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Preface High volume hydraulic fracturing of deep shale deposits has transformed the oil and gas industry, catapulting the United States (U.S.) into the biggest oil and natural gas producer in the world, surpassing Russia as of June 2015. Hydraulic fracturing has been a game changer providing an important measure of energy independence for the U.S. As one expert put it, “Shale deposits are a gift from God.” Hydraulic fracturing operations in North Dakota’s Bakken Shale, in the Marcellus formation in Pennsylvania, West Virginia, and Ohio, in Texas’ Eagle Ford and Barnett Shale, and in the vicinity of Pavillion, Wyoming, Bainbridge, Ohio, and Dimock and Dunkard Creek, Pennsylvania are the subject of increased media, public, and regulatory attention. New potential shale plays across the U.S. are also being examined, including the Monterey shale formation in California where hydraulic fracturing is a timely and significant environmental issue with California’s recently enacted hydraulic fracturing regulations and published scientific studies. Heightened interest in hydraulic fracturing is also found worldwide, particularly in the United Kingdom, France, and Poland where development of natural gas from unconventional sources are seen as a path to energy independence. More than half of the world's shale oil resources are located in Russia, China, Argentina, and Libya, and development of these resources is just beginning. Concurrent with the increased development of unconventional hydrocarbon resources are concerns over perceived risks to the environment that have been raised at hydraulic fracturing locations throughout the U.S. The injection of millions of gallons of drilling fluids with chemical additives in boreholes extending for miles to crack the shale and release oil and methane has led to reports of contaminated water supplies, releases of chemically contaminated flowback fluids, air pollution, increased greenhouse gas emissions, and induced earthquakes. Proposals for acid fracturing have also raised concerns for the environment. The 2015 U.S. Environmental Protection Agency (USEPA) report determined that hydraulic fracturing has not led to widespread impacts to drinking water resources. However, the USEPA noted specific instances could lead to contamination, such as wells with inadequate casing and cementing, improperly handled or treated flowback and production fluids, and stimulation in formations containing both oil and gas and drinking water resources. High volume fracturing of deep shale deposits also produces large quantities of wastewater over the production life of the well. The wastewaters are a mixture of the salts, metals, radionuclides, organics, and microorganisms in deep groundwater and dissolved from the geologic formation, as well as the introduced hydraulic fracturing fluids. The exact composition varies considerably ix In Hydraulic Fracturing: Environmental Issues; Drogos, Donna L.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.
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and depends upon the specific shale composition, the fracturing fluid chemical formulation tailored to that formation, and the source water for the hydraulic fracturing fluid. It is also dependent upon whether the wastewater is the initial flowback water produced in the first weeks of well development or the long-term production waters generated over the lifetime of the well. The composition of the injected fracturing fluid also alters the chemical composition of the formation water and the resulting production water. These biogeochemical changes occurring in the millions of gallons of hydraulic fracturing wastewater creates a unique dilemma for the disposal and potential reuse of these waters. Traditional disposal options, such as municipal wastewater treatment plants and deep injection wells, are now less available due to public concern over subsequent discharge to streams used as drinking water sources and the increasing reports of induced seismicity. Existing treatment options such as desalinization become cost prohibitive in treating wastewaters that are many times saltier than seawater. Water reuse is becoming common often requiring new treatment technologies to make the water suitable for reuse in the hydraulic fracturing process. These technical challenges posed by hydraulic fracturing have fostered increased research into the technologies needed to develop these oil and gas resources in an environmentally sound manner. The American Chemical Society (ACS) symposiums were the catalyst for the chapters in this volume focusing on the latest information on the environmental aspects of hydraulic fracturing, including technical challenges, environmental effects, and the political and regulatory climate. These works provide an opportunity to explore the results of ongoing research and consider multidisciplinary approaches needed to meet the challenges posed by this technology. I thank the many authors who contributed their works to this volume, ACS, and the ACS Environmental Chemistry Division for their support of the hydraulic fracturing symposiums. I especially thank Rafael Delgadillo for his unwavering support and encouragement on this project and on all of my other professional and educational pursuits.
Donna L. Drogos Department of Civil & Architectural Engineering University of Wyoming 1000 E. University Ave. Laramie, Wyoming 82071, United States
[email protected] (e-mail)
x In Hydraulic Fracturing: Environmental Issues; Drogos, Donna L.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.
