Exploration, drilling and production of shale gas plays such as the Barnett, Fayetteville, and Haynesville have transformed the unconventional gas industry. These and other existing and developing plays have had unimaginable economic impacts to many regions, created tens of thousands of jobs, and have generated royalty payments to a variety of state and local governments as well as many individuals. At the core of shale gas development are two key technologies: horizontal drilling and hydraulic fracturing. Techniques used to hydraulically fracture horizontal wells completed in shale reservoirs often require larger volumes of fracturing fluid than might be common for conventional, vertical well stimulations. The rapid development of shale gas across the country has created concerns on issues such as the use of infrastructure and environmental impacts. Specifically, the common practice of hydraulic fracturing of these shales has attracted critical interest regarding risks potentially posed to groundwater and surface water. This paper will present a summary and evaluation of the environmental implications of hydraulic fracturing in shale gas reservoirs, with examples from multiple basins.


Natural gas production from tight shale formations, known as "shale gas", is one of the most rapidly expanding trends in onshore, domestic natural gas exploration and production. In some areas, development of shale gas resources is bringing drilling and production to regions of the country that has previously seen little to no oil and gas development activity. In plays like the Barnett Shale of Texas, development is occurring in urban and suburban areas where both operators and regulators are adapting to this new environment. Shales are the most abundant sedimentary rock in the Earth's crust and are present across the U.S. (Figure 1).

Shales have been sources of natural gas in small but continuous volumes since the earliest years of gas development. The first producing gas well in the U.S. was completed in 1821 in Devonian-aged shale near the town of Fredonia, New York (Harper, 2008). Early sources of natural gas were shallow gas wells that were from dug wells and natural gas seeps (NY DEC, 1992). Shallow wells and seeps were capable of producing small amounts of natural gas which were used for illuminating city streets and households (Frantz and Jochen, 2005). These early gas wells played a key part in bringing illumination to the cities and towns of the eastern U.S. (Harper, 2008). In contrast, modern shale gas development has become a technological play, in which development is facilitated by the technological advances the oil and gas industry has made in hydraulic fracturing and horizontal drilling over the last two decades.

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