title: Evolution of water chemistry during Marcellus Shale gas development: A case study in West Virginia.
abstract: Hydraulic fracturing (HF) has been used with horizontal drilling to extract gas and natural gas liquids from source rock such as the Marcellus Shale in the Appalachian Basin. Horizontal drilling and HF generates large volumes of waste water known as flowback. While inorganic ion chemistry has been well characterized, and the general increase in concentration through the flowback is widely recognized, the literature contains little information relative to organic compounds and radionuclides. This study examined the chemical evolution of liquid process and waste streams (including makeup water, HF fluids, and flowback) in four Marcellus Shale gas well sites in north central West Virginia. Concentrations of organic and inorganic constituents and radioactive isotopes were measured to determine changes in waste water chemistry during shale gas development. We found that additives used in fracturing fluid may contribute to some of the constituents (e.g., Fe) found in flowback, but they appear to play a minor role. Time sequence samples collected during flowback indicated increasing concentrations of organic, inorganic and radioactive constituents. Nearly all constituents were found in much higher concentrations in flowback water than in injected HF fluids suggesting that the bulk of constituents originate in the Marcellus Shale formation rather than in the formulation of the injected HF fluids. Liquid wastes such as flowback and produced water, are largely recycled for subsequent fracturing operations. These practices limit environmental exposure to flowback.
authors.affiliation: West Virginia Water Research Institute, West Virginia University, 385 Evansdale Drive, Morgantown, WV 26506, United States.
authors.forename: Paul F
authors.initials: PF
authors.lastname: Ziemkiewicz
authors.affiliation: West Virginia Water Research Institute, West Virginia University, 385 Evansdale Drive, Morgantown, WV 26506, United States. Electronic address: Tom.He@mail.wvu.edu.
authors.forename: Y
authors.initials: Y
authors.lastname: Thomas He
mesh_terms: D019652:Extraction and Processing Industry; D059206:Natural Gas; D061329:Oil and Gas Fields; D009930:Organic Chemicals; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis; D014903:West Virginia
chemical_list: D059206:Natural Gas; D009930:Organic Chemicals; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Environmental impact; Flowback; Marcellus Shale; Water chemistry evolution