(389e) A Combined Microstructural and Chemical Study of Uranium in Unconventional Shale Reservoirs

A Combined Microstructural and Chemical Study of Uranium in Unconventional Shale Reservoirs

Joseph D. Levinthal^1*, Bryony Richardds-McClung², and Luther McDonald¹

¹University of Utah Nuclear Engineering Program

² Energy Geoscience Institute

Abstract: Unconventional ‘shale’ reservoirs have moved from a minority interest to center stage focus, and are being evaluated for their potentially large hydrocarbon (oil and/-or gas) reserves. During the hydraulic fracturing of these shale formations, many additional minerals are solubilized and brought to the surface, or potentially transported to ground water, which has generated some concerns over the safety of these techniques. This study focuses on the morphological properties of uranium, which were investigated to develop a knowledgeable interpretation of environments of deposition and uranium mineralogical associations within the shale. This knowledge leads to a more advanced understanding of the sedimentological evolution of micro- and macro-environments, and is key to the reconstruction of historical basins, oceans, landscapes, climates, climate cycles, and enables the future development of techniques that may help reduce the migration of radionuclides in these environments. It additionally supports the analysis of the feasibility of selectively extracting the uranium that has been brought to the surface with proppant, and associated hydraulic fracturing chemicals. The mineralogical and chemical evaluation of the shale samples was investigated by X-ray Diffraction (XRD), Quantitative Evaluation Of Minerals By Scanning Electron Microscopy (QEMSCAN^®), and by Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDX). Radiochemical separations were performed to extract the uranium and inductively coupled plasma mass spectrometry (ICP-MS) was used to quantify the uranium concentration for the samples.