The project team collected and analyzed 224 water samples and 101 matching rock samples. INL's improved method of measuring aqueous REEs allows study of samples previously thought too volume limited to measure. The study found that aqueous REEs occur at trace levels in all analyzed samples, and sometimes exceed ocean REE concentrations by a factor of 1,000. No significant predictive relationship to lithology, reservoir temperature, nor salinity was discovered, but aqueous REE concentration appears spatially controlled. Future work is needed to find the spatially-dependent variable that controls aqueous REE concentration.

This work was developed to complement the geochemical assessments of produced water and geothermal water samples. Specifically, this task was designed to test the influence of reservoir rock-type and corresponding mineralogy/geochemistry on the concentrations of REE found in oil and gas produced waters. There has been no direct investigation of REE reactions relative to rock-type in deep oil and gas brine prior to this investigation.

This work was developed to complement the geochemical assessments of produced water and geothermal water samples. Specifically, this task was designed to test the influence of reservoir rock-type and corresponding mineralogy/geochemistry on the concentrations of REE found in oil and gas produced waters. There has been no direct investigation of REE reactions relative to rock-type in deep oil and gas brine prior to this investigation.

These data represent major, minor, trace, isotopes, and rare earth element concentrations in geologic formations and water associated with oil and gas production. *Note - Link below contains updated version of spreadsheet (6/14/2017)

These data represent major, minor, trace, isotopes, and rare earth element concentrations in geologic formations and water associated with oil and gas production. *Note - Link below contains updated version of spreadsheet (6/14/2017)

Rare Earth elements (REE) are gaining importance due to their increasing industrial applications and usefulness as petrogenetic indicators. REE-sulfate complexes are some of the most stable REE aqueous species in hydrothermal fluids, and may be responsible for REE transport and deposition in a wide variety of geological environments, ranging from sedimentary basins to magmatic hydrothermal settings. However, the thermodynamic properties of most REE-sulfate complexes are derived from extrapolation of ambient temperature data, since direct information on REE-sulfate complexing under hydrothermal conditions is only available for Nd, Sm and Er to 250 ˚C (Migdisov and William-Jones, 2008, 2016). We employed ab initio molecular dynamics (MD) simulations to calculate the speciation and thermodynamic properties of yttrium(III) in sulfate and sulfate-chloride solutions at temperatures and pressures up to 500 ºC and 800 bar. The MD results were complemented by in situ X-ray absorption spectroscopy (XAS) measurements. Both MD and XAS show that yttrium(III) sulfate complexes form and become increasingly stable with temperature (≥200 ˚C). The MD results also suggest that mixed yttrium-sulfate-chloride complexes (that cannot be distinguished from mixtures of chloride and sulfate complexes experimentally) form at ≥350 ˚C. Two structures with two different Y(III)-S distances (monodentate and bidentate) are observed for Y(III)-sulfate bonding. The formation constants (derived via thermodynamic integration) for the Y(III) mono- and di-sulfate complexes parallel the trends for the those of Nd, Sm and Er determined experimentally to 250 ˚C. The derived formation constants were used to fit the revised Helgeson-Kirkham-Flowers equation-of-state parameters that enabled calculation of formation constants for Y(SO4)+ and Y(SO4)2- over a wide range of temperatures and pressures. The presence of sulfate increases the solubility of Y(III) under specific conditions. Since the stability of sulfate is redox sensitive, Y(III) solubility becomes highly redox-sensitive, with rapid precipitation of Y minerals upon destabilisation of aqueous sulfate. Citation: Qiushi Guan, Yuan Mei, Barbara Etschmann, Marion Louvel, Denis Testemale, Evgeniy Bastrakov, Joël Brugger, Yttrium speciation in sulfate-rich hydrothermal ore-forming fluids, Geochimica et Cosmochimica Acta, Volume 325, 2022, Pages 278-295, ISSN 0016-7037, https://doi.org/10.1016/j.gca.2022.03.011.

This study is part of a joint effort by the University of Wyoming (UW) School of Energy Resources (SER), the UW Engineering Department, Idaho National Laboratories (INL), and the United States Geological Survey (USGS) to describe rare earth element concentrations in oil and gas produced waters and in coal-fired power station ash ponds. In this work we present rare earth element (REE) and trace metal behavior in produced water from four Wyoming oil and gas fields and surface ash pond water from two coal-fired power stations. Using the methods of the INL team members, we measured REEs in high salinity oil and gas produced waters. Our results show that REEs exist as a dissolved species in all waters measured for this project, typically within the parts per trillion range.

This study is a joint effort by the University of Wyoming (UW), the UW Engineering Department (UW-ENG), and Idaho National Laboratories (INL) and the United States Geological Survey (USGS) to describe rare earth element concentrations in oil and gas produced waters. In this work we present the Rare Earth Element (REE) and trace metal character of produced water in several oil and gas fields and three coal fired power stations.

Heavy rare earth elements are essential in renewable energy and high-tech products. Some natural rare earth element (REE) deposits exhibit heavy rare earth element (HREE) enrichment from < 10% to ~85% of the REE budget (Williams-Jones et al., 2015). Controls on REE fractionation in hydrothermal systems are imposed by (1) changes in the relative stability of REE aqueous complexes with temperature (Migdisov et al., 2016) and (2) incorporation or rejection of REE by crystalline structures. Also, the REEs are invariably found as solid solutions but not as pure minerals. REE and yttrium (Y) sulphate complexes are some of the most stable REE and Y aqueous species in hydrothermal fluids (Migdisov and William-Jones, 2008, 2016; Guan et al., 2022) and may be responsible for REE transport and deposition in sediment-hosted deposits. Within the unconformity-related deposits, REEs are hosted mostly by xenotime ((Y,Dy,Er,Tb,Yb)PO4) and minor florencite ((La,Ce)Al3(PO4)2(OH)6) (Nazari-Dehkordi et al., 2019). Modelling the stability of xenotime in the H-O-Cl-(±F)-S-P aqueous system is critical for understanding HREE enrichment in this mineral system. We use a newly derived thermodynamic dataset depos for REESO4+ and REE(SO4)2‑ aqueous complexes to generate stability diagrams illustrating mechanisms of REE transport and deposition in the above deposits. Sulphate REE complexes may dominate even in chloride-rich brines and facilitate REE mobilization in acid oxidizing environments. Previously Nazari-Dehkordi et al. (2019) proposed an ore genesis model involving the mixing of discrete hydrothermal fluids that separately carried REE + yttrium and phosphorus. The speciation model that includes sulphate complexes expands this scenario; a process resulting in fluid neutralization or reduction will also promote precipitation of xenotime enriched in HREEs. This Abstract was submitted/presented to the 2022 Specialist Group in Geochemistry, Mineralogy and Petrology (SGGMP) Conference 7-11 November (https://gsasggmp.wixsite.com/home/biennial-conference-2021)

Version 2. This study is a joint effort by the University of Wyoming (UW), the UW Engineering Department (UW-ENG), and Idaho National Laboratories (INL) and the United States Geological Survey (USGS) to describe rare earth element concentrations in oil and gas produced waters. In this work we present the Rare Earth Element (REE) and trace metal character of produced water in several oil and gas fields and three coal fired power stations.