216 PETROLEUM TECHNOLOGY, ECONOMICS, AND POLITICS
universally agreed upon definition of what is meant by conventional sources, they can be produced using today's mainstream
technologies, compared to nonconventional sources that require
more complex or more expensive technologies to extract, such as
tar sand (oil sand in Canada) (Chapter 4) and oil shale (Chapter 9).
Distinguishing between conventional and nonconventional oil
sources is important because the additional cost and technological challenges surrounding production of nonconventional sources
make these resources more uncertain.
However, this distinction is further complicated because what is
considered to be a mainstream technology can change over time.
For example, offshore oil deposits were considered to be a nonconventional source 50 years ago; however, today they are considered conventional. This is consistent with the inclusion of tar sand
deposits and oil shale in nonconventional sources. Some oil is being
produced from these nonconventional sources today. For example,
in 2005 Canada produced about 1.6 million barrels per day of oil
from oil sands, and Venezuelan production of extra-heavy oil for
2005 was projected to be about 600,000 barrels per day. However,
current production from these sources is very small compared with
total world oil production.
Crude oil reserves (Chapter 1) are the estimated quantities of
oil that are claimed to be recoverable under existing operating and
economic conditions. However, because of reservoir characteristics
and the limitations of current recovery technologies only a fraction
of this oil can be brought to the surface; it is this producible fraction
that is considered to be reserves. Crude oil recovery varies greatly
from oil field to oil field based on the character of the field and the
operating history as well as in response to changes in technology
and economics.
Thus, in addition to geological factors, recovery depends on several other factors that are discussed in turn below.
8.1 Physical Factors
In region after region, the story is of ageing fields with depleted
oil reserves. For example, Britain's North Sea oil is at its peak, the
giant fields in Alaska, the former Soviet Union, Mexico, Venezuela
and Norway are all past their peak. Oil supply in the United States
now account for less than half the country's needs. There is always
universally agreed upon definition of what is meant by conventional sources, they can be produced using today's mainstream
technologies, compared to nonconventional sources that require
more complex or more expensive technologies to extract, such as
tar sand (oil sand in Canada) (Chapter 4) and oil shale (Chapter 9).
Distinguishing between conventional and nonconventional oil
sources is important because the additional cost and technological challenges surrounding production of nonconventional sources
make these resources more uncertain.
However, this distinction is further complicated because what is
considered to be a mainstream technology can change over time.
For example, offshore oil deposits were considered to be a nonconventional source 50 years ago; however, today they are considered conventional. This is consistent with the inclusion of tar sand
deposits and oil shale in nonconventional sources. Some oil is being
produced from these nonconventional sources today. For example,
in 2005 Canada produced about 1.6 million barrels per day of oil
from oil sands, and Venezuelan production of extra-heavy oil for
2005 was projected to be about 600,000 barrels per day. However,
current production from these sources is very small compared with
total world oil production.
Crude oil reserves (Chapter 1) are the estimated quantities of
oil that are claimed to be recoverable under existing operating and
economic conditions. However, because of reservoir characteristics
and the limitations of current recovery technologies only a fraction
of this oil can be brought to the surface; it is this producible fraction
that is considered to be reserves. Crude oil recovery varies greatly
from oil field to oil field based on the character of the field and the
operating history as well as in response to changes in technology
and economics.
Thus, in addition to geological factors, recovery depends on several other factors that are discussed in turn below.
8.1 Physical Factors
In region after region, the story is of ageing fields with depleted
oil reserves. For example, Britain's North Sea oil is at its peak, the
giant fields in Alaska, the former Soviet Union, Mexico, Venezuela
and Norway are all past their peak. Oil supply in the United States
now account for less than half the country's needs. There is always