Abstract
This article is intended to describe the most significant hazards associated with the operation of the aboveground parts of shale gas production technology and to compare them with possible hazard of the aboveground parts of natural gas storage technologies in underground storage reservoirs (in natural or artificial spaces in underground geological formations). In both cases, in addition to hazards of treatment of methane (natural gas and shale gas), there are used hazardous chemical substances that may threaten employees and surrounding population. These chemical substances are used for extraction or storage of gas.
The issue of prevention of serious accidents of aboveground part of technology for the extraction of shale gas has not yet been solved, but the information about safety and environmental aspects of extracting shale gas has already been described in the last two years, in the article (Pointet, 2011). Safety of chemical constituents used as propping agents is described in the study (Waxman at al., 2011).
At present there is no specific legislation of European Union regarding the management of risks of shale gas production, but the update of the European directive 96/82/EC includes storage of natural gas in underground storage. The new Directive 2012/18/EU is generally applicable to all such forms of storage, including the storage in natural gas fields (onshore underground gas storage in natural strata, aquifers, salt cavities and disused mines, and chemical and thermal processing operations and storage related to those operations which involve dangerous substances, as well as operational tailings disposal facilities, including tailing ponds or dams containing dangerous substances shall be included within the scope of the Directive).
Due to a larger volume of chemical substances stored in the aboveground part of the technology for extracting of shale gas (average amount about 230 m3 in stage of hydraulic fracturing) compared with volumes of chemical substances used in the aboveground part of technology of underground storage of natural gas (about 50 m3) the technology of shale gas extraction has significantly higher risk. However, in the case that the entire process of storage of chemical substances will be well managed and sufficient measures will be taken to minimize the risk, aboveground part of the technology for extracting of shale gas does not represent a significant difference from warehouses in chemical production plants.
From the comparison of hazards of the aboveground parts of natural gas storage technologies in underground storage reservoirs with hazards associated with the operation of the aboveground parts of shale gas production technology is obvious, that future legislation of European Union in the field of major accident prevention should include also the shale gas production facilities.
Although a research about hazards of the aboveground part of the shale gas extraction technology has been made to improve the knowledge on this risk source, more research would be required, especially with practical results of detailed risk analysis.
