Is the signature of the original plant communities preserved in coal, or is that signature overprinted by depositional and diagenetic processes? To address this question, Pennsylvanian coals from the Illinois and Appalachian basins were compared to Cretaceous, Paleocene, and Eocene coals of comparable coalification levels as shown by vitrinite reflectance. Three reflectance intervals—0.52–0.55, 0.58–0

This paper introduces the development of a new predictive model in support of proppant injection in naturally fractured coal seam gas (CSG) reservoirs. In the proposed model, the finite element method (FEM) is used for the prediction of proppant embedment and elastoplastic deformation of the coal. The lattice Boltzmann method (LBM) is applied to the modelling of fluid flow through propped fractures

Results are presented on the relationships between the vitrinite reflectance VRo, the Tmax temperatures determined with Rock-Eval pyrolysis, and the smectite (S) indices representing the percentage of smectite in the mixed-layer illite-smectite (I/S) from claystones. Samples locations are recovered from the Polish part of the Outer Carpathian fold-and-thrust belt. Organic indices show thermal maturities

Samples for inclusion analysis were collected to investigate reasons for carbon isotope rollover in the Yan'an gas field (YAGF). Homogenization temperature of fluid inclusions, constituents and carbon isotope of gases in fluid inclusions were measured. Geochemical parameters of gas in wells and fluid inclusions in the northern gas fields (NGF) and YAGF were compared. The results show that geochemical

Water sorption provides a great approach to understand water-shale interaction. In this research, water sorption isotherms of fourteen Wufeng-Longmaxi shale samples collected from the eastern Sichuan Basin of China were generated and then interpreted by classical sorption models. The sorption behavior of water and its relationship with pore structure, organic/inorganic composition, and temperature

Synthetic coal ash bearing 560 ppm europium oxide, blended with aluminum phosphate, was heat treated above its melting temperature and crystal evolutions with respect to europium concentration under controlled cooling were studied. The sample in a boat crucible was subjected to a temperature gradient of 100 °C across it to cause zone refining effects on crystallization behaviors in the melt (slag)

The study of coals affected by magmatic intrusions is important from a geological point of view, in order to understand how heat and magmatic fluids could affect the organic and inorganic fractions as well as the properties of the coals. These fluids may lead to an enrichment of trace elements and heavy metals of environmental concern or serve as unconventional sources of critical elements. Therefore

The Cretaceous Hue Shale is a condensed mudstone section of the Brookian sequence with type II and type III kerogen, and it is one of the major source rocks that fill the world-class conventional oil fields on the North Slope, Alaska. The bottom section of the Hue Shale is referred to as Gamma Ray Zone (GRZ) or Highly Radioactive Zone (HRZ) and believed to be the most organic-rich section. The thermal

Amorphous organic matter (AOM or bituminite) is a major oil-prone liptinite maceral in black shales that can be classified into two main types: low-reflectance AOM and micrinized AOM. In this study, we investigated the petrographic and chemical structure characteristics of these two types of AOM and discussed their origin based on 15 marine black shale samples from the Illinois Basin, including 5 samples

Coal mining in China is continually increasing, and the associated emitted coal mine dust is of growing environmental and occupational concern. In this study, deposited coal mine dust (DD) was analysed in three different regions of an active, highly-volatile bituminous open-pit coal mine in the Xingjian Province, Northwest of China: coal working fronts, tailings handling sites, and road traffic sites

The coal-hosted Ge deposit (Early Cretaceous) at Wulantuga, Inner Mongolia, northern China, is one of the largest Ge deposits in the world. Although the origin, modes of occurrence, and spatial distribution of Ge in this deposit have been investigated by several studies, the provenance and pathways of Ge from the source to the deposit are largely unknown. In this study, we investigated the 87Sr/86Sr

Occasionally, distinctive plant fragment (PF)-concentrated sandstone beds are found in the turbiditic sequence of the Miocene Kawabata Formation (Yubari, central Hokkaido, Japan) deposited in a foredeep basin. Sedimentological and organic geochemical analyses were carried out on the PF-concentrated sandstone bed to investigate the transport and depositional processes of the abundant PFs in the basin

Airfall volcanic ash deposited in the form of tuff layers is widely distributed in oil-shale bearing basins in western Liaoning Province, northeast China. In order to investigate the impacts of volcanic ash on algal productivity and the formation of organic-rich oil shales, the organic petrology and organic geochemistry of lacustrine sediments of the Lower Cretaceous Jiufotang Formation were investigated

An essential but missing component in our understanding of microbial interactions leading to coal bed methane (CBM) formation lies in the relationship between coal and coal-adhering microorganisms. Here, we explored the influence of surface physico-chemistry on the microbial cell attachment on coal, utilising a known coal-oxidising bacterium P. fluorescens Pf-5 as a model. Based on the interfacial

Raman spectroscopy has been applied in numerous sedimentary formations to infer thermal maturity of mostly Type-II kerogen in organic-rich mudrocks. Robust correlations have been established between the Raman spectroscopic signal and vitrinite reflectance equivalents (%VRE) of the organic matter. Herein, traditional evaluation methods, organic petrography and geochemistry, were applied in addition

Upper Jurassic Naokelekan Formation, being part of the intercepted strata of the well-known Miran oilfield in Kurdistan region of Northern Iraq, has been previously extensively evaluated as a potential/effective source rock, mainly by means of organic geochemistry. In the present study, a total of 60 samples were collected from four Naokelekan Fm. outcrops, those of Banik, Galy-Derash, Barsarin and

Lacustrine oil shale is an important unconventional energy source in China. Previous exploration has mainly focused on stable deep lake deposits, whereas lacustrine oil shale layers in unstable sedimentary settings, which are widely distributed in Cretaceous strata, having received little research attention. The present paper is focused on the Aptian Jiufotang Formation in the Beipiao Basin. In order

A suite of six naturally graphitized coals were separated by density-gradient centrifugation (DGC). The density profiles of anthracite and meta-anthracite samples show an average density increase from 1.50 g/mL to 1.93 g/mL with increased rank. Components of partially graphitized coals were separated into two distinct density peaks: a low-density peak at ~1.82 g/mL, and a high-density peak at ~2.0 g/mL;

A comprehensive geochemical and petrographic study was performed on 23 clay-rich shale samples collected from 18 wells drilled in the western part of the Ordos Basin to investigate the characteristics and thermal maturity of organic matter as well as the paleo-depositional environment of the Chang 7 Member within the Triassic Yanchang Formation. The samples are characterized by moderate to very high

Mining-induced microseismicity is widely considered as a result of slippage of pre-existing critically stressed fractures caused by stress perturbations around an advancing face. An in-depth analysis of the recorded microseismicity associated with longwall top coal caving mining at Coal Mine Velenje in Slovenia has been previously carried out and reported by the authors. It has been concluded that

Gas and water geochemistry in the No.2 coal reservoir of the Yanchuannan CBM block in the southeastern Ordos basin reflects a complex interaction of tectonic, hydrodynamic, thermogenic, and biogenic processes. Stable isotope and component analyses of gas and water samples from the No. 2 coal seam of 17 CBM wells were performed to determine the correlations between stable isotopes of gases and co-produced

The stable isotopic (δ34S, δ18O, δ2H) composition of mine waters has been examined from coal and metal mines, of varying depth, in Spain (Asturias), the UK (north Derbyshire/Yorkshire) and Poland (Bytom, Upper Silesia). δ18O and δ2H data confirm a meteoric origin for all waters. The mine waters have elevated sulphate concentrations relative to recent meteorically-derived groundwaters and have elevated

Three Miocene-age coal seams - a lower seam (kM2, subbituminous), a middle seam (kM3, subbituminous), and an upper seam (kP1, lignite) - in the Kınık coalfield, located in the southwesternmost part of the Soma Basin in western Turkey, and factors controlling mesoporosity and microporosity characteristics, were investigated using low-pressure N2 and CO2 adsorption techniques, respectively. In addition

Globally, there is significant economic interest in shale gas as a hydrocarbon resource. The success of unconventional shale gas exploration in the United State of America (USA) has raised interests for potential shale gas development in the Karoo Basin of South Africa. The Karoo Basin technically recoverable shale gas resource is estimated to be 13 Tcf, with 19–23 Tcf recoverable free gas. Due to

The Changling Sag in the petroliferous Songliao Basin has produced large amounts of conventional petroleum, but studies on unconventional resources are rare. A suite of core samples from the CY-1 well, drilled in the eastern Changling Sag, was analysed employing a series of micropetrographic, geochemical, and pyrolysis techniques to reveal the shale oil potential of the lower (K2qn1) and middle (K2qn2)

Pyrolysis and bulk kinetic studies were used to investigate the hydrocarbon generation potential and source rock organofacies variability of marine organic-rich rocks from the Middle Ordovician (Darriwilian) Goldwyer Formation in the Canning Basin, Western Australia. Rock-Eval pyrolysis results for the analysed immature to mid-mature calcareous mudstones imply that the upper Goldwyer Sequence I contains

This study aims to better understand the evolution of the organic matter (OM) ultrafine structure (designating the nanoscopic structure of the OM/macerals) and porosity with increasing thermal maturity of mudstones source-rocks. To this end, the particulate fractions of kerogen from organic-rich Kimmeridge clay mudstones were isolated by acidic treatment before and after laboratory thermal maturation

Rare earth elements (REE) are critically important in clean energy technologies, but their mining and refining is energy intensive and generates significant quantities of environmentally harmful waste. The treatment of acid mine drainage (AMD), which is both a global environmental problem and a potential source of these elements, preconcentrates REE and critical metals such as manganese and cobalt

Biological methane production from coal seams through their biological conversion is one of the methods that have been postulated to utilize unmineable resources. Furthermore, energy production from methane is considered less environmentally-harmful than the combustion of coal. In the current study, meta-bituminous coal extracted from the Upper Silesian Coal Basin (USCB) was investigated in terms of

The objective of this study was to evaluate rare earth elements and yttrium (REY) concentrations in Pennsylvanian coal-bearing strata in the eastern part of the Illinois Basin (Indiana), specifically targeting coals and marine shales associated with the coals. Samples were collected from several coal mines and three boreholes. In total, 105 samples were analyzed using inductively coupled plasma - optical

The control of depositional conditions on sedimentary records spanning the Ordovician Wufeng–Silurian Longmaxi successions on the Yangtze Platform is not fully understood due to a lack of high-resolution faices analysis. This study aims to build a regional depositional model of this stratigraphic interval, to reveal the fundamental controls on the mineral assemblage and organic matter (OM) accumulation

Significant knowledge has been assembled on the marine Longmaxi Shale in the Sichuan Basin over the past ten years. However, the distribution of shale gas resources on the periphery of the Sichuan Basin and in other source rock formations are still not sufficiently understood. To improve our understanding on the depositional environment and thermal maturity, and their relevance to the source rock quality

The nanoscale molecular composition of sedimentary organic matter is challenging to characterize in situ given the limited tools available that can adequately interrogate its complex chemical structure. This is a particularly relevant issue in source rocks, as kerogen composition will strongly impact its reactivity and so is critical to understanding petroleum generation processes during catagenesis

An in-depth understanding of the carbon dioxide (CO2) sorption behavior on coal is critical for CO2 sequestration in coal seams and enhanced coalbed methane recovery. However, CO2 induces the deformation of coal through physical and/or chemical reactions during the CO2 injection process, which has a significant effect on the gas flow and stability of the coal seams. This study investigates the isotherms

The Miocene Soma Coal Basin may be one of the most promising areas for low-rank coalbed methane in Turkey. So far, the coalbed methane potential of the coal seams in the Kınık Coalfield, Soma Basin has not been adequately studied. A systematic investigation was performed on the gas content distribution of the kP1 and kM2 coal seams and its geological controls, which has been based on the geological

Surface relaxivity (ρ) is an intrinsic rock property that makes low-field NMR a valuable tool for determining pore size distribution of geological formations. Its value can vary considerably in different rocks depending on the type and distribution of the rock minerals, rock surface wettability and petrophysical properties. Therefore, laboratory measurement of ρ is required on a case by case basis

The abnormal enrichment of the REY (rare earth elements and yttrium)-Zr (Hf)-Nb (Ta) assemblage in Late Permian coals occurring in some coalfields in SW China has been extensively investigated, but the geological controlling factors of this assemblage are still under debate. This study reports on the mineralogical and geochemical features of coals and noncoal rocks collected from the Yudai and Jinqi

This study presents results of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) elemental analysis of scattered dolomite crystals in the Upper Ordovician Utica Shale of southern Québec to investigate the geochemical cause(s) of color variation in dolomite fluorescence and its possible relationship to thermal maturity. Utica Shale dolomite crystals show fluorescence zonation under

The Herrin coal (Western Kentucky No. 11) “ragged edge” is composed of peculiar organic materials, including voids, which defy conventional maceral classification. These materials seem to have originated from natural pyrolysis caused by hot fluids migrating through low-rank coal. However, the observed petrographic patterns and the reflectance analysis were not enough to confirm this hypothesis. In

Calcium phosphate apatite, Ca5 (PO4)3(OH,F,Cl), is a common accessory mineral in coal seams. Although minor, its role in hosting phosphorus (P) and fluorine (F) can reduce the economic viability of coking and thermal coal deposits. Apatite in coal is commonly <50 μm and may have several modes of occurrence. The modes of occurrence investigated as part of this study include apatite infilling small (i

The Cenomanian—Turonian boundary is marked by worldwide paleoenvironmental and paleoceanographical changes that are associated with a perturbation of the global carbon cycle and black shale deposition, called the Oceanic Anoxic Event 2 (OAE2). The objective of this study is to precisely characterize the nature of the organic matter, its variability, paleoenvironmental significance and the preservation

The Jurassic terrestrial shale on the northern margin of Qaidam Basin is characterized by high contents of organic matter but low maturity resulting in a lack of further research on shale gas in this area. To better understanding the shale gas potential of organic matter with different types, we conducted thermal maturity experiment of hydrocarbon generation from different kerogen types of low-mature

The Permian period had the most oxygen-rich atmosphere in Earth's history. With the presence of large amounts of fuel from vegetation, there was therefore a high probability of igniting fires during this time. This study presents the geochemical characterization of charcoal-bearing Asselian sediments, represented by terrestrial to lagoonal facies, collected from the Quitéria and Curva do Belvedere

The late Cretaceous Naparima Hill Formation in the South Trinidad Basin (southeast Caribbean) is a prolific source rock with a potential for unconventional hydrocarbon exploration. It is exposed across the Central Range and extends to the city of San Fernando. This study characterized the Naparima Hill source rock using petrographic analysis techniques (X-ray diffraction and thin section analysis)

The Middle Pennsylvanian Herrin and Springfield coals contain the majority of the Illinois basin’s resources. Many mining issues of these two seams are directly related to the geology of the region, including regional stress, faulting, and facies changes. Some of these conditions are widespread, while others are locally restricted. The long history of mining in these seams has been associated with

Canister desorption of freshly drilled coal cores is routinely employed for exploratory assessments of coalbed gas. Coals are molecular sieves containing both open and closed pores. However, little attention has been paid to the differences between the carbon isotopic compositions of CH4 and C2H6 from open and closed pores in coal and their influence on isotopic fractionation during desorption. In

Assessment of thermal maturity by solid bitumen reflectance measurements in vitrinite-lean or vitrinite-barren shales is widely used in unconventional shale gas and shale oil plays but the method is commonly challenged by the complexity in the measurements. The Upper Jurassic marine Vaca Muerta shale in the Neuquén Basin in western Argentina is both a prolific conventional source rock and a primary

Reinhardt Thiessen introduced a thin-section-based, botanically oriented method of coal petrology to North America in 1920. The nomenclature derived from this system, although eventually reconciled with and largely superseded by the European reflected-light techniques and nomenclature, persisted for decades after Thiessen's death in 1938. The research by Thiessen and his colleagues at the U.S. Bureau

The accurate determination of mechanical parameters (namely, Young's modulus and hardness) of shale-constitutive minerals is crucial for predicting the macroscale mechanical parameters of shale composites. This study employed an advanced nanoindentation apparatus equipped with a high-resolution microscope (4000×) and a newly emerging nano-dynamic mechanical analysis (nano-DMA) module to conduct mineral-positioned

The Toarcian Oceanic Anoxic Event (TOAE) is characterised by a perturbation of the global carbon cycle and the widespread deposition of organic matter (OM)-rich strata/sediments in the northern areas of the West Tethys Shelf, in several northern European epicontinental basins. Contrariwise, in the southern areas of the West Tethys Shelf such as western and southern Iberian, and northern Gondwana margins

Activation energy distribution from kerogen kinetics study contains some integral characteristics of the host source rock thermal history over geological time scales. Extracting relevant information from pyrogram is critical for reconstruction of source rock maturation and hydrocarbon generation histories. In this study, in order to improve understanding of the Bakken shale source rock, we present

Tremendous amount of gas can be adsorbed in shale nanopores as a result of the high surface-to-volume ratio, and capillary condensation might occur in mesopores (2–50 nm) for subcritical gases, leading to sorption hysteresis. However, the sorption (adsorption and desorption) behavior in different pore systems in shale is not very well understood. Herein we use a D3Q19 lattice Boltzmann model (LBM)

Six solid bitumen samples from Paja Formation (Cretaceous of Colombia) were optically, chemically and structurally characterized using bulk chemistry, reflectance indicating surface (RIS), micro-Raman and X-ray diffraction (XRD) parameters. The volatile matter and carbon contents and high random reflectance (Ro%) placed these solid bitumens in the category of cata-impsonites according to Jacob's classification