National Research Program (NRP)
Increasing demand for fossil fuels and depletion of traditional oil and gas reservoirs has driven the application of enhanced recovery methods to depleted reservoirs and advanced technologies for the development of low matrix permeability reservoirs. Development of unconventional oil and gas (UOG) resources, such as by directional drilling and hydraulic fracturing, generates large volumes of liquid and solid, wastes. Waste materials may contain toxic or radioactive elements from the formation, additives used in the UOG development process, and organic compounds from the formation. In order to assess and to manage risks to human and ecosystem health associated with exposure to waste materials from UOG development there is a critical need to understand the composition of the range of solid and liquid wastes generated, to identify potential pathways to the environment, and to evaluate potential effects on receptor organisms from exposure to constituents of these wastes.
Liquid wastes, e.g., produced waters from UOG development processes, drilling fluids and chemical additives, are managed in a variety of ways that vary by geographic region. During disposal, treatment, or re-use of wastewater, environmental impacts can occur due to accidental or intentional releases. There is an urgent need to examine these emerging risks because of their potential impacts on human, wildlife, and ecological health, which are likely to accelerate with the growing pace of UOG development. The USGS is part of a Federal Interagency Steering Committee (EPA-DOE-DOI) focused on strategizing UOG-related research. USGS scientists supported by the Energy and Minerals Mission Areas, Water Mission Area, and Environmental Health Mission Area, are already conducting research that provides information and insight to the public, decision makers, scientists, and the energy industry about managing these wastes.
The Toxics Program has established a project to study the potential environmental impact of wastes produced from UOG development (UOG WW Project ; , Engle et al., 2014, Hladik et al., 2014, Skalak et al., 2013). The Toxics team is tasked with identifying the highest priority research questions to identify and study the human and ecological contaminant-exposure pathways of greatest concern. The research being conducted by this TRT described herein extends the work of that team by leveraging existing resources in order to advance the development of environmental tracers and increase the opportunities to accomplish field work. The work will be conducted in close collaboration with Mark Engle (Produced Waters Project, Energy Resources Program).
We are developing diagnostic monitoring techniques for contamination by UOG wastewaters by identifying chemical or biological signatures that can be readily measured and could act as early indicators of soil and water contamination. It is expected that produced water discharges into the shallow subsurface or at land surface will cause local degradation of soil and groundwater quality. We are focusing our initial field studies in two areas: brine spills in the Williston Basin (impacted by drilling activities in the Bakken formation), and leaks and spills from wastewater handling in the Northeast (impacted by development of the Marcellus Shale and coal-bed methane generation).
Water, soil, and sediment samples from produced-water spill sites or wastewater disposal sites are being examined to determine:
Akob, D. M., I. M. Cozzarelli, D. S. Dunlap, E. L. Rowan and M. M. Lorah. 2015. Organic and Inorganic Composition and Microbiology of Produced Waters from Pennsylvania Shale Gas Wells. Applied Geochemistry, 60:116-125
Engle, M.A., Cozzarelli, I.M., and Smith, B.D., 2014, USGS investigations of water produced during hydrocarbon reservoir development: U.S. Geological Survey Fact Sheet 2014–3104, 4 p.
Hladik, M.L., Focazio, M.J. and Engle, M., 2014. Discharges of produced waters from oil and gas extraction via wastewater treatment plants are sources of disinfection by-products to receiving streams, Sci. Tot. Environ., v. 466-467, 1085-1093. DOI: 10.1016/j.scitotenv.2013.08.008
Skalak, K. J., Engle, M. A., Rowan, E. L., Jolly, G. D., Conko, K. M., Benthem, A. J., & Kraemer, T. F. (2014). Surface disposal of produced waters in western and southwestern Pennsylvania: Potential for accumulation of alkali-earth elements in sediments. International Journal of Coal Geology 126: 162–170.