An Overview of the Risks to Water Resources from Unconventional Shale Gas Development and Hydraulic Fracturing

Avner Vengosh, Duke University, Nicholas School of the Environment, Durham, United States, Thomas Darrah, Ohio State University Main Campus, School of Earth Sciences, Columbus, OH, United States, Nathaniel R Warner, Dartmouth College, Hanover, NH, United States, Jennifer Harkness, Duke University, Durham, NC, United States and Robert B Jackson, Stanford University, Stanford, CA, United States

Contact First Author: Avner Vengosh; vengosh@duke.edu

Previously Published Material: This is an overview presentation based on several scientific publications on the environmental effects of shale gas exploration.

Abstract ID#: 33375

 

English Abstract:
The rise of unconventional shale gas development through horizontal drilling and high volume hydraulic fracturing has expanded oil and gas exploration in the USA. The rapid rate of shale gas exploration has triggered an intense public debate regarding the potential environmental and human health effects. Active research by the Duke team in different parts of the USA (Pennsylvania, West Virginia, New York, Arkansas, North Carolina, Texas) has identified four potential risks for impacts on water resources: (1) stray gas contamination of shallow aquifers near shale gas sites resulted in elevated methane levels in some drinking water wells located < 1 km from shale gas wells ; (2) contamination of surface water and shallow groundwater from spills, leaks, and disposal of inadequately treated oil and gas wastewater resulted in elevated levels of halides, ammonium, barium, radium among other contaminants in downstream waterways ; (3) accumulation of toxic and radioactive residues in soil and stream sediments near disposal or spill sites; and (4) over-extraction of water resources for drilling and hydraulic fracturing that could induce water shortages and conflicts with other water users, particularly in water-scarce areas. New state-of-the-art geochemical and isotopic techniques have been developed for delineating the origin of gases and contaminants in water resources. In particular, multiple geochemical and isotopic (carbon isotopes in hydrocarbons, noble gas, strontium, boron, lithium, radium isotopes) tracers have been utilized to distinguish (1) fugitive gas induced from leaking of shale gas wells relative to background naturally occurring methane flux in the subsurface; and (2) contamination from hydraulic fracturing fluids relative to produced water from conventional oil and gas wells and/or naturally occurring salinization. Overall, the environmental effects of unconventional shale gas exploration and hydraulic fracturing can be mitigated by improving the wells integrity and preventing leaking of stray gas, treating or preventing the release of flowback and produced waters to the environment, and using alternative water resources instead of fresh water for hydraulic fracturing.
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