Environmental impacts of hydraulic fracturing in shale gas development in the United States

Through comprehensive investigation of the environmental issues in shale gas development in the US, the environmental impacts of hydraulic fracturing in shale gas development are summarized to provide reference for the shale gas development and management in China. The environmental risks of large-scale commercial shale gas development in the United States include water consumption, water contamination, seismic inducement and air pollution. Compared to conventional oil and gas production and other energy producing industries, shale gas development is not exactly “high-water-consuming” in terms of water consuming intensity. Its water consumption, accounting for a small proportion of the total regional water consumption, will not add much more stress on water supply. In terms of water pollution, hydraulic fracturing is unlikely to cause fractures to directly connect reservoir to the shallow aquifer, the known contamination cases are most likely related to faulty well completion, therefore well integrity is the key to the prevention of contamination; the flow-back fluids in large scale shale gas development have the characteristics of large quantity, many kinds of pollutants and complex composition, thus improper treatment would lead to serious contamination, and continuous monitoring and assessment of the pollutants are necessary. Existing evidence shows that hydraulic fracturing is unlikely to trigger destructive earthquakes. Greenhouse gas emissions in the life cycle of shale gas wells were estimated differently, but no doubt more effective measures should be taken to minimize leakage. The research priorities include contamination monitoring program design, detection indicators, moving pattern of hydraulic fracturing fluid and formation fluid, the effects of shale gas development on high salinity formation water and methane migration, and treatment and re-use of flow-back fluid. Key words: shale gas, hydraulic fracturing, environmental risks, water consumption, water contamination, earthquake risk, air pollution