Environmental Engineering Reference
In-Depth Information
development, and production costs, and the environmental and social impacts. The role of
government — including direct financial support, and tax and royalty incentives — is also
assessed.
World Oil Sands Reserves and Resources[4]
Over 80% of the earth's technically recoverable natural bitumen (oil sands) lies in North
America, according to the U.S. Geological Survey (USGS) (see Appendix B). Canadian oil
sands account for about 14% of world oil reserves and about 11% of the world's technically
recoverable oil resources.
What Are Oil Sands?
Oil sands (also called tar sands) are mixtures of organic matter, quartz sand, bitumen, and
water that can either be mined or extracted in-situ[5] using thermal recovery techniques.
Typically, oil sands contain about 75% inorganic matter, 10% bitumen, 10% silt and clay, and
5% water.[6] Bitumen is a heavy crude that does not flow naturally because of its low API[7]
(less than 10 degrees) and high sulfur content. The bitumen has high density, high viscosity,
and high metal concentration. There is also a high carbon-to-hydrogen molecule count (i.e. oil
sands are low in hydrogen). This thick, black, tar-like substance must be upgraded with an
injection of hydrogen or by the removal of some of the carbon before it can be processed.
Oil sand products are sold in two forms: (1) as a raw bitumen that must be blended with a
diluent[8] (becoming a bit-blend) for transport and (2) as a synthetic crude oil (SCO) after
being upgraded to constitute a light crude. The diluent used for blending is less viscous and
often a by-product of natural gas, e.g., a natural gas condensate. The specifications for the bit
blend (heavy oil) are 21.5 API and a 3.3% sulfur content and for the SCO (light oil) are 36
API and a 0.015% sulfur content.[9]
U.S. Oil Sand Resources
The USGS, in collaboration with the U.S. Bureau of Mines, concluded in a 1984 study
that 53.7 billion barrels (21.6 billion measured plus 32.1 billion speculative) of oil sands
could be identified in the United States. An estimated 11 billion barrels of those oil sands
could be recoverable. Thirty-three major deposits each contain an estimated 100 million
barrels or more. Fifteen percent were considered mineable and 85% would require in-situ
production. Some of the largest measured U.S. oil sand deposits exist in Utah and Texas.
There are smaller deposits located in Kentucky, Alabama, and California. Most of the
deposits are scattered throughout the various states listed above. As of the 1980s, none of
these deposits were economically recoverable for oil supply. They are still not classified as
reserves (see figure 1).
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