Hydraulic fracturing is a method to increase the yield of oil and natural gas extraction from unconventional rock formations.  The process of hydrofracturing occurs via injecting water, sand, and chemicals into the production well and subjecting this mixture to high pressures (approximately 6,000 psi in the Marcellus Shale) to crack the rock shale, allowing increased amounts of gas and oil to seep out of the target rock formation.  The chemicals involved serve a variety of functions, from reducing the friction between fluid and pipe to preventing the growth of microorganisms that could corrode the infrastructure and produce hazardous gases.  However, very little is known about the persistence, fate, and toxicity of these chemicals when subjected to the high temperatures and pressures of down-hole conditions.  Therefore, this presentation will address these chemicals' potential for breakdown and transformation including hydrolysis, biodegradation, and mineral-induced transformation.            We will present an overview of our project and results from ongoing experiments related to the following overarching goal 'Determine the fate of priority organic chemicals used for hydraulic fracturing under conditions simulating down-hole conditions'. Using stainless steel reactors, the high pressures and temperatures of down-hole conditions in the Marcellus shale will be simulated while the behavior of certain selected chemicals is observed as a function of time using primarily LC/MS techniques.  Commonly used chemicals such as polyacrylamide (friction reducer) and glutaraldehyde (biocide) as well as certain priority chemicals have been chosen based on both frequency of use in hydrofracturing fluids and propensity for being environmentally persistent.  We will also be analyzing field samples (both sediments and flowback brine) from the Marcellus shale to verify that our lab simulation mirrors real-life conditions and results.

Fate of hydraulic fracturing chemicals under down-hole conditions

246th National Meeting (2013)

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