711
crude oil. A crude oil-specific gravity equal to 1 (API value is 10) is known as an
extra heavy oil.
1.2.2 Viscosity
Viscosity (η) measures the internal resistance to the flow of crude oil, and the
dynamic viscosity is generally expressed in Pa s. The viscosity of crude varies in a
wide range (10–1000 Pa s). Highly viscous crudes create problems in the refinery in
transportation and operations. Generally, light and heavy crudes also have low and
high viscosities, respectively. This is attributed to the presence of high molecular
weight asphaltenes or suspended particles. The crude oil viscosity mainly depends
upon temperature, pressure, and amount of emulsified water.
1.2.3 Interfacial Tension
Interfacial tension (IFT) and surface tension originate in the presence of two phases
(oil/water, gas/oil, or gas/water) having a difference in attractive intermolecular
force. Crude oil contains surface-active compounds such as asphaltenes which
affect static or dynamic tension. The interfacial films formed by asphaltenes and
resins are highly sensitive to the pH of the aqueous phase [12]. IFT is generally
expressed in dynes/cm (or mN/m) and has typical values in range 1–30 mN/m.
Interfacial tension strongly depends upon surfactant concentration, temperature,
pressure, pH, and the composition of each phase.
1.2.4 Crude Oil Conductivity
Electrical conductivity in crude oil can be attributed to the motion of polar organic
(predominantly asphaltenes), conductive solids, and inorganic constituents, apart
from dissolved water [26]. The conductivity of crude depends upon temperature,
pressure, soluble, and insoluble water in the crude oil, the composition of crude oil,
and conductive metallic species [27]. Conductivity is generally measured in Siemens
per centimeter (or Siemens per meter) and is usually in a range of 10
−10
to 10
−7
S/m.
The conductivity of crude oil increases with temperature [27].
2 Crude Oil-Water Emulsion
The crude oil recovered from oil wells is in the form of a water-in-oil emulsion.
Approximately two-thirds of the world’s crude is found in emulsion form that must
be treated before being marketed [28]. Emulsions generally consist of two immiscible liquids: one acts as a continuous phase and the other as a dispersed phase
Stability and Destabilization of Water-in-Crude Oil Emulsion
crude oil. A crude oil-specific gravity equal to 1 (API value is 10) is known as an
extra heavy oil.
1.2.2 Viscosity
Viscosity (η) measures the internal resistance to the flow of crude oil, and the
dynamic viscosity is generally expressed in Pa s. The viscosity of crude varies in a
wide range (10–1000 Pa s). Highly viscous crudes create problems in the refinery in
transportation and operations. Generally, light and heavy crudes also have low and
high viscosities, respectively. This is attributed to the presence of high molecular
weight asphaltenes or suspended particles. The crude oil viscosity mainly depends
upon temperature, pressure, and amount of emulsified water.
1.2.3 Interfacial Tension
Interfacial tension (IFT) and surface tension originate in the presence of two phases
(oil/water, gas/oil, or gas/water) having a difference in attractive intermolecular
force. Crude oil contains surface-active compounds such as asphaltenes which
affect static or dynamic tension. The interfacial films formed by asphaltenes and
resins are highly sensitive to the pH of the aqueous phase [12]. IFT is generally
expressed in dynes/cm (or mN/m) and has typical values in range 1–30 mN/m.
Interfacial tension strongly depends upon surfactant concentration, temperature,
pressure, pH, and the composition of each phase.
1.2.4 Crude Oil Conductivity
Electrical conductivity in crude oil can be attributed to the motion of polar organic
(predominantly asphaltenes), conductive solids, and inorganic constituents, apart
from dissolved water [26]. The conductivity of crude depends upon temperature,
pressure, soluble, and insoluble water in the crude oil, the composition of crude oil,
and conductive metallic species [27]. Conductivity is generally measured in Siemens
per centimeter (or Siemens per meter) and is usually in a range of 10
−10
to 10
−7
S/m.
The conductivity of crude oil increases with temperature [27].
2 Crude Oil-Water Emulsion
The crude oil recovered from oil wells is in the form of a water-in-oil emulsion.
Approximately two-thirds of the world’s crude is found in emulsion form that must
be treated before being marketed [28]. Emulsions generally consist of two immiscible liquids: one acts as a continuous phase and the other as a dispersed phase
Stability and Destabilization of Water-in-Crude Oil Emulsion