721
model. The author found that the dehydration and desalting efficiency of simulated
results were 98.48% and 96.06%, respectively, which is very close to the experimental result of 96.77% and 94.15%, respectively, in their study. They also observed
that by increasing the pressure of mixing valve from 20 to 30 psi, the efficiency of
dehydration does not change significantly. Aryafard et al. [50] studied the drop size
distribution, desalting, and dehydration efficiency by using a two-stage desalter
model. Aryafard et al.’s [50] simulation results show that by increasing the addition
of freshwater from 3% to 6%, the salts content in treated crude can be reduced from
2.06 to 0.71 PTB.
3.3.3 Electrical Method
Electrostatic fields are applied for the emulsion treatment and separating water from
the oil-water emulsion. When non-conductive continuous phase (oil) that contains a
small fraction of conductive dispersed phase (water) is subjected to an electrostatic
field, the water drops coalesce by following one of the three physical phenomena
[8, 29].
• Under the electric field, the water drops polarize and align along the electric field
lines so that positive-negative poles are developed on the water droplets leading
to their attraction and coalescence.
• In case of direct electric (DC) field, the charges are induced on the water drops;
the drops aggregate and attract towards the electrode or bounce in between the
electrodes until the drops become large and settle by gravity.
• Application of electric field disturbs or weakens the interfacial film of original
droplets. Under the application of sinusoidal alternating current (AC), the line of
forces is higher in the first half of the cycle. The drops elongate or make elliptical
shape, but because of surface tension, they try to retain their original shape. This
process is repeated again and again so that the interfacial film becomes weak and
it leads to coalescence.
However, it may be theorized that water droplets have a net charge and under the
electrostatic field, collision probability increases and coalescence increases. The
electrical field is generally measured in kV/cm, and with an increase in the field, the
rate of coalescence increases. However, at some point, it reaches a non-coalescence
regime when other factors also contribute to the interaction significantly such as salt
concentration and cone angle formed in between the drops discussed in detailed in
Sect. 4.
3.3.4 Chemical Method
Chemical method is one of the most common techniques for emulsion breaking. In
this method, a chemical called demulsifier is added, which neutralize the emulsifying agent. Some common demulsifiers such as epoxy resins, polyamines,
Stability and Destabilization of Water-in-Crude Oil Emulsion
model. The author found that the dehydration and desalting efficiency of simulated
results were 98.48% and 96.06%, respectively, which is very close to the experimental result of 96.77% and 94.15%, respectively, in their study. They also observed
that by increasing the pressure of mixing valve from 20 to 30 psi, the efficiency of
dehydration does not change significantly. Aryafard et al. [50] studied the drop size
distribution, desalting, and dehydration efficiency by using a two-stage desalter
model. Aryafard et al.’s [50] simulation results show that by increasing the addition
of freshwater from 3% to 6%, the salts content in treated crude can be reduced from
2.06 to 0.71 PTB.
3.3.3 Electrical Method
Electrostatic fields are applied for the emulsion treatment and separating water from
the oil-water emulsion. When non-conductive continuous phase (oil) that contains a
small fraction of conductive dispersed phase (water) is subjected to an electrostatic
field, the water drops coalesce by following one of the three physical phenomena
[8, 29].
• Under the electric field, the water drops polarize and align along the electric field
lines so that positive-negative poles are developed on the water droplets leading
to their attraction and coalescence.
• In case of direct electric (DC) field, the charges are induced on the water drops;
the drops aggregate and attract towards the electrode or bounce in between the
electrodes until the drops become large and settle by gravity.
• Application of electric field disturbs or weakens the interfacial film of original
droplets. Under the application of sinusoidal alternating current (AC), the line of
forces is higher in the first half of the cycle. The drops elongate or make elliptical
shape, but because of surface tension, they try to retain their original shape. This
process is repeated again and again so that the interfacial film becomes weak and
it leads to coalescence.
However, it may be theorized that water droplets have a net charge and under the
electrostatic field, collision probability increases and coalescence increases. The
electrical field is generally measured in kV/cm, and with an increase in the field, the
rate of coalescence increases. However, at some point, it reaches a non-coalescence
regime when other factors also contribute to the interaction significantly such as salt
concentration and cone angle formed in between the drops discussed in detailed in
Sect. 4.
3.3.4 Chemical Method
Chemical method is one of the most common techniques for emulsion breaking. In
this method, a chemical called demulsifier is added, which neutralize the emulsifying agent. Some common demulsifiers such as epoxy resins, polyamines,
Stability and Destabilization of Water-in-Crude Oil Emulsion