Paul Hackley is a Research Geologist with the USGS Geology, Energy & Minerals (GEM) Science Center in Reston, VA.
As project chief of the Thermal Indices project I pursue research on thermal maturity, chemical composition and physical state of sedimentary organic matter. The Thermal Indices project is part of the Geology, Energy & Minerals (GEM) Science Center and is funded by the Energy Resources Program (ERP). The Thermal Indices project team develops and applies petrographic methods for the reliable identification of different types of sedimentary organic matter, and measures and interprets the response of organic matter to thermal stress in natural environments and in laboratory-based heating experiments. Improved understanding of the thermal evolution of sedimentary organic matter enables more accurate assessment of petroleum source rock maturation, thereby decreasing uncertainty in the determination of thermal histories, the timing of petroleum generation and the placement of resource assessment spatial boundaries. This leads to the overall goal of improving estimates of undiscovered petroleum resources, which is a central mission of the ERP.
My work focuses on four integrated research task areas which have petrographic approaches to thermal indices as their common denominator: 1) standardization and reproducibility of measurement, 2) utilization of hydrous pyrolysis for (artificial) thermal conversion of sedimentary organic matter, 3) petrographic innovation areas for thermal indices and organic evolution, and 4) petrographic laboratory support.
Thermal indices research is accomplished from the Organic Petrology and Hydrous Pyrolysis laboratories in Reston. The laboratories include facilities for sample preparation, hydrous pyrolysis, optical and fluorescence microscopy, and infrared spectroscopy. The Thermal Indices project team works with external collaborators from global academic, government and industry groups. All thermal indices research efforts reach toward the goal of improving fossil fuel resource assessments by generating new understanding of the processes occurring during thermal evolution of sedimentary organic matter and its conversion to petroleum.
Professional Experience
Unconventional petroleum systems
Conventional oil and gas assessment
Coalbed methane
Coal
Application of organic petrology techniques to fossil fuel resource assessment
Education and Certifications
Ph.D., George Mason University
M.S., George Washington University
B.A., Shippensburg State University
Affiliations and Memberships*
The Society for Organic Petrology (TSOP)
International Committee for Coal and Organic Petrology (ICCP)
American Association of Petroleum Geologists (AAPG)
American Society for Testing and Materials (ASTM)
Geological Society of America (GSA)
Science and Products
Petrographic Thermal Indices Research
Photomicrograph Atlas
Vitrinite Reflectance Service
Thermal Indices Innovation
Hydrous Pyrolysis and Kerogen Conversion
Standardization of Petrographic Thermal Indices
Evaluation of pore-like features in sedimentary organic matter
Thermal evolution of graptolite and solid bitumen properties at high maturity under natural and artificial conditions
Reflectance measurements for eight samples submitted to the USGS Organic Petrology Laboratory in Reston
Strain induced molecular heterogeneity in ancient sedimentary organic matter mapped at nanoscales using optical photothermal infrared spectroscopy
Textural occurrence and organic porosity of solid bitumen in shales
Organic petrology of Cretaceous Mowry and Niobrara source-rock reservoirs, Powder River Basin, Wyoming, USA
Reflectance and spectral fluorescence data from the effect of diagenesis on the preservation of morphology and ultrastructural features of pollen
Maturation study of vitrinite in carbonaceous shales and coals
TOC, Reflectance and Raman Data from Eocene Green River Mahogany Zone
Solid bitumen and vitrinite reflectance suppression explored using hydrous pyrolysis of artificial source rock (2021)
Reflectance and confocal laser scanning fluorescence spectroscopy of bituminite in Kimmeridge Clay
Atomic Force Microscopy-based Infrared Spectroscopy Data within Immature Eagle Ford Shale at the Nanometer-scale
Mapping ancient sedimentary organic matter molecular structure at nanoscales using optical photothermal infrared spectroscopy
Relating systematic compositional variability to the textural occurrence of solid bitumen in shales
Maturation study of vitrinite in carbonaceous shales and coals: Insights from hydrous pyrolysis
Evaluating aromatization of solid bitumen generated in the presence and absence of water: Implications for solid bitumen reflectance as a thermal proxy
The effect of diagenesis and acetolysis on the preservation of morphology and ultrastructural features of pollen
Identification of thermal maturity-relevant organic matter in Shale Working Group Report 2021
Finalization of the Confocal Laser Scanning Microscopy (CLSM) working group
Molecular mechanisms of solid bitumen and vitrinite reflectance suppression explored using hydrous pyrolysis of artificial source rock
Characterization of bituminite in Kimmeridge Clay by confocal laser scanning and atomic force microscopy
The Confocal Laser Scanning Microscopy Working Group of the ICCP: Final report 2021
New insights into organic matter accumulation from high-resolution geochemical analysis of a black shale: Middle and Upper Devonian Horn River Group, Canada
Vitrinite reflectance analysis
Photomicrograph Atlas
A database of images related to the characterization of fossil fuel resources in the United States and the world.
Science and Products
- Science
Petrographic Thermal Indices Research
A petrographic thermal index is typically an organic matter indicator in sedimentary rocks that allows for estimations of burial temperature. Petrographic thermal indices include the commonly used proxy vitrinite reflectance as well as other approaches such as solid bitumen reflectance, fluorescence, micro-Raman, and micro-Fourier transform infrared (FTIR) spectroscopies. Measurements from these...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 is a maceral group that is derived from the remains of woody material from vascular plants and is composed of the thermally evolved products of lignin and cellulose. A maceral group is a set of organic matter types with similar properties and appearance. Vitrinite reflectance measures the percentage of incident light that is reflected from the surface of vitrinite as calibrated to a...Thermal Indices Innovation
Thermal indices innovation focuses on the utilization of correlative microscopy and spectroscopy techniques for innovative approaches to advance the understanding of thermal indices development. These techniques include correlative light and electron microscopy (CLEM), confocal laser scanning microscopy (CLSM), and atomic force microscopy and infrared microscopy (AFM-IR), among others. Use of...Hydrous Pyrolysis and Kerogen Conversion
Hydrous pyrolysis (HP) experimentation is a laboratory method used to thermally mature organic-rich sedimentary rocks. It simulates petroleum generation in the closest available analogue to that of a natural system. Artificial maturation of sedimentary organic matter (SOM) to petroleum allows for the examination of its molecular chemistry to address the issue of anomalous reflection measurement...Standardization of Petrographic Thermal Indices
Advent of the shale revolution since about 2005 caused increased demand for reliable petrographic measurements of thermal maturity in shale via vitrinite reflectance, which has long been considered the gold standard approach. The first standardized methodology for vitrinite reflectance measurement in shale became available in 2011. Subsequent interlaboratory studies demonstrated that significant... - Data
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Evaluation of pore-like features in sedimentary organic matter
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 flaThermal evolution of graptolite and solid bitumen properties at high maturity under natural and artificial conditions
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 theReflectance measurements for eight samples submitted to the USGS Organic Petrology Laboratory in Reston
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 3Strain induced molecular heterogeneity in ancient sedimentary organic matter mapped at nanoscales using optical photothermal infrared spectroscopy
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 resultTextural occurrence and organic porosity of solid bitumen in shales
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. %] NewOrganic petrology of Cretaceous Mowry and Niobrara source-rock reservoirs, Powder River Basin, Wyoming, USA
Imaging of Niobrara Formation and Mowry Shale samples from a range of thermal maturities provided observations and data on pore systems, organic matter (OM) types and associations with mineralogy and fabric, wettability, and microporosity associated with both diagenetic and detrital clays. Imaging techniques included scanning electron microscopy, organic petrography and correlative scanning electrReflectance and spectral fluorescence data from the effect of diagenesis on the preservation of morphology and ultrastructural features of pollen
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 preservatMaturation study of vitrinite in carbonaceous shales and coals
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 inTOC, Reflectance and Raman Data from Eocene Green River Mahogany Zone
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. percent total organic carbon, TOC) mudrock sampleSolid 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 thermalReflectance and confocal laser scanning fluorescence spectroscopy of bituminite in Kimmeridge Clay
This work investigates the characterization of bituminite (amorphous sedimentary organic matter) in Kimmeridge Clay source rock via confocal laser canning microscopy (CLSM) and atomic force microscopy (AFM). As part of an International Committee for Coal and Organic Petrology working group, an immature (0.42% vitrinite reflectance), organic-rich (44.1 wt.% total organic carbon content) sample of KAtomic Force Microscopy-based Infrared Spectroscopy Data within Immature Eagle Ford Shale at the Nanometer-scale
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, su - Publications
Filter Total Items: 131
Mapping ancient sedimentary organic matter molecular structure at nanoscales using optical photothermal infrared spectroscopy
Elucidating the molecular structure of sedimentary organic matter (SOM) is key to understanding petroleum generation processes, as well as ancient sedimentary environments. SOM structure is primarily controlled by biogenic source material (e.g., marine vs. terrigenous), depositional conditions, and subsurface thermal history. Additional factors, e.g., strain, may also impact the molecular structurAuthorsAaron M. Jubb, Martha (Rebecca) Stokes, Ryan J. McAleer, Paul C. Hackley, Eoghan Dillion, Jing QuRelating systematic compositional variability to the textural occurrence of solid bitumen in shales
This study presents Raman spectroscopic data paired with scanning electron microscopy (SEM) images to assess solid bitumen composition 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 sampleAuthorsMartha (Rebecca) Stokes, Brett J. Valentine, Aaron M. Jubb, Paul C. HackleyMaturation study of vitrinite in carbonaceous shales and coals: Insights from hydrous pyrolysis
The presence of vitrinite in sedimentary rocks of post-Silurian age allows its reflectance to be used to estimate the thermal maturation of organic matter in petroleum systems. Increasing reflectance of vitrinite, which is primarily driven by aromaticity, depends primarily on the time and temperature attributes of its evolutionary pathway. This study evaluated carbonaceous shales proximal to coalAuthorsDivya K. Mishra, Paul C. Hackley, Aaron M. Jubb, Margaret M. Sanders, Shailesh Agrawal, Atul K. VarmaEvaluating aromatization of solid bitumen generated in the presence and absence of water: Implications for solid bitumen reflectance as a thermal proxy
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 hydrogen from water, organic-rich (22 wt% total organic carbon, TOC) mudrock samples from the Eocene lacAuthorsPaul C. Hackley, Aaron M. Jubb, Patrick L. Smith, Ryan J. McAleer, Brett J. Valentine, Javin J. Hatcherian, Palma J. Botterell, Justin E. BirdwellThe effect of diagenesis and acetolysis on the preservation of morphology and ultrastructural features of pollen
Pollen morphology on its own and in conjunction with other characteristics has elucidated the origin and evolution of various plant groups. Previous studies of fossil pollen rarely discuss the effects of diagenesis and sample preparation on pollen characteristics, i.e., variability in staining, pollen morphology, and pollen wall ultrastructural characteristics. This paper examines the effect of acAuthorsMichael Zavada, Paul C. HackleyIdentification of thermal maturity-relevant organic matter in Shale Working Group Report 2021
The Identification of Thermal Maturity-Relevant Organic Matter in Shale Working Group of the ICCP was established in 2008 to provide guidelines for identifying and measuring the reflectance of the population of dispersed organic matter that is relevant to thermal maturity determination. Information products published by the working group include ASTM D7708 Standard Test Method for Microscopical DeAuthorsPaul C. Hackley, Javin J. Hatcherian, Jennifer L. Rivera, Margaret M. Sanders, Brett J. ValentineFinalization of the Confocal Laser Scanning Microscopy (CLSM) working group
A working group in Commission II to investigate applications of confocal laser scanning microscopy (CLSM) for organic petrology investigations has finalized with publication of the manuscript “Characterization of bituminite in Kimmeridge Clay by confocal laser scanning and atomic force microscopy” in the International Journal of Coal Geology. The manuscript is available via Open Access from https:AuthorsPaul C. Hackley, Jolanta KusMolecular mechanisms of solid bitumen and vitrinite reflectance suppression explored using hydrous pyrolysis of artificial source rock
The most commonly used parameter for thermal maturity calibration in basin modelling is mean random vitrinite reflectance (Ro). However, Ro suppression has been noted in samples containing a high proportion of liptinite macerals. This phenomenon has been demonstrated empirically using hydrous pyrolysis of artificial source rock containing various proportions of thermally immature Wyodak-Anderson cAuthorsMargaret M. Sanders, Aaron M. Jubb, Paul C. Hackley, Kenneth E. PetersCharacterization of bituminite in Kimmeridge Clay by confocal laser scanning and atomic force microscopy
This work investigates bituminite (amorphous sedimentary organic matter) in Upper Jurassic Kimmeridge Clay source rock via confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM). These petrographic tools were used to provide better understanding of the nature of bituminite, which has been historically difficult to identify and differentiate from similar organic matter types inAuthorsPaul C. Hackley, Jolanta Kus, João Graciano Mendonça Filho, Andrew D. Czaja, Angeles G. Borrego, Dragana Životić, Brett J. Valentine, Javin J. HatcherianThe Confocal Laser Scanning Microscopy Working Group of the ICCP: Final report 2021
This report summarizes the activities and results of the Confocal Laser Scanning Microscopy (CLSM) working group (WG) of the International Committee for Coal and Organic Petrology (ICCP), from its inception in September, 2015, to the present day (September, 2021). The purpose of this report is to document the history of the working group and to compile and evaluate its results. The CLSM WG examineAuthorsPaul C. Hackley, Jolanta Kus, João Graciano Mendonça Filho, Andrew D. Czaja, Angeles Borrego, Dragana ŽivotićNew insights into organic matter accumulation from high-resolution geochemical analysis of a black shale: Middle and Upper Devonian Horn River Group, Canada
Organic matter (OM) accumulation in organic matter-rich mudstones, or black shales, is generally recognized to be controlled by combinations of bioproductivity, preservation, and dilution. However, specific triggers of OM deposition in these formations are commonly difficult to identify with geochemical proxies, in part because of feedbacks that cause geochemical proxies for these controls to varyAuthorsHaolin Zhou, Nicholas B. Harris, Tian Dong, Korhan Ayranci, Jilu Feng, Benoit Rivard, Paul C. Hackley, Javin J. HatcherianVitrinite reflectance analysis
Vitrinite is a maceral group (a set of organic matter types with similar properties and appearance) derived from the remains of woody material from vascular plants and is composed of the thermally evolved products of lignin and cellulose. Vitrinite is the dominant component of humic coal and is found as a minor component dispersed into sedimentary rocks, especially mudrocks, the primary source rocAuthorsPaul C. Hackley - Web Tools
Photomicrograph Atlas
A database of images related to the characterization of fossil fuel resources in the United States and the world.
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government