This study investigates the role of zooclasts in the bulk organic matter composition, kerogen type, and hydrocarbon generation potential of the lower Paleozoic marine Alum shale in Baltoscandia, northwestern Europe. The results show that graptolite periderm is composed of non-granular cuticles and granular filling. The graptolite cuticle is non-fluorescing and has a well-polishing measurable surface

Inaccuracies in spatial modelling of coal properties can impact coal resource and reserve estimates. Geostatistical methods which account for compositional data have previously been recommended as a preferred method for modelling of coal properties. These methods can quantify uncertainty, can use auxiliary information to improve estimates, and ensure that compositional data (such as coal proximate

As one of the elements having significant affinity for organic matter in low-rank coals, aluminum (Al) can form strong complexes with organic matter. Measurable concentration of Al has been detected in ‘clean’ macerals of coal, especially vitrinite. This raises interesting questions on the modes of occurrence of Al in coal and the specific way of Al associated with organic matter. In this study, the

In recent 30 years, Th/U ratio has been using widely in evaluating the paleoredox conditions during the depositions of source rocks. However, there are few studies on the preconditions of the use of Th/U ratio for evaluating the paleoredox conditions. In many areas, the evaluation results of redox conditions in paleoenvironment obtained by Th/U ratio is different from that reflected by other parameters

Raman spectroscopy on carbonaceous matter reconstructs the progressive path of graphitization during granulite facies metamorphism in the Variscan collisional belt of the southern Bohemian Massif. In this area, heating to 650–750 °C gradually altered the graphite microstructure, attributed to a metamorphic field gradient. Late low-pressure and high-temperature metamorphism at temperatures above 800 °C

Microorganisms in coal bed can potentially convert coal to natural gas. A number of methods, including nutrient injection and microbial introduction, have been used to enhance coalbed methane (CBM) production. However, the recalcitrant composition and hydrophobic character of coal greatly limit its bioavailability, thus limiting the coal-to-methane conversion efficiency. Ubiquitous iron-bearing clay

The molecular composition of petroliferous organic matter and its compositional evolution throughout thermal maturation provides insight for understanding petroleum generation. This information is critical for understanding hydrocarbon resources in unconventional reservoirs, as source rock organic matter is highly dispersed, in contact with the surrounding mineral matrix, and may occur as multiple

Hydrous pyrolysis (HP) to simulate the maturation of organic matter (OM) and a variety of organic geochemical analyses and petrographic analyses of OM were performed to establish the origin and depositional environment in the Serpukhovian (Mississippian) and Pennsylvanian coals and carbonaceous shales from the Upper Silesian and Lublin coal basins. OM of coals and shales is dominated by vitrinite-

Gaiteiros-1 borehole, located in the central Lusitanian Basin (Portugal), drilled a continuous Jurassic (Hettangian to Kimmeridgian) sedimentary sequence. Forty-one samples were selected for this study to characterize the dispersed organic matter and its vertical variation along Gaiteiros-1 borehole and to evaluate the environmental changes based on palynofacies and bulk geochemistry analyses. Gaiteiros-1

The response of inertinite-rich Witbank coals (South Africa) to rapid heating was evaluated using petrography, selected Nuclear Magnetic Resonance (NMR) and X-Ray Diffraction (XRD) structural parameters. A total of thirteen (13) coal samples were collected from the No. 2 Seam; a set of six (6) samples from the western and the eastern sides of a ~ 0.4 m thick dolerite dyke emplaced into the coal seam

This study focuses on ascertaining controlling factors and differences on mineralogical and elemental contents for reconstructing palaeoenvironmental conditions of both seams applying standard coal characteristics, mineralogical, coal-petrologic, and elemental data of the Orhaneli coalfield. The studied coalfield, one of the important coalfields in NW Turkey, includes two workable coal seams, the lower

Determination of the geochemical and mineralogical characteristics of coal can provide useful information on the geological setting and evolution of coal basins and assist in identifying factors that control the distribution of the minerals and elements of interest. The Late Permian coals of southwestern China have received much attention because some of these coals are usually considered to be potential

Atomic force microscopy (AFM) has been widely used in materials science and chemistry research since it was invented in the 1980s. It is a relatively new tool for geosciences and is very powerful for micro- and nano-scale surface characterization with a resolution down to atomic scale. One of the major advantages of this microscopy technique is that it can perform continuous non-destructive measurements

Nanoindentation is a valuable tool, which enables insights into the material properties of natural, highly inhomogeneous composite materials such as shales and organic matter-rich rocks. However, the inherent complexity of these rocks and its constituents complicates the extraction of representative material parameters such as the reduced elastic modulus (Er) and hardness (H) for organic matter (OM)

At a symposium honoring the 50th anniversary of the University of Chicago, Gilbert Cady introduced the concept of phyterals as a means of distinguishing the actual plant fossils from the macerals composed of the fossils. In this sense, vitrinite and fusinite, while distinct macerals, are viewed as the same phyteral. In contrast to such process-induced contrast in macerals vs. phyterals, funginite,

Accessibility of pore space in unconventional reservoirs is an important factor influencing both methane storage capacity and the kinetics of methane desorption. The determination of open (accessible) versus closed (inaccessible) porosity is therefore vital for the prediction of gas production potential. This study investigates accessibility of pores to methane in overmature middle Devonian Marcellus

Predictions of the Hardgrove grindability index, a predictor of the crushing and pulverization propensity of coal, have been made using both regression and neural network techniques. All techniques suffer from shortcomings. In general, input parameters must be selected based on a sound knowledge of coal chemistry and petrology, with avoidance of redundant parameters, avoidance of closure in the data

We present an NMR measurement technique which has the unique ability to determine the in-situ adsorbed gas concentration within coal seams. The measurement of adsorbed gas content is of critical importance for operational safety and commercial resource evaluation in the development of coal mining operations and coal seam gas (CSG) resources. The current measurement technique involves laboratory core

This study evaluates the organofacies and petroleum generation potential of kerogen of Early Cretaceous Wealden Shales in the Lower Saxony Basin, Germany. Methods applied include open-system-and Curie-point-pyrolysis, attenuated total reflectance infrared spectroscopy, x-ray diffraction and x-ray fluorescence spectroscopy. The geochemical results give a comprehensive elemental characterization of the

Lacustrine black shales are widely developed within the Late Cretaceous Nenjiang Formation (k2n) of the Songliao Basin. These black shales provide an ideal natural laboratory for reconstructing the paleoclimate and paleoenvironment during the Late Cretaceous in Northeast China and have great significance in the exploration for potential oil and gas resources. According to the systematic analysis of

Hydrochemical data responds at a much slower rate to changes in groundwater conditions than does the propagation of hydraulic pressure, and therefore may provide more insight to groundwater flow paths. In low rank coal measures, where gas is biogenic, it is important to understand the fluid-rock and microbial interactions that affect the spatial and temporal distribution of groundwater composition

The contrast in the textures of high reflectance vitrinite and liptinite in the Ragged edge exposures of western Kentucky's Herrin (No. 11) coal versus the macerals in regionally metamorphosed anthracites opens a window into the metamorphic mechanisms prevailing for both of the Ragged edge and regionally metamorphosed coals. Regionally (Barrovian) metamorphosed anthracite, at least in the cases noted

A realistic three-dimensional (3D) kerogen molecular model adds significant values in petrographical evaluation in shale, especially it is essential to conduct molecular simulation for gas storage and transport behaviors in shale. In this study, the 3D kerogen molecular structure of Marcellus shale was reconstructed based on molecular simulation, and eight experimental techniques, including 13C nuclear

Large volumes of peatland deposits characterise the Holocene stratigraphy of the Po Plain. A combination of sedimentological and pollen-based paleoenvironmental analyses enables recognition and stratigraphic correlation of small-scale (2–5 m thick) packages of peat-bearing strata, stacked rhythmically in a retrogradational to progradational set and bounded by chronostratigraphically significant surfaces

Due to the low coalification degree of lignite, the colloid-like properties and loose characteristics lead to low energy utilization efficiency and seriously hinder the correct understanding of the original pore structure and its mechanical behavior. As a standard process for physical property test, removing the moisture in the pores by drying will cause the lignite to shrink sharply, destroying its

The overmature Precambrian to Lower Paleozoic marine shales from China contain relatively simple organic matter (OM) composition, which is dominated by in-source solid bitumen (i.e., solid bitumen in the hydrocarbon source rocks). The thermal evolution behavior of the original OM and the determination of thermal maturity in the Precambrian to Cambrian marine shales have been challenging for decades

The Thrace Basin hosts the second-largest natural gas and oil resource of Turkey. Several mineable late Oligocene coal seams are located close to natural gas fields in the basin. This study focuses on the assessment of late Oligocene seams in the Malkara coal field using mineralogical, petrographic, and Rock-Eval pyrolysis data. The variations in coal properties seem to be mainly controlled by common

More than 100 m-long core sections from Western Lithuania (Baltic Basin), presenting an almost continuous lower Silurian fine-grained siliciclastic organic matter-rich sedimentary record from Aeronian to Homerian, were investigated to evaluate the main forces governing the organic matter enrichment. The methods applied include organic and inorganic geochemistry, organic petrology, sedimentological

The development of pore and fracture networks at the nano-scale as a response to heating can reveal coupled physical relationships relevant to several energy applications. A combination of time-lapse 3D imaging and finite-element modelling (FEM) was performed on two typical thermally immature shale samples, Kimmeridge Clay and Akrabou shale, to investigate thermal response at the nm-scale for the first

The mineral and rare earth element distributions of Tunçbilek coal, Turkey were studied and their potential to be a source for REY was investigated. The studied samples were taken from the BYJ, BYL, 48P open-pit mine panels and Ömerler and İğdekuzu underground mines. In order to observe the mineral and REE element distributions along the coal seam profile, samples were taken by using channel sampling

Permeability of coal is highly dependent on the effective stress, which is found to decrease exponentially as effective stress increases. To study coal permeability at in-situ conditions, high pressure X-ray micro-CT imaging is performed. However, fractures are highly compressed at in-situ conditions, some of fracture apertures are below the resolution of images, which cannot be segmented properly

Thick Pleistocene fine-grained rocks in the central Qaidam Basin, China, are regarded as the principal source rocks for microbial gas there. Here, for the first time, a detailed investigation on the organic geochemistry and petrology of this sedimentary sequence is presented. Two different, immature, lacustrine source rocks facies are present in the study area. Organic facies A samples with high TOC

Thermal metamorphism of original coal adjacent to burning centers in coal waste heaps is a common phenomenon, and semi-coke and coke are formed during this process. In this study, changes taking place during the pyrolysis of both organic and inorganic constituents of coal in burning heaps are interpreted, and the volatility of major and trace elements is assessed. Experimental pyrolysis of bituminous

An integrated approach based on organic petrographic and geochemical proxies along with palynological and palynofacies analysis were employed using 24 rock samples representing the upper part of the Quse and Sewa formations in the southern Qiangtang Basin, Tibetan Plateau, SW China. This interval was deposited during the Early Jurassic Toarcian Oceanic Anoxic Event (T-OAE) and is investigated to assess

A suite of 72 samples of Illinois Basin coal was collected from 2015 to 2018, from 14 active coal mining and preparation operations in Illinois and Indiana. The goals of the study were to investigate the behavior of trace elements during coal preparation and provide current coal quality data for active mining operations in the Illinois Basin, which has become one of the most important suppliers of

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 misidentification

A change from a humid to an arid climate occurred during the Middle Jurassic. Information about this transitional phase is stored in two oil shales: the lower and upper units of the shale member of the Shimengou Formation (J2s) in the northern Qaidam Basin (NQB), Northwest China. The drastic changes in lithofacies are also reflected in the organic and inorganic inventory of the two oil shales, and

Methanotrophic bacteria (MB) are an important group of microorganisms, involved in the greenhouse gas (GHG) cycles. They are responsible for the utilization of methane, one of the main GHGs, which is released in large amounts (via biogenic and abiogenic processes) during coal formation. This study aimed to determine the main factors affecting the distribution of the MB in two lignite-bearing series

Reservoir properties of coal seams such as gas and water effective permeabilities and gas content, as well as spatial distributions thereof, affect the success of gas production and CO2-enhanced gas recovery (EGR) with simultaneous CO2 sequestration. These properties change during production and injection operations due to variations in reservoir pressure, matrix shrinkage/swelling, and water saturation

Coal mine gas originates from the gas emission zone (GEZ) of the mine, as well as the longwall face and pillars. Gas emissions are controlled directly at the sources using horizontal or vertical boreholes drilled from surface or from the entries in advance of mining, or it is captured from the fractured and caved zones (gob) using ventholes during mining. The rest of the gas, especially that gas that

This review examines new techniques and applications of organic petrography in source-rock reservoir petroleum systems that have occurred along with development of the global ‘shale revolution’ in energy resources. The review is limited to techniques and instrumentation that provide spatially resolved information, typically at or below microscales, for dispersed organic matter occurring in situ in

The impact of natural intra-deposit heating on the δ13C signature, organic geochemistry, and petrology of coal and coal-bearing rocks characterised by various degrees of coalification and palaeoenvironments in the Upper Silesian Coal Basin, Poland, is elaborated. Reconstruction of palaeofire performed by heating experiments up to 400 °C in open and semi-closed systems with different heating regimes

Middle Permian coal from the Yongan Coalfield, Fujian Province, China, with a maximum vitrinite reflectance (VRmax) of 5.33%–8.95%, indicating a typical meta-anthracite stage, enables the study of differential graphitization of macerals. The composition and optical properties of macerals were analyzed using optical (under non-polarized light, polarized light with gypsum test plate (1λ), and cross-polarized

In-source solid bitumen was found in some cracks within the calcareous concretion in an overmature (Rbitumen > 3.5%) black shale of the Lower Cambrian Niutitang Formation from Songtao, Guizhou, China. The solid bitumen (grain size >2 cm) concentrated in source rock, which was formed by the transformation of petroleum-like substances that have not been expelled from source rock. This provides a substitute

This paper describes a viable nanoindentation-enhanced technique for screening hydraulic fracturing fluid additives via quantifying the effects of rock-fluid interactions on the mechanical properties of a clay-rich shale. Big data nanoindentation testing was conducted on both the intact shale and counterparts hydrothermally treated by four fracturing fluids, including water, KCl solution, and two surfactants

The Surat Basin, which is a major eastern Australian Coal Seam Gas (CSG) reservoir, produces gas from its Middle to Late Jurassic sub-bituminous Walloon Coal Measures, and shows variability in initial reservoir permeability across the basin. For a given lithostatic stress, the presence of vitrinite group or telovitrinite macerals within the coal can influence the fracture abundance within the coal

This paper investigates the hyper-enrichments of molybdenum (Mo), uranium (U), and vanadium (V) in the lower Paleozoic, Alum Shale of Denmark, Sweden, Norway, and Estonia. Molybdenum and U are mainly associated with organic matter and the highest contents are found in the Furongian part of the Alum Shale. This Furongian hyper-enrichment of Mo and U commenced with the Steptoean Positive Carbon Isotope

The well log inversion has been widely applied to forecast coal texture distribution due to its effectiveness and low investment. However, most research missed the low resolution of well logging data caused by the “boundary effect”, which make it difficult to identify thin layers. Here a method to improve the vertical resolution of logging curves by Wavelet Transform was applied. The original logging

Hydraulic fracturing is an effective approach to improve the productivity of coalbed methane (CBM) reservoirs. However, during hydraulic fracturing and CBM production, massive coal fines are deposited on the surface of proppants, leading to a sharp reduction in fracture conductivity. Herein, the detachment of deposited coal fines, caused by single-phase water flow in proppant packs, was investigated

Measuring the degree of organic matter (OM) alteration caused by uranium (U) irradiation is important in the effective evaluation of the hydrocarbon potential and thermal maturity of U-rich source rocks. This study investigates OM alteration in the Baltoscandian U-rich, lower Paleozoic Alum shale obtained from three research wells in the thermally immature parts of eastern Sweden and western Estonia

The sedimentary succession of 51-m consisting of a thin coal seam (1 m) and oil shale with a marlstone and carbonate-mudstone matrix of the Lower Carboniferous (Viséan) Emma Fiord Formation located on the Grinnell Peninsula, Devon Island, Arctic Canada was examined. The techniques used include reflected light microscopy, and instrumental neutron activation analysis (INAA) for elemental concentration