Emulsified water is generally present in crude oil as a result of mixing occurring during production operations. The formation of emulsion leads to problems in production and also transportation. Therefore the need to break oil/water emulsions system through demulsification process using chemical surfactants for improved oil recovery operations. Selected cationic and anionic surfactants were found to be effective in separating oil-water emulsions expected during a surfactant/polymer (SP) process for improved oil recovery. Describe in detail the various factors that contribute to crude oil emulsion stability. What are the various methods that could be adopted to destabilize the crude oil emulsions? Identify conditions at which one method will be more effective that the other. Is there a condition at which none of the destabilization methods will work for crude oils? If so, please identify. Solution (A) various factors contributing to the stability of crude oil emulsion are as follows:- 1.Heavy polar fraction in crude oil:- Naturally occurring emulsifiers are concentrated in the higher-boiling polar fraction of the crude oil.These include: These compounds are the main constituents of the interfacial films surrounding the water droplets that give emulsions their stability. 2.PRESENCE OF SOLIDS Fine solid particles present in the crude oil are capable of effectively stabilizing emulsions. The effectiveness of these solids in stabilizing emulsions depends on factors such as- 3. TEMPERATURE Temperature can affect emulsion stability significantly. Temperature affects the physical properties of oil, water, interfacial films, and surfactant solubilities in the oil and water phases. These, in turn, affect the stability of the emulsion. Perhaps the most important effect of temperature is on the viscosity of emulsions because viscosity decreases with increasing temperatures.The effect of temperature on crude oil/water interfacial films was studied in some detail by Jones et al who showed that an increase in temperature led to a gradual destabilization of the crude oil/water interfacial films. However, even at higher temperatures, a kinetic barrier to drop coalescence still exists. 4.DROPLET SIZE Emulsion droplet sizes can range from less than a micron to more than 50 microns. Fig. 5 in Oil emulsions shows the typical droplet-size distributions for water-in-crude oil emulsion.Emulsions that have smaller size droplets will generally be more stable. For water separation, drops must coalesce—and the smaller the drops, the greater the time to separate. The droplet-size distribution affects emulsion viscosity because it is higher when droplets are smaller. Emulsion viscosity is also higher when the droplet-size distribution is narrow . 5.pH The pH of water has a strong influence on emulsion stability. The stabilizing, rigid emulsion film contains: Adding inorganic acids and bases strongly influences their ionization in the interfacial films and radically chang.

1. Emulsified water is generally present in crude oil as a result of mixing occurring during
production operations. The formation of emulsion leads to problems in production and also
transportation. Therefore the need to break oil/water emulsions system through demulsification
process using chemical surfactants for improved oil recovery operations. Selected cationic and
anionic surfactants were found to be effective in separating oil-water emulsions expected during
a surfactant/polymer (SP) process for improved oil recovery. Describe in detail the various
factors that contribute to crude oil emulsion stability. What are the various methods that could
be adopted to destabilize the crude oil emulsions? Identify conditions at which one method will
be more effective that the other. Is there a condition at which none of the destabilization
methods will work for crude oils? If so, please identify.
Solution
(A) various factors contributing to the stability of crude oil emulsion are as follows:-
1.Heavy polar fraction in crude oil:-
Naturally occurring emulsifiers are concentrated in the higher-boiling polar fraction of the crude
oil.These include:
These compounds are the main constituents of the interfacial films surrounding the water
droplets that give emulsions their stability.
2.PRESENCE OF SOLIDS
Fine solid particles present in the crude oil are capable of effectively stabilizing emulsions. The
effectiveness of these solids in stabilizing emulsions depends on factors such as-
3. TEMPERATURE
Temperature can affect emulsion stability significantly. Temperature affects the physical
properties of oil, water, interfacial films, and surfactant solubilities in the oil and water phases.
These, in turn, affect the stability of the emulsion. Perhaps the most important effect of
temperature is on the viscosity of emulsions because viscosity decreases with increasing
temperatures.The effect of temperature on crude oil/water interfacial films was studied in some
detail by Jones et al who showed that an increase in temperature led to a gradual destabilization
of the crude oil/water interfacial films. However, even at higher temperatures, a kinetic barrier to
drop coalescence still exists.
4.DROPLET SIZE
Emulsion droplet sizes can range from less than a micron to more than 50 microns. Fig. 5 in Oil
emulsions shows the typical droplet-size distributions for water-in-crude oil emulsion.Emulsions
that have smaller size droplets will generally be more stable. For water separation, drops must
coalesce—and the smaller the drops, the greater the time to separate. The droplet-size

2. distribution affects emulsion viscosity because it is higher when droplets are smaller. Emulsion
viscosity is also higher when the droplet-size distribution is narrow .
5.pH
The pH of water has a strong influence on emulsion stability. The stabilizing, rigid emulsion film
contains:
Adding inorganic acids and bases strongly influences their ionization in the interfacial films and
radically changes the physical properties of the films. The pH of water affects the rigidity of the
interfacial films. It was reported that interfacial films formed by asphaltenes are strongest in
acids (low pH) and become progressively weaker as the pH is increased. In alkaline medium, the
films become very weak or are converted to mobile films. The films formed by resins are
strongest in base and weakest in acid medium. Solids in the emulsions can be made oil-wet by
asphaltenes, an effect that is stronger in an acidic than in a basic medium. These partially oil-wet
solids tend to stabilize water-in-oil emulsions.
6.BRINE COMPOSITION
(B)
1.THERMAL METHODS.
Heating reduces the oil viscosity and increases the water-settling rates. Increased temperatures
also result in the destabilization of the rigid films because of reduced interfacial viscosity.
Furthermore, the coalescence frequency of water droplets is increased because of the higher
thermal energy of the droplets.
2. MECHANICAL METHODS.
Mechanical methods include:
Three-phase separators or production traps are used to separate the produced fluids into oil,
water, and gas. These separators can be either horizontal or vertical in configuration. Each
separator is sized with a set retention time to provide adequate separation at a given throughput
rate. The separator may include:Heater section,Wash water ,Filter section, Coalescing or
stabilizing section, Electrostatic grids.
3. ELECTRICAL METHODS
Electrostatic grids are sometimes used for emulsion treatment. When a nonconductive liquid (oil)
that contains a dispersed conductive liquid (water) is subjected to an electrostatic field, one of
three physical phenomena causes the conductive particles or droplets to combine:
4. CHEMICAL METHODS
The most common method of emulsion treatment is adding demulsifiers. These chemicals are
designed to neutralize the stabilizing effect of emulsifying agents. Demulsifiers are surface-
active compounds that, when added to the emulsion, migrate to the oil/water interface, rupture or
weaken the rigid film, and enhance water droplet coalescence. Optimum emulsion breaking with

3. a demulsifier requires a properly selected chemical for the given emulsion; adequate quantity of
this chemical; adequate mixing of the chemical in the emulsion; and sufficient retention time in
separators to settle water droplets.
Demulsifier chemicals contain the following components:
Solvents, such as benzene, toluene, xylene, short-chain alcohols, and heavy aromatic naptha, are
generally carriers for the active ingredients of the demulsifier. Some solvents change the
solubility conditions of the natural emulsifiers (e.g., asphaltenes) that are accumulated at the
oil/brine interface. These solvents dissolve the indigenous surface-active agents back into the
bulk phase, affecting the properties of the interfacial film that can facilitate coalescence and
water separation.
(C) A thorough evaluation of the emulsion-treatment facility may be worthwhile for optimizing
costs. Some of the factors to explore include the extent of: