Shale strategies can aid in reducing the severity

Shale gas
has recently received a high level of attention due to the potential negative
impacts that it might have on the surrounding environment. However, a
meticulous understanding of the methodologies used in order to extract the gas
and the preventive measures available is necessary in order to assess the
levels of risk involved. A very common concern about shale gas development is
that hydraulic fracturing operations might lead to fractures that extend beyond
the target formation to water aquifers allowing contaminants to migrate from
the target formation into drinking water supplies. With the exceptions of
Antrim and New Albany Shales, thousands of feet of rock isolate gas-bearing
shale formations from the aquifers’ base that contains drinkable water. Contamination
is highly improbable to take place in deep shale formations during
well-designed fracture jobs. The reason for this is that contamination of
underground sources of drinking water due to hydraulic fracturing requires
hydrofractures to spread several thousand feet beyond the upward boundary of
the target formation through many layers of rock. Water used for hydraulic
fracturing is usually fresh water that is extracted from groundwater or surface
water resources. In several countries, the average annual water volumes
reported for hydraulic fracturing were less than 1% of the estimated annual
volume of readily available fresh water. With some exceptions, hydraulic
fracturing relatively uses a small percentage of water when compared to the
total water use at large geographic scales. Water management strategies can aid
in reducing the severity of impacts on drinking water resources due to
hydraulic fracturing. Another concern with hydraulic fracturing is its effect
on the seismic activity. The hydraulic fracturing process results in a high
number of microseismic events, or micro-earthquakes. However, it is important
to note that the magnitudes of these are too small to be detected at the
surface. Therefore, seismic monitoring of hydraulic fracture jobs is crucial in
improving the understanding of how underground injection might result in an
unexpectedly high magnitude seismic activity. Additives usually make up the
smallest portion of the overall composition of hydraulic fracturing fluids.
However, additives have the greatest potential to affect the quality of
drinking water resources compared to proppant and base fluids. Additives can be
a single chemical or a mixture of different chemicals. Additives are added to
the base fluid in order to change its properties such as adjust pH, increase
fluid thickness, or limit bacterial growth. The properties and features of the
rock formation assist in making a choice regarding which additives to use. The
law does not currently require disclosure of chemicals stored in smaller
quantities and access to MSDSs can often be limited. Several efforts are
ongoing in order to obtain greater disclosure of fracturing fluids. Efforts
include a provision in draft climate legislation introduced by Senators John
Kerry (D-MA) and Joe Lieberman (I-CT) in May 2010. This provision would amend
EPCRA to mandate the disclosure of all chemicals used on public websites.