Hydraulic
Fracturing
Implications: Forensic
Ambiguity, Science and Rhetoric
Environmental and public concern about potential impacts on
drinking water resources from oil and gas industry hydraulic
fracturing
practices have led to a surge of media attention that has implicated the
practice for “fugitive” methane and shallow groundwater
contamination from
hydraulic
fracturing
chemicals.
In February, the EPA released a plan of seven case
studies to assess the potential impacts of hydraulic
fracturing
on drinking
water and groundwater. The case study sites were chosen where natural gas
resources are geographically extensive. The chances of naturally occurring gas
in domestic water wells is also highly probable in these locations. Information
from the Raton Basin, one of the EPA retrospective case study locations, is
presented to demonstrate some of the potential problems and limitations of the
proposed EPA study.
The EPA is using the same analyte suite for all study
sites. The analyte suite includes compounds and stable isotopes that are
selected as potential markers for hydraulic
fracturing
due to possible
occurrence in
hydraulic
fracturing
fluids or possible presence in natural gas
bearing formations. Many of these same constituents can be naturally occurring
in domestic water wells or present in common disinfection and rehabilitation
chemical mixtures used by water well contractors. Consequently, potential
markers for
hydraulic
fracturing
identified in the EPA study cannot be
considered a “fingerprint” or unique identifier of contamination by
hydraulic
fracturing
operations. The word “fingerprint” is often
used when addressing stable isotopes of carbon and hydrogen in methane and
insinuates a unique identifier. However, this is not the case and isotopes only
provide a marker for a general classification subject to deviations associated
with processes such as mixing and oxidation.
Correlations drawn in media “exposes” may be linked but not causative. Areas are targeted by gas exploration because the potential is high, which often correlates with naturally occurring gas in aquifers which may supply domestic water wells.
Well logs, well completion and maintenance records,
and baseline data need to be evaluated along with specific compounds and stable
isotopes observed in injection and produced water fluids and in monitoring and
domestic water supply wells to evaluate potential impacts due to hydraulic
fracturing
.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California