SusChEM: Geochemical Characterization and Evaluation of the Environmental Impacts of Hydraulic Fracturing Fluids

通过水力压裂和水平钻井开发非常规石油和天然气资源，增加了美国的能源产量，并在全球范围内扩张。然而，这种快速发展引发了关于这项技术对环境影响的激烈公众辩论。与非常规页岩气开发相关的环境风险之一是水资源污染。水力压裂液(HFF)是高度含盐的，含有大量的有毒元素，如钡，以及高水平的自然产生的放射性物质。然而，直接识别水力压裂液及其在环境中释放的能力尚不清楚。这个NSF项目寻求开发与水力压裂过程内在联系的新型和诊断性的地球化学示踪剂。环境取证方法将使我们能够将水力压裂液与其他形式的污染区分开来，包括自然形成的咸水地下水和过去常规石油和天然气勘探的遗留问题，这些问题可以掩盖划定水污染源和评估页岩气开发净影响的企图。随着水力压裂技术在全球的推广，NSF项目开发的方法学可普遍应用于其他非常规油藏。本研究将广泛收集页岩气和常规油气勘探的回流和产出水(共80个样品)，结合多种同位素指纹(d18O、d2H、d13C-DIC、d11B、87Sr/86Sr、d7Li、206Pb/208Pb)和放射性核素(228Ra/226Ra、210Pb/226Ra)，建立一个包括常量和微量元素的综合地球化学数据库。根据初步数据，假设新型多同位素示踪剂将使我们能够表征和识别HFFS的地球化学指纹，为评估其来源和可能对环境的影响提供依据。建议对已经收集的HFFS进行调查？除了在西弗吉尼亚州和宾夕法尼亚州页岩气开发地区收集新的水资源外，还收集了一些样品。特别是，这项研究的目的是(1)综合地球化学和同位素数据，以重建页岩地层中产出水和回流水的来源和演化，与传统油气井的产出水相比；(2)评估HFFS在处置未经充分处理的废水、泄漏或HFFS泄漏时可能对地表水造成的污染？该项目由美国国家科学基金会地球生物学和低温地球化学项目、美国国家科学基金会可持续化学、工程与材料计划(SusChEM)和美国国家科学基金会环境可持续发展计划联合支持。

Broader significance.The development of unconventional oil and gas resources through hydraulic fracturing and horizontal drilling has increased energy production in the USA and is expanding globally. Yet, this rapid development has triggered an intensive public debate over the environmental implications of this technology. One of the environmental risks associated with unconventional shale gas development is the contamination of water resources. Hydraulic fracturing fluids (HFFs) are highly saline and contain elevated levels of toxic elements such as barium along with high levels of naturally occurring radioactive materials. Yet the ability to directly identify hydraulic fracturing fluids and their release in the environment is not known. This NSF project seeks to develop novel and diagnostic geochemical tracers that are inherently connected to the hydraulic fracturing process. The environmental forensic approach will enable us to distinguish hydraulic fracturing fluids from other forms of contamination, including naturally occurring saline groundwater and the legacy of past conventional oil and gas exploration that can mask attempts to delineate water contamination sources and evaluate the net impact of shale gas development. The methodology developed in this NSF project could be applied universally to other unconventional reservoirs as hydraulic fracturing expands globally.Technical description.This study will use an extensive collection of flowback and produced waters from shale gas and conventional oil and gas exploration (total 80 samples) to establish a comprehensive geochemical database that includes major and trace elements, combined with multiple isotopic fingerprints (d18O,d2H, d13C-DIC, d11B, 87Sr/86Sr, d7Li, 206Pb/208Pb) and radionuclides (228Ra/226Ra, 210Pb/226Ra). Based on preliminary data, it is hypothesized that the novel multi-isotopes tracers will enable us to characterize and identify the geochemical fingerprints of HFFs, providing the basis for evaluation of their origin and possible impacts on the environment. It is proposed to investigate already collected HFFs? samples in addition to new collection of water resources in areas of shale gas development in WV and PA. In particular, the study aims to (1) integrate geochemical and isotopic data for reconstruction the origin and evolution of produced and flowback waters in shale formations as compared to produced waters from conventional oil and gas wells; (2) evaluate possible contamination of surface water by HFFs upon disposal of inadequately treated wastewater, spills, or leakage from HFFs? ponds; (3) simulate reactions of HFF with sediments and mixing with other water types through laboratory experiments and thermo-kinetic modeling; and (4) evaluate groundwater contamination in areas associated with shale gas development in WV.This project is being jointly supported by the NSF Geobiology and Low-Temperature Geochemistry program, the NSF Sustainable Chemistry, Engineering and Materials (SusChEM) initiative, and the NSF Environmental Sustainability program.