22 PETROLEUM TECHNOLOGY, ECONOMICS, AND POLITICS
origins and, especially, different degrees of natural processing of
these hydrocarbons (Speight, 2007, 2008). In fact, the term petroleum covers a wide assortment of materials consisting of mixtures of hydrocarbons and other compounds containing variable
amounts of sulfur, nitrogen, and oxygen, which may vary widely
in volatility, specific gravity, and viscosity. Metal-containing constituents, notably those compounds that contain vanadium and
nickel, usually occur in the more viscous crude oils in amounts up
to several thousand parts per million, and can have serious consequences during processing of these feedstocks (Speight, 2007).
Because petroleum is a mixture of widely varying constituents and
proportions, its physical properties also vary widely and the color
from colorless to black.
There is also another type of petroleum that is different from the
conventional petroleum insofar as they are much more difficult to
recover from the subsurface reservoir. This material, or heavy oil,
has a much higher viscosity and lower API gravity than conventional petroleum and recovery of heavy oil usually requires thermal stimulation of the reservoir (Speight, 2007; Speight, 2008).
The majority of crude oil reserves identified to date are located
in a relatively small number of very large fields, known as giants.
In fact, approximately 300 of the largest oil fields contain almost
75% of the available crude oil. Although most of the world's nations
produce at least minor amounts of oil, the primary concentrations
are in the Persian Gulf, North and West Africa, the North Sea, and
the Gulf of Mexico. In addition, of the 90 oil-producing nations, five
Middle Eastern countries contain almost 70% of the current, known
oil reserves.
For many years, petroleum and heavy oil were very generally
defined in terms of physical properties. For example, heavy oils
were considered to be those crude oils that had gravity somewhat
less than 20°API with the heavy oils falling into the API gravity
range 10 to 15°. For example, Cold Lake heavy crude oil has an API
gravity equal to 12°, and tar sand bitumen usually has an API gravity in the range 5-10° (Athabasca bitumen = 8°API). Residua would
vary depending upon the temperature at which distillation was
terminated, but usually vacuum residua fall into the approximate
range 2 to 8°API. However, the classification of crude oil by the use
of a single physical property is subject to the errors inherent in the
analytical method (by which the property is determined) and must
be used with caution (Chapter 4).
origins and, especially, different degrees of natural processing of
these hydrocarbons (Speight, 2007, 2008). In fact, the term petroleum covers a wide assortment of materials consisting of mixtures of hydrocarbons and other compounds containing variable
amounts of sulfur, nitrogen, and oxygen, which may vary widely
in volatility, specific gravity, and viscosity. Metal-containing constituents, notably those compounds that contain vanadium and
nickel, usually occur in the more viscous crude oils in amounts up
to several thousand parts per million, and can have serious consequences during processing of these feedstocks (Speight, 2007).
Because petroleum is a mixture of widely varying constituents and
proportions, its physical properties also vary widely and the color
from colorless to black.
There is also another type of petroleum that is different from the
conventional petroleum insofar as they are much more difficult to
recover from the subsurface reservoir. This material, or heavy oil,
has a much higher viscosity and lower API gravity than conventional petroleum and recovery of heavy oil usually requires thermal stimulation of the reservoir (Speight, 2007; Speight, 2008).
The majority of crude oil reserves identified to date are located
in a relatively small number of very large fields, known as giants.
In fact, approximately 300 of the largest oil fields contain almost
75% of the available crude oil. Although most of the world's nations
produce at least minor amounts of oil, the primary concentrations
are in the Persian Gulf, North and West Africa, the North Sea, and
the Gulf of Mexico. In addition, of the 90 oil-producing nations, five
Middle Eastern countries contain almost 70% of the current, known
oil reserves.
For many years, petroleum and heavy oil were very generally
defined in terms of physical properties. For example, heavy oils
were considered to be those crude oils that had gravity somewhat
less than 20°API with the heavy oils falling into the API gravity
range 10 to 15°. For example, Cold Lake heavy crude oil has an API
gravity equal to 12°, and tar sand bitumen usually has an API gravity in the range 5-10° (Athabasca bitumen = 8°API). Residua would
vary depending upon the temperature at which distillation was
terminated, but usually vacuum residua fall into the approximate
range 2 to 8°API. However, the classification of crude oil by the use
of a single physical property is subject to the errors inherent in the
analytical method (by which the property is determined) and must
be used with caution (Chapter 4).