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To test if reflectance increases to sedimentary organic matter (vitrinite) caused by broad ion beam (BIB) milling were related to molecular aromatization and condensation, we used Raman and Fourier transform infrared (FTIR) spectroscopies to evaluate potential compositional changes in the same vitrinite locations pre- and post-BIB milling. The same locations also were examined by atomic force microscopy (AFM) to determine topographic changes caused by BIB milling (as expressed by the areal root-mean-square roughness parameter Rq). Samples consisted of four medium volatile bituminous coals. We used a non-aggressive BIB milling approach with conditions of [(5 min, 4 keV, 15°incline, 360° rotation at 25 rpm and 100%...
Categories: Data;
Tags: Bituminous Coal,
Broad Ion Beam,
Coal resources,
Energy Resources,
Geochemistry,
Solid organic matter (OM) in sedimentary rocks produces petroleum and solid bitumen when it undergoes thermal maturation. The solid OM is a 'geomacromolecule', usually representing a mixture of various organisms with distinct biogenic origins, and can have high heterogeneity in composition. Programmed pyrolysis is a common conventional method to reveal bulk geochemical characteristics of the dominant OM while detailed organic petrography is required to reveal information about the biogenic origin of contributing macerals. Despite advantages of programmed pyrolysis, it cannot provide information about the heterogeneity of chemical compositions present in the individual OM types. Therefore, other analytical techniques...
Petroleum within unconventional source-rock reservoirs is hosted in organic matter and mineral pore space as well as in voids and microfractures. Recent work has shown that for source-rock reservoirs in the dry gas window, significant portions of methane (CH4), the main component of petroleum at elevated maturities, can be stored within fine organic matter porosity. However, within reservoirs at lower thermal maturities (e.g., peak oil or wet-gas conditions), the distribution and behavior of CH4 and the higher alkanes that comprise gas condensates across pore sizes is unclear, especially for fine pores with diameters <50 nm. Understanding CH4 within these settings provides insight for petroleum generation, movement,...
Categories: Data;
Tags: Colorado,
Contrast Matching,
Denver-Julesburg Basin,
Energy Resources,
Gas Condensate,
Germanium (Ge) is an increasingly important element used in critical technologies for communication, defense, and computing. However, Ge is scarce, and there is no United States (U.S.) primary production. Additionally, the environmental behavior of Ge is poorly understood. Germanium does not generally form its own minerals, but is instead recovered as a byproduct of zinc mining or of coal fly ash. It has been deemed critical by the U.S. and globally, and investigations of its geologic concentration, environmental fate and transport, and potential for recovery are crucial for maintaining a sustainable supply. A relevant study site to explore questions of environmental behavior and the potential to recover...
At recent technical conferences, many coal geoscientists in academia and government institutions as well as in industry organizations have expressed concern about the dwindling number of students and young staff members interested in careers in coal geoscience. To better understand what is driving these trends and to identify potential ways that the community can increase interest and participation in coal geoscience, two different surveys were sent to 94 coal geoscientists who were current or past members of The Society of Organic Petrology (TSOP) in February 2020. As the trends and perceptions in industry and government organizations may be different than in universities, one distinct survey was sent to members...
Inorganic compositions of flowback and co-produced waters from hydrocarbon extraction have been studied directly and through laboratory experiments that seek to replicate subsurface water-rock interaction. Here a broad analysis is made of compositions from the U.S. Geological Survey Produced Waters Database (v2.3) and leachates (water, hydrochloric acid, artificial brine) for 12 energy-resource related shales from across the United States. The database illustrates common ranges for 26 elements in 4 produced water types and enhanced solubility with increasing ionic strength is observed for Al, Ba, Fe, Li, Mn, Rb, Sr, and possibly 11 other elements. Differences are observed between laboratory leachates and produced...
Geological models for petroleum generation suggest thermal conversion of oil-prone sedimentary organic matter in the presence of water promotes increased liquid saturate yield, whereas absence of water causes formation of an aromatic, cross-linked solid bitumen residue. To test the influence of exchangeable hydrogen from water, organic-rich (22 wt.% total organic carbon, TOC) mudrock samples from the Eocene lacustrine Green River Mahogany zone oil shale were pyrolyzed under hydrous and anhydrous conditions at temperatures between 300 and 370°C for 72 hrs. Petrographic approaches including optical microscopy, reflectance, Raman spectroscopy, and scanning electron and transmission electron microscopy, supplemented...
Categories: Data;
Tags: Anhydrous pyrolysis,
Colorado,
Energy Resources,
Garfield County,
Geochemistry,
Germanium (Ge) is an element deemed critical globally, and used in electronics, communication, and defense applications. The supply of Ge is limited and as demand for it increases, its criticality increases. Germanium is exclusively recovered as a byproduct of either coal mining or zinc (Zn) mining, and the main mineral hosting Ge in Zn deposits is sphalerite (ZnS). However, the mechanisms of Ge enrichment in sphalerite during mineral deposit formation are poorly understood. Therefore, investigations on the mechanisms controlling geologic enrichment of Ge in ores is crucial for maintaining a sustainable supply. For this study, we used a combination of techniques including optical and electron microscopy, synchrotron-based...
This data release contains reflectance measurements for eight samples submitted to the USGS Organic Petrology Laboratory in Reston. Samples include two artificial rock samples made from cement with organic matter added (samples 001-002), a coal and shale sample (samples 003-004, respectively), and hydrous pyrolysis residues for samples 001-004. The hydrous pyrolysis experiments were conducted at 330°C for 72 hours at the United States Geological Survey's (USGS) Denver Federal Center. Samples were mounted into 1-inch circular briquettes in USGS-Reston according to ASTM D2797 for organic petrographic analysis. Cement plugs (samples 001-002, and pyrolysis residues 005-006) were crushed to approximately 1 mm top-size...
Categories: Data;
Tags: Bitumen Reflectance,
Colorado,
Energy Resources,
Energy Resources,
Geochemistry,
This study presents Raman spectroscopic data paired with scanning electron microscopy (SEM) to assess solid bitumen composition and porosity development as a function of solid bitumen texture and association with minerals. A series of hydrous pyrolysis experiments (1-103 days, 300-370°C) using a low maturity (0.25% solid bitumen reflectance, BRo), high total organic carbon [(TOC), 14.0 wt. %] New Albany Shale sample as the starting material yielded pyrolysis residues designed to evaluate the evolution of TOC, solid bitumen aromaticity, and organic porosity development with increasing temperature and heating duration. Solid bitumen was analyzed by Raman spectroscopy wherein point data was collected from accumulations...
Research examining organic-matter hosted porosity has significantly increased during the last ten years due to greater focus on understanding hydrocarbon migration and storage in source-rock reservoirs, and technological advances in scanning electron microscopy (SEM) capabilities. The examination of nanometer-scale organic-matter hosted porosity by SEM requires the preparation of exceptionally flat geologic samples beyond the abilities of traditional mechanical polishing which can deform or otherwise obscure organic surfaces. To meet this demand, broad ion beam (BIB) milling was introduced as a sample preparation technique for SEM petrographic analysis of geologic samples. But like with any sample preparation technique,...
Categories: Data;
Tags: Colorado,
Energy Resources,
England,
Geochemistry,
USGS Science Data Catalog (SDC),
Recent production of light sweet oil from shallow (~2,000 ft) horizontal wells in the Upper Devonian Berea Sandstone of eastern Kentucky and historical oil production from conventional wells in the Berea of adjoining southern Ohio has prompted re-evaluation of Devonian petroleum systems in the central Appalachian Basin. Herein, we examined Upper Devonian Ohio Shale (lower Huron Member) and Middle Devonian Marcellus Shale organic-rich source rocks from eastern Ohio and nearby areas using organic petrography and geochemical analyses of solvent extracts. The data indicate the organic matter in the Ohio and Marcellus Shales was primarily derived from marine algae and its degradation products including bacterial biomass....
For sample mounting, organic petrology laboratories typically use cold-setting epoxy-resin (e.g., 40°C, used by Oklahoma Geological Survey, OGS) or heat-setting plastic (e.g., 180°C, used by U.S. Geological Survey, USGS). Previous workers have suggested a systematic vitrinite reflectance (VRo) increase was associated with the thermoplastic preparation process, relative to epoxy mounting, which was attributed to moisture loss from the transient high temperatures of plastic mounting. In this study, we evaluated thermal effects to low maturity organic matter from transient exposure to elevated temperatures. A subbituminous coal sample was subjected to long-term (4 to 38 weeks) exposure to temperatures of 85 to 120°C...
As part of a larger study, organic petrographic features of Leonardian Wolfcamp A repetitive siliceous and calcareous mudrock and fine-grained carbonate lithofacies cycles occurring in the R. Ricker #1 core from Reagan County, Midland Basin, Texas were evaluated. The objectives of the petrographic investigation were to estimate thermal maturity, identify organic matter types and abundances, and identify the presence or absence of migrated hydrocarbons. An integrated analytical program included geochemical screening [total organic carbon (TOC) content by LECO, programmed pyrolysis by HAWK, including from solvent-extracted samples], X-ray diffraction mineralogy, organic petrography, SEM-EDS including correlative light...
Categories: Data;
Tags: Energy Resources,
Organic petrography,
Reagan County,
Texas,
USGS Science Data Catalog (SDC),
The U.S. Geological Survey assessed undiscovered unconventional hydrocarbon resources reservoired in the Upper Cretaceous Tuscaloosa marine shale (TMS) of southern Mississippi and adjacent Louisiana in 2018. As part of the assessment, oil- source rock correlations were examined in the study area where operators produce light (38-45° API), sweet oil from horizontal, hydraulically-fractured wells in an overpressured ‘high-resistivity’ (>5 ohm-m) zone (HRZ) at the base of the TMS. Our initial characterization of TMS samples indicated overall low organic carbon (avg. TOC ~1.0%) and dominance of a gas-prone Type III or mixed Type II/III kerogen, potentially inconsistent with a self-sourced petroleum system model for...
Categories: Data;
Tags: Amite County,
Biomarkers,
East Feliciana County,
Energy Resources,
Franklin County,
Electron microprobe analyses of sphalerite (ZnS) and hemimorphite (Zn4Si2O7(OH)2·H2O) from sampled historical waste piles were conducted with a specific focus on germanium (Ge). In mine wastes at the Tar Creek Superfund Site, Oklahoma, USA, Ge is associated with ZnS (sphalerite) as expected, but weathering in the waste piles has led to a significant amount of Ge being incorporated into a zinc-silicate, hemimorphite. Data and methods reported are part of a research study published here: White, S.J.O., Piatak, N.M., McAleer, R.J., Hayes. S.M., Seal, R.R. II, Schaider, L.A., Shine, J.P. Germanium redistribution during weathering of Zn mine wastes: implications for environmental mobility and recovery of a critical...
Pollen morphology and pollen morphology in conjunction with other characteristics have elucidated the origin and evolution of various plant groups. Many studies of fossil pollen rarely discuss the effects of diagenesis and sample preparation on pollen characteristics. This paper examines the relationship of diagenesis, sample preparation (e.g., acetolysis), and staining techniques on the preservation and interpretation of pollen characteristics viewed with light, scanning and transmission electron microscopy. Based on empirical studies, different species under similar experimental conditions have different reflectance values, indicating the individual species respond differently to diagenetic events. The quantitative...
Categories: Data;
Tags: Energy Resources,
Geochemistry,
Louisiana,
South Africa,
USGS Science Data Catalog (SDC),
Oxidation state and bonding environment of Ge and Cu in ZnS and Zn mineral concentrates from a variety of sources [Central Tennessee mining district (TN), Metaline mining district, (WA), and Red Dog mine (AK)] were determined by linear combination fits from x-ray absorption spectroscopy (XAS) analysis. Sphalerites from the East Tennessee mining district contained Ge in concentrations that were too low to generate a X-ray absorption spectra with an edge step. When applicable, Ge content in quartz was determined using XAS edge steps. Data and methods reported are part of a research study published in the 'Related External Resources' section below.
This study describes the application of organic petrology techniques to quantify the amount of coal and carbonaceous combustion by-products (i.e., coke, coal tar/pitch, cenospheres) in sediments taken from the Kinnickinnic River adjacent to the former site of the Milwaukee Solvay Coke and Gas Company. The site produced metallurgical coke and coal-gasification by-products from 1902-1983 and was assessed in 2001 as a potential Superfund site in part due to high levels of polycyclic aromatic hydrocarbons (PAHs) which readily absorb to coal and combustion by-products.
The nanoscale molecular composition of kerogen is a challenging parameter to characterize given the chemical and structural complexity exhibited by this important biopolymer. However, kerogen composition will strongly impact its reactivity and so is a critical parameter to understand petroleum generation processes during kerogen catagenesis. The recent advent of tip-enhanced analytical methods, such as atomic force microscopy-based infrared spectroscopy (AFM-IR), has allowed for the major compositional features of kerogen to be elucidated at spatial resolutions at or below 50 nm. Here we apply AFM-IR to examine inertinite, an important kerogen maceral type, from an immature Eagle Ford Shale sample. Our data show...
Categories: Data;
Tags: Atomic force microscopy-based infrared spectroscopy (AFM-IR),
Energy Resources,
Geochemistry,
Organic matter,
Shale,
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