Room:
Leipziger KUBUS | Hall 1 CD (1 CD)
Topic:
SE 5: Unconventional Gas and Oil Production Employing Hydraulic Fracturing
Form of presentation:
Oral presentation
Duration:
225 Minutes
Indications of Transformation Products from Hydraulic Fracturing Additives in Shale Gas Wastewater
Kathrin Hölzer | Helmholtz Center Munich | Germany
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Authors:
Kathrin Hölzer | Helmholtz Center Munich | Germany
Andrew Sumner | Yale University | United States
Robert Nelson | Woods Hole Oceanographic Institution | United States
Gordon Getzinger | Duke University | United States
Osman Karatum | Duke University | United States
Brian Drollette | Yale University | United States
Lee Fergusen | Duke University | United States
Chris Reddy | Woods Hole Oceanographic Institution | United States
PhD Martin Elsner | Helmholtz Zentrum München | Germany
Desiree Plata | Yale University | United States
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Hydraulic Fracturing Chemicals Reported in Unconventional Gas Exploitation
PhD Martin Elsner | Helmholtz Zentrum München | Germany
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Author:
PhD Martin Elsner | Helmholtz Zentrum München | Germany
Much interest is directed at the chemical structure of hydraulic fracturing (HF) additives and the frequency of their use in unconventional gas exploitation. We conducted a quantitative survey and structural classification of HF chemicals in the U.S. based on the House of Representatives (“Waxman”) report for the years 2005-2009 and the database FracFocus for the years 2011-2013. Out of over 800 reported substances, classification by functional groups yielded succinct chemical subclasses able to illustrate the frequency and rationale of their use. Water-based guar gum predominated over polyacrylamide/-acrylate as gelling agent, and borate over zirconium as crosslinker. Practically every operation relied on petroleum hydrocarbons as solvents and non-emulsifiers. Nonylphenols – known as persistent endocrine disruptors – potentially form as breakdown products of ethoxylated surfactants. Some organic esters appear to be designed to release carboxyl groups as delayed acids and complexing agents in the subsurface. Such deprotection reactions in highly saline water, alongside with strong oxidants as breakers, bear the danger of organohalide generation. Choline chloride and glutaraldehyde are increasingly used as “green” clay stabilizer and biocide. Otherwise the preference for HF chemicals changed little over time. Such a review can identify indicator substances for monitoring and provide a knowledge base to guide future investigations of subsurface transformations, toxicity assessments and for optimizing wastewater treatment