Page 194 - Synthetic Fuels Handbook

180 CHAPTER SIX

in the Piceance Creek Basin in western Colorado and the Uinta Basin in eastern Utah. The
shale oil can be extracted by surface and in situ methods of retorting: depending upon the
methods of mining and processing used, as much as one-third or more of this resource
might be recoverable. There is also the Devonian-Mississippian black shale in the eastern
United States.
Data reported for the present survey indicate the vastness of U S. oil shale resources: the
proved amount of shale in place is put at 3340 billion metric tons, with a shale oil content
of 242 billion metric tons, of which about 89 percent is located in the Green River deposits
and 11 percent in the Devonian black shale. Recoverable reserves of shale oil are estimated
to be within the range of 60 to 80 billion metric tons, with additional resources put at
62 billion metric tons.
Oil distilled from shale was burnt and used horticulturally in the second half of the
nineteenth century in Utah and Colorado but very little development occurred at that time.
It was not until the early 1900s that the deposits were first studied in detail by USGS (U.S.
Geological Survey) and the government established the Naval Petroleum and Oil Shale
Reserves, which for much of the twentieth century served as a contingency source of fuel
for the military. These properties were originally envisioned as a way to provide a reserve
supply of oil to fuel U.S. naval vessels.
Oil shale development had always been on a small-scale but the project that was to rep-
resent the greatest development of the shale deposits was begun immediately after World
War II in 1946—the U.S. Bureau of Mines established the Anvils Point oil shale demon-
stration project in Colorado. However, processing plants had been small and the cost of
production high. It was not until the United States had become a net oil importer, together
with the oil crises of 1973 and 1979, that interest in oil shale was reawakened.
In the latter part of the twentieth century, military fuel needs changed and the strategic
value of the shale reserves began to diminish. In the 1970s, ways to maximize domestic
oil supplies were devised and the oil shale fields were opened up for commercial produc-
tion. Oil companies led the investigations: leases were obtained and consolidated but
one-by-one these organizations gave up their oil shale interests. Unocal was the last to do
so in 1991.
Recoverable resources of shale oil from the marine black shale in the eastern United
States were estimated in 1980 to exceed 400 billion barrels. These deposits differ signifi-
cantly in chemical and mineralogic composition from Green River oil shale. Owing to its
lower atomic hydrogen/carbon ratio, the organic matter in eastern oil shale yields only
about one-third as much oil as Green River oil shale, as determined by conventional Fischer
assay analyses. However, when retorted in a hydrogen atmosphere, the oil yield of eastern
oil shale increases by as much as 2.0 to 2.5 times the Fischer assay yield.
Green River oil shale contains abundant carbonate minerals including dolomite, nahco-
lite, and dawsonite. The latter two minerals have potential by-product value for their soda
ash and alumina content, respectively. The eastern oil shale are low in carbonate content
but contain notable quantities of metals, including uranium, vanadium, molybdenum, and
others which could add significant by-product value to these deposits.
All field operations have ceased and at the present time shale oil is not being produced in
the United States. Large-scale commercial production of oil shale is not anticipated before
the second or third decade of the twenty-first century.
The most economically attractive deposits, containing an estimated 1.5 trillion barrels
(richness of >10 gal/ton) are found in the Green River Formation of Colorado (Piceance
Creek Basin), Utah (Uinta Basin), and Wyoming (Green River and Washakie Basins).
Eastern oil shale underlies 850,000 acres of land in Kentucky, Ohio, and Indiana. In the
Kentucky Knobs region in the Sunbury shale and the New Albany/Ohio shale, 16 billion
barrels, at a minimum grade of 25 gal/ton, are located. Due to differences in kerogen type
(compared to western shale) eastern oil shale requires different processing. Potential oil