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What Is Hydraulic Fracturing?
Injection of Toxic Chemicals Into Underground Shale
Hydraulic fracturing (also known as fracking) is a
technique used to create fractures that extend from the well bore
into rock or coal formations. These fractures allow the oil or gas
to travel more easily from the rock pores, where the oil or gas
is trapped, to the production well. Typically, in order to create
fractures a mixture of water, proppants (sand or ceramic beads)
& chemicals is pumped into rock or coal formations. (text continues
below).
Eventually, the formation will not be able to absorb the fluid as
quickly as it is being injected. At this point, the pressure created
causes the formation to crack or fracture. The fractures are held
open by the proppants, and the oil or gas is then able to flow through
the fractures to the well.[3] Some of the fracturing fluids are
pumped out of the well and into surface pits or tanks during the
process of extracting oil, gas and any produced water, but studies
have shown that anywhere from 20-40% of fracing fluids may remain
underground.
Acidizing involves pumping acid (usually hydrochloric acid), into
the formation. The acid dissolves some of the rock material so that
the rock pores open and fluid flows more quickly into the well.
Fracking and acidizing are sometimes performed simultaneously, in
an acid fracture treatment.
Hydraulic Fracturing - Issues and Impacts
Hydraulic Fracturing Chemicals - Coalbed fracture treatments use
anywhere from 50,000 to 350,000 gallons of various stimulation and
fracturing fluids, and from 75,000 to 320,000 pounds of proppant
during the hydraulic fracturing of a single well. Many fracturing
fluids contain chemicals that can be toxic to humans and wildlife,
and chemicals that are known to cause cancer. These include potentially
toxic substances such as diesel fuel, which contains benzene, ethylbenzene,
toluene, xylene, naphthalene and other chemicals; polycyclic aromatic
hydrocarbons; methanol; formaldehyde; ethylene glycol; glycol ethers;
hydrochloric acid; and sodium hydroxide Very small quantities of
chemicals such as benzene, which causes cancer, are capable of contaminating
millions of gallons of water.
Potential Groundwater Contamination
As mentioned previously, hydraulic fracturing is used in many coalbed
methane (CBM) production areas. Some coal beds contain groundwater
of high enough quality to be considered underground sources of drinking
water (USDWs). According to the U.S. Environmental Protection Agency
(EPA) ten out of eleven CBM basins in the U.S. are located, at least
in part, within USDWs. Furthermore, EPA has determined that in some
cases, hydraulic fracturing chemicals are injected directly into
USDWs during the course of normal fracturing operations.[8] (Read
stories by Peggy Hocutt and Laura Amos to learn how hydraulic fracturing
of coalbeds and other geological formations has affected their lives.)
Frac Pit PHOTO
Calculations performed by EPA show that at least nine hydraulic
fracturing chemicals may be injected into or close to USDWs at concentrations
that pose a threat to human health. These chemicals may be injected
at concentrations that are anywhere from 4 to almost 13,000 times
the acceptable concentration in drinking water.
Not only does the injection of these chemicals pose a short-term
threat to drinking water quality, it is quite possible that there
could be long-term negative consequences for USDWs from these fracturing
fluids. According to the EPA study, and studies conducted by the
oil and gas industry, [10] between 20 and 40% of the fracturing
fluids may remain in the formation, which means the fluids could
continue to be a source of groundwater contamination for years to
come.
The potential long-term consequences of dewatering and hydraulic
fracturing on water resources have been summed up by professional
hydrogeologist who spent 32 years with the U.S. Geological Survey:
At greatest risk of contamination are the coalbed aquifers currently
used as sources of drinking water. For example, in the Powder River
Basin (PRB) the coalbeds are the best aquifers. CBM production in
the PRB will destroy most of these water wells; BLM predicts drawdowns...that
will render the water wells in the coal unusable because the water
levels will drop 600 to 800 feet. The CBM production in the PRB
is predicted to be largely over by the year 2020. By the year 2060
water levels in the coalbeds are predicted to have recovered to
within 95% of their current levels; the coalbeds will again become
useful aquifers. However, contamination associated with hydrofracturing
in the basin could threaten the usefulness of the aquifers for future
use.
One potentially frustrating issue for surface owners is that it
may not be easy to find out what chemicals are being used during
the hydraulic fracturing operations in your neighborhood. According
to the Natural Resources Defense Council, attempts by various environmental
and ranching advocacy organizations to obtain chemical compositions
of hydraulic fracturing fluids have not been successful because
oil and gas companies refuse to reveal this "proprietary information."
As mentioned above, anywhere from 20-40% of fracing fluids remain
in the ground. Some fracturing gels remain stranded in the formation,
even when companies have tried to flush out the gels using water
and strong acids. [13] Also, studies show that gelling agents in
hydraulic fracturing fluids decrease the permeability of coals,
which is the opposite of what hydraulic fracturing is supposed to
do (i.e., increase the permeability of the coal formations). Other
similar, unwanted side effects from water- and chemical-based fracturing
include: solids plugging up the cracks; water retention in the formation;
and chemical reactions between the formation minerals and stimulation
fluids. All of these cause a reduction in the permeability in the
geological formations.
Hydraulic Fracturing Chemical Disposal -
When companies have an excess of hydraulic fracturing
fluids, they either use them at another job or dispose of them.
Some company Material Safety Data Sheets include information on
disposal options for fracturing fluids and additives. The table
below summarizes the disposal considerations that the company Schlumberger
Technology Corp. ("Schlumberger") includes in its MSDSs.
As seen in the table, Schlumberger recommends that many fracturing
fluid chemicals be disposed of at hazardous waste facilities. Yet
these same fluids (in diluted form) are allowed to be injected directly
into or adjacent to USDWs. Under the Safe Drinking Water Act, hazardous
wastes may not be injected into USDWs.[16] Moreover, even if hazardous
wastes are diluted with water so that the hazardous characteristics
of the fluids are removed, the wastes still cannot be injected into
USDWs. If unused hydraulic fracturing fluids are indeed "hazardous
wastes", it is unconscionable that EPA is allowing these substances
to be injected directly into underground sources of drinking water.
Hydraulic Fracturing Best Practices-
From a public health perspective, if hydraulic fracturing stimulation
takes place, the best option is to fracture formations using sand
and water without any additives, or sand and water with non-toxic
additives. Non-toxic additives are being used by the offshore oil
and gas industry, which has had to develop fracturing fluids that
are non-toxic to marine organisms.
It is common to use diesel in hydraulic fracturing fluids. This
should be avoided, since diesel contains the carcinogen benzene,
as well as other harmful chemicals such as naphthalene, toluene,
ethylbenzene and xylene. According to the company Halliburton, "Diesel
does not enhance the efficiency of the fracturing fluid; it is merely
a component of the delivery system." [18] It is technologically
feasible to replace diesel with non-toxic "delivery systems,"
such as plain water. According to the EPA, "Water-based alternatives
exist and from an environmental perspective, these water-based products
are preferable."
Mud Reserve Pit PHOTO
Torn pit liners can lead to groundwater contamination-
Oil and gas wastes are often flowed back to and stored in pits on
the surface. Often these pits are unlined. But even if they are
lined, the liners can tear and contaminate soil and possibly groundwater
with toxic chemicals. (Read more about pits.) As mentioned above,
toxic chemicals are used during hydraulic fracturing operations.
The same chemicals that are injected come back to the surface in
the flowed-back wastes. As well, hydrocarbons from the fractured
formation may flow back into the waste pits. A preferable way of
storing wastes would be to flow them back into steel tanks.
ENERGY POLICY ACT OF 2005- key paragraphs:
SEC. 322. HYDRAULIC FRACTURING.
Paragraph (1) of section 1421(d) of the Safe Drinking Water Act
(42 U.S.C. 300h(d)) is amended to read as follows:
‘‘(1) UNDERGROUND INJECTION.—The term ‘underground
injection’—
‘‘(A) means the subsurface emplacement of fluids by well
injection; and
‘‘(B) excludes—
‘‘(i) the underground injection of natural gas for purposes
of storage; and
‘‘(ii) the underground injection of fluids or propping
agents (other than diesel fuels) pursuant to hydraulic fracturing
operations related to oil, gas, or geothermal production activities.’’.
SEC. 323. OIL AND GAS EXPLORATION AND PRODUCTION DEFINED.
Section 502 of the Federal Water Pollution Control Act (33 U.S.C.
1362) is amended by adding at the end the following:
‘‘(24) OIL AND GAS EXPLORATION AND PRODUCTION.—The
term ‘oil and gas exploration, production, processing, or treatment
operations or transmission facilities’ means all field activities
or operations associated with exploration, production, processing,
or treatment operations, or transmission facilities, including activities
necessary to prepare a site for drilling and for the movement and
placement of drilling equipment, whether or not such field activities
or operations may be considered to be construction activities.’’.
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