Date of Award

Spring 1-1-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Karl G. Linden

Second Advisor

Earl M. Thurman

Third Advisor

Joseph Ryan

Fourth Advisor

JoAnn Silverstein

Fifth Advisor

Fernando Rosario-Ortiz

Abstract

Hydraulic fracturing simultaneously uses and generates billions of gallons of water every year that must be sourced and managed. Fracturing fluid chemicals, including many ethoxylated and propoxylated surfactants, are added to water to make fracturing fluid. Flowback and produced water, the primary contributors to the waste stream, are generated during the drilling operations and throughout the life of the well.

Inherent to developing a management approach is adequate methods of characterization and treatment for dissolved components. This research presents the development of a solid phase extraction method for identifying and detecting common fluid additives with mass spectrometry (MS). With this method, several new fracturing fluid additives were identified by comparing putative identifications to known standards, conducting MS-MS experiments, and applying the Kendrick mass defect. Poly(ethylene glycol) amines (PEG-amines), PEG-amine-carboxylates, and amino-PEG-amines were identified in 20 samples from different basins. Researchers now have an array of compounds that can be easily detected with MS in flowback and produced water and contribute to the “fingerprinting suite” of compounds identified by other researchers.

When flowback and produced water is treated as part of a management strategy, suspended solids, scaling ions, and dissolved organic compounds are typical targets. In this research, biological treatment of a flowback and produced water is examined for reduction of dissolved organic carbon (DOC) and ethoxylated fluid additives (PEGs and PEG-amines). Three flowback and produced water samples with different water qualities were treated in sequencing batch reactor with an acclimated culture. Observed DOC removal was between ~50-80% and the rate of removal slowed with each cycle. Final DOC concentration was between 6 and 50 mg/L. PEG transformation to PEG-carboxylates and PEG-dicarboxylates was observed in each sample but PEG-dicarboxylates were shown to be recalcitrant to treatment and slowly accumulated in the reactor. This persistence of PEGs could be due to a larger “pool” of ethoxylated compounds feeding the detectable PEGs via biotransformation and PEG shortening. This research highlights the ability of a well-acclimated culture to degrade 50-80% of the DOC in hydraulic fracturing flowback and produced waters and demonstrates the recalcitrance of PEGs and perhaps other ethoxylated compounds to biological treatment.

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