ORIGIN AND OCCURRENCE OF OIL 59
Furthermore, in contrast to conventional crude oils, heavy oils are
darker in color and may even be black. The term heavy oil has also
been arbitrarily used to describe both the heavy oils that require
thermal stimulation of recovery from the reservoir and the bitumen
in bituminous sand (tar sand) formations from which the heavy
bituminous material is recovered by a mining operation.
The Western Hemisphere has 69% of the world's technically
recoverable heavy oil and 82% of the technically recoverable natural bitumen (Meyer and Attanasi, 2003). In contrast, the Eastern
Hemisphere has about 85% of the world's light oil reserves.
On the assumption that heavy oil is oil with a gravity <20°API,
the U.S. heavy oil resource approaches 100 billion barrels (100 x 10
9
barrels) of original oil in-place (OOIP). The resource is concentrated
in 248 large reservoirs, holding 80 billion barrels of OOIP, primarily located in California, Alaska, and Wyoming. Numerous other
states, such as Arkansas, Louisiana, Mississippi and Texas, contain significant volumes of heavy oil. Some undeveloped heavy oil
resources underlie public lands, including much of the heavy oil
deposits in Alaska.
The largest heavy oil accumulation is the Venezuelan Orinoco
heavy-oil belt, which contains 90% of the world's heavy oil when
measured on an in-place basis. In addition to extra-heavy Orinoco
oil, South America has an estimated 40 billion barrels of technically
recoverable heavy oil, so that, in total, 61% of the known technically recoverable heavy oil is in South America. Of the 35 billion
barrels of heavy oil estimated to be technically recoverable in North
America, about 7.7 billion barrels are assigned to known producing accumulations in the lower 48 States, and 7 billion barrels are
assigned to the North Slope of Alaska.
Current production of heavy oil is difficult to assess because of
the loose definitions that are employed. Nevertheless, using API
gravity as the guide, production of heavy oil in various countries
has been calculated (Table 2.3).
2.6.4 Tar Sand Bitumen
Tar sands, also variously called oil sands or bituminous sands
(Chapter 1), are loose-to-consolidated sandstone or a porous carbonate rock, impregnated with bitumen — a high boiling asphaltic
material with an extremely high viscosity that is immobile under
reservoir conditions and vastly different to conventional petroleum
Furthermore, in contrast to conventional crude oils, heavy oils are
darker in color and may even be black. The term heavy oil has also
been arbitrarily used to describe both the heavy oils that require
thermal stimulation of recovery from the reservoir and the bitumen
in bituminous sand (tar sand) formations from which the heavy
bituminous material is recovered by a mining operation.
The Western Hemisphere has 69% of the world's technically
recoverable heavy oil and 82% of the technically recoverable natural bitumen (Meyer and Attanasi, 2003). In contrast, the Eastern
Hemisphere has about 85% of the world's light oil reserves.
On the assumption that heavy oil is oil with a gravity <20°API,
the U.S. heavy oil resource approaches 100 billion barrels (100 x 10
9
barrels) of original oil in-place (OOIP). The resource is concentrated
in 248 large reservoirs, holding 80 billion barrels of OOIP, primarily located in California, Alaska, and Wyoming. Numerous other
states, such as Arkansas, Louisiana, Mississippi and Texas, contain significant volumes of heavy oil. Some undeveloped heavy oil
resources underlie public lands, including much of the heavy oil
deposits in Alaska.
The largest heavy oil accumulation is the Venezuelan Orinoco
heavy-oil belt, which contains 90% of the world's heavy oil when
measured on an in-place basis. In addition to extra-heavy Orinoco
oil, South America has an estimated 40 billion barrels of technically
recoverable heavy oil, so that, in total, 61% of the known technically recoverable heavy oil is in South America. Of the 35 billion
barrels of heavy oil estimated to be technically recoverable in North
America, about 7.7 billion barrels are assigned to known producing accumulations in the lower 48 States, and 7 billion barrels are
assigned to the North Slope of Alaska.
Current production of heavy oil is difficult to assess because of
the loose definitions that are employed. Nevertheless, using API
gravity as the guide, production of heavy oil in various countries
has been calculated (Table 2.3).
2.6.4 Tar Sand Bitumen
Tar sands, also variously called oil sands or bituminous sands
(Chapter 1), are loose-to-consolidated sandstone or a porous carbonate rock, impregnated with bitumen — a high boiling asphaltic
material with an extremely high viscosity that is immobile under
reservoir conditions and vastly different to conventional petroleum