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Filters: partyWithName: Paul C Hackley (X) > partyWithName: Geology, Energy & Minerals Science Center (X) > partyWithName: Aaron M Jubb (X)

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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%...
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...
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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...
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High-resolution scanning electron microscopy (SEM) visualization of sedimentary organic matter (SOM) is widely utilized in the geosciences for evaluation of microscale rock properties relevant to depositional environment, diagenesis, and the processes of fluid generation, transport, and storage. However, despite thousands of studies which have incorporated SEM approaches, the inability of SEM to differentiate SOM types has hampered the pace of scientific advancement. In this study, we show that SEM-cathodoluminescence (CL) properties can be used to identify and characterize SOM at low thermal maturity conditions. Eleven varied mudstone samples with a broad array of SOM types, ranging from the Paleoproterozoic to...
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...
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Solid bitumen is a petrographically-defined secondary organic matter residue produced during petroleum generation and subsequent oil transformation. The presence of solid bitumen impacts many shale reservoir properties including porosity, permeability, and hydrocarbon generation and storage, amongst others. Furthermore, solid bitumen reflectance is an important parameter for assessing the thermal maturity of formations with little to no vitrinite. While the molecular composition of solid bitumen will strongly impact associated parameters such as the development of organic matter porosity, hydrocarbon generation, and optical reflectance, assessing the molecular composition of solid bitumen in situ within shale reservoirs...
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The most commonly used parameter for thermal maturity calibration in basin modelling is mean random vitrinite reflectance (Ro). However, Ro suppression, or lower than expected Ro, has been noted in samples containing a high proportion of liptinite macerals. This has been empirically demonstrated using hydrous pyrolysis experiments of artificial source rock containing various proportions of thermally immature Wyodak-Anderson coal and liptinite-rich kerogen from the Parachute Creek Member of the Green River Formation. Analysis of samples pyrolyzed at 330°C for 72 h demonstrates that the Ro values of both vitrinite and solid bitumen are suppressed, where the degree of suppression increases with increasing amounts of...
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Here we report ultra-high resolution infrared mapping of organic matter functional group distribution in Tasmanites (algal microfossils) from the Upper Devonian Ohio Shale using optical photothermal infrared spectroscopy (O-PTIR). O-PTIR is capable of rapidly measuring the vibrational response of samples in situ with ~500-nm spatial resolution, well below the infrared diffraction limit. Our results indicate that organic matter within the fold apices regions (zones of greatest deformation) of relatively large Tasmanites is more aliphatic and less oxygen-rich than organic matter in the surrounding Tasmanites body. This contrasts with data from relatively thinner Tasmanites which show statistically invariant chemical...
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The molecular composition of petroliferous organic matter and its composition evolution throughout thermal advance are key to understanding and insight into petroleum generation. This information is critical for comprehending hydrocarbon resources in unconventional reservoirs, as source rock organic matter is highly dispersed, in contact with the surrounding mineral matrix, and may be present as multiple organic matter types. Here, a combination of Raman spectroscopy and optical microscopy approaches was applied to a marginally mature (vitrinite reflectance ~0.5%) sample of the Late Cretaceous Boquillas Shale before and after hydrous pyrolysis (HP) at 300 °C and 330 °C for 72 hours. This experimental design allowed...
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This study evaluated carbonaceous shales proximal to coal measures and coal samples via isothermal hydrous pyrolysis (HP) to compare differences in the maturation pathways of vitrinite in different matrices and with different starting aromaticity. Sample residues were analysed via vitrinite reflectance (VRo), geochemical screening tests (organic carbon and programmed temperature pyrolysis), and infrared spectroscopy. The study included samples from Indian and North American basins, to observe differences in vitrinite evolution with respect to enclosing mineral matrix, starting degree of aromaticity, organic matter types, stratigraphic age, and depositional environment. Tmax, production index (PI), and VRo show intuitive...
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To refine the use of graptolite and solid bitumen properties as thermal proxies at overmature conditions, we evaluated their evolution via Raman and infrared spectroscopies, reflectance, and geochemical screening in high-temperature hydrous and anhydrous experiments in comparison to naturally matured samples. Naturally matured samples included four overmature Wufeng-Longmaxi marine shales from the Sichuan Basin, China, with solid bitumen reflectance (BRo) values of 2.5-3.6% and graptolite reflectance (GRo) values of 2.3-3.9%. Immature starting materials for pyrolysis experiments included Mesoproterozoic (Ectasian) Xiamaling marine shale from Hebei, China (0.34% BRo, graptolite absent) and graptolite-bearing Ordovician...


    map background search result map search result map Investigating the effects of broad ion beam milling to sedimentary organic matter Nanoscale Molecular Composition of Solid Bitumen from the Eagle Ford Group Across a Natural Thermal Maturity Gradient Atomic Force Microscopy-based Infrared Spectroscopy Data within Immature Eagle Ford Shale at the Nanometer-scale Reflectance, Raman band separation and Mean multivariant curve resolution (MCR) in organic matter in Boquillas Shale Solid bitumen and vitrinite reflectance suppression explored using hydrous pyrolysis of artificial source rock (2021) TOC, Reflectance and Raman Data from Eocene Green River Mahogany zone Textural occurrence and organic porosity of solid bitumen in shales Strain induced molecular heterogeneity in ancient sedimentary organic matter mapped at nanoscales using optical photothermal infrared spectroscopy Thermal evolution of graptolite and solid bitumen properties at high maturity under natural and artificial conditions SEM-CL investigation of sedimentary organic matter samples Reflectance, Raman band separation and Mean multivariant curve resolution (MCR) in organic matter in Boquillas Shale Solid bitumen and vitrinite reflectance suppression explored using hydrous pyrolysis of artificial source rock (2021) TOC, Reflectance and Raman Data from Eocene Green River Mahogany zone Textural occurrence and organic porosity of solid bitumen in shales Atomic Force Microscopy-based Infrared Spectroscopy Data within Immature Eagle Ford Shale at the Nanometer-scale Investigating the effects of broad ion beam milling to sedimentary organic matter Thermal evolution of graptolite and solid bitumen properties at high maturity under natural and artificial conditions SEM-CL investigation of sedimentary organic matter samples