We separated and identified polyethylene glycols (PEGs) and polypropylene glycols (PPGs) and their carboxylates in produced water from several hydraulically-fractured oil and gas wells in the Denver-Julesburg Basin (Niobrara Formation) in Weld County, Colorado, USA. This area of Weld County has been drilled extensively in the last five years for oil and gas between 7,000 and 8,000 feet below land surface. The polypropylene glycol and the polyethylene glycol carboxylates are the first reported detections in flowback and produced water from hydraulically-fractured oil and gas wells. These ethoxylated compounds are used as friction reducers, clay stabilizers, and surfactants. Ultrahigh performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UHPLC/QTOF-MS) was used to separate and identify the different classes of ethoxylates. The Kendrick mass scale was applied along with MS-MS for rapid and unequivocal identification. The compounds occur at the ppm concentration range and make an important contribution to the dissolved organic carbon in the flowback and produced water. Comparing these detections to the compounds used in the fracturing process from FracFocus 3.0<b> (</b>https://fracfocus.org) it appears that both PPG and PEG are labeled as their monomers (propylene glycol and ethylene glycol) rather than polymers. This is important for future studies because there are substantial differences in toxicity and remediation for the monomers and polymers of these ethoxylates.

Identification of polyethylene and polypropylene glycols and their carboxylates in flowback and produced water from hydraulic fracturing using LC/QTOF-MS

251st National Meeting (2016)

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