Environmental Engineering Reference
In-Depth Information
percent of our natural gas needs.
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The major forms of unconventional
gas are tight gas in sandstones and shales and coal bed methane, all of
whose production has been rising.
Tight gas is gas produced from sandstones that have very low porosi-
ties and permeabilities. Even gas will not fl ow through them. The rock
must be fractured repeatedly to release the gas. Until recently tight gas
was uneconomical to produce, but technological advances and increasing
prices for natural gas have made it the major unconventional source (66
percent).
Natural gas from shales forms 13 percent of America's supply of
unconventional gas. In June 2009 the Potential Gas Committee, the
authority on gas supplies, reported that the nation's estimated gas
reserves are 35 percent higher than estimated previously, mostly because
of an increase in the estimated amount of natural gas from shale rocks.
Gas prices need to be at least $4.00 per thousand cubic feet to justify
the cost of developing shale bed gas. In June 2009 the price was in the
range of $4.00 to $4.50 range; in December 2009, it was up to $5.70
because of increased worldwide demand.
Like tight sandstones, extensive fracturing is required to make the
shale productive. The fl uid that is forced into the gas-bearing rock to
fracture it is not plain water, but is loaded with more than two hundred
chemicals to enhance the “fracking” ability of the fl uid. The Endocrine
Disruption Exchange has determined that many of them are dangerous
to human health. Thirty percent of fi fty-four tested chemicals used in the
fl uid are carcinogenic; 74 percent can cause respiratory damage, and 54
percent pose a danger to the blood and cardiovascular systems.
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Recent evidence indicates that people living in areas where unconven-
tional gas is being exploited are suffering health problems as a result.
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The black rock layer in the Catskill Mountains of New York, western
Pennsylvania, and eastern Ohio known as the Marcellus Shale extends
over 44 million acres and contains at least 350 trillion cubic feet of
natural gas, enough to supply the entire U.S. demand for ten to fi fteen
years. But residents in the drilling area say their well water has become
discolored or foul smelling, their pets and farm animals have died from
drinking it, and their children have suffered from diarrhea and vomiting.
Bathing in well water can cause rashes and infl ammation, and ponds
bubble with methane that has escaped during drilling, they say. Escaped
methane has caused some well and tap water to become fl ammable.
According to a home owner living 500 feet from a drilling operation,
“The smell and the rotten taste [of his water], you couldn't take a shower
