73
Origin and Occurrence
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.
3.3.5 BItumen
In addition to conventional petroleum and heavy crude oil, there remains an even more viscous
material that offers some relief to the potential shortfalls in supply; such material is the bitumen
found in tar sand (oil sand) deposits (Chapter 1). It is therefore worth noting here the occurrence
and potential supply of these materials. However, many of these reserves are only available with
some difficulty and optional refinery scenarios will be necessary for conversion of these materials to liquid products (Chapters 18 through 20) because of the substantial differences in character
between conventional petroleum and tar sand bitumen (Table 3.3).
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.
As a historical note, it is evident that the Cree Indians, native to the Athabasca region of northeastern Alberta, have known about the tar sands for well over 200 years. The documents by an
itinerant New England fur trader note that the Indians used a sticky substance oozing from the river
banks to waterproof their canoes.
The first scientific interest in tar sands was taken by the Canadian Government in 1890. In
1897–1898, the sands were first drilled at Pelican Rapids on the Athabasca River, 129 km southwest
of Fort McMurray. Up to 1960, the development was mainly small commercial enterprises. Between
1957 and 1967, three extensive pilot-plant operations were conducted in the Athabasca region, each
TABLE 3.3
Comparison of Tar Sand Bitumen (Athabasca)
and Crude Oil Properties
Property
Bitumen (Athabasca)
Crude Oil
Specific gravity
1.03
0.85–0.90
Viscosity (cp)
38°C/100°F
750,000
<200
100°C/212°F
11,300
Pour point (°F)
>50
ca. −20
Elemental analysis (wt.%):
Carbon
83.0
86.0
Hydrogen
10.6
13.5
Nitrogen
0.5
0.2
Oxygen
0.9
<0.5
Sulfur
4.9
<2.0
Ash
0.8
0.0
Nickel (ppm)
250
<10.0
Vanadium (ppm)
100
<10.0
Fractional composition (wt.%)
Asphaltenes (pentane)
17.0
<10.0
Resins
34.0
<20.0
Aromatics
34.0
>30.0
Saturates
15.0
>30.0
Carbon residue (wt.%)
Conradson
14.0
<10.0
Origin and Occurrence
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.
3.3.5 BItumen
In addition to conventional petroleum and heavy crude oil, there remains an even more viscous
material that offers some relief to the potential shortfalls in supply; such material is the bitumen
found in tar sand (oil sand) deposits (Chapter 1). It is therefore worth noting here the occurrence
and potential supply of these materials. However, many of these reserves are only available with
some difficulty and optional refinery scenarios will be necessary for conversion of these materials to liquid products (Chapters 18 through 20) because of the substantial differences in character
between conventional petroleum and tar sand bitumen (Table 3.3).
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.
As a historical note, it is evident that the Cree Indians, native to the Athabasca region of northeastern Alberta, have known about the tar sands for well over 200 years. The documents by an
itinerant New England fur trader note that the Indians used a sticky substance oozing from the river
banks to waterproof their canoes.
The first scientific interest in tar sands was taken by the Canadian Government in 1890. In
1897–1898, the sands were first drilled at Pelican Rapids on the Athabasca River, 129 km southwest
of Fort McMurray. Up to 1960, the development was mainly small commercial enterprises. Between
1957 and 1967, three extensive pilot-plant operations were conducted in the Athabasca region, each
TABLE 3.3
Comparison of Tar Sand Bitumen (Athabasca)
and Crude Oil Properties
Property
Bitumen (Athabasca)
Crude Oil
Specific gravity
1.03
0.85–0.90
Viscosity (cp)
38°C/100°F
750,000
<200
100°C/212°F
11,300
Pour point (°F)
>50
ca. −20
Elemental analysis (wt.%):
Carbon
83.0
86.0
Hydrogen
10.6
13.5
Nitrogen
0.5
0.2
Oxygen
0.9
<0.5
Sulfur
4.9
<2.0
Ash
0.8
0.0
Nickel (ppm)
250
<10.0
Vanadium (ppm)
100
<10.0
Fractional composition (wt.%)
Asphaltenes (pentane)
17.0
<10.0
Resins
34.0
<20.0
Aromatics
34.0
>30.0
Saturates
15.0
>30.0
Carbon residue (wt.%)
Conradson
14.0
<10.0