Oil shale resource is called unconventional oil resources to distinguish them from oil which can be extracted using traditional oil well methods (e.g., conventional oil resources). Most of the world's oil reserves are recorded as unconventional crude oil. Oil shale deposits represent staggering resource figures. Estimates by the U.S. Geological Survey suggest a global resource of 3 trillion (1012) barrels of oil, but reasonable estimates as high as 12 trillion barrels have been made. About half of the resource is located in the western United States. This articles aims to sight some light on the oil shale as the important types of unconventional oil deposits in the earth as well as how much can be economically recovered from oil shale.

1. By Prof. Dr. Hassan Z. Harraz
hharraz2006@yahoo.com
Oil Shale

2. • Petroleum: A general term for all naturally occurring hydrocarbons (hydrogen + carbon)
• Solid Hydrocarbons: Asphalt
• Liquid Hydrocarbons: Crude oil
• Gas Hydrocarbons: Natural Gas: methane, butane, propane, etc.
What is petroleum?
Organic Matter
• Sedimentary rocks rich in organic matter (~ 0.5 - 2% by weight)
• Most commonly microscopic marine material, but it can be land based material
• Organic material cannot decay too much (It has to keep its carbon).
Source Rocks (i.e., Oil Shale)
The simplest hydrocarbon is Methane (CH4)
April 13, 2012 HZH
2

3. The origin of fossil fuels Biomass energy in general, starts
with photosynthesis.
Origin and Habitat of Petroleum
Fossil fuels : Local large concentrations of organic matter in
sedimentary rocks, in the form of coal, oil or natural gas.
Oil Shale
April 13, 2012 HZH 3

4. Origin and Habitat of Petroleum
Many organic carbon-rich marine and lake
shales never reach the burial temperature level
at which the original organic molecules are
converted into hydrocarbons forming oil and
natural gas. Instead, the alteration process is
limited to certain wax-like substances with
large molecules.
This material, which remains solid, is called
kerogen, and is the organic substance of so-
called oil shales.
Kerogen can be converted into oil and gas by
further burial by mining the shale and
subjecting it to heat it in a retort.
April 13, 2012 HZH 4

5. In nature, crude oil deposits are occurring in two different modes, namely:
i) Conventional oil reservoirs
Figure shows Crude oil reservoirs; Hydrocarbon trap; traditional oil well methods.
ii) Unconventional oil reservoirs.
Figure show oil shale and fossil in oil shale from
Messel pit, south of Frankfurt am Main, Germany.
Oil that has escaped to the surface and extracted by
mining techniques. Unconventional deposits, such as:-
• Marsh gas ,
• Coal-bed methane,
• Tar sands, and
• Oil shales.
Occurrence of Oil and Gas
 Oil Shale Considered a source rock for
conventional crude Reservoir resources
April 13, 2012 HZH 5

6. This articles aims to shows some light on the oil shale
(i.e., Burn rocks or Source Rocks) as the important
types of unconventional oil deposits in the earth.
Producing energy from rock that burns
is entering into a new research and
development phase.
Can these processes now in the
experimental stages unlock some of oil
shale’s enormous potential ?
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7. Oil Shale
(Burn Rocks or Source Rocks)
 Silty marlstone containing relatively large amounts of organic matter called kerogen
 Kerogen : heated produce oil and natural gas
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8. Figure shows mining method to exploited oil
shale deposits
Figure shows extracting oil from oil shale deposits oil
 Most of the world's oil reserves are recorded as unconventional
crude oil.
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9. OIL SHALE VARIETIES
Based on mineral content of Oil shales, three categories can recognized namely: –
i) Carbonate-rich oil shales
• content a large amount of carbonate minerals (such as calcite and dolomite)
that mixed with oil shale,
• have usually the organic-rich layers sandwiched between carbonate-rich
layers.
• are hard formations that are hard and resistant to weathering.
• are difficult to process using ex-situ methods.
ii) Siliceous oil shales
• are usually dark brown or black shales.
• are not rich in carbonates but rather in siliceous minerals (such as quartz,
feldspar, clay, chert and opal).
• are not as hard and weather-resistant
• may be better suited for extraction via ex-situ methods.
iii) Cannel oil shales
• are usually dark brown or black shales,
• consist of organic matter that completely encloses other mineral grains.
• are suitable for extraction via ex-situ methods
April 13, 2012 HZH 9

10. Fig.13: Shows Woodford Shale Formation at Oklahoma, USA.
Fig.14: Show tar sand in association with asphalt in
SeepViola Limestone, Oklahoma – USA.
Fig.15: Shows coals and Coaly Shales at San Juan Basin,
New Mexico- USA.
April 13, 2012 HZH 10

11. OIL SHALE CLASSIFICATION
There are varying classifications of oil shales depending: on their mineral content, type of kerogen,
age, depositional history, and organisms from which they are derived.
Figure shows Van Krevelen diagram which showing types of kerogen and pathways for
generation of methane and elimination of carbon dioxide and water during coalification.
Liptinite corresponds to types I and II kerogen, vitrinite to type III, and inertinite to type IV.
High quality
April 13, 2012 HZH 11

12. Table Classification of oil shales by environment of deposition (Hutton, 1987)
Terrestrial
(Type III, low quality (H/C))
Lacustrine
(lake-bottom-deposited)
(Type II)
Marine
(ocean bottom-deposited)
(Type I, High quality (H/C))
Cannel coal
Lamosite;
Torbanite
Kukersite;
Tasmanite;
Marinite
The most used classification of oil shales was developed between
1987 and 1991 by Adrian C. Hutton of the University of Wollongong, based
on the environment where the initial biomass was deposited .
Hutton's classification scheme has proven useful in estimating the yield and
composition of the extracted oil .
According to this classification oil shales are designated as:-
i) Terrestrial.
ii) Lacustrine (lake-bottom-deposited).
iii) Marine (ocean bottom-deposited.

13. Figure shows photographic of channel-Fill Sandstone
Resting on Marine Shale Red Fork, Oklahoma, USA
Figure shows fossils in Ordovician kukersite oil shale,
northern EstoniaApril 13, 2012 HZH 13

14. a) Organic matter (macerals) in oil shale
Three major types of organic matter (macerals) in oil shale are
i) Telalginite,
ii) Lamalginite, and
iii) Bituminite
b) Inorganic matrix matter in oil shale
Mineral matter in oil shale contains fine-grained silicate and carbonate minerals
such as calcite, dolomite, siderite, quartz, feldspar (orthoclase, albite, and anorthite),
clay minerals (illite and chlorite), marcasite, rutile, limonite, gypsum, nahcolite,
dawsonite and alum. Some oil-shale deposits also contain metals such as vanadium,
zinc, copper, and uranium among others
COMPOSITION OF OIL SHALE
Table General composition of oil shales (Altun, et al., 2006)
Inorganic matrix Bitumens Kerogens
Quartz; feldspars; clays (mainly
illite and chlorite); carbonates
(calcite and dolomite); pyrite and
others
Soluble in CS2
Insoluble in CS2;
Containing uranium, iron,
vanadium, nickel, molybdenum,
....... etc
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15. COMPOSITION OF OIL SHALE
Photomicrograph showing detail of the varves in a rich
Colorado oil shale specimen. The organic laminae are
themselves finely laminated. The mineral laminae
contain considerable organic matter, but they are
readily distinguished by their coarser grain and greater
thickness. Note sand grains (white). Enlarged 320
diameters.
Figure show intercalation of Organic-Rich Thin
Laminae with inorganic (minerals) laminae.
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16.  Largest oil shale deposits in the world are located in the Eocene Green
River Formation in Utah, Colorado, and Wyoming.
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17. In-Place Resources
• Total within the Green River Formation – 1.5 to 1.8 trillion bbls
– Colorado – 1.0 trillion barrels
– Wyoming – 300 billion barrels
– Utah – 165 billion to 321 billion barrels
World conventional crude reserves – 1.3 trillion barrels
U.S. conventional crude reserves – 22 billion barrels
 Saudi Arabia conventional crude reserves – 262 billion
barrels 5 18 25 35 58 69 90
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18. Recovery Methods
• Underground/surface mining and surface
retorting
Environmental concerns:
– Disturbance of land
– Use of water resources
– Greenhouse gas emissions
– Impacts on water and air quality
Room and pillar oil shale mine in Estonia
Oil Tech’s surface retort
April 13, 2012 HZH 19

19. Recovery Methods
• In-situ retorting
– Heat shale slowly to 650 to
700 degrees F
– Recover 1/3 gas and 2/3
light oil
– In Colorado, potential for 1
acre to yield 1 million
barrels of oil
Environmental concerns:
– Groundwater contamination
– Energy consumption
Advantages:
– Much less land disturbance
– No tailings
– Better recovery efficiency
– Allows access to deeper oil
shale reserves
– Higher-quality product
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20. White River Oil Shale Mine, Uinta Basin
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21. “Back-of-the-envelope”
Underground mine:
• Assumptions:
– 40 ft of 35 gpt oil shale
– 5,000 acre lease
– 50% material recovery
– 90% shale oil extraction efficiency
• Results:
– 200 million bbls of oil
– 30,000 bbls per day for 20 years
In-situ methods:
• Assumptions:
– 124 ft of 25 gpt oil shale
– 5,000 acre lease
– 60% shale oil extraction efficiency
• Results:
– 700 million bbls of oil
– 95,000 bbls per day for 20 years
• Utah crude oil production =
50,000 bbls per day
• Utah petroleum consumption
= 145,000 bbls per day
• U.S. crude oil production
= 5 million bbls per day
• U.S. petroleum consumption
= 21 million bbls per day
• U.S. crude oil imports
= 10 million bbls per day
• Utah’s refinery capacity =
167,000 bbls per day
• Utah’s refinery inputs =
151,000 bbls per day
• Utah’s spare refinery capacity =
16,000 bbls per day
(2006 data)
April 13, 2012 HZH 22

22. In nature, crude oil deposits are occurring in two different modes, namely:
i) Conventional oil reservoirs; and ii) Unconventional oil reservoirs.
Most of the world's oil reserves are recorded as unconventional oil type which oil shale is important types of this deposit in the
earth
Oil shale is a fine-grained sedimentary rocks containing significant amounts of kerogen, and belonging to the group of sapropel
fuels .
Oil shales can be classified by their composition (carbonate minerals such as calcite or detrital minerals such as quartz and clays)
or by their depositional environment (large lakes, shallow marine, and lagoon/small lake settings).
Much of the organic matter in oil shale is of algal origin, but may also include remains of vascular land plants. Three major type of
organic matter (macerals) in oil shale are telalginite, lamalginite, and bituminite . Some oil-shale deposits also contain metals which
include V, Zn, Cu, U.
Most oil shale deposits were formed during Middle Cambrian, Early and Middle Ordovician, Late Devonian, Late Jurassic, and
Paleogene times through burial by sedimentary loading on top of the algal swamp deposits, resulting in conversion of the organic matter
to kerogen by diagenetic processes . The largest deposits are found in the remains of large lakes such as the deposits of the Green River
Formation of Wyoming and Utah, USA.
Oil-shale deposits formed in the shallow seas of continental shelves generally are much thinner than large lake basin deposits
.
Oil shale is shale that contains abundant organic matter that has not decomposed completely to produce petroleum. Oil
shales are source rocks that have not been exposed to heat or pressure long enough to convert their trapped hydrocarbons into
crude oil. Technically speaking, oil shales are not really shales and do not really contain oil, but are usually relatively hard rocks
(i.e., marls) containing a waxy substance called kerogen.
Oil can be extracted from oil shales, but they must be heated to high enough temperatures to drive the oil out. Since this process
requires a lot of energy, exploitation of oil shales is not currently cost-effective, but may become so as other sources of petroleum become
depleted.
SUMMARY and CONCLUSIONS
April 13, 2012 HZH 23

23. 
Most of the world's oil reserves are recorded as unconventional
crude oil.

Fossil fuels will continuous for ever .
April 13, 2012 HZH 24

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