Detection of Organic-Rich Oil Shales of the Green River Formation, Utah, with Ground-Based Imaging Spectroscopy

Oil shales contain abundant immature organic matter and are a potential unconventional petroleum resource. Prior studies have used visible/shortwave infrared imaging spectroscopy to map surface exposures of deposits from satellite and airborne platforms and image cores in the laboratory. Here, we work at an intermediate, outcrop-scale, testing the ability of field-based imaging spectroscopy to identify oil shale strata and characterize the depositional environments that led to enrichment of organic matter in sedimentary rocks within the Green River Formation, Utah, USA. The oil shale layers as well as carbonates, phyllosilicates, gypsum, hydrated silica, and ferric oxides are identified in discrete lithologic units and successfully mapped in the images, showing a transition from siliciclastic to carbonate- and organic-rich rocks consistent with previous stratigraphic studies conducted with geological fieldwork

Geologic characterization of Utah oil shale deposits

presentationWhy Geology? Economic prospectivity of oil shale development in the Uinta Basin relies heavily on establishing a solid geologic framework. Understanding lake evolution matters

Core-based integrated sedimentologic, stratigraphic, and geochemical analysis of the oil shale bearing Green River Formation, Uinta Basin, Utah

reportAn integrated detailed sedimentologic, stratigraphic, and geochemical study of Utah's Green River Formation has found that Lake Uinta evolved in three phases 1) a freshwater rising lake phase below the Mahogany zone, 2) an anoxic deep lake phase above the base of the Mahogany zone and 3) a hypersaline lake phase within the middle and upper R-8. This long term lake evolution was driven by tectonic basin development and the balance of sediment and water fill with the neighboring basins, as postulated by models developed from the Greater Green River Basin by Carroll and Bohacs (1999). Early Eocene abrupt global-warming events may have had significant control on deposition through the amount of sediment production and deposition rates, such that lean zones below the Mahogany zone record hyperthermal events and rich zones record periods between hyperthermals. This type of climatic control on short-term and long-term lake evolution and deposition has been previously overlooked. This geologic history contains key points relevant to oil shale development and engineering design including: 1) Stratigraphic changes in oil shale quality and composition are systematic and can be related to spatial and temporal changes in the depositional environment and basin dynamics. 2) The inorganic mineral matrix of oil shale units changes significantly from clay mineral/dolomite dominated to calcite above the base of the Mahogany zone. This variation may result in significant differences in pyrolysis products and geomechanical properties relevant to development and should be incorporated into engineering experiments. 3) This study includes a region in the Uinta Basin that would be highly prospective for application of in-situ production techniques. Stratigraphic targets for in-situ recovery techniques should extend above and below the Mahogany zone and include the upper R-6 and lower R-8

A sedimentologic, stratigraphic, and geochemical study of the late Paleozoic ice age, Eastern Australia

This study is a sedimentologic, stratigraphic, and geochemical analysis of the glacial record from eastern Australia, which lay at high latitudes during the late Paleozoic. Its goal is to constrain the exact timing, duration, and nature of late Paleozoic climate change. Because the understanding of glacial processes and products has changed since prior evaluation, Carboniferous and Permian units in eastern Australia were re-examined, and glacial facies were diagnosed using modern lithologic criteria. The ages of stratigraphic units were constrained using biostratigraphic and radiogenic isotopic age data. A plot of the temporal and spatial framework of glacially-influenced units in eastern Australia defines eight discrete glacial episodes (C1-C4 and P1-P4), ranging in duration from 1-8.8 m.y., which are separated from each other by periods of non-glacial deposition. The pattern of alternating glacial and non-glacial intervals demonstrates that late Paleozoic glaciation in eastern Australia was resticted to several, discrete intervals of shorter duration and climate was more dynamic than concluded by previous models. Detailed sedimentologic documentation and facies analysis of Carboniferous deposits from New South Wales, Australia, such as the Spion Kop, Rocky Creek and Johnsons Creek Conglomerate and the Currabubula and Seaham Formation, demonstrate proglacial glaciofluvial and glaciolacustrine sedimentation but also documents nonglacial sediments. Age constraints on these sediments suggest that glacial advance and retreat occurred on less than 1 to 5.5 m.y. timescales. The short-term climatic fluctuations evident in Carboniferous glacial deposits may reflect orbital controls on sedimentation at high latitudes. Bulk organic carbon stable isotopic analysis was performed on organic matter-rich facies from Permian glacial and non-glacial deposits across eastern Australia in order to construct a δ13Corg curve and compare resulting isotopic shifts with the stratigraphic record of glaciation from the region. Results indicate a relationship between positive and negative δ13Corg shifts and the onset and termination of glacial episodes P2-P4 in eastern Australia, respectively. Therefore, δ13Corg shifts are interpreted to record global changes in atmospheric pCO2 and climate. This study confirms (1) pCO2 was strongly coupled with climate during the Permian, and (2) bulk organic carbon isotopic records constructed from a mixed terrestrial and marine organic matter source can be a useful climate proxy

Integrated sedimentary and geochemical investigation of core form the upper Green River Formation lacustrine deposits, Uinta Basin, Utah

presentationDescription of the upper Green River Formation has been largely based on outcrop exposures, but this core-based investigation provides newly detailed subsurface data that can be used to examine basin-wide lithologic and geochemical variability of he Parachute Creek Member of the upper Green River Formation in the Uinta Basin, Utah

Integrated Sedimentary and Geochemical Investigation of Core from Upper Green River Formation Lacustrine Deposits, Uinta Basin, Utah

presentationDescription of the upper Green River Formation has been largely based on outcrop exposures, but this core-based investigation provides new detailed subsurface data that can be used to examine basin-wide lithologic and geochemical variability of the Parachute Creek Member of the upper Green River Formation in the Uinta Basin, Utah. Such an understanding is integral to potential oil shale development in the region. The 1200-foot EX-1 core captures a complete view of the richest oil shale interval (middle R-4 to middle R-8) neat the depo-center of the basin. Because the vast majority of the succession is fine-grained, stratigraphic geochemical characterization has proven key to accurate description and facies delineation within the formation. Qualitative, whole rock X-ray fluorescence (XRF) was performed in order to define intervals as dominantly siliciclastic, calcareous, or dolomitic. This technique is non-destructive, relatively quick, and adequately defines relative elemental abundances in core. The XRF data highlight a major statigraphic geochemical boundary; beds below the Mahogany oil shale zone are dominantly dolomitic, where as beds above are calcareous rich, matching a transition from fluvial-lacustrine to fluctuating profundal lithofacies. Stratigraphic bulk organic carbon isotopic analysis provide an independent proxy of organic matter source and paleoenvironmental changes through the succession. This integrated investigation has let to the delineation of ten informal lithostratigraphic units recording three successive phases of lake development in the Uinta Basin, as originally defined by Carroll and Bohacs (1999) from the Green River Basin in Wyoming: 1) fluvial-lacustrine litofacies (overfilled basin), 2) fluctuating profundal litofacies (balanced-filled basin), and 3) evaporative lithofacies (underfilled basin). Each of the three lithofacies contains internal stratigraphic changes in lithology, sedimentary structures, and fossil type and occurrence. These changes document both abrupt and gradational paleoenvironmental changes at a more detailed scale within each lithofacies and are interpreted in a preliminary sequence statigraphic framework

Skyline 16 Stratigraphic Column

Well log of Skyline 16

Core-Based Integrated Sedimentologic, Stratigraphic, and Geochemical Analysis of the Oil Shale Bearing Green River Formation, Uinta Basin, Utah

An integrated detailed sedimentologic, stratigraphic, and geochemical study of Utah's Green River Formation has found that Lake Uinta evolved in three phases (1) a freshwater rising lake phase below the Mahogany zone, (2) an anoxic deep lake phase above the base of the Mahogany zone and (3) a hypersaline lake phase within the middle and upper R-8. This long term lake evolution was driven by tectonic basin development and the balance of sediment and water fill with the neighboring basins, as postulated by models developed from the Greater Green River Basin by Carroll and Bohacs (1999). Early Eocene abrupt global-warming events may have had significant control on deposition through the amount of sediment production and deposition rates, such that lean zones below the Mahogany zone record hyperthermal events and rich zones record periods between hyperthermals. This type of climatic control on short-term and long-term lake evolution and deposition has been previously overlooked. This geologic history contains key points relevant to oil shale development and engineering design including: (1) Stratigraphic changes in oil shale quality and composition are systematic and can be related to spatial and temporal changes in the depositional environment and basin dynamics. (2) The inorganic mineral matrix of oil shale units changes significantly from clay mineral/dolomite dominated to calcite above the base of the Mahogany zone. This variation may result in significant differences in pyrolysis products and geomechanical properties relevant to development and should be incorporated into engineering experiments. (3) This study includes a region in the Uinta Basin that would be highly prospective for application of in-situ production techniques. Stratigraphic targets for in-situ recovery techniques should extend above and below the Mahogany zone and include the upper R-6 and lower R-8

Coupled carbon isotopic and sedimentological records from the Permian system of eastern Australia reveal the response of atmospheric carbon dioxide to glacial growth and decay during the late Paleozoic Ice Age

Proxy geochemical records from high-latitude, ice-proximal deposits have the potential to provide key insights into past icehouse climates, but such records are rare. The Permian System of eastern Australia contains a rich record of environmental and climatic changes that occurred in areas proximal to glaciation during the acme and waning stages of the late Paleozoic ice age. Within this succession, a wealth of fine-grained, organic matter-rich facies provides an opportunity to construct a bulk δ13Corg record that records changes in atmospheric CO2 through the Permian. Fluctuations in δ13Corg track changes in climate determined independently on the basis of sedimentological criteria in the same strata. These patterns are also broadly consistent with multiple proxy records derived from paleoequatorial sites. The results of this geochemical investigation 1) support recent studies using the high-latitude, ice-proximal, sedimentologic and stratigraphic record and paleoequatorial geochemical proxies that document highly variable climatic conditions within the overall Permian icehouse-to-greenhouse transition, and 2) confirms that the sedimentary record of glaciation from eastern Australia reflects global changes in atmospheric CO2 on several m.y.-order timescales