Geochemical and Strontium Isotope Characterization of Produced Waters from Marcellus Shale Natural Gas Extraction

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• 作者：Elizabeth C. Chapman ; Rosemary C. Capo ; Brian W. Stewart ; Carl S. Kirby ; Richard W. Hammack ; Karl T. Schroeder ; Harry M. Edenborn
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：March 20, 2012
• 年：2012
• 卷：46
• 期：6
• 页码：3545-3553
• 全文大小：399K
• 年卷期：v.46,no.6(March 20, 2012)
• ISSN：1520-5851

文摘

Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of 375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (蔚_Sr^SW = +13.8 to +41.6, where 蔚_Sr^SW is the deviation of the ⁸⁷Sr/⁸⁶Sr ratio from that of seawater in parts per 10⁴); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters.