanearornatlc ratio will have some effect on the contact angle between the particles and the Interface since oil composition will Influence the wettability of particles A simple experiment was performed which demonstrated the Importance of the alkanearornatlc ratio on the contact angle A series of oils of the same alkanearomatlc composition as prevtously tested were prepared and subjected to the emulsification test but Instead of asphaltenes graphite powder (005 gml) was used as the emulsifying agent Graphite Is Insoluble In both xylene and paraffin oil Therefore there wDI

I

93

be no changes In Its physical form The results from this experiment showed that stable emulsions only formed at an alkanearomatlc ratio of 11 Unfortunately facRltles to measure contact angle were not avaRable and therefore this effect of alkanearomatlc ratio upon contact angle and In tum upon emulsification could not be substantiated The results from this experiment Indicate that this Influence upon contact angle Is an extremely Important determinant for emulsification by solid partldes

94

Figure 3 Fo versus i alkane at different asphaltene concentrations

j

obull

middot

middot 0

I middot

0

middot

middot

~ elkane 1n oil

middotmiddotmiddotmiddot~middotmiddotmiddot 01 gL ---0--- 0 05 gllllmiddotmiddotmiddot-0middotmiddotmiddot 0 OZ5 ol- --9-- omiddot01 om1

Figure 4 F t inal versus X alkane

o

middot

ii

~

I middot I

lI

middot

I I middot--middot-9-middot

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n bull bull bull bull shy

X alkane

88

0

0

0

filrn formation has yet to be fully understood Although the role of solid particles In petroleum emulsllicatlon has been recognized for

some time (van der Waarden 1958) the Importance of this mechanism to mousse formation has not been completely appreciated Eley et al (1976) examined the lnterlaclal surfaces of water-In-oil emulsions using an electron microscope Their mlcrographs dearly showed particulate formations on the oil side of the Interlace They Isolated structures which they conduded to be asphaltene granules (dimensions 10-30 nm) and plates of wax (lt 100nm) Thompson et al (1984) showed that wax particles and associated solids exert considerable influence upon the emulsion stability of a waxy North Sea crude They found that removal of partides reduced emulsion stability They also showed that the emulsion behaviour of an oil can be changed dramatically by altering the size of the wax particles The Importance of this finding Is that whether or not the oil formed a stable emulsion was dependent upon the physical form of the emulsifying agent (small versus large wax crystals) and not upon any changes In the oils chemical composition or bulk properties Similarly Eley et al (1988) demonstrated that by varying the aromaticaliphatic ratio of a synthetic oil they could control the precipitation of asphaltenes and in tum the extent of emulsification

The aim of the work described in this paper was to elucidate the role that physiochemical factors play In determining an oUs susceptibility to emulsify This was done by using model oils of known composition to examine the importance of oil chemistry in the emulsification process

Oil Chemistry The main constituents of any oD can be grouped Into lour broad classes of chemicals

These being Alkanes (also sometimes called saturates or allphatlcs) Aromatics Resins and Asphaltenes Previous studies have Identified that asphaltenes resins and waxes (which are part of the alkane group) play a role in emulsification It Is Important to realize how these components are defined and to have an understanding of their basic chemistry Different methods of separating these fractions from oft are likely to produce different materials

~ Simple definitions of petroleum wax are the material In an asphalteneresin-free oil which

are Insoluble In the solvent methyl ethyl ketone or Insoluble In dlchlorornethane at 32degC Another definition for petroleum wax is the high molecular weight parafllnlc substances which crystallize out from an oil when cooled below the pour point Petroleum wax Is nonnaJly divided Into two sub-categories paraffin wax and mlcrocrystalllne wax Paraffin waxes are normal alkanes with 20 to 40 carbon atoms and melting points from 32 to 71degC Mlcrocrystalllne wax mainly consists of lso-alkanes with 35 to 75 carbon atoms and has a melting point from 54 to 93degC (Oarllt 1988)

Bnm Resins are complex high molecular weight compounds containing oxygen nitrogen and

sulphur atoms They are polar and have strong adsorption tendencies The term resins has been defined In various ways but it is generally considered to be the material that remains In solution after the asphaltenes have been removed by precipitation and which will adsorb onto surlacamp-actlve material (such as Fullers earth)

Petroleum resins are often considered to be low molecular weight asphaltenes but usuaJIY contain a higher percentage of saturated aliphatic and naphthenlc structures In their molecules Molecular weights of resins are assumed to range from about 800 to 1500

0

c

0

0

i

_

bull gt

i~-

89

Asphaltenes

Asphaltenes are defined by their solubility behaviour asphaltenes are soluble In aromatic solvents and Insoluble In alkane solvents Asphaltenes are generally considered to consist of condensed aromatic nuclei which carry alkyl and allcydlc systems with heteroatoms (nitrogen oxygen sulphur metals salts) scattered throughout In various locations Asphaltene molecules can have carbon numbers from 30 to over 40 and molecular weights from 500 to 10000 have been cited In the literature Asphaltenes are characterized by a CH ratio of dose to one and a specific gravity near one Relatively little Is known about asphaltene structures and much of the data Is inferred Figure 2 shows a hypothetical structure of an asphaltene (Speight 1981 l

The physical nature of asphaltenes as they exist in petroleum Is still speculative But It Is now generally accepted that petroleum should be viewed as a colloidal system Asphaltene molecules agglomerate to form dusters simDar to micelles These asphaltene micelles interact with the resins which In tum peptize the asphaltenes and enables a stable colloidal dispersion to exist Since these colloids contain most of the polar material found in the oD they essentially determine the interfacial properties (Oark 1988 Long 1979 Speight 1981 Neumann et al 1981)

Solubility Theory Griffith and Siegmund (1985) used the concept of solubility to describe the precipitation

behaviour of asphaltenes from fuel oils In this context oU is viewed as being comprised of a solute and a solvent the solute being the asphaltenes and the solvent being the rest of the oil The Hildebrand-Scatchard equation (Barton 1983) Is the basic equation that can be used to describe the solubility behaviour of asphaltenes in petroleum

RT In (A8XJ =

Pa

where A = activity coefficient of asphaltenes8

X = mole fraction of asphaltenes8

M = molecular weight of asphaltenes8

bull = volume fraction of solvent

08

= Hildebrand solubility parameter of the asphaltenes

o1

= Hildebrand solubUity parameter of the solvent

Pa = density of asphaltenes R = gas constant T = temperature

It Is assumed that asphaltenes can be treated as homogeneous material and that A = 1 The equation can be written In terms of the maximum amount of asphaltenes soluble In ol XL If the amount of asphaltenes present In the ol exceeds X8 the excess asphaltenes wDI precipitate

In X =

8

I middot~

0

0

90

Figure 1 Three ways solid particles may be distributed Jn an oilwater Interface The particle on the left is more wetted by the water than the oil thus being situated primariry in the aqueous phase whereas the particle 1o the right egttlsts primarily In the oil phase The center situation illostrates a soiid particle equally wetted by both the oil and water phase

__ __

_ - __

__

_ _ _

middot_ middotmiddot _ -bull bull

middotmiddot __ --v _ v v - _ - shy_ __ _ _ __ --- _ middotmiddot-v _

WATER

Figure 2 Hypothetical structure of a CaJifornia crude oil asphaltene

middot middot middot

~1 -~ bull ~

$ 1117

0 ~y

f

- f

~ ~middot

ff ~

E

alalTmppRwuC

TwpsfoFimcFefral

R(frofa

middot V

middot si

o to 025 025 to 075 075 to 1

91

xperimental The model offs us0d In these experiments consisted ol three main compotients 1 an

kane component 2 an aromatic component and 3 the potential emulsifying agent(s) The kanes tested were n-octane n-tetradecane a light paraffin oil and a heavy paraffin on he aromatics used were p-xylene phenyl octane dimethyl naphthalene and diphenyl ethane Asphaltenes were precipitated from a California crude oQ (API gravity 11) using nshyentane at a pentane to oil ratio of 401 (Speight 1981) Asphaltenes and resins were recipitated together from the California crude using ethyl acetate (Neumann et al 1981) esins were precipitated from de-asphaltized oil using ethyl acetate Precipitated materials ere collected on a 045 micron filter dried by a nitrogen purge and stored in the dark nder a nitrogen headspace Other materials used were paraffin wax (Aldrich Chemical ompany melting point SltHgt1degC) and graphite powder (Aldrich Chemical Company)

Model oUs were prepared by adding the emulsifying agent to the aromatic component he miXture was vigorously shaken for one hour on a shaker table The alkane component as then added and the mixture was again shaken for one hour 30 ml of the oK was oured into a 500 ml Fieaker containing 300 ml of artificial seawater The Fieaker was ealed and allowed to stand for approximately 20 hours before undergoing the emulsion rmation and stability test described by Bobra (1989) Briefly the test involves rotating the eaker at 65 rpm for one hour and then allowing the mixture to rest for one-half hour before easuring the size of the emulsion and the fraction of oU that emulsifies F The rotationrest

ycle Is repeated three more times An indiction of an ois tendency to emulsify is given by the fraction of oil that emulsifies when F Is extrapolated to time zero The stability of the0 mulsion is obtained by allowing the emulsion to rest for 24 hours and then measuring the action of oQ that remains in the emulsion F1 The water content of stable emulsions were so measured The following criteria set by Mackay et al(1982) classify emulsion behaviour

o to 025 025 to 075

Emulsion formation tendency

not likely fairly likely

very likely

Emulsion stabRity

unstable fairly stable very stable

The rheol

o75 to 1

ogical properties of stable emulsions were measured using a Haake RV20 otovlscometer equipped with a MSSV1 senSOf The programmed shear rate was o to 100 81

) In 10 minutes and 100 too (s-1) In 10 minutes The yield point values were detennlned om the Increasing shear rate curves The yield point can be considered to be an indlctlon the solid character of the emulsion It Is the force required to change the emulsion from solid to a flowing llquid For the sake of comparison under these same shear conditions

mayonnaise has a yield point of 114 Pa and two samples of 18 day-old mousse from the aldez spRI had values of 17 and 121 Pa

The size distribution ol water droplets were determined using a lab-Tee 1000 particle ze analyser and a Zeiss Axloskop lightfluorescence microscope

AR experiments were conducted at 15degC

92

Results and Discussion Effect ofmiddotAsohaltenes

Figures 3 to 6 show the Influence of the alkanearomatlc ratio and the Influence of increasing asphaltene content upon F

0 F1 water content and yield point The alkane

component Is heavy paraffin oil and the aromatic component Is xylene At an asphaltene concentration of 001 gml (1 ) no stable emulsions are formed At an asphaltene concentration of 0025 gml (25) the model oil has a tendency to emulsify (F =1) when

0

the oil Is 50 alkane and 50 aromatic and this emulsion Is only marginally stable (F=05) When the asphaltene content is Increased to 005 gml (5) stable emulsions are readily produced for oils containing 50 to 95 alkane component Likewise at an asphaltene concentration of 01 gml stable emulsions form for oUs containing 35 to a0 alkane Figure 5 shows that the water content of stable emulsions are between 80 to 90 The change in yield point as a function of alkane composition Figure 6 clearly shows that there Is a maximum value for each concentration of asphaltenes For oDs containing 5 asphaltenes this maxima occurs at 80 alkane and for oils containing 10 asphaltenes this occurs at 70

The results illustrate several important points concerning the influence of the alkanearomatic ratio upon an oils emulsification behaviour The amount of asphaltenes precipitated out of solution is determined by the alkane concentration Figure 7 shows the percent of asphaltenes precipitated as a function of alkane concentration for an oU containing 5 asphaltenes Clearly the amount precipitated Is important in determining the emulsification of the oil But it would also appear that the alkanearornatlc ratio controls other factors which are involved In emulsification The size of the asphaltene particles are determined by the alkanearornatlc ratio and this Is particularly true given the method by which these model oils were prepared Asphaltenes were first dissolved In the appropriate quantity of xylene and then the paraffin oil was added which causes the asphaltenes to precipitate out of solution When the model on Is predominantly composed of paraffin oil this precipitation mechanism does not occur and the asphaltene particles maintain their original dimensions ( gt 1 microns) These particles are too large to effectively stabilize water droplets This was confirmed by microscopic examination of the oils When model oils which were prone to emulsification were examined under the microscope Individual particle sizes could not be accurately determined because the particles were at the limit of resolution (lt05 microns) But it could be seen that collectively the particles formed a continuous layer of finely dispersed particulates which are closely packed together As the alkane content of the oU Increased the particles became more tightly packed and Increased In size An Interesting phenomenon was observed when model oils with high aromatic content were viewed under the microscope The actual precipitation of asphaltenes could be observed as the oil evaporated Particles would precipitate out In a uniform distribution covering the slide with a IDm of subshymicron particles

Figure 8 shows the lnterfaclal tension as measured by the duNuoy ring method decreases as the aromatic content of the oil Increases It would appear that changes In lnterfaclal tension have little to do with the emulslflcatlon behaviour of the model oils

It would be expected that the alkanearornatlc ratio will have some effect on the contact angle between the particles and the Interface since oil composition will Influence the wettability of particles A simple experiment was performed which demonstrated the Importance of the alkanearornatlc ratio on the contact angle A series of oils of the same alkanearomatlc composition as prevtously tested were prepared and subjected to the emulsification test but Instead of asphaltenes graphite powder (005 gml) was used as the emulsifying agent Graphite Is Insoluble In both xylene and paraffin oil Therefore there wDI

I

93

be no changes In Its physical form The results from this experiment showed that stable emulsions only formed at an alkanearomatlc ratio of 11 Unfortunately facRltles to measure contact angle were not avaRable and therefore this effect of alkanearomatlc ratio upon contact angle and In tum upon emulsification could not be substantiated The results from this experiment Indicate that this Influence upon contact angle Is an extremely Important determinant for emulsification by solid partldes

94

Figure 3 Fo versus i alkane at different asphaltene concentrations

j

obull

middot

middot 0

I middot

0

middot

middot

~ elkane 1n oil

middotmiddotmiddotmiddot~middotmiddotmiddot 01 gL ---0--- 0 05 gllllmiddotmiddotmiddot-0middotmiddotmiddot 0 OZ5 ol- --9-- omiddot01 om1

Figure 4 F t inal versus X alkane

o

middot

ii

~

I middot I

lI

middot

I I middot--middot-9-middot

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n bull bull bull bull shy

X alkane

c

0

0

i

_

bull gt

i~-

89

Asphaltenes

Asphaltenes are defined by their solubility behaviour asphaltenes are soluble In aromatic solvents and Insoluble In alkane solvents Asphaltenes are generally considered to consist of condensed aromatic nuclei which carry alkyl and allcydlc systems with heteroatoms (nitrogen oxygen sulphur metals salts) scattered throughout In various locations Asphaltene molecules can have carbon numbers from 30 to over 40 and molecular weights from 500 to 10000 have been cited In the literature Asphaltenes are characterized by a CH ratio of dose to one and a specific gravity near one Relatively little Is known about asphaltene structures and much of the data Is inferred Figure 2 shows a hypothetical structure of an asphaltene (Speight 1981 l

The physical nature of asphaltenes as they exist in petroleum Is still speculative But It Is now generally accepted that petroleum should be viewed as a colloidal system Asphaltene molecules agglomerate to form dusters simDar to micelles These asphaltene micelles interact with the resins which In tum peptize the asphaltenes and enables a stable colloidal dispersion to exist Since these colloids contain most of the polar material found in the oD they essentially determine the interfacial properties (Oark 1988 Long 1979 Speight 1981 Neumann et al 1981)

Solubility Theory Griffith and Siegmund (1985) used the concept of solubility to describe the precipitation

behaviour of asphaltenes from fuel oils In this context oU is viewed as being comprised of a solute and a solvent the solute being the asphaltenes and the solvent being the rest of the oil The Hildebrand-Scatchard equation (Barton 1983) Is the basic equation that can be used to describe the solubility behaviour of asphaltenes in petroleum

RT In (A8XJ =

Pa

where A = activity coefficient of asphaltenes8

X = mole fraction of asphaltenes8

M = molecular weight of asphaltenes8

bull = volume fraction of solvent

08

= Hildebrand solubility parameter of the asphaltenes

o1

= Hildebrand solubUity parameter of the solvent

Pa = density of asphaltenes R = gas constant T = temperature

It Is assumed that asphaltenes can be treated as homogeneous material and that A = 1 The equation can be written In terms of the maximum amount of asphaltenes soluble In ol XL If the amount of asphaltenes present In the ol exceeds X8 the excess asphaltenes wDI precipitate

In X =

8

I middot~

0

0

90

Figure 1 Three ways solid particles may be distributed Jn an oilwater Interface The particle on the left is more wetted by the water than the oil thus being situated primariry in the aqueous phase whereas the particle 1o the right egttlsts primarily In the oil phase The center situation illostrates a soiid particle equally wetted by both the oil and water phase

__ __

_ - __

__

_ _ _

middot_ middotmiddot _ -bull bull

middotmiddot __ --v _ v v - _ - shy_ __ _ _ __ --- _ middotmiddot-v _

WATER

Figure 2 Hypothetical structure of a CaJifornia crude oil asphaltene

middot middot middot

~1 -~ bull ~

$ 1117

0 ~y

f

- f

~ ~middot

ff ~

E

alalTmppRwuC

TwpsfoFimcFefral

R(frofa

middot V

middot si

o to 025 025 to 075 075 to 1

91

xperimental The model offs us0d In these experiments consisted ol three main compotients 1 an

kane component 2 an aromatic component and 3 the potential emulsifying agent(s) The kanes tested were n-octane n-tetradecane a light paraffin oil and a heavy paraffin on he aromatics used were p-xylene phenyl octane dimethyl naphthalene and diphenyl ethane Asphaltenes were precipitated from a California crude oQ (API gravity 11) using nshyentane at a pentane to oil ratio of 401 (Speight 1981) Asphaltenes and resins were recipitated together from the California crude using ethyl acetate (Neumann et al 1981) esins were precipitated from de-asphaltized oil using ethyl acetate Precipitated materials ere collected on a 045 micron filter dried by a nitrogen purge and stored in the dark nder a nitrogen headspace Other materials used were paraffin wax (Aldrich Chemical ompany melting point SltHgt1degC) and graphite powder (Aldrich Chemical Company)

Model oUs were prepared by adding the emulsifying agent to the aromatic component he miXture was vigorously shaken for one hour on a shaker table The alkane component as then added and the mixture was again shaken for one hour 30 ml of the oK was oured into a 500 ml Fieaker containing 300 ml of artificial seawater The Fieaker was ealed and allowed to stand for approximately 20 hours before undergoing the emulsion rmation and stability test described by Bobra (1989) Briefly the test involves rotating the eaker at 65 rpm for one hour and then allowing the mixture to rest for one-half hour before easuring the size of the emulsion and the fraction of oU that emulsifies F The rotationrest

ycle Is repeated three more times An indiction of an ois tendency to emulsify is given by the fraction of oil that emulsifies when F Is extrapolated to time zero The stability of the0 mulsion is obtained by allowing the emulsion to rest for 24 hours and then measuring the action of oQ that remains in the emulsion F1 The water content of stable emulsions were so measured The following criteria set by Mackay et al(1982) classify emulsion behaviour

o to 025 025 to 075

Emulsion formation tendency

not likely fairly likely

very likely

Emulsion stabRity

unstable fairly stable very stable

The rheol

o75 to 1

ogical properties of stable emulsions were measured using a Haake RV20 otovlscometer equipped with a MSSV1 senSOf The programmed shear rate was o to 100 81

) In 10 minutes and 100 too (s-1) In 10 minutes The yield point values were detennlned om the Increasing shear rate curves The yield point can be considered to be an indlctlon the solid character of the emulsion It Is the force required to change the emulsion from solid to a flowing llquid For the sake of comparison under these same shear conditions

mayonnaise has a yield point of 114 Pa and two samples of 18 day-old mousse from the aldez spRI had values of 17 and 121 Pa

The size distribution ol water droplets were determined using a lab-Tee 1000 particle ze analyser and a Zeiss Axloskop lightfluorescence microscope

AR experiments were conducted at 15degC

92

Results and Discussion Effect ofmiddotAsohaltenes

Figures 3 to 6 show the Influence of the alkanearomatlc ratio and the Influence of increasing asphaltene content upon F

0 F1 water content and yield point The alkane

component Is heavy paraffin oil and the aromatic component Is xylene At an asphaltene concentration of 001 gml (1 ) no stable emulsions are formed At an asphaltene concentration of 0025 gml (25) the model oil has a tendency to emulsify (F =1) when

0

the oil Is 50 alkane and 50 aromatic and this emulsion Is only marginally stable (F=05) When the asphaltene content is Increased to 005 gml (5) stable emulsions are readily produced for oils containing 50 to 95 alkane component Likewise at an asphaltene concentration of 01 gml stable emulsions form for oUs containing 35 to a0 alkane Figure 5 shows that the water content of stable emulsions are between 80 to 90 The change in yield point as a function of alkane composition Figure 6 clearly shows that there Is a maximum value for each concentration of asphaltenes For oDs containing 5 asphaltenes this maxima occurs at 80 alkane and for oils containing 10 asphaltenes this occurs at 70

The results illustrate several important points concerning the influence of the alkanearomatic ratio upon an oils emulsification behaviour The amount of asphaltenes precipitated out of solution is determined by the alkane concentration Figure 7 shows the percent of asphaltenes precipitated as a function of alkane concentration for an oU containing 5 asphaltenes Clearly the amount precipitated Is important in determining the emulsification of the oil But it would also appear that the alkanearornatlc ratio controls other factors which are involved In emulsification The size of the asphaltene particles are determined by the alkanearornatlc ratio and this Is particularly true given the method by which these model oils were prepared Asphaltenes were first dissolved In the appropriate quantity of xylene and then the paraffin oil was added which causes the asphaltenes to precipitate out of solution When the model on Is predominantly composed of paraffin oil this precipitation mechanism does not occur and the asphaltene particles maintain their original dimensions ( gt 1 microns) These particles are too large to effectively stabilize water droplets This was confirmed by microscopic examination of the oils When model oils which were prone to emulsification were examined under the microscope Individual particle sizes could not be accurately determined because the particles were at the limit of resolution (lt05 microns) But it could be seen that collectively the particles formed a continuous layer of finely dispersed particulates which are closely packed together As the alkane content of the oU Increased the particles became more tightly packed and Increased In size An Interesting phenomenon was observed when model oils with high aromatic content were viewed under the microscope The actual precipitation of asphaltenes could be observed as the oil evaporated Particles would precipitate out In a uniform distribution covering the slide with a IDm of subshymicron particles

Figure 8 shows the lnterfaclal tension as measured by the duNuoy ring method decreases as the aromatic content of the oil Increases It would appear that changes In lnterfaclal tension have little to do with the emulslflcatlon behaviour of the model oils

It would be expected that the alkanearornatlc ratio will have some effect on the contact angle between the particles and the Interface since oil composition will Influence the wettability of particles A simple experiment was performed which demonstrated the Importance of the alkanearornatlc ratio on the contact angle A series of oils of the same alkanearomatlc composition as prevtously tested were prepared and subjected to the emulsification test but Instead of asphaltenes graphite powder (005 gml) was used as the emulsifying agent Graphite Is Insoluble In both xylene and paraffin oil Therefore there wDI

I

93

be no changes In Its physical form The results from this experiment showed that stable emulsions only formed at an alkanearomatlc ratio of 11 Unfortunately facRltles to measure contact angle were not avaRable and therefore this effect of alkanearomatlc ratio upon contact angle and In tum upon emulsification could not be substantiated The results from this experiment Indicate that this Influence upon contact angle Is an extremely Important determinant for emulsification by solid partldes

94

Figure 3 Fo versus i alkane at different asphaltene concentrations

j

obull

middot

middot 0

I middot

0

middot

middot

~ elkane 1n oil

middotmiddotmiddotmiddot~middotmiddotmiddot 01 gL ---0--- 0 05 gllllmiddotmiddotmiddot-0middotmiddotmiddot 0 OZ5 ol- --9-- omiddot01 om1

Figure 4 F t inal versus X alkane

o

middot

ii

~

I middot I

lI

middot

I I middot--middot-9-middot

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n bull bull bull bull shy

X alkane

I middot~

0

0

90

Figure 1 Three ways solid particles may be distributed Jn an oilwater Interface The particle on the left is more wetted by the water than the oil thus being situated primariry in the aqueous phase whereas the particle 1o the right egttlsts primarily In the oil phase The center situation illostrates a soiid particle equally wetted by both the oil and water phase

__ __

_ - __

__

_ _ _

middot_ middotmiddot _ -bull bull

middotmiddot __ --v _ v v - _ - shy_ __ _ _ __ --- _ middotmiddot-v _

WATER

Figure 2 Hypothetical structure of a CaJifornia crude oil asphaltene

middot middot middot

~1 -~ bull ~

$ 1117

0 ~y

f

- f

~ ~middot

ff ~

E

alalTmppRwuC

TwpsfoFimcFefral

R(frofa

middot V

middot si

o to 025 025 to 075 075 to 1

91

xperimental The model offs us0d In these experiments consisted ol three main compotients 1 an

kane component 2 an aromatic component and 3 the potential emulsifying agent(s) The kanes tested were n-octane n-tetradecane a light paraffin oil and a heavy paraffin on he aromatics used were p-xylene phenyl octane dimethyl naphthalene and diphenyl ethane Asphaltenes were precipitated from a California crude oQ (API gravity 11) using nshyentane at a pentane to oil ratio of 401 (Speight 1981) Asphaltenes and resins were recipitated together from the California crude using ethyl acetate (Neumann et al 1981) esins were precipitated from de-asphaltized oil using ethyl acetate Precipitated materials ere collected on a 045 micron filter dried by a nitrogen purge and stored in the dark nder a nitrogen headspace Other materials used were paraffin wax (Aldrich Chemical ompany melting point SltHgt1degC) and graphite powder (Aldrich Chemical Company)

Model oUs were prepared by adding the emulsifying agent to the aromatic component he miXture was vigorously shaken for one hour on a shaker table The alkane component as then added and the mixture was again shaken for one hour 30 ml of the oK was oured into a 500 ml Fieaker containing 300 ml of artificial seawater The Fieaker was ealed and allowed to stand for approximately 20 hours before undergoing the emulsion rmation and stability test described by Bobra (1989) Briefly the test involves rotating the eaker at 65 rpm for one hour and then allowing the mixture to rest for one-half hour before easuring the size of the emulsion and the fraction of oU that emulsifies F The rotationrest

ycle Is repeated three more times An indiction of an ois tendency to emulsify is given by the fraction of oil that emulsifies when F Is extrapolated to time zero The stability of the0 mulsion is obtained by allowing the emulsion to rest for 24 hours and then measuring the action of oQ that remains in the emulsion F1 The water content of stable emulsions were so measured The following criteria set by Mackay et al(1982) classify emulsion behaviour

o to 025 025 to 075

Emulsion formation tendency

not likely fairly likely

very likely

Emulsion stabRity

unstable fairly stable very stable

The rheol

o75 to 1

ogical properties of stable emulsions were measured using a Haake RV20 otovlscometer equipped with a MSSV1 senSOf The programmed shear rate was o to 100 81

) In 10 minutes and 100 too (s-1) In 10 minutes The yield point values were detennlned om the Increasing shear rate curves The yield point can be considered to be an indlctlon the solid character of the emulsion It Is the force required to change the emulsion from solid to a flowing llquid For the sake of comparison under these same shear conditions

mayonnaise has a yield point of 114 Pa and two samples of 18 day-old mousse from the aldez spRI had values of 17 and 121 Pa

The size distribution ol water droplets were determined using a lab-Tee 1000 particle ze analyser and a Zeiss Axloskop lightfluorescence microscope

AR experiments were conducted at 15degC

92

Results and Discussion Effect ofmiddotAsohaltenes

Figures 3 to 6 show the Influence of the alkanearomatlc ratio and the Influence of increasing asphaltene content upon F

0 F1 water content and yield point The alkane

component Is heavy paraffin oil and the aromatic component Is xylene At an asphaltene concentration of 001 gml (1 ) no stable emulsions are formed At an asphaltene concentration of 0025 gml (25) the model oil has a tendency to emulsify (F =1) when

0

the oil Is 50 alkane and 50 aromatic and this emulsion Is only marginally stable (F=05) When the asphaltene content is Increased to 005 gml (5) stable emulsions are readily produced for oils containing 50 to 95 alkane component Likewise at an asphaltene concentration of 01 gml stable emulsions form for oUs containing 35 to a0 alkane Figure 5 shows that the water content of stable emulsions are between 80 to 90 The change in yield point as a function of alkane composition Figure 6 clearly shows that there Is a maximum value for each concentration of asphaltenes For oDs containing 5 asphaltenes this maxima occurs at 80 alkane and for oils containing 10 asphaltenes this occurs at 70

The results illustrate several important points concerning the influence of the alkanearomatic ratio upon an oils emulsification behaviour The amount of asphaltenes precipitated out of solution is determined by the alkane concentration Figure 7 shows the percent of asphaltenes precipitated as a function of alkane concentration for an oU containing 5 asphaltenes Clearly the amount precipitated Is important in determining the emulsification of the oil But it would also appear that the alkanearornatlc ratio controls other factors which are involved In emulsification The size of the asphaltene particles are determined by the alkanearornatlc ratio and this Is particularly true given the method by which these model oils were prepared Asphaltenes were first dissolved In the appropriate quantity of xylene and then the paraffin oil was added which causes the asphaltenes to precipitate out of solution When the model on Is predominantly composed of paraffin oil this precipitation mechanism does not occur and the asphaltene particles maintain their original dimensions ( gt 1 microns) These particles are too large to effectively stabilize water droplets This was confirmed by microscopic examination of the oils When model oils which were prone to emulsification were examined under the microscope Individual particle sizes could not be accurately determined because the particles were at the limit of resolution (lt05 microns) But it could be seen that collectively the particles formed a continuous layer of finely dispersed particulates which are closely packed together As the alkane content of the oU Increased the particles became more tightly packed and Increased In size An Interesting phenomenon was observed when model oils with high aromatic content were viewed under the microscope The actual precipitation of asphaltenes could be observed as the oil evaporated Particles would precipitate out In a uniform distribution covering the slide with a IDm of subshymicron particles

Figure 8 shows the lnterfaclal tension as measured by the duNuoy ring method decreases as the aromatic content of the oil Increases It would appear that changes In lnterfaclal tension have little to do with the emulslflcatlon behaviour of the model oils

It would be expected that the alkanearornatlc ratio will have some effect on the contact angle between the particles and the Interface since oil composition will Influence the wettability of particles A simple experiment was performed which demonstrated the Importance of the alkanearornatlc ratio on the contact angle A series of oils of the same alkanearomatlc composition as prevtously tested were prepared and subjected to the emulsification test but Instead of asphaltenes graphite powder (005 gml) was used as the emulsifying agent Graphite Is Insoluble In both xylene and paraffin oil Therefore there wDI

I

93

be no changes In Its physical form The results from this experiment showed that stable emulsions only formed at an alkanearomatlc ratio of 11 Unfortunately facRltles to measure contact angle were not avaRable and therefore this effect of alkanearomatlc ratio upon contact angle and In tum upon emulsification could not be substantiated The results from this experiment Indicate that this Influence upon contact angle Is an extremely Important determinant for emulsification by solid partldes

94

Figure 3 Fo versus i alkane at different asphaltene concentrations

j

obull

middot

middot 0

I middot

0

middot

middot

~ elkane 1n oil

middotmiddotmiddotmiddot~middotmiddotmiddot 01 gL ---0--- 0 05 gllllmiddotmiddotmiddot-0middotmiddotmiddot 0 OZ5 ol- --9-- omiddot01 om1

Figure 4 F t inal versus X alkane

o

middot

ii

~

I middot I

lI

middot

I I middot--middot-9-middot

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n bull bull bull bull shy

X alkane

middot middot middot

~1 -~ bull ~

$ 1117

0 ~y

f

- f

~ ~middot

ff ~

E

alalTmppRwuC

TwpsfoFimcFefral

R(frofa

middot V

middot si

o to 025 025 to 075 075 to 1

91

xperimental The model offs us0d In these experiments consisted ol three main compotients 1 an

kane component 2 an aromatic component and 3 the potential emulsifying agent(s) The kanes tested were n-octane n-tetradecane a light paraffin oil and a heavy paraffin on he aromatics used were p-xylene phenyl octane dimethyl naphthalene and diphenyl ethane Asphaltenes were precipitated from a California crude oQ (API gravity 11) using nshyentane at a pentane to oil ratio of 401 (Speight 1981) Asphaltenes and resins were recipitated together from the California crude using ethyl acetate (Neumann et al 1981) esins were precipitated from de-asphaltized oil using ethyl acetate Precipitated materials ere collected on a 045 micron filter dried by a nitrogen purge and stored in the dark nder a nitrogen headspace Other materials used were paraffin wax (Aldrich Chemical ompany melting point SltHgt1degC) and graphite powder (Aldrich Chemical Company)

Model oUs were prepared by adding the emulsifying agent to the aromatic component he miXture was vigorously shaken for one hour on a shaker table The alkane component as then added and the mixture was again shaken for one hour 30 ml of the oK was oured into a 500 ml Fieaker containing 300 ml of artificial seawater The Fieaker was ealed and allowed to stand for approximately 20 hours before undergoing the emulsion rmation and stability test described by Bobra (1989) Briefly the test involves rotating the eaker at 65 rpm for one hour and then allowing the mixture to rest for one-half hour before easuring the size of the emulsion and the fraction of oU that emulsifies F The rotationrest

ycle Is repeated three more times An indiction of an ois tendency to emulsify is given by the fraction of oil that emulsifies when F Is extrapolated to time zero The stability of the0 mulsion is obtained by allowing the emulsion to rest for 24 hours and then measuring the action of oQ that remains in the emulsion F1 The water content of stable emulsions were so measured The following criteria set by Mackay et al(1982) classify emulsion behaviour

o to 025 025 to 075

Emulsion formation tendency

not likely fairly likely

very likely

Emulsion stabRity

unstable fairly stable very stable

The rheol

o75 to 1

ogical properties of stable emulsions were measured using a Haake RV20 otovlscometer equipped with a MSSV1 senSOf The programmed shear rate was o to 100 81

) In 10 minutes and 100 too (s-1) In 10 minutes The yield point values were detennlned om the Increasing shear rate curves The yield point can be considered to be an indlctlon the solid character of the emulsion It Is the force required to change the emulsion from solid to a flowing llquid For the sake of comparison under these same shear conditions

mayonnaise has a yield point of 114 Pa and two samples of 18 day-old mousse from the aldez spRI had values of 17 and 121 Pa

The size distribution ol water droplets were determined using a lab-Tee 1000 particle ze analyser and a Zeiss Axloskop lightfluorescence microscope

AR experiments were conducted at 15degC

92

Results and Discussion Effect ofmiddotAsohaltenes

Figures 3 to 6 show the Influence of the alkanearomatlc ratio and the Influence of increasing asphaltene content upon F

0 F1 water content and yield point The alkane

component Is heavy paraffin oil and the aromatic component Is xylene At an asphaltene concentration of 001 gml (1 ) no stable emulsions are formed At an asphaltene concentration of 0025 gml (25) the model oil has a tendency to emulsify (F =1) when

0

the oil Is 50 alkane and 50 aromatic and this emulsion Is only marginally stable (F=05) When the asphaltene content is Increased to 005 gml (5) stable emulsions are readily produced for oils containing 50 to 95 alkane component Likewise at an asphaltene concentration of 01 gml stable emulsions form for oUs containing 35 to a0 alkane Figure 5 shows that the water content of stable emulsions are between 80 to 90 The change in yield point as a function of alkane composition Figure 6 clearly shows that there Is a maximum value for each concentration of asphaltenes For oDs containing 5 asphaltenes this maxima occurs at 80 alkane and for oils containing 10 asphaltenes this occurs at 70

The results illustrate several important points concerning the influence of the alkanearomatic ratio upon an oils emulsification behaviour The amount of asphaltenes precipitated out of solution is determined by the alkane concentration Figure 7 shows the percent of asphaltenes precipitated as a function of alkane concentration for an oU containing 5 asphaltenes Clearly the amount precipitated Is important in determining the emulsification of the oil But it would also appear that the alkanearornatlc ratio controls other factors which are involved In emulsification The size of the asphaltene particles are determined by the alkanearornatlc ratio and this Is particularly true given the method by which these model oils were prepared Asphaltenes were first dissolved In the appropriate quantity of xylene and then the paraffin oil was added which causes the asphaltenes to precipitate out of solution When the model on Is predominantly composed of paraffin oil this precipitation mechanism does not occur and the asphaltene particles maintain their original dimensions ( gt 1 microns) These particles are too large to effectively stabilize water droplets This was confirmed by microscopic examination of the oils When model oils which were prone to emulsification were examined under the microscope Individual particle sizes could not be accurately determined because the particles were at the limit of resolution (lt05 microns) But it could be seen that collectively the particles formed a continuous layer of finely dispersed particulates which are closely packed together As the alkane content of the oU Increased the particles became more tightly packed and Increased In size An Interesting phenomenon was observed when model oils with high aromatic content were viewed under the microscope The actual precipitation of asphaltenes could be observed as the oil evaporated Particles would precipitate out In a uniform distribution covering the slide with a IDm of subshymicron particles

Figure 8 shows the lnterfaclal tension as measured by the duNuoy ring method decreases as the aromatic content of the oil Increases It would appear that changes In lnterfaclal tension have little to do with the emulslflcatlon behaviour of the model oils

It would be expected that the alkanearornatlc ratio will have some effect on the contact angle between the particles and the Interface since oil composition will Influence the wettability of particles A simple experiment was performed which demonstrated the Importance of the alkanearornatlc ratio on the contact angle A series of oils of the same alkanearomatlc composition as prevtously tested were prepared and subjected to the emulsification test but Instead of asphaltenes graphite powder (005 gml) was used as the emulsifying agent Graphite Is Insoluble In both xylene and paraffin oil Therefore there wDI

I

93

be no changes In Its physical form The results from this experiment showed that stable emulsions only formed at an alkanearomatlc ratio of 11 Unfortunately facRltles to measure contact angle were not avaRable and therefore this effect of alkanearomatlc ratio upon contact angle and In tum upon emulsification could not be substantiated The results from this experiment Indicate that this Influence upon contact angle Is an extremely Important determinant for emulsification by solid partldes

94

Figure 3 Fo versus i alkane at different asphaltene concentrations

j

obull

middot

middot 0

I middot

0

middot

middot

~ elkane 1n oil

middotmiddotmiddotmiddot~middotmiddotmiddot 01 gL ---0--- 0 05 gllllmiddotmiddotmiddot-0middotmiddotmiddot 0 OZ5 ol- --9-- omiddot01 om1

Figure 4 F t inal versus X alkane

o

middot

ii

~

I middot I

lI

middot

I I middot--middot-9-middot

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n bull bull bull bull shy

X alkane

92

Results and Discussion Effect ofmiddotAsohaltenes

Figures 3 to 6 show the Influence of the alkanearomatlc ratio and the Influence of increasing asphaltene content upon F

0 F1 water content and yield point The alkane

component Is heavy paraffin oil and the aromatic component Is xylene At an asphaltene concentration of 001 gml (1 ) no stable emulsions are formed At an asphaltene concentration of 0025 gml (25) the model oil has a tendency to emulsify (F =1) when

0

the oil Is 50 alkane and 50 aromatic and this emulsion Is only marginally stable (F=05) When the asphaltene content is Increased to 005 gml (5) stable emulsions are readily produced for oils containing 50 to 95 alkane component Likewise at an asphaltene concentration of 01 gml stable emulsions form for oUs containing 35 to a0 alkane Figure 5 shows that the water content of stable emulsions are between 80 to 90 The change in yield point as a function of alkane composition Figure 6 clearly shows that there Is a maximum value for each concentration of asphaltenes For oDs containing 5 asphaltenes this maxima occurs at 80 alkane and for oils containing 10 asphaltenes this occurs at 70

The results illustrate several important points concerning the influence of the alkanearomatic ratio upon an oils emulsification behaviour The amount of asphaltenes precipitated out of solution is determined by the alkane concentration Figure 7 shows the percent of asphaltenes precipitated as a function of alkane concentration for an oU containing 5 asphaltenes Clearly the amount precipitated Is important in determining the emulsification of the oil But it would also appear that the alkanearornatlc ratio controls other factors which are involved In emulsification The size of the asphaltene particles are determined by the alkanearornatlc ratio and this Is particularly true given the method by which these model oils were prepared Asphaltenes were first dissolved In the appropriate quantity of xylene and then the paraffin oil was added which causes the asphaltenes to precipitate out of solution When the model on Is predominantly composed of paraffin oil this precipitation mechanism does not occur and the asphaltene particles maintain their original dimensions ( gt 1 microns) These particles are too large to effectively stabilize water droplets This was confirmed by microscopic examination of the oils When model oils which were prone to emulsification were examined under the microscope Individual particle sizes could not be accurately determined because the particles were at the limit of resolution (lt05 microns) But it could be seen that collectively the particles formed a continuous layer of finely dispersed particulates which are closely packed together As the alkane content of the oU Increased the particles became more tightly packed and Increased In size An Interesting phenomenon was observed when model oils with high aromatic content were viewed under the microscope The actual precipitation of asphaltenes could be observed as the oil evaporated Particles would precipitate out In a uniform distribution covering the slide with a IDm of subshymicron particles

Figure 8 shows the lnterfaclal tension as measured by the duNuoy ring method decreases as the aromatic content of the oil Increases It would appear that changes In lnterfaclal tension have little to do with the emulslflcatlon behaviour of the model oils

It would be expected that the alkanearornatlc ratio will have some effect on the contact angle between the particles and the Interface since oil composition will Influence the wettability of particles A simple experiment was performed which demonstrated the Importance of the alkanearornatlc ratio on the contact angle A series of oils of the same alkanearomatlc composition as prevtously tested were prepared and subjected to the emulsification test but Instead of asphaltenes graphite powder (005 gml) was used as the emulsifying agent Graphite Is Insoluble In both xylene and paraffin oil Therefore there wDI

I

93

be no changes In Its physical form The results from this experiment showed that stable emulsions only formed at an alkanearomatlc ratio of 11 Unfortunately facRltles to measure contact angle were not avaRable and therefore this effect of alkanearomatlc ratio upon contact angle and In tum upon emulsification could not be substantiated The results from this experiment Indicate that this Influence upon contact angle Is an extremely Important determinant for emulsification by solid partldes

94

Figure 3 Fo versus i alkane at different asphaltene concentrations

j

obull

middot

middot 0

I middot

0

middot

middot

~ elkane 1n oil

middotmiddotmiddotmiddot~middotmiddotmiddot 01 gL ---0--- 0 05 gllllmiddotmiddotmiddot-0middotmiddotmiddot 0 OZ5 ol- --9-- omiddot01 om1

Figure 4 F t inal versus X alkane

o

middot

ii

~

I middot I

lI

middot

I I middot--middot-9-middot

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n bull bull bull bull shy

X alkane

I

93

be no changes In Its physical form The results from this experiment showed that stable emulsions only formed at an alkanearomatlc ratio of 11 Unfortunately facRltles to measure contact angle were not avaRable and therefore this effect of alkanearomatlc ratio upon contact angle and In tum upon emulsification could not be substantiated The results from this experiment Indicate that this Influence upon contact angle Is an extremely Important determinant for emulsification by solid partldes

94

Figure 3 Fo versus i alkane at different asphaltene concentrations

j

obull

middot

middot 0

I middot

0

middot

middot

~ elkane 1n oil

middotmiddotmiddotmiddot~middotmiddotmiddot 01 gL ---0--- 0 05 gllllmiddotmiddotmiddot-0middotmiddotmiddot 0 OZ5 ol- --9-- omiddot01 om1

Figure 4 F t inal versus X alkane

o

middot

ii

~

I middot I

lI

middot

I I middot--middot-9-middot

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n bull bull bull bull shy

X alkane

94

Figure 3 Fo versus i alkane at different asphaltene concentrations

j

obull

middot

middot 0

I middot

0

middot

middot

~ elkane 1n oil

middotmiddotmiddotmiddot~middotmiddotmiddot 01 gL ---0--- 0 05 gllllmiddotmiddotmiddot-0middotmiddotmiddot 0 OZ5 ol- --9-- omiddot01 om1

Figure 4 F t inal versus X alkane

o

middot

ii

~

I middot I

lI

middot

I I middot--middot-9-middot

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n bull bull bull bull shy

X alkane

95

a-I

+ I

H

0 sofN I I M

=t ~T

~T

=t

~ i~ 0

middott poundfij ~ -it)

~middot - middot~-

f~~middot

1 i

I middot~t _

bull I T 5 ~

bull ~ bull

Flgure 5 ltOater content vs II alkane

middotX middotmiddotmiddotmiddotmiddotxmiddotmiddot

I i

I

I yen I 75 bullO ~

Figure 6

X alkane

middotmiddotmiddotmiddotJCmiddotmiddotmiddot o s gi --0-- 005 g_ middot--o-- 0 025 gm( ___ 001 gllt_

Y1ela point vs X alkane

-----olt-----lt--ltO--~-----ltx~Cbullbullbullbull middot Gmiddot-middotmiddot -middot middotmiddotmiddotmiddot- 1 bullbullbull bullbullbull bullbullbullbullbull CTmiddot

bull bull bullbull

X e lkane

bullbull

I

0

96

Ftgure 7 X asphaltenes prcc1pitatcd versus= alkane tn 011 mociel 011 heavy paratftn oilxylene containing O OS gmL esphaltcnes

~ ~bullwbullw

O bullu

c Q

w x

c 0

bullc gt-bull -zshy-middotu e

bullc w c ~

~

~

raquo

obull bull n oo

a lkane

Figure 9 nter-facial Tension vs X alkane for heavy paraffin oilxylene model oil

~ T

=tT 0 01 gmL asphaltenesT T 0025 gmL asphaltenes

raquoT

0

x

x 0 0

x Q

X llllkane tn oil

0

0

bull J

i-

lt

~~

~~

lt

middot ~4s middot-

97

Effect of Aromatic Comoonent Figures 9 to 12 show F0 F1 watercontent and yield point versus percent alkane for five

different model oils coosisting of heavy paraffin oil (HPO) 5 asphaltenes and five different aromatic solvents These being xylene phenyl octane (PO) dimethyl naphthalene (DMN) dlphenyl methane (DPM) and an equal volume mixture of the four solvents (MIX) As the results Illustrate the aromatic component has a profound effect upon the emulsification behaviour ol the oil This can be best explained In terms of the Hildebrand solubility

parameter a (units MPa 112) These parameters can be either determined experimentally

calculated or found in reference text (Barton 1983) The values for these parameters are 247 for the asphaltenes 150 for heavy paraffin oil 180 for xylene 175 for phenyl octane 210 for dimethyl naphthalene 195 for diphenylmethane and 190 for the mixture From the Hildebrand-Scatchard equation it can be seen that the amount of asphaltenes soluble In oil

X8

is controlled by the term (a -a)2 As (a -os)2 increases the amount of asphaltenes

8 8

soluble In on decreases and any excess asphaltenes will precipitate Therefore the likelihood of producing a stable emulsion increases

Figures 13 to 16 show F0 F1 water content and yield point as a function of (08-0)2 for

the five model oils It can be seen that most stable emulsions are formed when (08-0 has

a value between 60 and 90 Stable emulsions are not formed above a (a -a)2 value of 908

In these experiments because as previously mentioned the asphaltene particles are too large to stabilize the water droplets This is an artnact of the experimental design It is expected that stable emulsions would form above this value n the chosen alkanearomatic pairs allowed for the precipitation of asphaltenes to occur within the oil thus providing particles which are an effective size

The solvency power of the model oil bullmiddot controls the amount of asphaltenes that

precipitate If the solvency strength of the aromatic component is decreased asphaltenes wHI be less soluble in the oil This is shown In Figures 9 and 10 the oil containing phenyl

octane (the lowest a value of the aromatics tested) has the largest range over which stable

emulsions are formed

bullbull

98

F1gure 9 Fo vs X alkane

different aromat1c components

)

0

middot

middot

_0 ~

_

o o

-

_Dmiddotmiddotmiddotmiddotmiddot i middotmiddotmiddotmiddotmiddotmiddotmiddotmiddot I I)

I I I

I I I

A

I __) I ---r

- ----- I I i

i middot II ~ I

_ ___ j

bull bull m bull - - bull bull bull - - - M R bull - - - - ~ X alkane

~ HOxylene middotmiddot middot0middotmiddotmiddot rPOPO -6-- rODMN --0-- H011x -9-- HPOOPM

Figure 10 F f 1nal vs alkane

PmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotDmiddotmiddotmiddotmiddot

o I I

ltgt---f-i o

Ii j

I f f

II

fl bullc ~ I middotI I~ ~ -------r1 i

----- bull

- j

i i I

I I II middot I J

0

bull

X alkano

-~

bullbull

bull bull

ll

99

Ftgure 11 Water content vs X alkane

r--------------~-

1 _--A- - bull 0 middot middotmiddotmiddotlrmiddotmiddotmiddotmiddotmiddotmiddotmiddotr~~~middot~~-

I I middotmiddot middot middot ~I bull I II 1 middot

bull I c bull

I I II 1~middotI j ~

bull l ~

middot1 j I ~1

-middot I I I middot I f t middot l 1 I

+------------~----- j

0 deg m deg - bull bull bull - bull bull bull - N - deg -X alkane

---0-- li01eylene middotmiddotmiddotmiddot0middotmiddotmiddot J90PO -tr- HOOMN ---gt--- H01111iJ --fl- HPOOPM

Figure 12 Y1eld po1nt vs X alkane

~ I I I I I

o I I

~~ I

J ~ I )

I

i 11 r-

middot I -

deg II lt -I i ) --

_Ii ~~ a ~middot~ I --__ -

---- df-_L Omiddot hmiddot9-_ -bull middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot -- -------_-_----e -~amps-~

o o deg g bull bull bull bull bull bull bull bull bull U N n bull M deg H

X alkane

bull

shy

shy

bullbull

bull bull

100

bull

o t

0 bull

0 0 ~

obull

ogt

obull

0 I

00

bullo

obull

obull

- 5 obull ~

~ ogt

F1gure 13 Fo vs Oa-Os) -2 for different aromatic components

bullmiddot--middotmiddotmiddotmiddot----tgtmiddotmiddotmiddot-middotmiddotmiddotmiddot Jilmiddotf gt-+1~gt---f-HJ-- 8-S-rtt-lt~I

I _ El - 1middot 1

bull

1 1 I 1middot1 ~~

l I ~ -- Ji ~~ r------ -- ~~

I I I

i jltJo V--middot+-- shy

70 7S IO as to 9

Coa-Os) middotz

eo bull5 90

--0-- HPOxy lene middotmiddotmiddotmiddot0middotmiddotmiddot HPOPO middotmiddot-ampmiddot-middot HPOQMN ---1J-- HPOOPM --ltgt- HPOHIX

Figure 14 F f 1nal vs (Oa-Osl -2

~-----------e-_t---4~-tl-t-ltB_euro-t~_

I I

I lJ I

i j i I J

--- - ---------+-I 1 - i f

ci 6-------------------LJ~--

iiI

shy

0

0

) -----

101 Figure 15 Wampter content vs (Oa-Osl middot2

r-------------- ~--middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot -Je~

~ ~~-bull

Ibull ~ ) middot~~middot

middot bull I ~~ bullbull I

~ I

y ~ A ~ If

CJmiddotmiddotmiddotmiddotmiddotli-------------------middotlf---l- bullbull middot (Oa-Osl middot2

--0--- HPOxylene middotmiddotmiddotmiddot0 HPOPO middotmiddotmiddotmiddott--middot HPOOMN --9-- HPOOPM --gt--- HPOMIX

Figure 16 Yield point vs (Ca-Os) middot2

0I_

middot ~

I I I

iI I middot II

~ ~ Ij I

bullbullAi _ - --

i _~--_middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

----- J-middot6-------------li---~---_ ------shy (Oa-Os) -2

i

0

102

Effect of AJkane Component

The effect of using different alkane solvents as the precipitation medium for asphaltenes has been studied by Long 1979) Speight and Moschopedls (1979) Their findings indicate that as the carbon number of the alkane solvent Increases the amount ol asphaltenes which precipitate decreases and that the composition of the precipitated material also changes Higher alkane solvents were shown to yield asphal1enes which have a higher degree of aromaticity a higher proportion ol heteroatoms a higher degree ol polarity and higher molecular weights

Figures 17 to 20 show F0 F1 water content and yield point versus percent alkane for four different model oils consisting of xylene (XYL) 5 asphal1enes and four different alkane

components n-octane (OCT)(o= 154) n-tetradecane (C14)o= 163) light paraffin oil

(lPO)(o= 147) and heavy paraffin oR (HPO)(o= 150) The results show that the model oils

containing the paraffin oils (a complex mixture of alkanes) have a stonger tendency to form stable emulsions than do the oils made with the n-alkane solvents The emulsions formed by oil containing the heavy paraffin oU are structurally stronger (higher yield points) than those formed by the light paraffin oil When the emulsification behaviour of the model oils containing octane and tetradecane are compared the tetradecanexylene oR has a stronger tendency to form stable emulsions (higher F1 values) but these emulsions have less structural strength Qoover yield point)

Comoarlson of Asohaltenes from Different Crudes Asphaltenes from different oils will differ in elemental composition structure and molecular

weight Therefore the solubility precipitation behaviour of asphal1enes from different sources could potentially differ The experiments using the heavy paraffin oDxylene oil containing 5 asphal1enes were repeated for asphaltenes extracted from Prudhoe Bay crude oR Overall the emulsification behaviour was very simflar to the California crude asphaltenes The asphal1enes from the California crude were slightly more effective emulsifiers

i I j

)

)

-

~o

0

103

Figure 17 Fo versus x alkane

deg Cli f terent alkane components

middot I

I

I ~ y

I I I

rfmiddot I

I I

I0 I

III I

I]

I

I bull I middot

middot 0 -L GI_

gt_ x alkane

fi bull

--0- HPOXYL1 middotmiddotmiddotmiddot9middotmiddotmiddot OCTICYL -)-- LPOXYLmiddotmiddot-middotmiddot -0- C1ltXY_

tmiddot t

Figure 18 F final VS x alkane ~middot ~

1r--~- -----iif -OrI middot~middot I

f I I I

Imiddot1 I I

imiddotmiddot1 I ~ IY_

I I I M

bull I I ~

s I middotI I

I I

I -j

0

I v 9middot

middotmiddotmiddotmiddotmiddotmiddotmiddot amp--- bull bullbull ~ so

bull alkane

~ Lbullubull

middot~

0

O

104

~1gure 19 ~amptcr Content vs X alkane

middotmiddot

I middot1~I

middotI I middot

middot I_

bull bull bull bull bull bull bull bull bull bull bull ~ raquo n bull bull ~ bull X akane

--0-- MPOXYL middot-middotbull9middotmiddotmiddot OCTXV --0-- LPOXlL ~C1AXYL

Figure 20 Yield Po1nt vs X alkane

9

I

I bull -- ~-------~-

bull~

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n n bull bull bull bull

X alkane

0

shy

shy

~ 105

ll

t J

z

Effect o Resins Flgures 21 to 24 present the emulsification behaviour for model oils where the emulsifying

agents are 1 asphaltenes 2 resins and 3 asphaltenes and reslns together The results show that stable emulsions can be produced by resins alone Although the range of alkanearomatlc ratios over which stable emulsions are produced ls small these emulsions have greater structural strength than emulsions stabilized by asphaltenes When asphaltenes and resins are both present the range over which stable emulsions are formed Is larger than either resins or asphaltenes alone But emulsions stabUlzed by the asphalteneresin combination lack the maxima peak in yield point

Effect of Wax Figures 25 to 28 show the effect of adding 005 and 01 gml of wax to a model oD

containing 1 asphaltenes The model oil containing 1 asphaltenes has no tendency to form stable emulsions but the addition of wax increases the emulsification tendency at all alkanearomatlc ratios The range of alkanearornatlc ratios over which stable emulsions are produced increases as wax content increases Increasing the wax content also Increased the mechanical strength of the emulsions Similar results were obtained when wax was added to the oil containing 25 asphaltenes

The effect of adding 01 gml of wax to the model oH containing 5 asphaltenes Is shown in Figures 29 to 32 The addition of wax has little effect upon F

0 F1 and water content

but decreases the maxima yield point of the emulsions formed Figures 33 to 36 show the effect of increasing asphaltene content upon an oD containing

005 gml grams of wax Model ons containing only wax as the emulslfyfng agent had no tendency to emulsify As the Figures Blustrate the addition of asphaltenes results in the formation of stable emulsions As the concentration of asphaltenes ls Increased the oils have a greater tendency to produce stable emulsions

i

bull bull 0

106

Flgure 21 Fo versus alkane effect of res1ns

LO

0

0 bull

middot

0 0-

i e

i

middotmiddotOmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotdl 100 X alkane

~x~ o 05 g9L asphaltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 0 05 g_ resins ----6bullmiddot O 05 9_ asphaltenes

Figure 22 F f1nal vs alkane

e ~ 0

lmiddot

0 bull

cbull

shy ci u

~ ooo~~IO~middot--+--+---t--+--~

S 10 ISbull

X alkane

c

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

bullbull

I

0

96

Ftgure 7 X asphaltenes prcc1pitatcd versus= alkane tn 011 mociel 011 heavy paratftn oilxylene containing O OS gmL esphaltcnes

~ ~bullwbullw

O bullu

c Q

w x

c 0

bullc gt-bull -zshy-middotu e

bullc w c ~

~

~

raquo

obull bull n oo

a lkane

Figure 9 nter-facial Tension vs X alkane for heavy paraffin oilxylene model oil

~ T

=tT 0 01 gmL asphaltenesT T 0025 gmL asphaltenes

raquoT

0

x

x 0 0

x Q

X llllkane tn oil

0

0

bull J

i-

lt

~~

~~

lt

middot ~4s middot-

97

Effect of Aromatic Comoonent Figures 9 to 12 show F0 F1 watercontent and yield point versus percent alkane for five

different model oils coosisting of heavy paraffin oil (HPO) 5 asphaltenes and five different aromatic solvents These being xylene phenyl octane (PO) dimethyl naphthalene (DMN) dlphenyl methane (DPM) and an equal volume mixture of the four solvents (MIX) As the results Illustrate the aromatic component has a profound effect upon the emulsification behaviour ol the oil This can be best explained In terms of the Hildebrand solubility

parameter a (units MPa 112) These parameters can be either determined experimentally

calculated or found in reference text (Barton 1983) The values for these parameters are 247 for the asphaltenes 150 for heavy paraffin oil 180 for xylene 175 for phenyl octane 210 for dimethyl naphthalene 195 for diphenylmethane and 190 for the mixture From the Hildebrand-Scatchard equation it can be seen that the amount of asphaltenes soluble In oil

X8

is controlled by the term (a -a)2 As (a -os)2 increases the amount of asphaltenes

8 8

soluble In on decreases and any excess asphaltenes will precipitate Therefore the likelihood of producing a stable emulsion increases

Figures 13 to 16 show F0 F1 water content and yield point as a function of (08-0)2 for

the five model oils It can be seen that most stable emulsions are formed when (08-0 has

a value between 60 and 90 Stable emulsions are not formed above a (a -a)2 value of 908

In these experiments because as previously mentioned the asphaltene particles are too large to stabilize the water droplets This is an artnact of the experimental design It is expected that stable emulsions would form above this value n the chosen alkanearomatic pairs allowed for the precipitation of asphaltenes to occur within the oil thus providing particles which are an effective size

The solvency power of the model oil bullmiddot controls the amount of asphaltenes that

precipitate If the solvency strength of the aromatic component is decreased asphaltenes wHI be less soluble in the oil This is shown In Figures 9 and 10 the oil containing phenyl

octane (the lowest a value of the aromatics tested) has the largest range over which stable

emulsions are formed

bullbull

98

F1gure 9 Fo vs X alkane

different aromat1c components

)

0

middot

middot

_0 ~

_

o o

-

_Dmiddotmiddotmiddotmiddotmiddot i middotmiddotmiddotmiddotmiddotmiddotmiddotmiddot I I)

I I I

I I I

A

I __) I ---r

- ----- I I i

i middot II ~ I

_ ___ j

bull bull m bull - - bull bull bull - - - M R bull - - - - ~ X alkane

~ HOxylene middotmiddot middot0middotmiddotmiddot rPOPO -6-- rODMN --0-- H011x -9-- HPOOPM

Figure 10 F f 1nal vs alkane

PmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotDmiddotmiddotmiddotmiddot

o I I

ltgt---f-i o

Ii j

I f f

II

fl bullc ~ I middotI I~ ~ -------r1 i

----- bull

- j

i i I

I I II middot I J

0

bull

X alkano

-~

bullbull

bull bull

ll

99

Ftgure 11 Water content vs X alkane

r--------------~-

1 _--A- - bull 0 middot middotmiddotmiddotlrmiddotmiddotmiddotmiddotmiddotmiddotmiddotr~~~middot~~-

I I middotmiddot middot middot ~I bull I II 1 middot

bull I c bull

I I II 1~middotI j ~

bull l ~

middot1 j I ~1

-middot I I I middot I f t middot l 1 I

+------------~----- j

0 deg m deg - bull bull bull - bull bull bull - N - deg -X alkane

---0-- li01eylene middotmiddotmiddotmiddot0middotmiddotmiddot J90PO -tr- HOOMN ---gt--- H01111iJ --fl- HPOOPM

Figure 12 Y1eld po1nt vs X alkane

~ I I I I I

o I I

~~ I

J ~ I )

I

i 11 r-

middot I -

deg II lt -I i ) --

_Ii ~~ a ~middot~ I --__ -

---- df-_L Omiddot hmiddot9-_ -bull middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot -- -------_-_----e -~amps-~

o o deg g bull bull bull bull bull bull bull bull bull U N n bull M deg H

X alkane

bull

shy

shy

bullbull

bull bull

100

bull

o t

0 bull

0 0 ~

obull

ogt

obull

0 I

00

bullo

obull

obull

- 5 obull ~

~ ogt

F1gure 13 Fo vs Oa-Os) -2 for different aromatic components

bullmiddot--middotmiddotmiddotmiddot----tgtmiddotmiddotmiddot-middotmiddotmiddotmiddot Jilmiddotf gt-+1~gt---f-HJ-- 8-S-rtt-lt~I

I _ El - 1middot 1

bull

1 1 I 1middot1 ~~

l I ~ -- Ji ~~ r------ -- ~~

I I I

i jltJo V--middot+-- shy

70 7S IO as to 9

Coa-Os) middotz

eo bull5 90

--0-- HPOxy lene middotmiddotmiddotmiddot0middotmiddotmiddot HPOPO middotmiddot-ampmiddot-middot HPOQMN ---1J-- HPOOPM --ltgt- HPOHIX

Figure 14 F f 1nal vs (Oa-Osl -2

~-----------e-_t---4~-tl-t-ltB_euro-t~_

I I

I lJ I

i j i I J

--- - ---------+-I 1 - i f

ci 6-------------------LJ~--

iiI

shy

0

0

) -----

101 Figure 15 Wampter content vs (Oa-Osl middot2

r-------------- ~--middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot -Je~

~ ~~-bull

Ibull ~ ) middot~~middot

middot bull I ~~ bullbull I

~ I

y ~ A ~ If

CJmiddotmiddotmiddotmiddotmiddotli-------------------middotlf---l- bullbull middot (Oa-Osl middot2

--0--- HPOxylene middotmiddotmiddotmiddot0 HPOPO middotmiddotmiddotmiddott--middot HPOOMN --9-- HPOOPM --gt--- HPOMIX

Figure 16 Yield point vs (Ca-Os) middot2

0I_

middot ~

I I I

iI I middot II

~ ~ Ij I

bullbullAi _ - --

i _~--_middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

----- J-middot6-------------li---~---_ ------shy (Oa-Os) -2

i

0

102

Effect of AJkane Component

The effect of using different alkane solvents as the precipitation medium for asphaltenes has been studied by Long 1979) Speight and Moschopedls (1979) Their findings indicate that as the carbon number of the alkane solvent Increases the amount ol asphaltenes which precipitate decreases and that the composition of the precipitated material also changes Higher alkane solvents were shown to yield asphal1enes which have a higher degree of aromaticity a higher proportion ol heteroatoms a higher degree ol polarity and higher molecular weights

Figures 17 to 20 show F0 F1 water content and yield point versus percent alkane for four different model oils consisting of xylene (XYL) 5 asphal1enes and four different alkane

components n-octane (OCT)(o= 154) n-tetradecane (C14)o= 163) light paraffin oil

(lPO)(o= 147) and heavy paraffin oR (HPO)(o= 150) The results show that the model oils

containing the paraffin oils (a complex mixture of alkanes) have a stonger tendency to form stable emulsions than do the oils made with the n-alkane solvents The emulsions formed by oil containing the heavy paraffin oU are structurally stronger (higher yield points) than those formed by the light paraffin oil When the emulsification behaviour of the model oils containing octane and tetradecane are compared the tetradecanexylene oR has a stronger tendency to form stable emulsions (higher F1 values) but these emulsions have less structural strength Qoover yield point)

Comoarlson of Asohaltenes from Different Crudes Asphaltenes from different oils will differ in elemental composition structure and molecular

weight Therefore the solubility precipitation behaviour of asphal1enes from different sources could potentially differ The experiments using the heavy paraffin oDxylene oil containing 5 asphal1enes were repeated for asphaltenes extracted from Prudhoe Bay crude oR Overall the emulsification behaviour was very simflar to the California crude asphaltenes The asphal1enes from the California crude were slightly more effective emulsifiers

i I j

)

)

-

~o

0

103

Figure 17 Fo versus x alkane

deg Cli f terent alkane components

middot I

I

I ~ y

I I I

rfmiddot I

I I

I0 I

III I

I]

I

I bull I middot

middot 0 -L GI_

gt_ x alkane

fi bull

--0- HPOXYL1 middotmiddotmiddotmiddot9middotmiddotmiddot OCTICYL -)-- LPOXYLmiddotmiddot-middotmiddot -0- C1ltXY_

tmiddot t

Figure 18 F final VS x alkane ~middot ~

1r--~- -----iif -OrI middot~middot I

f I I I

Imiddot1 I I

imiddotmiddot1 I ~ IY_

I I I M

bull I I ~

s I middotI I

I I

I -j

0

I v 9middot

middotmiddotmiddotmiddotmiddotmiddotmiddot amp--- bull bullbull ~ so

bull alkane

~ Lbullubull

middot~

0

O

104

~1gure 19 ~amptcr Content vs X alkane

middotmiddot

I middot1~I

middotI I middot

middot I_

bull bull bull bull bull bull bull bull bull bull bull ~ raquo n bull bull ~ bull X akane

--0-- MPOXYL middot-middotbull9middotmiddotmiddot OCTXV --0-- LPOXlL ~C1AXYL

Figure 20 Yield Po1nt vs X alkane

9

I

I bull -- ~-------~-

bull~

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n n bull bull bull bull

X alkane

0

shy

shy

~ 105

ll

t J

z

Effect o Resins Flgures 21 to 24 present the emulsification behaviour for model oils where the emulsifying

agents are 1 asphaltenes 2 resins and 3 asphaltenes and reslns together The results show that stable emulsions can be produced by resins alone Although the range of alkanearomatlc ratios over which stable emulsions are produced ls small these emulsions have greater structural strength than emulsions stabilized by asphaltenes When asphaltenes and resins are both present the range over which stable emulsions are formed Is larger than either resins or asphaltenes alone But emulsions stabUlzed by the asphalteneresin combination lack the maxima peak in yield point

Effect of Wax Figures 25 to 28 show the effect of adding 005 and 01 gml of wax to a model oD

containing 1 asphaltenes The model oil containing 1 asphaltenes has no tendency to form stable emulsions but the addition of wax increases the emulsification tendency at all alkanearomatlc ratios The range of alkanearornatlc ratios over which stable emulsions are produced increases as wax content increases Increasing the wax content also Increased the mechanical strength of the emulsions Similar results were obtained when wax was added to the oil containing 25 asphaltenes

The effect of adding 01 gml of wax to the model oH containing 5 asphaltenes Is shown in Figures 29 to 32 The addition of wax has little effect upon F

0 F1 and water content

but decreases the maxima yield point of the emulsions formed Figures 33 to 36 show the effect of increasing asphaltene content upon an oD containing

005 gml grams of wax Model ons containing only wax as the emulslfyfng agent had no tendency to emulsify As the Figures Blustrate the addition of asphaltenes results in the formation of stable emulsions As the concentration of asphaltenes ls Increased the oils have a greater tendency to produce stable emulsions

i

bull bull 0

106

Flgure 21 Fo versus alkane effect of res1ns

LO

0

0 bull

middot

0 0-

i e

i

middotmiddotOmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotdl 100 X alkane

~x~ o 05 g9L asphaltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 0 05 g_ resins ----6bullmiddot O 05 9_ asphaltenes

Figure 22 F f1nal vs alkane

e ~ 0

lmiddot

0 bull

cbull

shy ci u

~ ooo~~IO~middot--+--+---t--+--~

S 10 ISbull

X alkane

c

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

0

bull J

i-

lt

~~

~~

lt

middot ~4s middot-

97

Effect of Aromatic Comoonent Figures 9 to 12 show F0 F1 watercontent and yield point versus percent alkane for five

different model oils coosisting of heavy paraffin oil (HPO) 5 asphaltenes and five different aromatic solvents These being xylene phenyl octane (PO) dimethyl naphthalene (DMN) dlphenyl methane (DPM) and an equal volume mixture of the four solvents (MIX) As the results Illustrate the aromatic component has a profound effect upon the emulsification behaviour ol the oil This can be best explained In terms of the Hildebrand solubility

parameter a (units MPa 112) These parameters can be either determined experimentally

calculated or found in reference text (Barton 1983) The values for these parameters are 247 for the asphaltenes 150 for heavy paraffin oil 180 for xylene 175 for phenyl octane 210 for dimethyl naphthalene 195 for diphenylmethane and 190 for the mixture From the Hildebrand-Scatchard equation it can be seen that the amount of asphaltenes soluble In oil

X8

is controlled by the term (a -a)2 As (a -os)2 increases the amount of asphaltenes

8 8

soluble In on decreases and any excess asphaltenes will precipitate Therefore the likelihood of producing a stable emulsion increases

Figures 13 to 16 show F0 F1 water content and yield point as a function of (08-0)2 for

the five model oils It can be seen that most stable emulsions are formed when (08-0 has

a value between 60 and 90 Stable emulsions are not formed above a (a -a)2 value of 908

In these experiments because as previously mentioned the asphaltene particles are too large to stabilize the water droplets This is an artnact of the experimental design It is expected that stable emulsions would form above this value n the chosen alkanearomatic pairs allowed for the precipitation of asphaltenes to occur within the oil thus providing particles which are an effective size

The solvency power of the model oil bullmiddot controls the amount of asphaltenes that

precipitate If the solvency strength of the aromatic component is decreased asphaltenes wHI be less soluble in the oil This is shown In Figures 9 and 10 the oil containing phenyl

octane (the lowest a value of the aromatics tested) has the largest range over which stable

emulsions are formed

bullbull

98

F1gure 9 Fo vs X alkane

different aromat1c components

)

0

middot

middot

_0 ~

_

o o

-

_Dmiddotmiddotmiddotmiddotmiddot i middotmiddotmiddotmiddotmiddotmiddotmiddotmiddot I I)

I I I

I I I

A

I __) I ---r

- ----- I I i

i middot II ~ I

_ ___ j

bull bull m bull - - bull bull bull - - - M R bull - - - - ~ X alkane

~ HOxylene middotmiddot middot0middotmiddotmiddot rPOPO -6-- rODMN --0-- H011x -9-- HPOOPM

Figure 10 F f 1nal vs alkane

PmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotDmiddotmiddotmiddotmiddot

o I I

ltgt---f-i o

Ii j

I f f

II

fl bullc ~ I middotI I~ ~ -------r1 i

----- bull

- j

i i I

I I II middot I J

0

bull

X alkano

-~

bullbull

bull bull

ll

99

Ftgure 11 Water content vs X alkane

r--------------~-

1 _--A- - bull 0 middot middotmiddotmiddotlrmiddotmiddotmiddotmiddotmiddotmiddotmiddotr~~~middot~~-

I I middotmiddot middot middot ~I bull I II 1 middot

bull I c bull

I I II 1~middotI j ~

bull l ~

middot1 j I ~1

-middot I I I middot I f t middot l 1 I

+------------~----- j

0 deg m deg - bull bull bull - bull bull bull - N - deg -X alkane

---0-- li01eylene middotmiddotmiddotmiddot0middotmiddotmiddot J90PO -tr- HOOMN ---gt--- H01111iJ --fl- HPOOPM

Figure 12 Y1eld po1nt vs X alkane

~ I I I I I

o I I

~~ I

J ~ I )

I

i 11 r-

middot I -

deg II lt -I i ) --

_Ii ~~ a ~middot~ I --__ -

---- df-_L Omiddot hmiddot9-_ -bull middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot -- -------_-_----e -~amps-~

o o deg g bull bull bull bull bull bull bull bull bull U N n bull M deg H

X alkane

bull

shy

shy

bullbull

bull bull

100

bull

o t

0 bull

0 0 ~

obull

ogt

obull

0 I

00

bullo

obull

obull

- 5 obull ~

~ ogt

F1gure 13 Fo vs Oa-Os) -2 for different aromatic components

bullmiddot--middotmiddotmiddotmiddot----tgtmiddotmiddotmiddot-middotmiddotmiddotmiddot Jilmiddotf gt-+1~gt---f-HJ-- 8-S-rtt-lt~I

I _ El - 1middot 1

bull

1 1 I 1middot1 ~~

l I ~ -- Ji ~~ r------ -- ~~

I I I

i jltJo V--middot+-- shy

70 7S IO as to 9

Coa-Os) middotz

eo bull5 90

--0-- HPOxy lene middotmiddotmiddotmiddot0middotmiddotmiddot HPOPO middotmiddot-ampmiddot-middot HPOQMN ---1J-- HPOOPM --ltgt- HPOHIX

Figure 14 F f 1nal vs (Oa-Osl -2

~-----------e-_t---4~-tl-t-ltB_euro-t~_

I I

I lJ I

i j i I J

--- - ---------+-I 1 - i f

ci 6-------------------LJ~--

iiI

shy

0

0

) -----

101 Figure 15 Wampter content vs (Oa-Osl middot2

r-------------- ~--middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot -Je~

~ ~~-bull

Ibull ~ ) middot~~middot

middot bull I ~~ bullbull I

~ I

y ~ A ~ If

CJmiddotmiddotmiddotmiddotmiddotli-------------------middotlf---l- bullbull middot (Oa-Osl middot2

--0--- HPOxylene middotmiddotmiddotmiddot0 HPOPO middotmiddotmiddotmiddott--middot HPOOMN --9-- HPOOPM --gt--- HPOMIX

Figure 16 Yield point vs (Ca-Os) middot2

0I_

middot ~

I I I

iI I middot II

~ ~ Ij I

bullbullAi _ - --

i _~--_middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

----- J-middot6-------------li---~---_ ------shy (Oa-Os) -2

i

0

102

Effect of AJkane Component

The effect of using different alkane solvents as the precipitation medium for asphaltenes has been studied by Long 1979) Speight and Moschopedls (1979) Their findings indicate that as the carbon number of the alkane solvent Increases the amount ol asphaltenes which precipitate decreases and that the composition of the precipitated material also changes Higher alkane solvents were shown to yield asphal1enes which have a higher degree of aromaticity a higher proportion ol heteroatoms a higher degree ol polarity and higher molecular weights

Figures 17 to 20 show F0 F1 water content and yield point versus percent alkane for four different model oils consisting of xylene (XYL) 5 asphal1enes and four different alkane

components n-octane (OCT)(o= 154) n-tetradecane (C14)o= 163) light paraffin oil

(lPO)(o= 147) and heavy paraffin oR (HPO)(o= 150) The results show that the model oils

containing the paraffin oils (a complex mixture of alkanes) have a stonger tendency to form stable emulsions than do the oils made with the n-alkane solvents The emulsions formed by oil containing the heavy paraffin oU are structurally stronger (higher yield points) than those formed by the light paraffin oil When the emulsification behaviour of the model oils containing octane and tetradecane are compared the tetradecanexylene oR has a stronger tendency to form stable emulsions (higher F1 values) but these emulsions have less structural strength Qoover yield point)

Comoarlson of Asohaltenes from Different Crudes Asphaltenes from different oils will differ in elemental composition structure and molecular

weight Therefore the solubility precipitation behaviour of asphal1enes from different sources could potentially differ The experiments using the heavy paraffin oDxylene oil containing 5 asphal1enes were repeated for asphaltenes extracted from Prudhoe Bay crude oR Overall the emulsification behaviour was very simflar to the California crude asphaltenes The asphal1enes from the California crude were slightly more effective emulsifiers

i I j

)

)

-

~o

0

103

Figure 17 Fo versus x alkane

deg Cli f terent alkane components

middot I

I

I ~ y

I I I

rfmiddot I

I I

I0 I

III I

I]

I

I bull I middot

middot 0 -L GI_

gt_ x alkane

fi bull

--0- HPOXYL1 middotmiddotmiddotmiddot9middotmiddotmiddot OCTICYL -)-- LPOXYLmiddotmiddot-middotmiddot -0- C1ltXY_

tmiddot t

Figure 18 F final VS x alkane ~middot ~

1r--~- -----iif -OrI middot~middot I

f I I I

Imiddot1 I I

imiddotmiddot1 I ~ IY_

I I I M

bull I I ~

s I middotI I

I I

I -j

0

I v 9middot

middotmiddotmiddotmiddotmiddotmiddotmiddot amp--- bull bullbull ~ so

bull alkane

~ Lbullubull

middot~

0

O

104

~1gure 19 ~amptcr Content vs X alkane

middotmiddot

I middot1~I

middotI I middot

middot I_

bull bull bull bull bull bull bull bull bull bull bull ~ raquo n bull bull ~ bull X akane

--0-- MPOXYL middot-middotbull9middotmiddotmiddot OCTXV --0-- LPOXlL ~C1AXYL

Figure 20 Yield Po1nt vs X alkane

9

I

I bull -- ~-------~-

bull~

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n n bull bull bull bull

X alkane

0

shy

shy

~ 105

ll

t J

z

Effect o Resins Flgures 21 to 24 present the emulsification behaviour for model oils where the emulsifying

agents are 1 asphaltenes 2 resins and 3 asphaltenes and reslns together The results show that stable emulsions can be produced by resins alone Although the range of alkanearomatlc ratios over which stable emulsions are produced ls small these emulsions have greater structural strength than emulsions stabilized by asphaltenes When asphaltenes and resins are both present the range over which stable emulsions are formed Is larger than either resins or asphaltenes alone But emulsions stabUlzed by the asphalteneresin combination lack the maxima peak in yield point

Effect of Wax Figures 25 to 28 show the effect of adding 005 and 01 gml of wax to a model oD

containing 1 asphaltenes The model oil containing 1 asphaltenes has no tendency to form stable emulsions but the addition of wax increases the emulsification tendency at all alkanearomatlc ratios The range of alkanearornatlc ratios over which stable emulsions are produced increases as wax content increases Increasing the wax content also Increased the mechanical strength of the emulsions Similar results were obtained when wax was added to the oil containing 25 asphaltenes

The effect of adding 01 gml of wax to the model oH containing 5 asphaltenes Is shown in Figures 29 to 32 The addition of wax has little effect upon F

0 F1 and water content

but decreases the maxima yield point of the emulsions formed Figures 33 to 36 show the effect of increasing asphaltene content upon an oD containing

005 gml grams of wax Model ons containing only wax as the emulslfyfng agent had no tendency to emulsify As the Figures Blustrate the addition of asphaltenes results in the formation of stable emulsions As the concentration of asphaltenes ls Increased the oils have a greater tendency to produce stable emulsions

i

bull bull 0

106

Flgure 21 Fo versus alkane effect of res1ns

LO

0

0 bull

middot

0 0-

i e

i

middotmiddotOmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotdl 100 X alkane

~x~ o 05 g9L asphaltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 0 05 g_ resins ----6bullmiddot O 05 9_ asphaltenes

Figure 22 F f1nal vs alkane

e ~ 0

lmiddot

0 bull

cbull

shy ci u

~ ooo~~IO~middot--+--+---t--+--~

S 10 ISbull

X alkane

c

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

bullbull

98

F1gure 9 Fo vs X alkane

different aromat1c components

)

0

middot

middot

_0 ~

_

o o

-

_Dmiddotmiddotmiddotmiddotmiddot i middotmiddotmiddotmiddotmiddotmiddotmiddotmiddot I I)

I I I

I I I

A

I __) I ---r

- ----- I I i

i middot II ~ I

_ ___ j

bull bull m bull - - bull bull bull - - - M R bull - - - - ~ X alkane

~ HOxylene middotmiddot middot0middotmiddotmiddot rPOPO -6-- rODMN --0-- H011x -9-- HPOOPM

Figure 10 F f 1nal vs alkane

PmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotDmiddotmiddotmiddotmiddot

o I I

ltgt---f-i o

Ii j

I f f

II

fl bullc ~ I middotI I~ ~ -------r1 i

----- bull

- j

i i I

I I II middot I J

0

bull

X alkano

-~

bullbull

bull bull

ll

99

Ftgure 11 Water content vs X alkane

r--------------~-

1 _--A- - bull 0 middot middotmiddotmiddotlrmiddotmiddotmiddotmiddotmiddotmiddotmiddotr~~~middot~~-

I I middotmiddot middot middot ~I bull I II 1 middot

bull I c bull

I I II 1~middotI j ~

bull l ~

middot1 j I ~1

-middot I I I middot I f t middot l 1 I

+------------~----- j

0 deg m deg - bull bull bull - bull bull bull - N - deg -X alkane

---0-- li01eylene middotmiddotmiddotmiddot0middotmiddotmiddot J90PO -tr- HOOMN ---gt--- H01111iJ --fl- HPOOPM

Figure 12 Y1eld po1nt vs X alkane

~ I I I I I

o I I

~~ I

J ~ I )

I

i 11 r-

middot I -

deg II lt -I i ) --

_Ii ~~ a ~middot~ I --__ -

---- df-_L Omiddot hmiddot9-_ -bull middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot -- -------_-_----e -~amps-~

o o deg g bull bull bull bull bull bull bull bull bull U N n bull M deg H

X alkane

bull

shy

shy

bullbull

bull bull

100

bull

o t

0 bull

0 0 ~

obull

ogt

obull

0 I

00

bullo

obull

obull

- 5 obull ~

~ ogt

F1gure 13 Fo vs Oa-Os) -2 for different aromatic components

bullmiddot--middotmiddotmiddotmiddot----tgtmiddotmiddotmiddot-middotmiddotmiddotmiddot Jilmiddotf gt-+1~gt---f-HJ-- 8-S-rtt-lt~I

I _ El - 1middot 1

bull

1 1 I 1middot1 ~~

l I ~ -- Ji ~~ r------ -- ~~

I I I

i jltJo V--middot+-- shy

70 7S IO as to 9

Coa-Os) middotz

eo bull5 90

--0-- HPOxy lene middotmiddotmiddotmiddot0middotmiddotmiddot HPOPO middotmiddot-ampmiddot-middot HPOQMN ---1J-- HPOOPM --ltgt- HPOHIX

Figure 14 F f 1nal vs (Oa-Osl -2

~-----------e-_t---4~-tl-t-ltB_euro-t~_

I I

I lJ I

i j i I J

--- - ---------+-I 1 - i f

ci 6-------------------LJ~--

iiI

shy

0

0

) -----

101 Figure 15 Wampter content vs (Oa-Osl middot2

r-------------- ~--middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot -Je~

~ ~~-bull

Ibull ~ ) middot~~middot

middot bull I ~~ bullbull I

~ I

y ~ A ~ If

CJmiddotmiddotmiddotmiddotmiddotli-------------------middotlf---l- bullbull middot (Oa-Osl middot2

--0--- HPOxylene middotmiddotmiddotmiddot0 HPOPO middotmiddotmiddotmiddott--middot HPOOMN --9-- HPOOPM --gt--- HPOMIX

Figure 16 Yield point vs (Ca-Os) middot2

0I_

middot ~

I I I

iI I middot II

~ ~ Ij I

bullbullAi _ - --

i _~--_middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

----- J-middot6-------------li---~---_ ------shy (Oa-Os) -2

i

0

102

Effect of AJkane Component

The effect of using different alkane solvents as the precipitation medium for asphaltenes has been studied by Long 1979) Speight and Moschopedls (1979) Their findings indicate that as the carbon number of the alkane solvent Increases the amount ol asphaltenes which precipitate decreases and that the composition of the precipitated material also changes Higher alkane solvents were shown to yield asphal1enes which have a higher degree of aromaticity a higher proportion ol heteroatoms a higher degree ol polarity and higher molecular weights

Figures 17 to 20 show F0 F1 water content and yield point versus percent alkane for four different model oils consisting of xylene (XYL) 5 asphal1enes and four different alkane

components n-octane (OCT)(o= 154) n-tetradecane (C14)o= 163) light paraffin oil

(lPO)(o= 147) and heavy paraffin oR (HPO)(o= 150) The results show that the model oils

containing the paraffin oils (a complex mixture of alkanes) have a stonger tendency to form stable emulsions than do the oils made with the n-alkane solvents The emulsions formed by oil containing the heavy paraffin oU are structurally stronger (higher yield points) than those formed by the light paraffin oil When the emulsification behaviour of the model oils containing octane and tetradecane are compared the tetradecanexylene oR has a stronger tendency to form stable emulsions (higher F1 values) but these emulsions have less structural strength Qoover yield point)

Comoarlson of Asohaltenes from Different Crudes Asphaltenes from different oils will differ in elemental composition structure and molecular

weight Therefore the solubility precipitation behaviour of asphal1enes from different sources could potentially differ The experiments using the heavy paraffin oDxylene oil containing 5 asphal1enes were repeated for asphaltenes extracted from Prudhoe Bay crude oR Overall the emulsification behaviour was very simflar to the California crude asphaltenes The asphal1enes from the California crude were slightly more effective emulsifiers

i I j

)

)

-

~o

0

103

Figure 17 Fo versus x alkane

deg Cli f terent alkane components

middot I

I

I ~ y

I I I

rfmiddot I

I I

I0 I

III I

I]

I

I bull I middot

middot 0 -L GI_

gt_ x alkane

fi bull

--0- HPOXYL1 middotmiddotmiddotmiddot9middotmiddotmiddot OCTICYL -)-- LPOXYLmiddotmiddot-middotmiddot -0- C1ltXY_

tmiddot t

Figure 18 F final VS x alkane ~middot ~

1r--~- -----iif -OrI middot~middot I

f I I I

Imiddot1 I I

imiddotmiddot1 I ~ IY_

I I I M

bull I I ~

s I middotI I

I I

I -j

0

I v 9middot

middotmiddotmiddotmiddotmiddotmiddotmiddot amp--- bull bullbull ~ so

bull alkane

~ Lbullubull

middot~

0

O

104

~1gure 19 ~amptcr Content vs X alkane

middotmiddot

I middot1~I

middotI I middot

middot I_

bull bull bull bull bull bull bull bull bull bull bull ~ raquo n bull bull ~ bull X akane

--0-- MPOXYL middot-middotbull9middotmiddotmiddot OCTXV --0-- LPOXlL ~C1AXYL

Figure 20 Yield Po1nt vs X alkane

9

I

I bull -- ~-------~-

bull~

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n n bull bull bull bull

X alkane

0

shy

shy

~ 105

ll

t J

z

Effect o Resins Flgures 21 to 24 present the emulsification behaviour for model oils where the emulsifying

agents are 1 asphaltenes 2 resins and 3 asphaltenes and reslns together The results show that stable emulsions can be produced by resins alone Although the range of alkanearomatlc ratios over which stable emulsions are produced ls small these emulsions have greater structural strength than emulsions stabilized by asphaltenes When asphaltenes and resins are both present the range over which stable emulsions are formed Is larger than either resins or asphaltenes alone But emulsions stabUlzed by the asphalteneresin combination lack the maxima peak in yield point

Effect of Wax Figures 25 to 28 show the effect of adding 005 and 01 gml of wax to a model oD

containing 1 asphaltenes The model oil containing 1 asphaltenes has no tendency to form stable emulsions but the addition of wax increases the emulsification tendency at all alkanearomatlc ratios The range of alkanearornatlc ratios over which stable emulsions are produced increases as wax content increases Increasing the wax content also Increased the mechanical strength of the emulsions Similar results were obtained when wax was added to the oil containing 25 asphaltenes

The effect of adding 01 gml of wax to the model oH containing 5 asphaltenes Is shown in Figures 29 to 32 The addition of wax has little effect upon F

0 F1 and water content

but decreases the maxima yield point of the emulsions formed Figures 33 to 36 show the effect of increasing asphaltene content upon an oD containing

005 gml grams of wax Model ons containing only wax as the emulslfyfng agent had no tendency to emulsify As the Figures Blustrate the addition of asphaltenes results in the formation of stable emulsions As the concentration of asphaltenes ls Increased the oils have a greater tendency to produce stable emulsions

i

bull bull 0

106

Flgure 21 Fo versus alkane effect of res1ns

LO

0

0 bull

middot

0 0-

i e

i

middotmiddotOmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotdl 100 X alkane

~x~ o 05 g9L asphaltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 0 05 g_ resins ----6bullmiddot O 05 9_ asphaltenes

Figure 22 F f1nal vs alkane

e ~ 0

lmiddot

0 bull

cbull

shy ci u

~ ooo~~IO~middot--+--+---t--+--~

S 10 ISbull

X alkane

c

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

bullbull

bull bull

ll

99

Ftgure 11 Water content vs X alkane

r--------------~-

1 _--A- - bull 0 middot middotmiddotmiddotlrmiddotmiddotmiddotmiddotmiddotmiddotmiddotr~~~middot~~-

I I middotmiddot middot middot ~I bull I II 1 middot

bull I c bull

I I II 1~middotI j ~

bull l ~

middot1 j I ~1

-middot I I I middot I f t middot l 1 I

+------------~----- j

0 deg m deg - bull bull bull - bull bull bull - N - deg -X alkane

---0-- li01eylene middotmiddotmiddotmiddot0middotmiddotmiddot J90PO -tr- HOOMN ---gt--- H01111iJ --fl- HPOOPM

Figure 12 Y1eld po1nt vs X alkane

~ I I I I I

o I I

~~ I

J ~ I )

I

i 11 r-

middot I -

deg II lt -I i ) --

_Ii ~~ a ~middot~ I --__ -

---- df-_L Omiddot hmiddot9-_ -bull middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot -- -------_-_----e -~amps-~

o o deg g bull bull bull bull bull bull bull bull bull U N n bull M deg H

X alkane

bull

shy

shy

bullbull

bull bull

100

bull

o t

0 bull

0 0 ~

obull

ogt

obull

0 I

00

bullo

obull

obull

- 5 obull ~

~ ogt

F1gure 13 Fo vs Oa-Os) -2 for different aromatic components

bullmiddot--middotmiddotmiddotmiddot----tgtmiddotmiddotmiddot-middotmiddotmiddotmiddot Jilmiddotf gt-+1~gt---f-HJ-- 8-S-rtt-lt~I

I _ El - 1middot 1

bull

1 1 I 1middot1 ~~

l I ~ -- Ji ~~ r------ -- ~~

I I I

i jltJo V--middot+-- shy

70 7S IO as to 9

Coa-Os) middotz

eo bull5 90

--0-- HPOxy lene middotmiddotmiddotmiddot0middotmiddotmiddot HPOPO middotmiddot-ampmiddot-middot HPOQMN ---1J-- HPOOPM --ltgt- HPOHIX

Figure 14 F f 1nal vs (Oa-Osl -2

~-----------e-_t---4~-tl-t-ltB_euro-t~_

I I

I lJ I

i j i I J

--- - ---------+-I 1 - i f

ci 6-------------------LJ~--

iiI

shy

0

0

) -----

101 Figure 15 Wampter content vs (Oa-Osl middot2

r-------------- ~--middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot -Je~

~ ~~-bull

Ibull ~ ) middot~~middot

middot bull I ~~ bullbull I

~ I

y ~ A ~ If

CJmiddotmiddotmiddotmiddotmiddotli-------------------middotlf---l- bullbull middot (Oa-Osl middot2

--0--- HPOxylene middotmiddotmiddotmiddot0 HPOPO middotmiddotmiddotmiddott--middot HPOOMN --9-- HPOOPM --gt--- HPOMIX

Figure 16 Yield point vs (Ca-Os) middot2

0I_

middot ~

I I I

iI I middot II

~ ~ Ij I

bullbullAi _ - --

i _~--_middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

----- J-middot6-------------li---~---_ ------shy (Oa-Os) -2

i

0

102

Effect of AJkane Component

The effect of using different alkane solvents as the precipitation medium for asphaltenes has been studied by Long 1979) Speight and Moschopedls (1979) Their findings indicate that as the carbon number of the alkane solvent Increases the amount ol asphaltenes which precipitate decreases and that the composition of the precipitated material also changes Higher alkane solvents were shown to yield asphal1enes which have a higher degree of aromaticity a higher proportion ol heteroatoms a higher degree ol polarity and higher molecular weights

Figures 17 to 20 show F0 F1 water content and yield point versus percent alkane for four different model oils consisting of xylene (XYL) 5 asphal1enes and four different alkane

components n-octane (OCT)(o= 154) n-tetradecane (C14)o= 163) light paraffin oil

(lPO)(o= 147) and heavy paraffin oR (HPO)(o= 150) The results show that the model oils

containing the paraffin oils (a complex mixture of alkanes) have a stonger tendency to form stable emulsions than do the oils made with the n-alkane solvents The emulsions formed by oil containing the heavy paraffin oU are structurally stronger (higher yield points) than those formed by the light paraffin oil When the emulsification behaviour of the model oils containing octane and tetradecane are compared the tetradecanexylene oR has a stronger tendency to form stable emulsions (higher F1 values) but these emulsions have less structural strength Qoover yield point)

Comoarlson of Asohaltenes from Different Crudes Asphaltenes from different oils will differ in elemental composition structure and molecular

weight Therefore the solubility precipitation behaviour of asphal1enes from different sources could potentially differ The experiments using the heavy paraffin oDxylene oil containing 5 asphal1enes were repeated for asphaltenes extracted from Prudhoe Bay crude oR Overall the emulsification behaviour was very simflar to the California crude asphaltenes The asphal1enes from the California crude were slightly more effective emulsifiers

i I j

)

)

-

~o

0

103

Figure 17 Fo versus x alkane

deg Cli f terent alkane components

middot I

I

I ~ y

I I I

rfmiddot I

I I

I0 I

III I

I]

I

I bull I middot

middot 0 -L GI_

gt_ x alkane

fi bull

--0- HPOXYL1 middotmiddotmiddotmiddot9middotmiddotmiddot OCTICYL -)-- LPOXYLmiddotmiddot-middotmiddot -0- C1ltXY_

tmiddot t

Figure 18 F final VS x alkane ~middot ~

1r--~- -----iif -OrI middot~middot I

f I I I

Imiddot1 I I

imiddotmiddot1 I ~ IY_

I I I M

bull I I ~

s I middotI I

I I

I -j

0

I v 9middot

middotmiddotmiddotmiddotmiddotmiddotmiddot amp--- bull bullbull ~ so

bull alkane

~ Lbullubull

middot~

0

O

104

~1gure 19 ~amptcr Content vs X alkane

middotmiddot

I middot1~I

middotI I middot

middot I_

bull bull bull bull bull bull bull bull bull bull bull ~ raquo n bull bull ~ bull X akane

--0-- MPOXYL middot-middotbull9middotmiddotmiddot OCTXV --0-- LPOXlL ~C1AXYL

Figure 20 Yield Po1nt vs X alkane

9

I

I bull -- ~-------~-

bull~

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n n bull bull bull bull

X alkane

0

shy

shy

~ 105

ll

t J

z

Effect o Resins Flgures 21 to 24 present the emulsification behaviour for model oils where the emulsifying

agents are 1 asphaltenes 2 resins and 3 asphaltenes and reslns together The results show that stable emulsions can be produced by resins alone Although the range of alkanearomatlc ratios over which stable emulsions are produced ls small these emulsions have greater structural strength than emulsions stabilized by asphaltenes When asphaltenes and resins are both present the range over which stable emulsions are formed Is larger than either resins or asphaltenes alone But emulsions stabUlzed by the asphalteneresin combination lack the maxima peak in yield point

Effect of Wax Figures 25 to 28 show the effect of adding 005 and 01 gml of wax to a model oD

containing 1 asphaltenes The model oil containing 1 asphaltenes has no tendency to form stable emulsions but the addition of wax increases the emulsification tendency at all alkanearomatlc ratios The range of alkanearornatlc ratios over which stable emulsions are produced increases as wax content increases Increasing the wax content also Increased the mechanical strength of the emulsions Similar results were obtained when wax was added to the oil containing 25 asphaltenes

The effect of adding 01 gml of wax to the model oH containing 5 asphaltenes Is shown in Figures 29 to 32 The addition of wax has little effect upon F

0 F1 and water content

but decreases the maxima yield point of the emulsions formed Figures 33 to 36 show the effect of increasing asphaltene content upon an oD containing

005 gml grams of wax Model ons containing only wax as the emulslfyfng agent had no tendency to emulsify As the Figures Blustrate the addition of asphaltenes results in the formation of stable emulsions As the concentration of asphaltenes ls Increased the oils have a greater tendency to produce stable emulsions

i

bull bull 0

106

Flgure 21 Fo versus alkane effect of res1ns

LO

0

0 bull

middot

0 0-

i e

i

middotmiddotOmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotdl 100 X alkane

~x~ o 05 g9L asphaltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 0 05 g_ resins ----6bullmiddot O 05 9_ asphaltenes

Figure 22 F f1nal vs alkane

e ~ 0

lmiddot

0 bull

cbull

shy ci u

~ ooo~~IO~middot--+--+---t--+--~

S 10 ISbull

X alkane

c

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

bullbull

bull bull

100

bull

o t

0 bull

0 0 ~

obull

ogt

obull

0 I

00

bullo

obull

obull

- 5 obull ~

~ ogt

F1gure 13 Fo vs Oa-Os) -2 for different aromatic components

bullmiddot--middotmiddotmiddotmiddot----tgtmiddotmiddotmiddot-middotmiddotmiddotmiddot Jilmiddotf gt-+1~gt---f-HJ-- 8-S-rtt-lt~I

I _ El - 1middot 1

bull

1 1 I 1middot1 ~~

l I ~ -- Ji ~~ r------ -- ~~

I I I

i jltJo V--middot+-- shy

70 7S IO as to 9

Coa-Os) middotz

eo bull5 90

--0-- HPOxy lene middotmiddotmiddotmiddot0middotmiddotmiddot HPOPO middotmiddot-ampmiddot-middot HPOQMN ---1J-- HPOOPM --ltgt- HPOHIX

Figure 14 F f 1nal vs (Oa-Osl -2

~-----------e-_t---4~-tl-t-ltB_euro-t~_

I I

I lJ I

i j i I J

--- - ---------+-I 1 - i f

ci 6-------------------LJ~--

iiI

shy

0

0

) -----

101 Figure 15 Wampter content vs (Oa-Osl middot2

r-------------- ~--middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot -Je~

~ ~~-bull

Ibull ~ ) middot~~middot

middot bull I ~~ bullbull I

~ I

y ~ A ~ If

CJmiddotmiddotmiddotmiddotmiddotli-------------------middotlf---l- bullbull middot (Oa-Osl middot2

--0--- HPOxylene middotmiddotmiddotmiddot0 HPOPO middotmiddotmiddotmiddott--middot HPOOMN --9-- HPOOPM --gt--- HPOMIX

Figure 16 Yield point vs (Ca-Os) middot2

0I_

middot ~

I I I

iI I middot II

~ ~ Ij I

bullbullAi _ - --

i _~--_middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

----- J-middot6-------------li---~---_ ------shy (Oa-Os) -2

i

0

102

Effect of AJkane Component

The effect of using different alkane solvents as the precipitation medium for asphaltenes has been studied by Long 1979) Speight and Moschopedls (1979) Their findings indicate that as the carbon number of the alkane solvent Increases the amount ol asphaltenes which precipitate decreases and that the composition of the precipitated material also changes Higher alkane solvents were shown to yield asphal1enes which have a higher degree of aromaticity a higher proportion ol heteroatoms a higher degree ol polarity and higher molecular weights

Figures 17 to 20 show F0 F1 water content and yield point versus percent alkane for four different model oils consisting of xylene (XYL) 5 asphal1enes and four different alkane

components n-octane (OCT)(o= 154) n-tetradecane (C14)o= 163) light paraffin oil

(lPO)(o= 147) and heavy paraffin oR (HPO)(o= 150) The results show that the model oils

containing the paraffin oils (a complex mixture of alkanes) have a stonger tendency to form stable emulsions than do the oils made with the n-alkane solvents The emulsions formed by oil containing the heavy paraffin oU are structurally stronger (higher yield points) than those formed by the light paraffin oil When the emulsification behaviour of the model oils containing octane and tetradecane are compared the tetradecanexylene oR has a stronger tendency to form stable emulsions (higher F1 values) but these emulsions have less structural strength Qoover yield point)

Comoarlson of Asohaltenes from Different Crudes Asphaltenes from different oils will differ in elemental composition structure and molecular

weight Therefore the solubility precipitation behaviour of asphal1enes from different sources could potentially differ The experiments using the heavy paraffin oDxylene oil containing 5 asphal1enes were repeated for asphaltenes extracted from Prudhoe Bay crude oR Overall the emulsification behaviour was very simflar to the California crude asphaltenes The asphal1enes from the California crude were slightly more effective emulsifiers

i I j

)

)

-

~o

0

103

Figure 17 Fo versus x alkane

deg Cli f terent alkane components

middot I

I

I ~ y

I I I

rfmiddot I

I I

I0 I

III I

I]

I

I bull I middot

middot 0 -L GI_

gt_ x alkane

fi bull

--0- HPOXYL1 middotmiddotmiddotmiddot9middotmiddotmiddot OCTICYL -)-- LPOXYLmiddotmiddot-middotmiddot -0- C1ltXY_

tmiddot t

Figure 18 F final VS x alkane ~middot ~

1r--~- -----iif -OrI middot~middot I

f I I I

Imiddot1 I I

imiddotmiddot1 I ~ IY_

I I I M

bull I I ~

s I middotI I

I I

I -j

0

I v 9middot

middotmiddotmiddotmiddotmiddotmiddotmiddot amp--- bull bullbull ~ so

bull alkane

~ Lbullubull

middot~

0

O

104

~1gure 19 ~amptcr Content vs X alkane

middotmiddot

I middot1~I

middotI I middot

middot I_

bull bull bull bull bull bull bull bull bull bull bull ~ raquo n bull bull ~ bull X akane

--0-- MPOXYL middot-middotbull9middotmiddotmiddot OCTXV --0-- LPOXlL ~C1AXYL

Figure 20 Yield Po1nt vs X alkane

9

I

I bull -- ~-------~-

bull~

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n n bull bull bull bull

X alkane

0

shy

shy

~ 105

ll

t J

z

Effect o Resins Flgures 21 to 24 present the emulsification behaviour for model oils where the emulsifying

agents are 1 asphaltenes 2 resins and 3 asphaltenes and reslns together The results show that stable emulsions can be produced by resins alone Although the range of alkanearomatlc ratios over which stable emulsions are produced ls small these emulsions have greater structural strength than emulsions stabilized by asphaltenes When asphaltenes and resins are both present the range over which stable emulsions are formed Is larger than either resins or asphaltenes alone But emulsions stabUlzed by the asphalteneresin combination lack the maxima peak in yield point

Effect of Wax Figures 25 to 28 show the effect of adding 005 and 01 gml of wax to a model oD

containing 1 asphaltenes The model oil containing 1 asphaltenes has no tendency to form stable emulsions but the addition of wax increases the emulsification tendency at all alkanearomatlc ratios The range of alkanearornatlc ratios over which stable emulsions are produced increases as wax content increases Increasing the wax content also Increased the mechanical strength of the emulsions Similar results were obtained when wax was added to the oil containing 25 asphaltenes

The effect of adding 01 gml of wax to the model oH containing 5 asphaltenes Is shown in Figures 29 to 32 The addition of wax has little effect upon F

0 F1 and water content

but decreases the maxima yield point of the emulsions formed Figures 33 to 36 show the effect of increasing asphaltene content upon an oD containing

005 gml grams of wax Model ons containing only wax as the emulslfyfng agent had no tendency to emulsify As the Figures Blustrate the addition of asphaltenes results in the formation of stable emulsions As the concentration of asphaltenes ls Increased the oils have a greater tendency to produce stable emulsions

i

bull bull 0

106

Flgure 21 Fo versus alkane effect of res1ns

LO

0

0 bull

middot

0 0-

i e

i

middotmiddotOmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotdl 100 X alkane

~x~ o 05 g9L asphaltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 0 05 g_ resins ----6bullmiddot O 05 9_ asphaltenes

Figure 22 F f1nal vs alkane

e ~ 0

lmiddot

0 bull

cbull

shy ci u

~ ooo~~IO~middot--+--+---t--+--~

S 10 ISbull

X alkane

c

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

) -----

101 Figure 15 Wampter content vs (Oa-Osl middot2

r-------------- ~--middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot -Je~

~ ~~-bull

Ibull ~ ) middot~~middot

middot bull I ~~ bullbull I

~ I

y ~ A ~ If

CJmiddotmiddotmiddotmiddotmiddotli-------------------middotlf---l- bullbull middot (Oa-Osl middot2

--0--- HPOxylene middotmiddotmiddotmiddot0 HPOPO middotmiddotmiddotmiddott--middot HPOOMN --9-- HPOOPM --gt--- HPOMIX

Figure 16 Yield point vs (Ca-Os) middot2

0I_

middot ~

I I I

iI I middot II

~ ~ Ij I

bullbullAi _ - --

i _~--_middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

----- J-middot6-------------li---~---_ ------shy (Oa-Os) -2

i

0

102

Effect of AJkane Component

The effect of using different alkane solvents as the precipitation medium for asphaltenes has been studied by Long 1979) Speight and Moschopedls (1979) Their findings indicate that as the carbon number of the alkane solvent Increases the amount ol asphaltenes which precipitate decreases and that the composition of the precipitated material also changes Higher alkane solvents were shown to yield asphal1enes which have a higher degree of aromaticity a higher proportion ol heteroatoms a higher degree ol polarity and higher molecular weights

Figures 17 to 20 show F0 F1 water content and yield point versus percent alkane for four different model oils consisting of xylene (XYL) 5 asphal1enes and four different alkane

components n-octane (OCT)(o= 154) n-tetradecane (C14)o= 163) light paraffin oil

(lPO)(o= 147) and heavy paraffin oR (HPO)(o= 150) The results show that the model oils

containing the paraffin oils (a complex mixture of alkanes) have a stonger tendency to form stable emulsions than do the oils made with the n-alkane solvents The emulsions formed by oil containing the heavy paraffin oU are structurally stronger (higher yield points) than those formed by the light paraffin oil When the emulsification behaviour of the model oils containing octane and tetradecane are compared the tetradecanexylene oR has a stronger tendency to form stable emulsions (higher F1 values) but these emulsions have less structural strength Qoover yield point)

Comoarlson of Asohaltenes from Different Crudes Asphaltenes from different oils will differ in elemental composition structure and molecular

weight Therefore the solubility precipitation behaviour of asphal1enes from different sources could potentially differ The experiments using the heavy paraffin oDxylene oil containing 5 asphal1enes were repeated for asphaltenes extracted from Prudhoe Bay crude oR Overall the emulsification behaviour was very simflar to the California crude asphaltenes The asphal1enes from the California crude were slightly more effective emulsifiers

i I j

)

)

-

~o

0

103

Figure 17 Fo versus x alkane

deg Cli f terent alkane components

middot I

I

I ~ y

I I I

rfmiddot I

I I

I0 I

III I

I]

I

I bull I middot

middot 0 -L GI_

gt_ x alkane

fi bull

--0- HPOXYL1 middotmiddotmiddotmiddot9middotmiddotmiddot OCTICYL -)-- LPOXYLmiddotmiddot-middotmiddot -0- C1ltXY_

tmiddot t

Figure 18 F final VS x alkane ~middot ~

1r--~- -----iif -OrI middot~middot I

f I I I

Imiddot1 I I

imiddotmiddot1 I ~ IY_

I I I M

bull I I ~

s I middotI I

I I

I -j

0

I v 9middot

middotmiddotmiddotmiddotmiddotmiddotmiddot amp--- bull bullbull ~ so

bull alkane

~ Lbullubull

middot~

0

O

104

~1gure 19 ~amptcr Content vs X alkane

middotmiddot

I middot1~I

middotI I middot

middot I_

bull bull bull bull bull bull bull bull bull bull bull ~ raquo n bull bull ~ bull X akane

--0-- MPOXYL middot-middotbull9middotmiddotmiddot OCTXV --0-- LPOXlL ~C1AXYL

Figure 20 Yield Po1nt vs X alkane

9

I

I bull -- ~-------~-

bull~

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n n bull bull bull bull

X alkane

0

shy

shy

~ 105

ll

t J

z

Effect o Resins Flgures 21 to 24 present the emulsification behaviour for model oils where the emulsifying

agents are 1 asphaltenes 2 resins and 3 asphaltenes and reslns together The results show that stable emulsions can be produced by resins alone Although the range of alkanearomatlc ratios over which stable emulsions are produced ls small these emulsions have greater structural strength than emulsions stabilized by asphaltenes When asphaltenes and resins are both present the range over which stable emulsions are formed Is larger than either resins or asphaltenes alone But emulsions stabUlzed by the asphalteneresin combination lack the maxima peak in yield point

Effect of Wax Figures 25 to 28 show the effect of adding 005 and 01 gml of wax to a model oD

containing 1 asphaltenes The model oil containing 1 asphaltenes has no tendency to form stable emulsions but the addition of wax increases the emulsification tendency at all alkanearomatlc ratios The range of alkanearornatlc ratios over which stable emulsions are produced increases as wax content increases Increasing the wax content also Increased the mechanical strength of the emulsions Similar results were obtained when wax was added to the oil containing 25 asphaltenes

The effect of adding 01 gml of wax to the model oH containing 5 asphaltenes Is shown in Figures 29 to 32 The addition of wax has little effect upon F

0 F1 and water content

but decreases the maxima yield point of the emulsions formed Figures 33 to 36 show the effect of increasing asphaltene content upon an oD containing

005 gml grams of wax Model ons containing only wax as the emulslfyfng agent had no tendency to emulsify As the Figures Blustrate the addition of asphaltenes results in the formation of stable emulsions As the concentration of asphaltenes ls Increased the oils have a greater tendency to produce stable emulsions

i

bull bull 0

106

Flgure 21 Fo versus alkane effect of res1ns

LO

0

0 bull

middot

0 0-

i e

i

middotmiddotOmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotdl 100 X alkane

~x~ o 05 g9L asphaltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 0 05 g_ resins ----6bullmiddot O 05 9_ asphaltenes

Figure 22 F f1nal vs alkane

e ~ 0

lmiddot

0 bull

cbull

shy ci u

~ ooo~~IO~middot--+--+---t--+--~

S 10 ISbull

X alkane

c

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

0

102

Effect of AJkane Component

The effect of using different alkane solvents as the precipitation medium for asphaltenes has been studied by Long 1979) Speight and Moschopedls (1979) Their findings indicate that as the carbon number of the alkane solvent Increases the amount ol asphaltenes which precipitate decreases and that the composition of the precipitated material also changes Higher alkane solvents were shown to yield asphal1enes which have a higher degree of aromaticity a higher proportion ol heteroatoms a higher degree ol polarity and higher molecular weights

Figures 17 to 20 show F0 F1 water content and yield point versus percent alkane for four different model oils consisting of xylene (XYL) 5 asphal1enes and four different alkane

components n-octane (OCT)(o= 154) n-tetradecane (C14)o= 163) light paraffin oil

(lPO)(o= 147) and heavy paraffin oR (HPO)(o= 150) The results show that the model oils

containing the paraffin oils (a complex mixture of alkanes) have a stonger tendency to form stable emulsions than do the oils made with the n-alkane solvents The emulsions formed by oil containing the heavy paraffin oU are structurally stronger (higher yield points) than those formed by the light paraffin oil When the emulsification behaviour of the model oils containing octane and tetradecane are compared the tetradecanexylene oR has a stronger tendency to form stable emulsions (higher F1 values) but these emulsions have less structural strength Qoover yield point)

Comoarlson of Asohaltenes from Different Crudes Asphaltenes from different oils will differ in elemental composition structure and molecular

weight Therefore the solubility precipitation behaviour of asphal1enes from different sources could potentially differ The experiments using the heavy paraffin oDxylene oil containing 5 asphal1enes were repeated for asphaltenes extracted from Prudhoe Bay crude oR Overall the emulsification behaviour was very simflar to the California crude asphaltenes The asphal1enes from the California crude were slightly more effective emulsifiers

i I j

)

)

-

~o

0

103

Figure 17 Fo versus x alkane

deg Cli f terent alkane components

middot I

I

I ~ y

I I I

rfmiddot I

I I

I0 I

III I

I]

I

I bull I middot

middot 0 -L GI_

gt_ x alkane

fi bull

--0- HPOXYL1 middotmiddotmiddotmiddot9middotmiddotmiddot OCTICYL -)-- LPOXYLmiddotmiddot-middotmiddot -0- C1ltXY_

tmiddot t

Figure 18 F final VS x alkane ~middot ~

1r--~- -----iif -OrI middot~middot I

f I I I

Imiddot1 I I

imiddotmiddot1 I ~ IY_

I I I M

bull I I ~

s I middotI I

I I

I -j

0

I v 9middot

middotmiddotmiddotmiddotmiddotmiddotmiddot amp--- bull bullbull ~ so

bull alkane

~ Lbullubull

middot~

0

O

104

~1gure 19 ~amptcr Content vs X alkane

middotmiddot

I middot1~I

middotI I middot

middot I_

bull bull bull bull bull bull bull bull bull bull bull ~ raquo n bull bull ~ bull X akane

--0-- MPOXYL middot-middotbull9middotmiddotmiddot OCTXV --0-- LPOXlL ~C1AXYL

Figure 20 Yield Po1nt vs X alkane

9

I

I bull -- ~-------~-

bull~

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n n bull bull bull bull

X alkane

0

shy

shy

~ 105

ll

t J

z

Effect o Resins Flgures 21 to 24 present the emulsification behaviour for model oils where the emulsifying

agents are 1 asphaltenes 2 resins and 3 asphaltenes and reslns together The results show that stable emulsions can be produced by resins alone Although the range of alkanearomatlc ratios over which stable emulsions are produced ls small these emulsions have greater structural strength than emulsions stabilized by asphaltenes When asphaltenes and resins are both present the range over which stable emulsions are formed Is larger than either resins or asphaltenes alone But emulsions stabUlzed by the asphalteneresin combination lack the maxima peak in yield point

Effect of Wax Figures 25 to 28 show the effect of adding 005 and 01 gml of wax to a model oD

containing 1 asphaltenes The model oil containing 1 asphaltenes has no tendency to form stable emulsions but the addition of wax increases the emulsification tendency at all alkanearomatlc ratios The range of alkanearornatlc ratios over which stable emulsions are produced increases as wax content increases Increasing the wax content also Increased the mechanical strength of the emulsions Similar results were obtained when wax was added to the oil containing 25 asphaltenes

The effect of adding 01 gml of wax to the model oH containing 5 asphaltenes Is shown in Figures 29 to 32 The addition of wax has little effect upon F

0 F1 and water content

but decreases the maxima yield point of the emulsions formed Figures 33 to 36 show the effect of increasing asphaltene content upon an oD containing

005 gml grams of wax Model ons containing only wax as the emulslfyfng agent had no tendency to emulsify As the Figures Blustrate the addition of asphaltenes results in the formation of stable emulsions As the concentration of asphaltenes ls Increased the oils have a greater tendency to produce stable emulsions

i

bull bull 0

106

Flgure 21 Fo versus alkane effect of res1ns

LO

0

0 bull

middot

0 0-

i e

i

middotmiddotOmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotdl 100 X alkane

~x~ o 05 g9L asphaltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 0 05 g_ resins ----6bullmiddot O 05 9_ asphaltenes

Figure 22 F f1nal vs alkane

e ~ 0

lmiddot

0 bull

cbull

shy ci u

~ ooo~~IO~middot--+--+---t--+--~

S 10 ISbull

X alkane

c

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

)

)

-

~o

0

103

Figure 17 Fo versus x alkane

deg Cli f terent alkane components

middot I

I

I ~ y

I I I

rfmiddot I

I I

I0 I

III I

I]

I

I bull I middot

middot 0 -L GI_

gt_ x alkane

fi bull

--0- HPOXYL1 middotmiddotmiddotmiddot9middotmiddotmiddot OCTICYL -)-- LPOXYLmiddotmiddot-middotmiddot -0- C1ltXY_

tmiddot t

Figure 18 F final VS x alkane ~middot ~

1r--~- -----iif -OrI middot~middot I

f I I I

Imiddot1 I I

imiddotmiddot1 I ~ IY_

I I I M

bull I I ~

s I middotI I

I I

I -j

0

I v 9middot

middotmiddotmiddotmiddotmiddotmiddotmiddot amp--- bull bullbull ~ so

bull alkane

~ Lbullubull

middot~

0

O

104

~1gure 19 ~amptcr Content vs X alkane

middotmiddot

I middot1~I

middotI I middot

middot I_

bull bull bull bull bull bull bull bull bull bull bull ~ raquo n bull bull ~ bull X akane

--0-- MPOXYL middot-middotbull9middotmiddotmiddot OCTXV --0-- LPOXlL ~C1AXYL

Figure 20 Yield Po1nt vs X alkane

9

I

I bull -- ~-------~-

bull~

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n n bull bull bull bull

X alkane

0

shy

shy

~ 105

ll

t J

z

Effect o Resins Flgures 21 to 24 present the emulsification behaviour for model oils where the emulsifying

agents are 1 asphaltenes 2 resins and 3 asphaltenes and reslns together The results show that stable emulsions can be produced by resins alone Although the range of alkanearomatlc ratios over which stable emulsions are produced ls small these emulsions have greater structural strength than emulsions stabilized by asphaltenes When asphaltenes and resins are both present the range over which stable emulsions are formed Is larger than either resins or asphaltenes alone But emulsions stabUlzed by the asphalteneresin combination lack the maxima peak in yield point

Effect of Wax Figures 25 to 28 show the effect of adding 005 and 01 gml of wax to a model oD

containing 1 asphaltenes The model oil containing 1 asphaltenes has no tendency to form stable emulsions but the addition of wax increases the emulsification tendency at all alkanearomatlc ratios The range of alkanearornatlc ratios over which stable emulsions are produced increases as wax content increases Increasing the wax content also Increased the mechanical strength of the emulsions Similar results were obtained when wax was added to the oil containing 25 asphaltenes

The effect of adding 01 gml of wax to the model oH containing 5 asphaltenes Is shown in Figures 29 to 32 The addition of wax has little effect upon F

0 F1 and water content

but decreases the maxima yield point of the emulsions formed Figures 33 to 36 show the effect of increasing asphaltene content upon an oD containing

005 gml grams of wax Model ons containing only wax as the emulslfyfng agent had no tendency to emulsify As the Figures Blustrate the addition of asphaltenes results in the formation of stable emulsions As the concentration of asphaltenes ls Increased the oils have a greater tendency to produce stable emulsions

i

bull bull 0

106

Flgure 21 Fo versus alkane effect of res1ns

LO

0

0 bull

middot

0 0-

i e

i

middotmiddotOmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotdl 100 X alkane

~x~ o 05 g9L asphaltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 0 05 g_ resins ----6bullmiddot O 05 9_ asphaltenes

Figure 22 F f1nal vs alkane

e ~ 0

lmiddot

0 bull

cbull

shy ci u

~ ooo~~IO~middot--+--+---t--+--~

S 10 ISbull

X alkane

c

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

~ Lbullubull

middot~

0

O

104

~1gure 19 ~amptcr Content vs X alkane

middotmiddot

I middot1~I

middotI I middot

middot I_

bull bull bull bull bull bull bull bull bull bull bull ~ raquo n bull bull ~ bull X akane

--0-- MPOXYL middot-middotbull9middotmiddotmiddot OCTXV --0-- LPOXlL ~C1AXYL

Figure 20 Yield Po1nt vs X alkane

9

I

I bull -- ~-------~-

bull~

bull bull bull bull bull bull bull bull bull bull bull bull bull bull n n bull bull bull bull

X alkane

0

shy

shy

~ 105

ll

t J

z

Effect o Resins Flgures 21 to 24 present the emulsification behaviour for model oils where the emulsifying

agents are 1 asphaltenes 2 resins and 3 asphaltenes and reslns together The results show that stable emulsions can be produced by resins alone Although the range of alkanearomatlc ratios over which stable emulsions are produced ls small these emulsions have greater structural strength than emulsions stabilized by asphaltenes When asphaltenes and resins are both present the range over which stable emulsions are formed Is larger than either resins or asphaltenes alone But emulsions stabUlzed by the asphalteneresin combination lack the maxima peak in yield point

Effect of Wax Figures 25 to 28 show the effect of adding 005 and 01 gml of wax to a model oD

containing 1 asphaltenes The model oil containing 1 asphaltenes has no tendency to form stable emulsions but the addition of wax increases the emulsification tendency at all alkanearomatlc ratios The range of alkanearornatlc ratios over which stable emulsions are produced increases as wax content increases Increasing the wax content also Increased the mechanical strength of the emulsions Similar results were obtained when wax was added to the oil containing 25 asphaltenes

The effect of adding 01 gml of wax to the model oH containing 5 asphaltenes Is shown in Figures 29 to 32 The addition of wax has little effect upon F

0 F1 and water content

but decreases the maxima yield point of the emulsions formed Figures 33 to 36 show the effect of increasing asphaltene content upon an oD containing

005 gml grams of wax Model ons containing only wax as the emulslfyfng agent had no tendency to emulsify As the Figures Blustrate the addition of asphaltenes results in the formation of stable emulsions As the concentration of asphaltenes ls Increased the oils have a greater tendency to produce stable emulsions

i

bull bull 0

106

Flgure 21 Fo versus alkane effect of res1ns

LO

0

0 bull

middot

0 0-

i e

i

middotmiddotOmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotdl 100 X alkane

~x~ o 05 g9L asphaltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 0 05 g_ resins ----6bullmiddot O 05 9_ asphaltenes

Figure 22 F f1nal vs alkane

e ~ 0

lmiddot

0 bull

cbull

shy ci u

~ ooo~~IO~middot--+--+---t--+--~

S 10 ISbull

X alkane

c

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

~ 105

ll

t J

z

Effect o Resins Flgures 21 to 24 present the emulsification behaviour for model oils where the emulsifying

agents are 1 asphaltenes 2 resins and 3 asphaltenes and reslns together The results show that stable emulsions can be produced by resins alone Although the range of alkanearomatlc ratios over which stable emulsions are produced ls small these emulsions have greater structural strength than emulsions stabilized by asphaltenes When asphaltenes and resins are both present the range over which stable emulsions are formed Is larger than either resins or asphaltenes alone But emulsions stabUlzed by the asphalteneresin combination lack the maxima peak in yield point

Effect of Wax Figures 25 to 28 show the effect of adding 005 and 01 gml of wax to a model oD

containing 1 asphaltenes The model oil containing 1 asphaltenes has no tendency to form stable emulsions but the addition of wax increases the emulsification tendency at all alkanearomatlc ratios The range of alkanearornatlc ratios over which stable emulsions are produced increases as wax content increases Increasing the wax content also Increased the mechanical strength of the emulsions Similar results were obtained when wax was added to the oil containing 25 asphaltenes

The effect of adding 01 gml of wax to the model oH containing 5 asphaltenes Is shown in Figures 29 to 32 The addition of wax has little effect upon F

0 F1 and water content

but decreases the maxima yield point of the emulsions formed Figures 33 to 36 show the effect of increasing asphaltene content upon an oD containing

005 gml grams of wax Model ons containing only wax as the emulslfyfng agent had no tendency to emulsify As the Figures Blustrate the addition of asphaltenes results in the formation of stable emulsions As the concentration of asphaltenes ls Increased the oils have a greater tendency to produce stable emulsions

i

bull bull 0

106

Flgure 21 Fo versus alkane effect of res1ns

LO

0

0 bull

middot

0 0-

i e

i

middotmiddotOmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotdl 100 X alkane

~x~ o 05 g9L asphaltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 0 05 g_ resins ----6bullmiddot O 05 9_ asphaltenes

Figure 22 F f1nal vs alkane

e ~ 0

lmiddot

0 bull

cbull

shy ci u

~ ooo~~IO~middot--+--+---t--+--~

S 10 ISbull

X alkane

c

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

bull bull 0

106

Flgure 21 Fo versus alkane effect of res1ns

LO

0

0 bull

middot

0 0-

i e

i

middotmiddotOmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotdl 100 X alkane

~x~ o 05 g9L asphaltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 0 05 g_ resins ----6bullmiddot O 05 9_ asphaltenes

Figure 22 F f1nal vs alkane

e ~ 0

lmiddot

0 bull

cbull

shy ci u

~ ooo~~IO~middot--+--+---t--+--~

S 10 ISbull

X alkane

c

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

107

Figure 23 Water content vs X alkane

T

bullc u

bullbull

T

~ i degT T middot+ f I

I

~

u 0 a -bull a ~-bull

bull

lFmiddot-~middot-~-~--~--~-~--~--~-~--~--~-~--~middototgt- a ---_middotmiddotmiddot- 0

0 ~

bull

x alkane

-x- 005 g111 bullsohbullltenes+res1ns middotmiddotmiddotmiddotOmiddotmiddotmiddot 005 gl- resins middotmiddotmiddotmiddotbrmiddot- 005 glllL bullbullohbullltenes

Figure 24 Yiela Point vs X alkane

IiI

l

i

I l

~

I 1 II j

p

i 6-__

- - -- x itlkane

shy shy

--

0

108

FlQUfe 25 Fo vs x a lkane ertect of increasing wax content

bullbull --(~

I I

I

I I

bullbull

I I I I i0

------ ---r

T

I

I

- I bull

u ~ ~

bull alkanes

- -o 01 9oL asPllbull ltenes O wax

-ltgt-- 0 01 9oL asplhll tenes 005 ge wa111

-1(-0 01 9oL asPhltenes 0 1 glll wai

Figule 26 F t1nal vs X alkane

middot-middotmiddot-I(middot--i(-middotmiddot

I II T I

~ I bullc i I

1 ~middot

0

bull middot~ x elkane

0

t

o

109

Figure 27 Water content vs yen elkene

bullL

i ubullbulll

f l

--------ltgt--middot--middot-+--middot--middot--middot--middot-+--middot ---- f X alkane

middot ---+- O Ot glllL esphaltenes 0 wbullbull --o- O 01 01- bullsPhbullltenes 0 05 o111L wabull -x-middot o 01 gML bullsphbullltenes 01 oiL wax

Figure 28 Y1eld Point vs X alkane

u

I0 ~-0

bull -- I

) I

gt

bull II

__ __f-~==~---middot-middot-+-- ---- ----==-=====t bull bull X alkene

bullbull

bull bull

bull bull

0

llO

iO 0 0

0

00

0

bulls

i

0

Figure 29 Fo versus X alkane effect of adding wax

--

X alkane

~ O 05 o_ esohbullltenes O ax ---tr-middot 005 9ML llSPhbullltenes 01 glllL wax

Figure 30 F f ~nal vs alkane

00

middot-middot

bull bull

middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotampmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

I

f

jl

bullbull

I alkene

bull bullbull bullbull bullbull

111

F1gure 3t water content vs ~ alkane

middotmiddotmiddot-- middotmiddot--o------ ----shy

ie

bullL bull ~

i

e1

I

I II

I alkanebull-j

I I 1

--0-- 005 asphaltenes 0 bullbullbull ---tr--- 0 05 asphaltenes 0 t bull-

middot~ I

Figure 3~ Yield point vs ~ alkaneI I I o

I I

uo

bull~ gt- middot-

middot-bullbullA

-A ------------middotmiddotmiddotmiddotmiddot middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

bull bull X alkanes

112

Figure 33 Fo versus alkane eftect of 1ncreas1ng asphaltene concentration

tn an 011 hav1ng a wax concentrat1o_n of 005 gmL

bull 0

0

0 bull

0

0 bull 0 shy

0

0

oo

lC alkane

-0- 0 75Q as S O wa11I I) --0--03 o as 5 g ax

Figure 3A F final vs X alkane

I)

~ shy

0 bull

~

X alkane

bullbull

I -i 113

gt

middotO

bull

~i

~

0

0

0

io

j

0

Mi I

T 25-shy

I loT l

I

tmiddot1 F~gure 35 Water content VS bull alkampnebull

IOOT

~ WT l I +

bull st~

bull ~bull I

middotmiddotr~ I

0

0

J bull

l -0-- 07Sg 5 bull ---0-- 0 3 g 5 bull bullbullbull lt l bulli Figure 36 Y1eld point VS bull a 11ltane

~ middot ~ t ~

oo ~ middot

-

p s ~

middot

0

bull - bullo

~-

gtshy _

middot 00

~ N N N 0 bull bullbull bullbull bullbull

bull alkane

o

bull bull bull

Figure 37 Flow curve tor mousse Shear stress versus shear rate

O

bullbull

~ 1ncreas1n9 L shear rate ~-

=X- decreas in9 bullbull cshy~

shi_~r rate

~

SHEAR RATE (1s)

0

0

114

Rheooaical Prooerties All the stable emulsions formed during this study exhibited non-Newtonian flow behaviour

Flow curves for mousse (Figure 37) Indicate that they behave as pseudoplastic liquids which have a definite yield point and a thixotropic flow behaviour This complex flow behaviour means that viscosity is extremely dependent upon shear conditions (shear rate and length of time shear Is applied) Therefore a single viscosity number can not properly characterize the fluidity of mousse Figure 38 demonstrates this effect of shear rate on apparent viscosity

Drooet Size Distribution Figure 39 shows the droplet size distribution for a typical mousse formed by the model

oils The droplet diameters are very heterogeneous and appear to have at least a bi-modal distribution This multi-modal size distribution means that the water content of emulsions can exceed the water content of uni-modal distributions which theoretically has a maximum value of 74 In effect this allows droplets of a smaller size to occupy the gaps between larger droplets thus creating an extremely dense packing of droplets The yield point of emulsions increases as the droplet size distribution shifts to smaller values

0

gt -- NT 0 u bull ~ i gt

O

~-

- ]

IHi

bull bull T

~--T middotmiddott ~ middot1 T middott bullbull ~ ~ ~ middot~

--ltgt-- lncreastng shear rate

x- aecreas tng shear rate

SHEAR RATE (1sl

Figure 39 Droplet size distribution

20

10

0

lt1 1 25 5 9 14 18 23 27 32 MEAN DROPLET DIAMETER

(microns)

115 Ft9ure 38 Efect of shear rate on apparent viscosity of ousse

bull

0

0

o

116

Conclusions

The results from this study demonstrate the Importance that the physical state of an

emulsifying agent has upon Its ability to stabilize emulsions It was found that to be effective

emulsifiers asphaltenes resins and waxes must be in the form of finely divided partides The

chemical composition of the ol determines not only the amount and size of these partldes but also their composition and their wetting properties All these factors were shown to have

an Influence upltin the emulsification process Asphaltenes and resins by themselves and In combination were effective emulsifying

agents Model oils containing only wax as the emulsifying agent did not form stable emulsions But the addition of a nominal amount of asphaltenes an amount insufficient by

Itself to produce emulsions to oDs containing wax lead to the formation of stable emulsions This indicates that different emulsifying agents can synergically Interact to stabUize emulsions

The solubllity precipitation behaviour of asphaltenes In model oils follows the solubllity theory as described by the HUdebrand-Scatchard equation The use of solubility parameters

can be applied to petroleum fractions and therefore may be useful In predicting the physiochemical conditions which favour emulsification

Acknowledgements

This study was co-funded by the United States Minerals Management Service and the Environmental Emergencies Technology Division of Environment Canada

References

Barton AFM Handbook of Solubility Parameters and Other Cohesion Parameters CRC Press 1983) Becher P Emulsions Theory and Practice Kreiger Publishing 2 (1977) Becher P Encydopedia of Emulsion Technology Marcel Dekker 1 (1983)

Blair C M Chem Ind (London) (1960) 538 Bobra M A Catalogue of Cnide Oil and Oil Product Properties Envir Canada EE-114 (1989) Bridle A L Wanders TH H Zegveld W and Vander Heijde H B Marine Pollution Bulletin

11 (1980) 343 Canevari G P Marine Pollution Bulletin 13 1982) 49

Clark G H Industrial and Marine Fuels Reference Book Butterworth and Co (1988) Desrnaison M Desrnarquest J-P Plekarsld C and Piekarski S Revue de Llnstltut Francals du Petole vol 39 5 (1984)

8ey D 0 Hey M J and Lee M A Colloids and Surfaces 24 (1987 173

8ey 0 o Hey M J and Symonds J o Colloids and Surfaces 32 (1988) 87103 8ey o 0 Hey M J Symonds J 0 and Willison J H M J Colloid Interface Sci 54 (1976) 462 Graham 0 E Crude OU Emulsions Their Stability and Resolution 3rd Ind Sym on Chemistry In the 01 Industry Northwest Region of the Industrial OMslon Royal Soc ofChemistry Special Pub 67 (1988)

Grlll1th M G and Siegmund C W Controlling Compatibility of Residual Fuel Oils Marine Fuels ASTM STP 878 C H Jones Ed Amer Soc for Testing and Materials Phlladelphla (1985) 227 Haslba H H and Jessen F W Film Forming Compounds from Crude Oils lnterlaclal Ams and Paraffin Deposition 18th Annual Tech Meeting Petrol Soc of CIM 1967) Lawrence A S C and KDlner W J Inst Petrol 34 (1948) 821 Long R B The Concept of Asphaltenes Sym OMsion of Petrol Chemistry Inc Washington

middot-

shy

- f

I

lfllt -~

I ~

bull

I

c 1

_

c

117

(1979)

Mackay 0 Formation and StabUity ol Water-In-oil Emulslons Envlr Canada EE-93 (1987)Mackay 0 and Zagorski W Studies ol Water-In-oil Emulsions Envlr Canada EE-34 (1982)Neumann H J Paczynska-Lahme B and Severin D Composition and Properties of Petroleum Geology ol Petrol H Beckmann Ed Halsted Press 5 (1981) Rosen M J Surfactants and lnterfacfal Phenomena John Wiley amp Son (1978) Speight JG The Chemistry and Technology ol Petroleum Marcel Dekker Inc (1980) Speight JG and Moschopedls SE Sone Observations on the Molecular Nature of Petroleum Asphaltenes Sym OMslon ol Petrol Chemistry Inc Washington (1979) Thompson 0 G Taylor A S and Graham 0 E Emulsification and Oemufsificatlon Related to Crude 01 Production Sym Formation ol Liq-Liq Dispersions Chemical and EngineeringAspects Inst ol Chem Engineers and Southeast Branch Fluid Mixing Process Subject Grp (Feb 1984) Van der Waarden M Kolloid Z 156 (1958) 116

• A study of the formation of water in oil emulsions

t

o

109

Figure 27 Water content vs yen elkene

bullL

i ubullbulll

f l

--------ltgt--middot--middot-+--middot--middot--middot--middot-+--middot ---- f X alkane

middot ---+- O Ot glllL esphaltenes 0 wbullbull --o- O 01 01- bullsPhbullltenes 0 05 o111L wabull -x-middot o 01 gML bullsphbullltenes 01 oiL wax

Figure 28 Y1eld Point vs X alkane

u

I0 ~-0

bull -- I

) I

gt

bull II

__ __f-~==~---middot-middot-+-- ---- ----==-=====t bull bull X alkene

bullbull

bull bull

bull bull

0

llO

iO 0 0

0

00

0

bulls

i

0

Figure 29 Fo versus X alkane effect of adding wax

--

X alkane

~ O 05 o_ esohbullltenes O ax ---tr-middot 005 9ML llSPhbullltenes 01 glllL wax

Figure 30 F f ~nal vs alkane

00

middot-middot

bull bull

middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotampmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

I

f

jl

bullbull

I alkene

bull bullbull bullbull bullbull

111

F1gure 3t water content vs ~ alkane

middotmiddotmiddot-- middotmiddot--o------ ----shy

ie

bullL bull ~

i

e1

I

I II

I alkanebull-j

I I 1

--0-- 005 asphaltenes 0 bullbullbull ---tr--- 0 05 asphaltenes 0 t bull-

middot~ I

Figure 3~ Yield point vs ~ alkaneI I I o

I I

uo

bull~ gt- middot-

middot-bullbullA

-A ------------middotmiddotmiddotmiddotmiddot middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

bull bull X alkanes

112

Figure 33 Fo versus alkane eftect of 1ncreas1ng asphaltene concentration

tn an 011 hav1ng a wax concentrat1o_n of 005 gmL

bull 0

0

0 bull

0

0 bull 0 shy

0

0

oo

lC alkane

-0- 0 75Q as S O wa11I I) --0--03 o as 5 g ax

Figure 3A F final vs X alkane

I)

~ shy

0 bull

~

X alkane

bullbull

I -i 113

gt

middotO

bull

~i

~

0

0

0

io

j

0

Mi I

T 25-shy

I loT l

I

tmiddot1 F~gure 35 Water content VS bull alkampnebull

IOOT

~ WT l I +

bull st~

bull ~bull I

middotmiddotr~ I

0

0

J bull

l -0-- 07Sg 5 bull ---0-- 0 3 g 5 bull bullbullbull lt l bulli Figure 36 Y1eld point VS bull a 11ltane

~ middot ~ t ~

oo ~ middot

-

p s ~

middot

0

bull - bullo

~-

gtshy _

middot 00

~ N N N 0 bull bullbull bullbull bullbull

bull alkane

o

bull bull bull

Figure 37 Flow curve tor mousse Shear stress versus shear rate

O

bullbull

~ 1ncreas1n9 L shear rate ~-

=X- decreas in9 bullbull cshy~

shi_~r rate

~

SHEAR RATE (1s)

0

0

114

Rheooaical Prooerties All the stable emulsions formed during this study exhibited non-Newtonian flow behaviour

Flow curves for mousse (Figure 37) Indicate that they behave as pseudoplastic liquids which have a definite yield point and a thixotropic flow behaviour This complex flow behaviour means that viscosity is extremely dependent upon shear conditions (shear rate and length of time shear Is applied) Therefore a single viscosity number can not properly characterize the fluidity of mousse Figure 38 demonstrates this effect of shear rate on apparent viscosity

Drooet Size Distribution Figure 39 shows the droplet size distribution for a typical mousse formed by the model

oils The droplet diameters are very heterogeneous and appear to have at least a bi-modal distribution This multi-modal size distribution means that the water content of emulsions can exceed the water content of uni-modal distributions which theoretically has a maximum value of 74 In effect this allows droplets of a smaller size to occupy the gaps between larger droplets thus creating an extremely dense packing of droplets The yield point of emulsions increases as the droplet size distribution shifts to smaller values

0

gt -- NT 0 u bull ~ i gt

O

~-

- ]

IHi

bull bull T

~--T middotmiddott ~ middot1 T middott bullbull ~ ~ ~ middot~

--ltgt-- lncreastng shear rate

x- aecreas tng shear rate

SHEAR RATE (1sl

Figure 39 Droplet size distribution

20

10

0

lt1 1 25 5 9 14 18 23 27 32 MEAN DROPLET DIAMETER

(microns)

115 Ft9ure 38 Efect of shear rate on apparent viscosity of ousse

bull

0

0

o

116

Conclusions

The results from this study demonstrate the Importance that the physical state of an

emulsifying agent has upon Its ability to stabilize emulsions It was found that to be effective

emulsifiers asphaltenes resins and waxes must be in the form of finely divided partides The

chemical composition of the ol determines not only the amount and size of these partldes but also their composition and their wetting properties All these factors were shown to have

an Influence upltin the emulsification process Asphaltenes and resins by themselves and In combination were effective emulsifying

agents Model oils containing only wax as the emulsifying agent did not form stable emulsions But the addition of a nominal amount of asphaltenes an amount insufficient by

Itself to produce emulsions to oDs containing wax lead to the formation of stable emulsions This indicates that different emulsifying agents can synergically Interact to stabUize emulsions

The solubllity precipitation behaviour of asphaltenes In model oils follows the solubllity theory as described by the HUdebrand-Scatchard equation The use of solubility parameters

can be applied to petroleum fractions and therefore may be useful In predicting the physiochemical conditions which favour emulsification

Acknowledgements

This study was co-funded by the United States Minerals Management Service and the Environmental Emergencies Technology Division of Environment Canada

References

Barton AFM Handbook of Solubility Parameters and Other Cohesion Parameters CRC Press 1983) Becher P Emulsions Theory and Practice Kreiger Publishing 2 (1977) Becher P Encydopedia of Emulsion Technology Marcel Dekker 1 (1983)

Blair C M Chem Ind (London) (1960) 538 Bobra M A Catalogue of Cnide Oil and Oil Product Properties Envir Canada EE-114 (1989) Bridle A L Wanders TH H Zegveld W and Vander Heijde H B Marine Pollution Bulletin

11 (1980) 343 Canevari G P Marine Pollution Bulletin 13 1982) 49

Clark G H Industrial and Marine Fuels Reference Book Butterworth and Co (1988) Desrnaison M Desrnarquest J-P Plekarsld C and Piekarski S Revue de Llnstltut Francals du Petole vol 39 5 (1984)

8ey D 0 Hey M J and Lee M A Colloids and Surfaces 24 (1987 173

8ey 0 o Hey M J and Symonds J o Colloids and Surfaces 32 (1988) 87103 8ey o 0 Hey M J Symonds J 0 and Willison J H M J Colloid Interface Sci 54 (1976) 462 Graham 0 E Crude OU Emulsions Their Stability and Resolution 3rd Ind Sym on Chemistry In the 01 Industry Northwest Region of the Industrial OMslon Royal Soc ofChemistry Special Pub 67 (1988)

Grlll1th M G and Siegmund C W Controlling Compatibility of Residual Fuel Oils Marine Fuels ASTM STP 878 C H Jones Ed Amer Soc for Testing and Materials Phlladelphla (1985) 227 Haslba H H and Jessen F W Film Forming Compounds from Crude Oils lnterlaclal Ams and Paraffin Deposition 18th Annual Tech Meeting Petrol Soc of CIM 1967) Lawrence A S C and KDlner W J Inst Petrol 34 (1948) 821 Long R B The Concept of Asphaltenes Sym OMsion of Petrol Chemistry Inc Washington

middot-

shy

- f

I

lfllt -~

I ~

bull

I

c 1

_

c

117

(1979)

Mackay 0 Formation and StabUity ol Water-In-oil Emulslons Envlr Canada EE-93 (1987)Mackay 0 and Zagorski W Studies ol Water-In-oil Emulsions Envlr Canada EE-34 (1982)Neumann H J Paczynska-Lahme B and Severin D Composition and Properties of Petroleum Geology ol Petrol H Beckmann Ed Halsted Press 5 (1981) Rosen M J Surfactants and lnterfacfal Phenomena John Wiley amp Son (1978) Speight JG The Chemistry and Technology ol Petroleum Marcel Dekker Inc (1980) Speight JG and Moschopedls SE Sone Observations on the Molecular Nature of Petroleum Asphaltenes Sym OMslon ol Petrol Chemistry Inc Washington (1979) Thompson 0 G Taylor A S and Graham 0 E Emulsification and Oemufsificatlon Related to Crude 01 Production Sym Formation ol Liq-Liq Dispersions Chemical and EngineeringAspects Inst ol Chem Engineers and Southeast Branch Fluid Mixing Process Subject Grp (Feb 1984) Van der Waarden M Kolloid Z 156 (1958) 116

• A study of the formation of water in oil emulsions

bullbull

bull bull

bull bull

0

llO

iO 0 0

0

00

0

bulls

i

0

Figure 29 Fo versus X alkane effect of adding wax

--

X alkane

~ O 05 o_ esohbullltenes O ax ---tr-middot 005 9ML llSPhbullltenes 01 glllL wax

Figure 30 F f ~nal vs alkane

00

middot-middot

bull bull

middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotampmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

I

f

jl

bullbull

I alkene

bull bullbull bullbull bullbull

111

F1gure 3t water content vs ~ alkane

middotmiddotmiddot-- middotmiddot--o------ ----shy

ie

bullL bull ~

i

e1

I

I II

I alkanebull-j

I I 1

--0-- 005 asphaltenes 0 bullbullbull ---tr--- 0 05 asphaltenes 0 t bull-

middot~ I

Figure 3~ Yield point vs ~ alkaneI I I o

I I

uo

bull~ gt- middot-

middot-bullbullA

-A ------------middotmiddotmiddotmiddotmiddot middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

bull bull X alkanes

112

Figure 33 Fo versus alkane eftect of 1ncreas1ng asphaltene concentration

tn an 011 hav1ng a wax concentrat1o_n of 005 gmL

bull 0

0

0 bull

0

0 bull 0 shy

0

0

oo

lC alkane

-0- 0 75Q as S O wa11I I) --0--03 o as 5 g ax

Figure 3A F final vs X alkane

I)

~ shy

0 bull

~

X alkane

bullbull

I -i 113

gt

middotO

bull

~i

~

0

0

0

io

j

0

Mi I

T 25-shy

I loT l

I

tmiddot1 F~gure 35 Water content VS bull alkampnebull

IOOT

~ WT l I +

bull st~

bull ~bull I

middotmiddotr~ I

0

0

J bull

l -0-- 07Sg 5 bull ---0-- 0 3 g 5 bull bullbullbull lt l bulli Figure 36 Y1eld point VS bull a 11ltane

~ middot ~ t ~

oo ~ middot

-

p s ~

middot

0

bull - bullo

~-

gtshy _

middot 00

~ N N N 0 bull bullbull bullbull bullbull

bull alkane

o

bull bull bull

Figure 37 Flow curve tor mousse Shear stress versus shear rate

O

bullbull

~ 1ncreas1n9 L shear rate ~-

=X- decreas in9 bullbull cshy~

shi_~r rate

~

SHEAR RATE (1s)

0

0

114

Rheooaical Prooerties All the stable emulsions formed during this study exhibited non-Newtonian flow behaviour

Flow curves for mousse (Figure 37) Indicate that they behave as pseudoplastic liquids which have a definite yield point and a thixotropic flow behaviour This complex flow behaviour means that viscosity is extremely dependent upon shear conditions (shear rate and length of time shear Is applied) Therefore a single viscosity number can not properly characterize the fluidity of mousse Figure 38 demonstrates this effect of shear rate on apparent viscosity

Drooet Size Distribution Figure 39 shows the droplet size distribution for a typical mousse formed by the model

oils The droplet diameters are very heterogeneous and appear to have at least a bi-modal distribution This multi-modal size distribution means that the water content of emulsions can exceed the water content of uni-modal distributions which theoretically has a maximum value of 74 In effect this allows droplets of a smaller size to occupy the gaps between larger droplets thus creating an extremely dense packing of droplets The yield point of emulsions increases as the droplet size distribution shifts to smaller values

0

gt -- NT 0 u bull ~ i gt

O

~-

- ]

IHi

bull bull T

~--T middotmiddott ~ middot1 T middott bullbull ~ ~ ~ middot~

--ltgt-- lncreastng shear rate

x- aecreas tng shear rate

SHEAR RATE (1sl

Figure 39 Droplet size distribution

20

10

0

lt1 1 25 5 9 14 18 23 27 32 MEAN DROPLET DIAMETER

(microns)

115 Ft9ure 38 Efect of shear rate on apparent viscosity of ousse

bull

0

0

o

116

Conclusions

The results from this study demonstrate the Importance that the physical state of an

emulsifying agent has upon Its ability to stabilize emulsions It was found that to be effective

emulsifiers asphaltenes resins and waxes must be in the form of finely divided partides The

chemical composition of the ol determines not only the amount and size of these partldes but also their composition and their wetting properties All these factors were shown to have

an Influence upltin the emulsification process Asphaltenes and resins by themselves and In combination were effective emulsifying

agents Model oils containing only wax as the emulsifying agent did not form stable emulsions But the addition of a nominal amount of asphaltenes an amount insufficient by

Itself to produce emulsions to oDs containing wax lead to the formation of stable emulsions This indicates that different emulsifying agents can synergically Interact to stabUize emulsions

The solubllity precipitation behaviour of asphaltenes In model oils follows the solubllity theory as described by the HUdebrand-Scatchard equation The use of solubility parameters

can be applied to petroleum fractions and therefore may be useful In predicting the physiochemical conditions which favour emulsification

Acknowledgements

This study was co-funded by the United States Minerals Management Service and the Environmental Emergencies Technology Division of Environment Canada

References

Barton AFM Handbook of Solubility Parameters and Other Cohesion Parameters CRC Press 1983) Becher P Emulsions Theory and Practice Kreiger Publishing 2 (1977) Becher P Encydopedia of Emulsion Technology Marcel Dekker 1 (1983)

Blair C M Chem Ind (London) (1960) 538 Bobra M A Catalogue of Cnide Oil and Oil Product Properties Envir Canada EE-114 (1989) Bridle A L Wanders TH H Zegveld W and Vander Heijde H B Marine Pollution Bulletin

11 (1980) 343 Canevari G P Marine Pollution Bulletin 13 1982) 49

Clark G H Industrial and Marine Fuels Reference Book Butterworth and Co (1988) Desrnaison M Desrnarquest J-P Plekarsld C and Piekarski S Revue de Llnstltut Francals du Petole vol 39 5 (1984)

8ey D 0 Hey M J and Lee M A Colloids and Surfaces 24 (1987 173

8ey 0 o Hey M J and Symonds J o Colloids and Surfaces 32 (1988) 87103 8ey o 0 Hey M J Symonds J 0 and Willison J H M J Colloid Interface Sci 54 (1976) 462 Graham 0 E Crude OU Emulsions Their Stability and Resolution 3rd Ind Sym on Chemistry In the 01 Industry Northwest Region of the Industrial OMslon Royal Soc ofChemistry Special Pub 67 (1988)

Grlll1th M G and Siegmund C W Controlling Compatibility of Residual Fuel Oils Marine Fuels ASTM STP 878 C H Jones Ed Amer Soc for Testing and Materials Phlladelphla (1985) 227 Haslba H H and Jessen F W Film Forming Compounds from Crude Oils lnterlaclal Ams and Paraffin Deposition 18th Annual Tech Meeting Petrol Soc of CIM 1967) Lawrence A S C and KDlner W J Inst Petrol 34 (1948) 821 Long R B The Concept of Asphaltenes Sym OMsion of Petrol Chemistry Inc Washington

middot-

shy

- f

I

lfllt -~

I ~

bull

I

c 1

_

c

117

(1979)

Mackay 0 Formation and StabUity ol Water-In-oil Emulslons Envlr Canada EE-93 (1987)Mackay 0 and Zagorski W Studies ol Water-In-oil Emulsions Envlr Canada EE-34 (1982)Neumann H J Paczynska-Lahme B and Severin D Composition and Properties of Petroleum Geology ol Petrol H Beckmann Ed Halsted Press 5 (1981) Rosen M J Surfactants and lnterfacfal Phenomena John Wiley amp Son (1978) Speight JG The Chemistry and Technology ol Petroleum Marcel Dekker Inc (1980) Speight JG and Moschopedls SE Sone Observations on the Molecular Nature of Petroleum Asphaltenes Sym OMslon ol Petrol Chemistry Inc Washington (1979) Thompson 0 G Taylor A S and Graham 0 E Emulsification and Oemufsificatlon Related to Crude 01 Production Sym Formation ol Liq-Liq Dispersions Chemical and EngineeringAspects Inst ol Chem Engineers and Southeast Branch Fluid Mixing Process Subject Grp (Feb 1984) Van der Waarden M Kolloid Z 156 (1958) 116

• A study of the formation of water in oil emulsions

bull bullbull bullbull bullbull

111

F1gure 3t water content vs ~ alkane

middotmiddotmiddot-- middotmiddot--o------ ----shy

ie

bullL bull ~

i

e1

I

I II

I alkanebull-j

I I 1

--0-- 005 asphaltenes 0 bullbullbull ---tr--- 0 05 asphaltenes 0 t bull-

middot~ I

Figure 3~ Yield point vs ~ alkaneI I I o

I I

uo

bull~ gt- middot-

middot-bullbullA

-A ------------middotmiddotmiddotmiddotmiddot middotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot

bull bull X alkanes

112

Figure 33 Fo versus alkane eftect of 1ncreas1ng asphaltene concentration

tn an 011 hav1ng a wax concentrat1o_n of 005 gmL

bull 0

0

0 bull

0

0 bull 0 shy

0

0

oo

lC alkane

-0- 0 75Q as S O wa11I I) --0--03 o as 5 g ax

Figure 3A F final vs X alkane

I)

~ shy

0 bull

~

X alkane

bullbull

I -i 113

gt

middotO

bull

~i

~

0

0

0

io

j

0

Mi I

T 25-shy

I loT l

I

tmiddot1 F~gure 35 Water content VS bull alkampnebull

IOOT

~ WT l I +

bull st~

bull ~bull I

middotmiddotr~ I

0

0

J bull

l -0-- 07Sg 5 bull ---0-- 0 3 g 5 bull bullbullbull lt l bulli Figure 36 Y1eld point VS bull a 11ltane

~ middot ~ t ~

oo ~ middot

-

p s ~

middot

0

bull - bullo

~-

gtshy _

middot 00

~ N N N 0 bull bullbull bullbull bullbull

bull alkane

o

bull bull bull

Figure 37 Flow curve tor mousse Shear stress versus shear rate

O

bullbull

~ 1ncreas1n9 L shear rate ~-

=X- decreas in9 bullbull cshy~

shi_~r rate

~

SHEAR RATE (1s)

0

0

114

Rheooaical Prooerties All the stable emulsions formed during this study exhibited non-Newtonian flow behaviour

Flow curves for mousse (Figure 37) Indicate that they behave as pseudoplastic liquids which have a definite yield point and a thixotropic flow behaviour This complex flow behaviour means that viscosity is extremely dependent upon shear conditions (shear rate and length of time shear Is applied) Therefore a single viscosity number can not properly characterize the fluidity of mousse Figure 38 demonstrates this effect of shear rate on apparent viscosity

Drooet Size Distribution Figure 39 shows the droplet size distribution for a typical mousse formed by the model

oils The droplet diameters are very heterogeneous and appear to have at least a bi-modal distribution This multi-modal size distribution means that the water content of emulsions can exceed the water content of uni-modal distributions which theoretically has a maximum value of 74 In effect this allows droplets of a smaller size to occupy the gaps between larger droplets thus creating an extremely dense packing of droplets The yield point of emulsions increases as the droplet size distribution shifts to smaller values

0

gt -- NT 0 u bull ~ i gt

O

~-

- ]

IHi

bull bull T

~--T middotmiddott ~ middot1 T middott bullbull ~ ~ ~ middot~

--ltgt-- lncreastng shear rate

x- aecreas tng shear rate

SHEAR RATE (1sl

Figure 39 Droplet size distribution

20

10

0

lt1 1 25 5 9 14 18 23 27 32 MEAN DROPLET DIAMETER

(microns)

115 Ft9ure 38 Efect of shear rate on apparent viscosity of ousse

bull

0

0

o

116

Conclusions

The results from this study demonstrate the Importance that the physical state of an

emulsifying agent has upon Its ability to stabilize emulsions It was found that to be effective

emulsifiers asphaltenes resins and waxes must be in the form of finely divided partides The

chemical composition of the ol determines not only the amount and size of these partldes but also their composition and their wetting properties All these factors were shown to have

an Influence upltin the emulsification process Asphaltenes and resins by themselves and In combination were effective emulsifying

agents Model oils containing only wax as the emulsifying agent did not form stable emulsions But the addition of a nominal amount of asphaltenes an amount insufficient by

Itself to produce emulsions to oDs containing wax lead to the formation of stable emulsions This indicates that different emulsifying agents can synergically Interact to stabUize emulsions

The solubllity precipitation behaviour of asphaltenes In model oils follows the solubllity theory as described by the HUdebrand-Scatchard equation The use of solubility parameters

can be applied to petroleum fractions and therefore may be useful In predicting the physiochemical conditions which favour emulsification

Acknowledgements

This study was co-funded by the United States Minerals Management Service and the Environmental Emergencies Technology Division of Environment Canada

References

Barton AFM Handbook of Solubility Parameters and Other Cohesion Parameters CRC Press 1983) Becher P Emulsions Theory and Practice Kreiger Publishing 2 (1977) Becher P Encydopedia of Emulsion Technology Marcel Dekker 1 (1983)

Blair C M Chem Ind (London) (1960) 538 Bobra M A Catalogue of Cnide Oil and Oil Product Properties Envir Canada EE-114 (1989) Bridle A L Wanders TH H Zegveld W and Vander Heijde H B Marine Pollution Bulletin

11 (1980) 343 Canevari G P Marine Pollution Bulletin 13 1982) 49

Clark G H Industrial and Marine Fuels Reference Book Butterworth and Co (1988) Desrnaison M Desrnarquest J-P Plekarsld C and Piekarski S Revue de Llnstltut Francals du Petole vol 39 5 (1984)

8ey D 0 Hey M J and Lee M A Colloids and Surfaces 24 (1987 173

8ey 0 o Hey M J and Symonds J o Colloids and Surfaces 32 (1988) 87103 8ey o 0 Hey M J Symonds J 0 and Willison J H M J Colloid Interface Sci 54 (1976) 462 Graham 0 E Crude OU Emulsions Their Stability and Resolution 3rd Ind Sym on Chemistry In the 01 Industry Northwest Region of the Industrial OMslon Royal Soc ofChemistry Special Pub 67 (1988)

Grlll1th M G and Siegmund C W Controlling Compatibility of Residual Fuel Oils Marine Fuels ASTM STP 878 C H Jones Ed Amer Soc for Testing and Materials Phlladelphla (1985) 227 Haslba H H and Jessen F W Film Forming Compounds from Crude Oils lnterlaclal Ams and Paraffin Deposition 18th Annual Tech Meeting Petrol Soc of CIM 1967) Lawrence A S C and KDlner W J Inst Petrol 34 (1948) 821 Long R B The Concept of Asphaltenes Sym OMsion of Petrol Chemistry Inc Washington

middot-

shy

- f

I

lfllt -~

I ~

bull

I

c 1

_

c

117

(1979)

Mackay 0 Formation and StabUity ol Water-In-oil Emulslons Envlr Canada EE-93 (1987)Mackay 0 and Zagorski W Studies ol Water-In-oil Emulsions Envlr Canada EE-34 (1982)Neumann H J Paczynska-Lahme B and Severin D Composition and Properties of Petroleum Geology ol Petrol H Beckmann Ed Halsted Press 5 (1981) Rosen M J Surfactants and lnterfacfal Phenomena John Wiley amp Son (1978) Speight JG The Chemistry and Technology ol Petroleum Marcel Dekker Inc (1980) Speight JG and Moschopedls SE Sone Observations on the Molecular Nature of Petroleum Asphaltenes Sym OMslon ol Petrol Chemistry Inc Washington (1979) Thompson 0 G Taylor A S and Graham 0 E Emulsification and Oemufsificatlon Related to Crude 01 Production Sym Formation ol Liq-Liq Dispersions Chemical and EngineeringAspects Inst ol Chem Engineers and Southeast Branch Fluid Mixing Process Subject Grp (Feb 1984) Van der Waarden M Kolloid Z 156 (1958) 116

• A study of the formation of water in oil emulsions

112

Figure 33 Fo versus alkane eftect of 1ncreas1ng asphaltene concentration

tn an 011 hav1ng a wax concentrat1o_n of 005 gmL

bull 0

0

0 bull

0

0 bull 0 shy

0

0

oo

lC alkane

-0- 0 75Q as S O wa11I I) --0--03 o as 5 g ax

Figure 3A F final vs X alkane

I)

~ shy

0 bull

~

X alkane

bullbull

I -i 113

gt

middotO

bull

~i

~

0

0

0

io

j

0

Mi I

T 25-shy

I loT l

I

tmiddot1 F~gure 35 Water content VS bull alkampnebull

IOOT

~ WT l I +

bull st~

bull ~bull I

middotmiddotr~ I

0

0

J bull

l -0-- 07Sg 5 bull ---0-- 0 3 g 5 bull bullbullbull lt l bulli Figure 36 Y1eld point VS bull a 11ltane

~ middot ~ t ~

oo ~ middot

-

p s ~

middot

0

bull - bullo

~-

gtshy _

middot 00

~ N N N 0 bull bullbull bullbull bullbull

bull alkane

o

bull bull bull

Figure 37 Flow curve tor mousse Shear stress versus shear rate

O

bullbull

~ 1ncreas1n9 L shear rate ~-

=X- decreas in9 bullbull cshy~

shi_~r rate

~

SHEAR RATE (1s)

0

0

114

Rheooaical Prooerties All the stable emulsions formed during this study exhibited non-Newtonian flow behaviour

Flow curves for mousse (Figure 37) Indicate that they behave as pseudoplastic liquids which have a definite yield point and a thixotropic flow behaviour This complex flow behaviour means that viscosity is extremely dependent upon shear conditions (shear rate and length of time shear Is applied) Therefore a single viscosity number can not properly characterize the fluidity of mousse Figure 38 demonstrates this effect of shear rate on apparent viscosity

Drooet Size Distribution Figure 39 shows the droplet size distribution for a typical mousse formed by the model

oils The droplet diameters are very heterogeneous and appear to have at least a bi-modal distribution This multi-modal size distribution means that the water content of emulsions can exceed the water content of uni-modal distributions which theoretically has a maximum value of 74 In effect this allows droplets of a smaller size to occupy the gaps between larger droplets thus creating an extremely dense packing of droplets The yield point of emulsions increases as the droplet size distribution shifts to smaller values

0

gt -- NT 0 u bull ~ i gt

O

~-

- ]

IHi

bull bull T

~--T middotmiddott ~ middot1 T middott bullbull ~ ~ ~ middot~

--ltgt-- lncreastng shear rate

x- aecreas tng shear rate

SHEAR RATE (1sl

Figure 39 Droplet size distribution

20

10

0

lt1 1 25 5 9 14 18 23 27 32 MEAN DROPLET DIAMETER

(microns)

115 Ft9ure 38 Efect of shear rate on apparent viscosity of ousse

bull

0

0

o

116

Conclusions

The results from this study demonstrate the Importance that the physical state of an

emulsifying agent has upon Its ability to stabilize emulsions It was found that to be effective

emulsifiers asphaltenes resins and waxes must be in the form of finely divided partides The

chemical composition of the ol determines not only the amount and size of these partldes but also their composition and their wetting properties All these factors were shown to have

an Influence upltin the emulsification process Asphaltenes and resins by themselves and In combination were effective emulsifying

agents Model oils containing only wax as the emulsifying agent did not form stable emulsions But the addition of a nominal amount of asphaltenes an amount insufficient by

Itself to produce emulsions to oDs containing wax lead to the formation of stable emulsions This indicates that different emulsifying agents can synergically Interact to stabUize emulsions

The solubllity precipitation behaviour of asphaltenes In model oils follows the solubllity theory as described by the HUdebrand-Scatchard equation The use of solubility parameters

can be applied to petroleum fractions and therefore may be useful In predicting the physiochemical conditions which favour emulsification

Acknowledgements

This study was co-funded by the United States Minerals Management Service and the Environmental Emergencies Technology Division of Environment Canada

References

Barton AFM Handbook of Solubility Parameters and Other Cohesion Parameters CRC Press 1983) Becher P Emulsions Theory and Practice Kreiger Publishing 2 (1977) Becher P Encydopedia of Emulsion Technology Marcel Dekker 1 (1983)

Blair C M Chem Ind (London) (1960) 538 Bobra M A Catalogue of Cnide Oil and Oil Product Properties Envir Canada EE-114 (1989) Bridle A L Wanders TH H Zegveld W and Vander Heijde H B Marine Pollution Bulletin

11 (1980) 343 Canevari G P Marine Pollution Bulletin 13 1982) 49

Clark G H Industrial and Marine Fuels Reference Book Butterworth and Co (1988) Desrnaison M Desrnarquest J-P Plekarsld C and Piekarski S Revue de Llnstltut Francals du Petole vol 39 5 (1984)

8ey D 0 Hey M J and Lee M A Colloids and Surfaces 24 (1987 173

8ey 0 o Hey M J and Symonds J o Colloids and Surfaces 32 (1988) 87103 8ey o 0 Hey M J Symonds J 0 and Willison J H M J Colloid Interface Sci 54 (1976) 462 Graham 0 E Crude OU Emulsions Their Stability and Resolution 3rd Ind Sym on Chemistry In the 01 Industry Northwest Region of the Industrial OMslon Royal Soc ofChemistry Special Pub 67 (1988)

Grlll1th M G and Siegmund C W Controlling Compatibility of Residual Fuel Oils Marine Fuels ASTM STP 878 C H Jones Ed Amer Soc for Testing and Materials Phlladelphla (1985) 227 Haslba H H and Jessen F W Film Forming Compounds from Crude Oils lnterlaclal Ams and Paraffin Deposition 18th Annual Tech Meeting Petrol Soc of CIM 1967) Lawrence A S C and KDlner W J Inst Petrol 34 (1948) 821 Long R B The Concept of Asphaltenes Sym OMsion of Petrol Chemistry Inc Washington

middot-

shy

- f

I

lfllt -~

I ~

bull

I

c 1

_

c

117

(1979)

Mackay 0 Formation and StabUity ol Water-In-oil Emulslons Envlr Canada EE-93 (1987)Mackay 0 and Zagorski W Studies ol Water-In-oil Emulsions Envlr Canada EE-34 (1982)Neumann H J Paczynska-Lahme B and Severin D Composition and Properties of Petroleum Geology ol Petrol H Beckmann Ed Halsted Press 5 (1981) Rosen M J Surfactants and lnterfacfal Phenomena John Wiley amp Son (1978) Speight JG The Chemistry and Technology ol Petroleum Marcel Dekker Inc (1980) Speight JG and Moschopedls SE Sone Observations on the Molecular Nature of Petroleum Asphaltenes Sym OMslon ol Petrol Chemistry Inc Washington (1979) Thompson 0 G Taylor A S and Graham 0 E Emulsification and Oemufsificatlon Related to Crude 01 Production Sym Formation ol Liq-Liq Dispersions Chemical and EngineeringAspects Inst ol Chem Engineers and Southeast Branch Fluid Mixing Process Subject Grp (Feb 1984) Van der Waarden M Kolloid Z 156 (1958) 116

• A study of the formation of water in oil emulsions

bullbull

I -i 113

gt

middotO

bull

~i

~

0

0

0

io

j

0

Mi I

T 25-shy

I loT l

I

tmiddot1 F~gure 35 Water content VS bull alkampnebull

IOOT

~ WT l I +

bull st~

bull ~bull I

middotmiddotr~ I

0

0

J bull

l -0-- 07Sg 5 bull ---0-- 0 3 g 5 bull bullbullbull lt l bulli Figure 36 Y1eld point VS bull a 11ltane

~ middot ~ t ~

oo ~ middot

-

p s ~

middot

0

bull - bullo

~-

gtshy _

middot 00

~ N N N 0 bull bullbull bullbull bullbull

bull alkane

o

bull bull bull

Figure 37 Flow curve tor mousse Shear stress versus shear rate

O

bullbull

~ 1ncreas1n9 L shear rate ~-

=X- decreas in9 bullbull cshy~

shi_~r rate

~

SHEAR RATE (1s)

0

0

114

Rheooaical Prooerties All the stable emulsions formed during this study exhibited non-Newtonian flow behaviour

Flow curves for mousse (Figure 37) Indicate that they behave as pseudoplastic liquids which have a definite yield point and a thixotropic flow behaviour This complex flow behaviour means that viscosity is extremely dependent upon shear conditions (shear rate and length of time shear Is applied) Therefore a single viscosity number can not properly characterize the fluidity of mousse Figure 38 demonstrates this effect of shear rate on apparent viscosity

Drooet Size Distribution Figure 39 shows the droplet size distribution for a typical mousse formed by the model

oils The droplet diameters are very heterogeneous and appear to have at least a bi-modal distribution This multi-modal size distribution means that the water content of emulsions can exceed the water content of uni-modal distributions which theoretically has a maximum value of 74 In effect this allows droplets of a smaller size to occupy the gaps between larger droplets thus creating an extremely dense packing of droplets The yield point of emulsions increases as the droplet size distribution shifts to smaller values

0

gt -- NT 0 u bull ~ i gt

O

~-

- ]

IHi

bull bull T

~--T middotmiddott ~ middot1 T middott bullbull ~ ~ ~ middot~

--ltgt-- lncreastng shear rate

x- aecreas tng shear rate

SHEAR RATE (1sl

Figure 39 Droplet size distribution

20

10

0

lt1 1 25 5 9 14 18 23 27 32 MEAN DROPLET DIAMETER

(microns)

115 Ft9ure 38 Efect of shear rate on apparent viscosity of ousse

bull

0

0

o

116

Conclusions

The results from this study demonstrate the Importance that the physical state of an

emulsifying agent has upon Its ability to stabilize emulsions It was found that to be effective

emulsifiers asphaltenes resins and waxes must be in the form of finely divided partides The

chemical composition of the ol determines not only the amount and size of these partldes but also their composition and their wetting properties All these factors were shown to have

an Influence upltin the emulsification process Asphaltenes and resins by themselves and In combination were effective emulsifying

agents Model oils containing only wax as the emulsifying agent did not form stable emulsions But the addition of a nominal amount of asphaltenes an amount insufficient by

Itself to produce emulsions to oDs containing wax lead to the formation of stable emulsions This indicates that different emulsifying agents can synergically Interact to stabUize emulsions

The solubllity precipitation behaviour of asphaltenes In model oils follows the solubllity theory as described by the HUdebrand-Scatchard equation The use of solubility parameters

can be applied to petroleum fractions and therefore may be useful In predicting the physiochemical conditions which favour emulsification

Acknowledgements

This study was co-funded by the United States Minerals Management Service and the Environmental Emergencies Technology Division of Environment Canada

References

Barton AFM Handbook of Solubility Parameters and Other Cohesion Parameters CRC Press 1983) Becher P Emulsions Theory and Practice Kreiger Publishing 2 (1977) Becher P Encydopedia of Emulsion Technology Marcel Dekker 1 (1983)

Blair C M Chem Ind (London) (1960) 538 Bobra M A Catalogue of Cnide Oil and Oil Product Properties Envir Canada EE-114 (1989) Bridle A L Wanders TH H Zegveld W and Vander Heijde H B Marine Pollution Bulletin

11 (1980) 343 Canevari G P Marine Pollution Bulletin 13 1982) 49

Clark G H Industrial and Marine Fuels Reference Book Butterworth and Co (1988) Desrnaison M Desrnarquest J-P Plekarsld C and Piekarski S Revue de Llnstltut Francals du Petole vol 39 5 (1984)

8ey D 0 Hey M J and Lee M A Colloids and Surfaces 24 (1987 173

8ey 0 o Hey M J and Symonds J o Colloids and Surfaces 32 (1988) 87103 8ey o 0 Hey M J Symonds J 0 and Willison J H M J Colloid Interface Sci 54 (1976) 462 Graham 0 E Crude OU Emulsions Their Stability and Resolution 3rd Ind Sym on Chemistry In the 01 Industry Northwest Region of the Industrial OMslon Royal Soc ofChemistry Special Pub 67 (1988)

Grlll1th M G and Siegmund C W Controlling Compatibility of Residual Fuel Oils Marine Fuels ASTM STP 878 C H Jones Ed Amer Soc for Testing and Materials Phlladelphla (1985) 227 Haslba H H and Jessen F W Film Forming Compounds from Crude Oils lnterlaclal Ams and Paraffin Deposition 18th Annual Tech Meeting Petrol Soc of CIM 1967) Lawrence A S C and KDlner W J Inst Petrol 34 (1948) 821 Long R B The Concept of Asphaltenes Sym OMsion of Petrol Chemistry Inc Washington

middot-

shy

- f

I

lfllt -~

I ~

bull

I

c 1

_

c

117

(1979)

Mackay 0 Formation and StabUity ol Water-In-oil Emulslons Envlr Canada EE-93 (1987)Mackay 0 and Zagorski W Studies ol Water-In-oil Emulsions Envlr Canada EE-34 (1982)Neumann H J Paczynska-Lahme B and Severin D Composition and Properties of Petroleum Geology ol Petrol H Beckmann Ed Halsted Press 5 (1981) Rosen M J Surfactants and lnterfacfal Phenomena John Wiley amp Son (1978) Speight JG The Chemistry and Technology ol Petroleum Marcel Dekker Inc (1980) Speight JG and Moschopedls SE Sone Observations on the Molecular Nature of Petroleum Asphaltenes Sym OMslon ol Petrol Chemistry Inc Washington (1979) Thompson 0 G Taylor A S and Graham 0 E Emulsification and Oemufsificatlon Related to Crude 01 Production Sym Formation ol Liq-Liq Dispersions Chemical and EngineeringAspects Inst ol Chem Engineers and Southeast Branch Fluid Mixing Process Subject Grp (Feb 1984) Van der Waarden M Kolloid Z 156 (1958) 116

• A study of the formation of water in oil emulsions

bull bull bull

Figure 37 Flow curve tor mousse Shear stress versus shear rate

O

bullbull

~ 1ncreas1n9 L shear rate ~-

=X- decreas in9 bullbull cshy~

shi_~r rate

~

SHEAR RATE (1s)

0

0

114

Rheooaical Prooerties All the stable emulsions formed during this study exhibited non-Newtonian flow behaviour

Flow curves for mousse (Figure 37) Indicate that they behave as pseudoplastic liquids which have a definite yield point and a thixotropic flow behaviour This complex flow behaviour means that viscosity is extremely dependent upon shear conditions (shear rate and length of time shear Is applied) Therefore a single viscosity number can not properly characterize the fluidity of mousse Figure 38 demonstrates this effect of shear rate on apparent viscosity

Drooet Size Distribution Figure 39 shows the droplet size distribution for a typical mousse formed by the model

oils The droplet diameters are very heterogeneous and appear to have at least a bi-modal distribution This multi-modal size distribution means that the water content of emulsions can exceed the water content of uni-modal distributions which theoretically has a maximum value of 74 In effect this allows droplets of a smaller size to occupy the gaps between larger droplets thus creating an extremely dense packing of droplets The yield point of emulsions increases as the droplet size distribution shifts to smaller values

0

gt -- NT 0 u bull ~ i gt

O

~-

- ]

IHi

bull bull T

~--T middotmiddott ~ middot1 T middott bullbull ~ ~ ~ middot~

--ltgt-- lncreastng shear rate

x- aecreas tng shear rate

SHEAR RATE (1sl

Figure 39 Droplet size distribution

20

10

0

lt1 1 25 5 9 14 18 23 27 32 MEAN DROPLET DIAMETER

(microns)

115 Ft9ure 38 Efect of shear rate on apparent viscosity of ousse

bull

0

0

o

116

Conclusions

The results from this study demonstrate the Importance that the physical state of an

emulsifying agent has upon Its ability to stabilize emulsions It was found that to be effective

emulsifiers asphaltenes resins and waxes must be in the form of finely divided partides The

chemical composition of the ol determines not only the amount and size of these partldes but also their composition and their wetting properties All these factors were shown to have

an Influence upltin the emulsification process Asphaltenes and resins by themselves and In combination were effective emulsifying

agents Model oils containing only wax as the emulsifying agent did not form stable emulsions But the addition of a nominal amount of asphaltenes an amount insufficient by

Itself to produce emulsions to oDs containing wax lead to the formation of stable emulsions This indicates that different emulsifying agents can synergically Interact to stabUize emulsions

The solubllity precipitation behaviour of asphaltenes In model oils follows the solubllity theory as described by the HUdebrand-Scatchard equation The use of solubility parameters

can be applied to petroleum fractions and therefore may be useful In predicting the physiochemical conditions which favour emulsification

Acknowledgements

This study was co-funded by the United States Minerals Management Service and the Environmental Emergencies Technology Division of Environment Canada

References

Barton AFM Handbook of Solubility Parameters and Other Cohesion Parameters CRC Press 1983) Becher P Emulsions Theory and Practice Kreiger Publishing 2 (1977) Becher P Encydopedia of Emulsion Technology Marcel Dekker 1 (1983)

Blair C M Chem Ind (London) (1960) 538 Bobra M A Catalogue of Cnide Oil and Oil Product Properties Envir Canada EE-114 (1989) Bridle A L Wanders TH H Zegveld W and Vander Heijde H B Marine Pollution Bulletin

11 (1980) 343 Canevari G P Marine Pollution Bulletin 13 1982) 49

Clark G H Industrial and Marine Fuels Reference Book Butterworth and Co (1988) Desrnaison M Desrnarquest J-P Plekarsld C and Piekarski S Revue de Llnstltut Francals du Petole vol 39 5 (1984)

8ey D 0 Hey M J and Lee M A Colloids and Surfaces 24 (1987 173

8ey 0 o Hey M J and Symonds J o Colloids and Surfaces 32 (1988) 87103 8ey o 0 Hey M J Symonds J 0 and Willison J H M J Colloid Interface Sci 54 (1976) 462 Graham 0 E Crude OU Emulsions Their Stability and Resolution 3rd Ind Sym on Chemistry In the 01 Industry Northwest Region of the Industrial OMslon Royal Soc ofChemistry Special Pub 67 (1988)

Grlll1th M G and Siegmund C W Controlling Compatibility of Residual Fuel Oils Marine Fuels ASTM STP 878 C H Jones Ed Amer Soc for Testing and Materials Phlladelphla (1985) 227 Haslba H H and Jessen F W Film Forming Compounds from Crude Oils lnterlaclal Ams and Paraffin Deposition 18th Annual Tech Meeting Petrol Soc of CIM 1967) Lawrence A S C and KDlner W J Inst Petrol 34 (1948) 821 Long R B The Concept of Asphaltenes Sym OMsion of Petrol Chemistry Inc Washington

middot-

shy

- f

I

lfllt -~

I ~

bull

I

c 1

_

c

117

(1979)

Mackay 0 Formation and StabUity ol Water-In-oil Emulslons Envlr Canada EE-93 (1987)Mackay 0 and Zagorski W Studies ol Water-In-oil Emulsions Envlr Canada EE-34 (1982)Neumann H J Paczynska-Lahme B and Severin D Composition and Properties of Petroleum Geology ol Petrol H Beckmann Ed Halsted Press 5 (1981) Rosen M J Surfactants and lnterfacfal Phenomena John Wiley amp Son (1978) Speight JG The Chemistry and Technology ol Petroleum Marcel Dekker Inc (1980) Speight JG and Moschopedls SE Sone Observations on the Molecular Nature of Petroleum Asphaltenes Sym OMslon ol Petrol Chemistry Inc Washington (1979) Thompson 0 G Taylor A S and Graham 0 E Emulsification and Oemufsificatlon Related to Crude 01 Production Sym Formation ol Liq-Liq Dispersions Chemical and EngineeringAspects Inst ol Chem Engineers and Southeast Branch Fluid Mixing Process Subject Grp (Feb 1984) Van der Waarden M Kolloid Z 156 (1958) 116

• A study of the formation of water in oil emulsions

0

gt -- NT 0 u bull ~ i gt

O

~-

- ]

IHi

bull bull T

~--T middotmiddott ~ middot1 T middott bullbull ~ ~ ~ middot~

--ltgt-- lncreastng shear rate

x- aecreas tng shear rate

SHEAR RATE (1sl

Figure 39 Droplet size distribution

20

10

0

lt1 1 25 5 9 14 18 23 27 32 MEAN DROPLET DIAMETER

(microns)

115 Ft9ure 38 Efect of shear rate on apparent viscosity of ousse

bull

0

0

o

116

Conclusions

The results from this study demonstrate the Importance that the physical state of an

emulsifying agent has upon Its ability to stabilize emulsions It was found that to be effective

emulsifiers asphaltenes resins and waxes must be in the form of finely divided partides The

chemical composition of the ol determines not only the amount and size of these partldes but also their composition and their wetting properties All these factors were shown to have

an Influence upltin the emulsification process Asphaltenes and resins by themselves and In combination were effective emulsifying

agents Model oils containing only wax as the emulsifying agent did not form stable emulsions But the addition of a nominal amount of asphaltenes an amount insufficient by

Itself to produce emulsions to oDs containing wax lead to the formation of stable emulsions This indicates that different emulsifying agents can synergically Interact to stabUize emulsions

The solubllity precipitation behaviour of asphaltenes In model oils follows the solubllity theory as described by the HUdebrand-Scatchard equation The use of solubility parameters

can be applied to petroleum fractions and therefore may be useful In predicting the physiochemical conditions which favour emulsification

Acknowledgements

This study was co-funded by the United States Minerals Management Service and the Environmental Emergencies Technology Division of Environment Canada

References

Barton AFM Handbook of Solubility Parameters and Other Cohesion Parameters CRC Press 1983) Becher P Emulsions Theory and Practice Kreiger Publishing 2 (1977) Becher P Encydopedia of Emulsion Technology Marcel Dekker 1 (1983)

Blair C M Chem Ind (London) (1960) 538 Bobra M A Catalogue of Cnide Oil and Oil Product Properties Envir Canada EE-114 (1989) Bridle A L Wanders TH H Zegveld W and Vander Heijde H B Marine Pollution Bulletin

11 (1980) 343 Canevari G P Marine Pollution Bulletin 13 1982) 49

Clark G H Industrial and Marine Fuels Reference Book Butterworth and Co (1988) Desrnaison M Desrnarquest J-P Plekarsld C and Piekarski S Revue de Llnstltut Francals du Petole vol 39 5 (1984)

8ey D 0 Hey M J and Lee M A Colloids and Surfaces 24 (1987 173

8ey 0 o Hey M J and Symonds J o Colloids and Surfaces 32 (1988) 87103 8ey o 0 Hey M J Symonds J 0 and Willison J H M J Colloid Interface Sci 54 (1976) 462 Graham 0 E Crude OU Emulsions Their Stability and Resolution 3rd Ind Sym on Chemistry In the 01 Industry Northwest Region of the Industrial OMslon Royal Soc ofChemistry Special Pub 67 (1988)

Grlll1th M G and Siegmund C W Controlling Compatibility of Residual Fuel Oils Marine Fuels ASTM STP 878 C H Jones Ed Amer Soc for Testing and Materials Phlladelphla (1985) 227 Haslba H H and Jessen F W Film Forming Compounds from Crude Oils lnterlaclal Ams and Paraffin Deposition 18th Annual Tech Meeting Petrol Soc of CIM 1967) Lawrence A S C and KDlner W J Inst Petrol 34 (1948) 821 Long R B The Concept of Asphaltenes Sym OMsion of Petrol Chemistry Inc Washington

middot-

shy

- f

I

lfllt -~

I ~

bull

I

c 1

_

c

117

(1979)

Mackay 0 Formation and StabUity ol Water-In-oil Emulslons Envlr Canada EE-93 (1987)Mackay 0 and Zagorski W Studies ol Water-In-oil Emulsions Envlr Canada EE-34 (1982)Neumann H J Paczynska-Lahme B and Severin D Composition and Properties of Petroleum Geology ol Petrol H Beckmann Ed Halsted Press 5 (1981) Rosen M J Surfactants and lnterfacfal Phenomena John Wiley amp Son (1978) Speight JG The Chemistry and Technology ol Petroleum Marcel Dekker Inc (1980) Speight JG and Moschopedls SE Sone Observations on the Molecular Nature of Petroleum Asphaltenes Sym OMslon ol Petrol Chemistry Inc Washington (1979) Thompson 0 G Taylor A S and Graham 0 E Emulsification and Oemufsificatlon Related to Crude 01 Production Sym Formation ol Liq-Liq Dispersions Chemical and EngineeringAspects Inst ol Chem Engineers and Southeast Branch Fluid Mixing Process Subject Grp (Feb 1984) Van der Waarden M Kolloid Z 156 (1958) 116

• A study of the formation of water in oil emulsions

bull

0

0

o

116

Conclusions

The results from this study demonstrate the Importance that the physical state of an

emulsifying agent has upon Its ability to stabilize emulsions It was found that to be effective

emulsifiers asphaltenes resins and waxes must be in the form of finely divided partides The

chemical composition of the ol determines not only the amount and size of these partldes but also their composition and their wetting properties All these factors were shown to have

an Influence upltin the emulsification process Asphaltenes and resins by themselves and In combination were effective emulsifying

agents Model oils containing only wax as the emulsifying agent did not form stable emulsions But the addition of a nominal amount of asphaltenes an amount insufficient by

Itself to produce emulsions to oDs containing wax lead to the formation of stable emulsions This indicates that different emulsifying agents can synergically Interact to stabUize emulsions

The solubllity precipitation behaviour of asphaltenes In model oils follows the solubllity theory as described by the HUdebrand-Scatchard equation The use of solubility parameters

can be applied to petroleum fractions and therefore may be useful In predicting the physiochemical conditions which favour emulsification

Acknowledgements

This study was co-funded by the United States Minerals Management Service and the Environmental Emergencies Technology Division of Environment Canada

References

Barton AFM Handbook of Solubility Parameters and Other Cohesion Parameters CRC Press 1983) Becher P Emulsions Theory and Practice Kreiger Publishing 2 (1977) Becher P Encydopedia of Emulsion Technology Marcel Dekker 1 (1983)

Blair C M Chem Ind (London) (1960) 538 Bobra M A Catalogue of Cnide Oil and Oil Product Properties Envir Canada EE-114 (1989) Bridle A L Wanders TH H Zegveld W and Vander Heijde H B Marine Pollution Bulletin

11 (1980) 343 Canevari G P Marine Pollution Bulletin 13 1982) 49

Clark G H Industrial and Marine Fuels Reference Book Butterworth and Co (1988) Desrnaison M Desrnarquest J-P Plekarsld C and Piekarski S Revue de Llnstltut Francals du Petole vol 39 5 (1984)

8ey D 0 Hey M J and Lee M A Colloids and Surfaces 24 (1987 173

8ey 0 o Hey M J and Symonds J o Colloids and Surfaces 32 (1988) 87103 8ey o 0 Hey M J Symonds J 0 and Willison J H M J Colloid Interface Sci 54 (1976) 462 Graham 0 E Crude OU Emulsions Their Stability and Resolution 3rd Ind Sym on Chemistry In the 01 Industry Northwest Region of the Industrial OMslon Royal Soc ofChemistry Special Pub 67 (1988)

Grlll1th M G and Siegmund C W Controlling Compatibility of Residual Fuel Oils Marine Fuels ASTM STP 878 C H Jones Ed Amer Soc for Testing and Materials Phlladelphla (1985) 227 Haslba H H and Jessen F W Film Forming Compounds from Crude Oils lnterlaclal Ams and Paraffin Deposition 18th Annual Tech Meeting Petrol Soc of CIM 1967) Lawrence A S C and KDlner W J Inst Petrol 34 (1948) 821 Long R B The Concept of Asphaltenes Sym OMsion of Petrol Chemistry Inc Washington

middot-

shy

- f

I

lfllt -~

I ~

bull

I

c 1

_

c

117

(1979)

Mackay 0 Formation and StabUity ol Water-In-oil Emulslons Envlr Canada EE-93 (1987)Mackay 0 and Zagorski W Studies ol Water-In-oil Emulsions Envlr Canada EE-34 (1982)Neumann H J Paczynska-Lahme B and Severin D Composition and Properties of Petroleum Geology ol Petrol H Beckmann Ed Halsted Press 5 (1981) Rosen M J Surfactants and lnterfacfal Phenomena John Wiley amp Son (1978) Speight JG The Chemistry and Technology ol Petroleum Marcel Dekker Inc (1980) Speight JG and Moschopedls SE Sone Observations on the Molecular Nature of Petroleum Asphaltenes Sym OMslon ol Petrol Chemistry Inc Washington (1979) Thompson 0 G Taylor A S and Graham 0 E Emulsification and Oemufsificatlon Related to Crude 01 Production Sym Formation ol Liq-Liq Dispersions Chemical and EngineeringAspects Inst ol Chem Engineers and Southeast Branch Fluid Mixing Process Subject Grp (Feb 1984) Van der Waarden M Kolloid Z 156 (1958) 116

• A study of the formation of water in oil emulsions

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117

(1979)

Mackay 0 Formation and StabUity ol Water-In-oil Emulslons Envlr Canada EE-93 (1987)Mackay 0 and Zagorski W Studies ol Water-In-oil Emulsions Envlr Canada EE-34 (1982)Neumann H J Paczynska-Lahme B and Severin D Composition and Properties of Petroleum Geology ol Petrol H Beckmann Ed Halsted Press 5 (1981) Rosen M J Surfactants and lnterfacfal Phenomena John Wiley amp Son (1978) Speight JG The Chemistry and Technology ol Petroleum Marcel Dekker Inc (1980) Speight JG and Moschopedls SE Sone Observations on the Molecular Nature of Petroleum Asphaltenes Sym OMslon ol Petrol Chemistry Inc Washington (1979) Thompson 0 G Taylor A S and Graham 0 E Emulsification and Oemufsificatlon Related to Crude 01 Production Sym Formation ol Liq-Liq Dispersions Chemical and EngineeringAspects Inst ol Chem Engineers and Southeast Branch Fluid Mixing Process Subject Grp (Feb 1984) Van der Waarden M Kolloid Z 156 (1958) 116

• A study of the formation of water in oil emulsions