The use of hydraulic fracturing and horizontal drilling has resulted in the rapid development of oil and gas resources in many areas of the United States; however, the potential effects of hydraulic fracturing on shallow groundwater resources are not fully understood. Several shallow pathways exist that may result in groundwater contamination by fracturing fluids, including surface spills and possibly compromised well integrity. The objective of our study was to assess the potential for contamination of an aquifer along one of these shallow pathways by examining the environmental behavior of four organic compounds frequently used in hydraulic fracturing fluids. Four compounds were selected based on their frequent presence in fracturing fluids and their potential for transport in porous media: isopropanol, 2-butoxyethanol, ethylene glycol, and glutaraldehyde. Flow-through column experiments were used to measure breakthrough curves of the four organic compounds. Fate and transport parameters were determined by fitting the breakthrough curves to a one-dimensional advection-dispersion-first-order reactive transport model. The organic compounds were added to a synthetic groundwater mixture and simultaneously injected into two stainless steel columns containing sandstone collected from the Arapahoe Formation in the Denver-Julesburg Basin. One column was maintained as an abiotic control using sodium azide and biodegradation was observed in the other column. As expected for these water-soluble compounds, sorption in the flow-through columns was minimal. Rapid biodegradation was observed for glutaraldehyde and ethylene glycol (measured first-order half-lives of 1.7 and 1.9 d, respectively). Isopropanol and 2-butoxyethanol were found to be more persistent (first-order half-lives of 22 d and &gt;44 d, respectively). Biodegradation of three compounds was observed only after one of the compounds, glutaraldehyde, was &gt;50% removed, suggesting that glutaraldehyde, which is used in the fracturing fluids as a biocide, inhibited the overall biodegradation of the synthetic fracturing fluid mixture at higher concentrations.<br/>

Fate and transport of four organic compounds frequently used in hydraulic fracturing fluids in laboratory columns containing aquifer sediments

249th National Meeting (2015)

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