A study by Duke University and Kent State University researchers has concluded that wastewater from hydraulic fracturing in Pennsylvania’s Marcellus shale region could overwhelm wastewater disposal facilities. The article notes that because of advances in directional drilling and hydraulic fracturing, shale gas extraction has become more economical, which has caused gas prices to drop, and, as a result, “natural gas has recently replaced coal as the dominant source of energy in power generation for the first time in U.S. history.”
The authors observe, however, that environmental concerns, such as the potential to contaminate groundwater and for natural gas to escape into the atmosphere, exist and suggest that such impacts can be minimized while developing these resources. “Wastewater is an obligate byproduct and volumes of wastewater will increase as the industry expands,” they write. The wastewater includes drilling and flowback wastewater as well as produced water—brine— which may contain residual hydraulic-fracturing fluids. The authors note that current conventional gas production in the United States generates 5.6 billion barrels of wastewater per year and suggest that developing shale gas resources will increase that total as well as change where gas production-related wastewater is generated and disposed.
Using available documentation of wastewater disposal, the authors concluded that while shale gas development yields more wastewater per well than conventional methods, it actually results in fewer gallons of wastewater per unit of gas produced than conventional production. But they note that as shale exploitation expands so will the wastewater it generates. They also observe that although hydraulic-fracturing fluid is present, “the vast majority” of dissolved material in Marcellus shale wastewater consists of inorganic ions, metals, organics, and radioactive material derived from the subsurface. Underground injection is evidently the most common disposal method for natural gas wastewater, and disposal of the water in connection with Marcellus shale development is evidently challenging because there is little suitable geology nearby for injection disposal. The majority of these wastewaters end up in municipal and industrial treatment facilities.
The authors assert that technological solutions for wastewater management come at a high cost and conclude that “advances in unconventional methods for wastewater management, comparable to the advances that facilitated the development of unconventional gas resource, are now needed.”