It is well known that the process of hydraulic fracturing uses large numbers and quantities of chemical compounds, some of which are used in very high volumes and are acutely and chronically toxic. However, absent from most scientific and regulatory conversations is the fact that chemical use in hydraulic fracturing is only one instance throughout the entire oil and gas (O&G) development process when chemical additives, sometimes in high volumes, are used. Increasingly produced water from O&G development is being considered and deployed for “beneficial reuse” such as in the irrigation of agriculture, for recharging aquifers, or to increase flow in streams and other aquatic environments. However, other methods of O&G development (e.g., steam injection, water flooding, enhanced oil recovery) also use chemicals and these chemicals are not considered in regulation governing the reuse of produced water for purposes such as irrigation. The only jurisdiction in the United States that mandates the disclosure of chemical use in O&G wells from purposes other than hydraulic fracturing and well stimulation (e.g., acidizing, wellbore maintenance, drilling, etc.) is the South Coast Air Quality Management District in California. In this study, we analyze the chemical types, toxicity, environmental persistence of these chemical constituents, the mass and frequency of the chemicals injected, among other factors to determine the potential risks of “beneficial reuse” of these produced waters. Our results indicate that out of 548 compounds identified as used down-hole, 70% do not have a unique CASRN and/or lack information on their toxicity, making it difficult to assess their risk to human health and the environment. Of the compounds identified by unique CASRN in non-hydraulic fracturing events, approximately 50% were also used in hydraulic fracturing fluids in California according to the list of hydraulic fracturing compounds in the Independent Scientific Study of Well Stimulation in California, commissioned by Senate Bill 4.

From fracking to oil and gas development: Chemical constituents and potential implications for the beneficial reuse of produced water

251st National Meeting (2016)

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