Extraction of radioactive and toxic element contaminants from organic-rich shale in contact with hydraulic fracturing fluids

最近定向钻井和油井增产技术的进步使得通过大体积水力压裂从页岩地层中提取天然气和石油在经济上是可行的。 水力压裂的一个副作用是暴露以前水力隔离的矿物，这些矿物可能含有天然存在的放射性物质和有毒金属元素。 这些成分可能会释放到流回地面的压裂液中，必须妥善处理以避免污染淡水资源。 本研究的主要目的是表征水力压裂液和富含有机物的页岩之间的相互作用，以确定水力压裂液化学品动员不需要的微量有毒金属和放射性核素返排液成分的潜力。 虽然回流流体预期会受到某种程度的污染，例如，已知这些流体可能是高盐的，并且含有高水平的痕量有毒金属和放射性元素，这些污染物作为页岩组成、井下条件和水力压裂流体制剂中存在的化学添加剂的函数被浸出的可能性尚未确定。 为了解决这一知识缺口，将进行一系列的分批和流通实验，以评估这些参数对污染物浸出的影响。 将在现场遇到的典型原位温度和压力条件下，对来自两个密歇根页岩气藏的天然页岩样品进行实验。 将为这项研究建造独特的和最先进的高温和高压装置，并用于开发标准化方法，以评估控制无机有毒和放射性元素从有机物中释放的化学过程和机制。与地下水力压裂液接触的丰富页岩。目前评估返排水质量的努力依赖于水一旦返回，表面上为了正确解决或消除与水力压裂相关的水质影响问题，需要更好地了解地下水力压裂液的化学演变。 这项研究的结果将有助于指导可持续开发国内页岩气资源和减少与水力压裂完井相关的潜在水质影响的行业最佳实践。 此外，了解注入流体的化学演变将有助于制定合理的监管政策，解决回流水管理实践，包括处理，再利用和处置。

CBET 1336719Ellis, Brian R.University of Michigan Ann ArborRecent advances in directional drilling and well stimulation techniques have made extraction of natural gas and oil from shale formations economically viable via high-volume hydraulic fracturing. A side effect of hydraulic fracturing is the exposure of previously hydraulically isolated minerals that may contain naturally occurring radioactive material and toxic metal elements. These constituents may be released into the fracturing fluids that flow back to the surface, which must be properly handled to avoid contamination of fresh water resources. The primary objective of this study is to characterize the interactions between the hydraulic fracturing fluid and organic-rich shales in order to determine the potential for hydraulic fracturing fluid chemicals to mobilize undesirable trace toxic metal and radionuclide flowback fluid constituents. While flowback fluids are expected to be contaminated to some degree, e.g., it is known that these fluids may be highly saline and contain elevated levels of trace toxic metals and radioactive elements, the potential for these contaminants to be leached as a function of the shale composition, down-hole conditions, and chemical additives present in hydraulic fracturing fluid formulations has not yet been determined. To address this knowledge gap, a series of batch and flow-through experiments will be performed to assess the impact of these parameters on contaminant leaching. Experiments will be conducted on natural shale rock samples from two Michigan shale gas reservoirs, under typical in situ temperature and pressure conditions encountered in the field. Unique and state-of-the art high temperature and pressure apparatuses will be constructed for this research and used to development standardized methods for evaluating the chemical processes and mechanisms controlling the release of inorganic toxic and radioactive elements from organic-rich shales in contact with hydraulic fracturing fluids in the subsurface.Current efforts to assess flowback water quality rely on the analysis of the water once it has returned to the surface. To properly address or dismiss concerns regarding water quality impacts associated with hydraulic fracturing, a better understanding of the chemical evolution of hydraulic fracturing fluids in the subsurface is required. The results of this study will help guide industry best practices for sustainably developing domestic shale gas resources and for reducing potential water quality impacts associated with hydraulic fracturing well completions. Furthermore, understanding the chemical evolution of the injected fluids will aid in forming sound regulatory policy addressing flowback water management practices, including treatment, reuse and disposal.