This work is directed at understanding the kinetics of vitrinite and solid bitumen maturation through hydrous pyrolysis experiments, potentially enabling a direct methodology to detect ‘vitrinite reflectance suppression,’ a commonly reported problem in the early- to mid-oil window. This task also examines the molecular chemistry of kerogen conversion to petroleum via in situ chemical probing by micro-Fourier transform infrared spectroscopy (micro-FTIR) and other chemical probes during thermal maturity advance. These goals are achieved by using natural and artificial maturation sequences of organic-rich shale and mudrock. Results have shown that the kinetics of solid bitumen maturation are slower than vitrinite, potentially explaining the commonly reported ‘vitrinite reflectance suppression’ effect as simple misidentification of solid bitumen as vitrinite. The significance of this work was recognized with bestowment of the 2018 Ralph Gray Award for Best Refereed Paper in Coal and Organic Petrology from The Society of Organic Petrology.
Objectives:
- Characterize the in situ chemical transformation of kerogen conversionsedimentary organic matter to hydrocarbons petroleum via micro-spectroscopy approaches, i.e., micro-FTIR and micro-Raman, among others
Below are other science projects associated with this project task.
Photomicrograph Atlas
Vitrinite Reflectance Service
Thermal Indices Innovation
Standardization of Petrographic Measurements
Solid bitumen and vitrinite reflectance suppression explored using hydrous pyrolysis of artificial source rock (2021)
Petroleum geology data from hydrous and anhydrous pyrolysis residues for coals and shales from the Cambrian through the Miocene
Below are publications associated with this project task.
Relating Tmax and hydrogen index to vitrinite and solid bitumen reflectance in hydrous pyrolysis residues: Comparisons to natural thermal indices
Experimental study on the impact of thermal maturity on shale microstructures using hydrous pyrolysis
Application of Raman spectroscopy as thermal maturity probe in shale petroleum systems: Insights from natural and artificial maturation series
Suppression of vitrinite reflectance by bitumen generated from liptinite during hydrous pyrolysis of artificial source rock
Understanding and distinguishing reflectance measurements of solid bitumen and vitrinite using hydrous pyrolysis: Implications to petroleum assessment
Analysis of artificially matured shales with confocal laser scanning raman microscopy: Applications to organic matter characterization
Nanoscale geochemical and geomechanical characterization of dispersed organic matter in shale by infrared nanoscopy
Organic petrology and micro-spectroscopy of Tasmanites microfossils: Applications to kerogen transformations in the early oil window
Utilization of integrated correlative light and electron microscopy (iCLEM) for imaging sedimentary organic matter
- Overview
This work is directed at understanding the kinetics of vitrinite and solid bitumen maturation through hydrous pyrolysis experiments, potentially enabling a direct methodology to detect ‘vitrinite reflectance suppression,’ a commonly reported problem in the early- to mid-oil window. This task also examines the molecular chemistry of kerogen conversion to petroleum via in situ chemical probing by micro-Fourier transform infrared spectroscopy (micro-FTIR) and other chemical probes during thermal maturity advance. These goals are achieved by using natural and artificial maturation sequences of organic-rich shale and mudrock. Results have shown that the kinetics of solid bitumen maturation are slower than vitrinite, potentially explaining the commonly reported ‘vitrinite reflectance suppression’ effect as simple misidentification of solid bitumen as vitrinite. The significance of this work was recognized with bestowment of the 2018 Ralph Gray Award for Best Refereed Paper in Coal and Organic Petrology from The Society of Organic Petrology.
Objectives:
- Characterize the in situ chemical transformation of kerogen conversionsedimentary organic matter to hydrocarbons petroleum via micro-spectroscopy approaches, i.e., micro-FTIR and micro-Raman, among others
- Science
Below are other science projects associated with this project task.
Photomicrograph Atlas
The Photomicrograph Atlas provides a basic tutorial in the nomenclature of organic materials as they occur in sedimentary rocks such as coal and shale, information on the taxonomies used by various groups and organizations, and a database of images related to the characterization of fossil fuel resources in the United States and the world.Vitrinite Reflectance Service
Vitrinite reflectance is regarded as the gold standard thermal maturity parameter and vitrinite reflectance data is needed for energy resource assessment and other types of basin analysis studies. This effort provides vitrinite reflectance and qualitative organic petrography of shale, mudrock, coal and other unconventional reservoir samples as a routine in-house service, from the Organic Petrology...Thermal Indices Innovation
Thermal indices innovation utilizes correlative microscopy techniques for innovative approaches to thermal indices development, including confocal laser scanning microscopy (CLSM), AFM-IR (combined atomic force and infrared microscopy), atomic force microscopy (AFM), and SEM of Argon ion-milled sample surfaces combined with traditional organic petrography. The innovation task also is testing...Standardization of Petrographic Measurements
Advent of the ‘shale revolution’ since about 2005 has caused increased demand for reliable petrographic measurements of thermal maturity in shale via vitrinite reflectance, long considered the ‘gold standard’ approach. A standardized methodology for organic reflectance measurement in shale first became available in 2011 (ASTM D7708), based on prior work by task members. However, interlaboratory... - Data
Solid bitumen and vitrinite reflectance suppression explored using hydrous pyrolysis of artificial source rock (2021)
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 thermalPetroleum geology data from hydrous and anhydrous pyrolysis residues for coals and shales from the Cambrian through the Miocene
This data release contains programmed pyrolysis, organic petrographic (reflectance), and semiquantitative X-ray diffraction mineralogy data for subsurface coal and shale samples from around the world. Samples were subjected to hydrous or anhydrous pyrolysis experiments at varying temperatures and the resulting residues were analyzed via programmed pyrolysis and reflectance to document changes in t - Publications
Below are publications associated with this project task.
Relating Tmax and hydrogen index to vitrinite and solid bitumen reflectance in hydrous pyrolysis residues: Comparisons to natural thermal indices
Vitrinite reflectance (VRo; %) generally is considered the most reliable technique to determine the thermal maturity of sedimentary rocks. However, it is a time-consuming process to collect reflectance (Ro; %) measurements and is subjective to the interpretation of each trained technician, who must be able to discern between vitrinite and solid bitumen and other organic matter types. Inadvertent mExperimental study on the impact of thermal maturity on shale microstructures using hydrous pyrolysis
Hydrous pyrolysis was applied to four low-maturity aliquots from the Utica, Excello, Monterey, and Niobrara Shale Formations in North America to create artificial maturation sequences, which could be used to study the impact of maturation on geochemical and microstructural properties. Modified Rock-Eval pyrolysis, reflectance, organic petrology, and Fourier transform infrared spectroscopy (FTIR) wApplication of Raman spectroscopy as thermal maturity probe in shale petroleum systems: Insights from natural and artificial maturation series
Raman spectroscopy was studied as a thermal maturity probe in a series of Upper Devonian Ohio Shale samples from the Appalachian Basin spanning from immature to dry gas conditions. Raman spectroscopy also was applied to samples spanning a similar thermal range created from 72-h hydrous pyrolysis (HP) experiments of the Ohio Shale at temperatures from 300 to 360 °C and isothermal HP experiments lasSuppression of vitrinite reflectance by bitumen generated from liptinite during hydrous pyrolysis of artificial source rock
Mean random vitrinite reflectance (Ro) is the most widely accepted method to determine thermal maturity of coal and other sedimentary rocks. However, oil-immersion Ro of polished rock or kerogen samples is commonly lower than Ro values measured in samples from adjacent vitrinite-rich coals that have undergone the same level of thermal stress. So-called suppressed Ro values have also been observedUnderstanding and distinguishing reflectance measurements of solid bitumen and vitrinite using hydrous pyrolysis: Implications to petroleum assessment
Solid bitumen is a common organic component of thermally mature shales and typically is identified by embayment against euhedral mineral terminations and by groundmass textures. However, because these textures are not always present, solid bitumen can be easily misidentified as vitrinite. Hydrous-pyrolysis experiments (72 hr, 300°C–360°C) on shale and coal samples show that solid-bitumen reflectanAnalysis of artificially matured shales with confocal laser scanning raman microscopy: Applications to organic matter characterization
Raman spectroscopy has been suggested as a method for characterizing the thermal maturity of rocks. The literature contains many empirical correlations between thermal maturity proxies, such as vitrinite reflectance (VRo) and pyrolysis-Tmax, with spectral metrics such as Raman peak-widths, peak-center positions, peak-areas and all manner of differences and ratios of these parameters. However, whilNanoscale geochemical and geomechanical characterization of dispersed organic matter in shale by infrared nanoscopy
Solid organic matter (OM) plays an essential role in the generation, migration, storage, and production of hydrocarbons from economically important shale rock formations. Electron microscopy images have documented spatial heterogeneity in the porosity of OM at nanoscale, and bulk spectroscopy measurements have documented large variation in the chemical composition of OM during petroleum generationOrganic petrology and micro-spectroscopy of Tasmanites microfossils: Applications to kerogen transformations in the early oil window
The transformation of kerogen to hydrocarbons in the early stages of oil generation is critical for understanding the resource potential of liquid-rich shale plays. Organic petrology commonly is used for visual evaluation of type, quality, and thermal maturity of organic matter, but the relationship of visual petrographic changes to chemical transformations is not well characterized. To improve unUtilization of integrated correlative light and electron microscopy (iCLEM) for imaging sedimentary organic matter
We report here a new microscopic technique for imaging and identifying sedimentary organic matter in geologic materials that combines inverted fluorescence microscopy with scanning electron microscopy and allows for sequential imaging of the same region of interest without transferring the sample between instruments. This integrated correlative light and electron microscopy technique is demonstrat