Page 401 - Fundamentals of Gas Shale Reservoirs

18

GAS SHALE ENVIRONMENTAL ISSUES
AND CHALLENGES

Terence H. Thorn
JKM 2E Consulting, Houston, TX, USA

18.1 OVERVIEW (ii) Climate: Emissions of CO , methane, and other
2
greenhouse gases during the production, processing,
Experts agree that the storage and treatment of liquid drilling and transportation of shale gas;
wastes, methane emissions, water usage, and site construction (iii) Air Quality: the local impact of emissions from dril-
are among the biggest environment issues surrounding shale ling rigs, trucks, and compressors;
gas development. These environmental priorities were con- (iv) The social impacts on shale gas communities
firmed in Resources For the Future’s (RFF) Center for Energy including demands on local infrastructure and
Economics and Policy, Pathways to Dialogue: What the social services and environmental degradation; and
Experts Say about the Environmental Risks of Development, (v) Earthquakes caused by wastewater disposal in deep
released in early 2013 (Krupnick et al., 2013). The report was injection wells.
the first survey‐based, statistical analysis of experts from
government agencies, industry, academia, and nongovern-
mental organizations to identify the priority environmental 18.2 WATER USE
risks related to shale gas development. What was most inter-
esting about the survey was a high degree of consensus as to Access to water is critical to shale gas development. The
the risks that should be identified as priorities. Only two of amount of water needed to hydraulically fracture a well var-
the consensus risks identified by the experts are unique to ies greatly, depending on how hard it is to extract oil and gas
the shale gas development process, and both have potential from each geological formation, but on average it can take
impacts on surface water. The remaining 10 consensus risks 2–5 million gallons (7–19 million liters) of water to frack a
relate to practices common to gas and oil development in gen- well, and a well may be fracked multiple times. Depending
eral, such as the construction of roads, well pads and facilities on state and local water laws, producers may draw their
related to the actual drilling of the well, and pipelines, gath- water for free from underground aquifers or rivers, or may
ering and processing facilities, and the potential for leaks in buy and lease supplies belonging to water districts, cities,
well casing and cementing. and farmers. Even if some of the water can be recycled, the
The environmental concerns about the effects of shale gas process requires a major withdrawal from an aquifer or other
development can be grouped into five general categories: water resources during the fracking process.
The U.S. Environmental Protection Agency (EPA) in the
(i) Water: the overall water consumption requirements, 2011 draft study on the impact of fracking on drinking water
the improper disposal of wastewater, and the possi- estimated that that the 35,000 oil and gas wells used for
bility that underground fracking fluids can migrate fracking consume between 70 billion and 140 billion gallons
into aquifers; of water every year (EPA, 2011a ). That’s about equal, EPA

Fundamentals of Gas Shale Reservoirs, First Edition. Edited by Reza Rezaee.
© 2015 John Wiley & Sons, Inc. Published 2015 by John Wiley & Sons, Inc.