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Geology
Approximately 300 million years ago, what is today ANWR was the Alaskan
Arctic microplate, independent of the rest of the Alaskan continent. The
accumulation of organic matter (detritus) on the plate over millions of
years led it to sink substantially and begin to move. Over time and through
various geological and chemical processes, the organic matter turned into
sandstone and shale--carbonate rocks. Through the upwelling of heat from the
earth's mantle, this trapped organic matter was converted to oil and natural
gas reservoirs. The Alaskan Arctic Microplate eventually collided with the
Alaskan plate creating the the Brooks Range and the other impressive topographic
features of Alaska as we know them today.
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Through photosynthesis, plants convert solar energy into chemical energy
which they store in bonds. Other organisms eat these autotrophs and either
immediatly expend the acquired energy (as heat) or store the energy in bonds
as increased biomass. Millions of years ago, these ancient organisms died
and sank to the bottom of lakes and lagoons densely piling layer upon layer
of organic detritus. Silt and debris covered the organic matter, putting
the organic matter under conditions of high pressure. Because oxygen was
not present (trapped in silt), anaerobic bacteria further broke down the
organic matter in a series of chemical reactions. Over millions of years,
the organic matter was turned into the hydrocarbons we know as fossil fuels.
The hydrocarbons were not as we know them today; they were mixed with silt,
water, and other impurities. Over time, the increasing pressure (from the
layers of silt piled up) forced the oil through porous rock of either lime
or sand stones. The oil then coagulated beneath the surface in pools. Millions
of these various pools exist beneath the Earth's crust, but only the large
pools are economically viable for exploitation. The sandstone and shale-carbonate
rock that make up the Alaskan Arctic Microplate provide the appropriate
geological conditions for fossil fuel formation.
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Alaska's Fossil
Fuels
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Despite modern technology, accurately determing the extent of an oil
reserve remains complicated, and even if large oil reserves are discovered,
oil excavation is a difficult process from which only a small percentage
of oil in an oil field is recoverable. Harsh conditions, complicated geology,
high fixed costs (of establishing infrastructure, i.e. Trans-Alaskan pipeline),
deteriorating infrastructure, and anti-drilling sentiment create heavy financial
risk as well. Oil exploration in Alaska's Northern Slope has revealed an
estimated 20.7 billion barrels of oil. Unfortunately, most of this oil, according
to a US Geological Survey, is in "a multitude of small reservoirs" which
are not economically efficient to exploit. The feasibility of oil exploration
is given as two percentages. For example, there is a 95% chance that developing
the North Slope will yield only 5-7 billion barrels of oil, and there is
a 5% chance that it will yield 16 billion barrels. People who are pro-drilling
like to quote the high statistic while those who are anti-drilling quote
the low end. Something in between the two is most likely, and the according
to the US Geological Survey, there is a 50% chance that 10 billion barrels
of oil will be recoverable.
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