RESUMO
Extraction of oil and gas from unconventional sources, such as shale, has dramatically increased over the past ten years, raising the potential for spills or releases of chemicals, waste materials, and oil and gas. We analyzed spill data associated with unconventional wells from Colorado, New Mexico, North Dakota and Pennsylvania from 2005 to 2014, where we defined unconventional wells as horizontally drilled into an unconventional formation. We identified materials spilled by state and for each material we summarized frequency, volumes and spill rates. We evaluated the environmental risk of spills by calculating distance to the nearest stream and compared these distances to existing setback regulations. Finally, we summarized relative importance to drinking water in watersheds where spills occurred. Across all four states, we identified 21,300 unconventional wells and 6622 reported spills. The number of horizontal well bores increased sharply beginning in the late 2000s; spill rates also increased for all states except PA where the rate initially increased, reached a maximum in 2009 and then decreased. Wastewater, crude oil, drilling waste, and hydraulic fracturing fluid were the materials most often spilled; spilled volumes of these materials largely ranged from 100 to 10,000L. Across all states, the average distance of spills to a stream was highest in New Mexico (1379m), followed by Colorado (747m), North Dakota (598m) and then Pennsylvania (268m), and 7.0, 13.3, and 20.4% of spills occurred within existing surface water setback regulations of 30.5, 61.0, and 91.4m, respectively. Pennsylvania spills occurred in watersheds with a higher relative importance to drinking water than the other three states. Results from this study can inform risk assessments by providing improved input parameters on volume and rates of materials spilled, and guide regulations and the management policy of spills.
RESUMO
The development of natural gas and oil from unconventional formations in the United States has grown substantially in recent years and has created governance challenges. In light of this recent growth, and increasing attention to global shale gas resources, the successes and failures of governance efforts in this country serve as important lessons for other nations that have their own unconventional petroleum resources and are beginning to move forward with development, thus calling for a more in-depth examination of the laws governing shale gas development and their implementation. Governance includes both the substance of laws and the activities of entities that implement and influence laws, and in the case of oil and gas, states are primarily responsible for risk governance. Nongovernmental actors and industry also work with states to shape and implement regulations and standards. This Policy Analysis introduces the role of various actors in U.S. shale gas governance, explaining why the states are primarily responsible for risk governance, and explores the capacity of states to conduct governance, examining the content of their laws and the strength of their regulatory entities. The Analysis concludes that states are, to a degree, addressing the changing risks of development. Gaps remain in the substance of regulations, however, and many states appear to lack adequate support or policies for training industry in compliance matters, monitoring activity at sites, prioritizing certain types of regulatory violations that pose the highest risks, enforcing laws, and ensuring that the public is aware of inspections and enforcement and can therefore monitor state activity.