The chemistry of rare earth elements (REE) and selected critical elements was examined in the high volatile A bituminous Pond Creek coal in Pike County, Kentucky. The Pond Creek coal has been one of the most important coal resources in eastern Kentucky but, up to now, no modern methods, such as Inductively coupled plasma – mass spectroscopy (ICP-MS) have been applied to the characterization of the

Shale diagenesis controls the generation, migration and accumulation of hydrocarbons through time and has become a frontier area of study in the fields of sedimentology and petroleum geology. There have been only a few studies on the generation of organic pores in lacustrine shale oil reservoirs during the oil generation thermal evolution stage. In this study, lacustrine organic-rich shale samples

To extract hydrocarbons from unconventional shale systems, it is necessary to assess oil retention and accumulation. This study presents experimental findings on oil retention, migration, and accumulation in a lacustrine shale system from the Chang 7 member of the Upper Triassic Yanchang Formation, Ordos Basin. 68 core samples were collected from the target layer to investigate the migration behavior

Inertinite in coals contains important information regarding the palaeo-wildfire history and can provide insights into its triggers and relationship with the evolution of local ecosystems. However, such information in the Middle Jurassic coal is often overlooked, and the impacts of incidental mercury emission from wildfires on the mercury enrichment in coal are also underestimation. In this study,

Unlike the free biomarkers, which can be routinely recovered via solvent extraction, the bound biomarkers are covalently linked to the kerogen or asphaltene macrostructures and are more resistant to secondary alteration processes. Although similarities have been identified between these two types of biomarkers using different techniques, it remains unclear how the kerogen- and asphaltene-bound biomarkers

The variations of mechanical properties of coals in nano-to-micro scale play vital roles in defining the coal deformative and failure behaviors with a wide range of engineering applications, including coal stimulation for gas recovery and/or CO2 sequestration in coal seams. Based on the assumption that the heterogeneity in the mechanical properties of coals is combinedly determined by the mineralogical/carbon

Thermal maturation is traditionally evaluated based on vitrinite reflectance (VRo) measurements and its relationship to oil and gas generation and diagenetic transformation are ingrained in many basin modeling tools. However, vitrinite derives from higher land plants that evolved in Devonian. In pre-Devonian rocks graptolite reflectance (GR) is the most significant thermal index for establishing thermal

This paper presents the first attempt to develop the facies model of the entire coal deposit belonging to the Carboniferous productive sequence located in the western part of the Upper Silesian Coal Basin. To achieve this objective, six seams from the Knurów deposit were examined. The deposit belongs to the largest producer of coking coal in Europe, which is Jastrzębska Spółka Węglowa SA (Polish state-run

Sorption time is a key parameter for calculating the gas mass exchange between the matrix and the fracture system of coal, and which is generally defined as the time taken for coals to desorbed 63.2% of the total adsorbed CH4. It's usually measured through CH4 isothermal adsorption-desorption experiments with coal particles or blocks. However, the conventional method has many problems in determining

Longwall coal mines in the Bowen Basin of Australia are highly productive and gassy, comprising many coal seams above the working seam. Predictive modelling of specific gas emission (SGE) using the conventional Winter model developed in Germany or other European based models often results in significant discrepancies from reality. To improve methane emission prediction and management, significant efforts

Some important progress has been made in coalbed gas (CBG) exploration in the Kuqa-Bay coalfield in the northern Tarim Basin, where a demonstration base of CBG development and utilization has been established in the Tieliekedong (TD) region. Currently, there has been no detailed study of the formation mechanism of the CBG in the TD region, which has restricted the next phase of the CBG exploration

Lamina, a common lithologic unit in shale, is the smallest unit for organic–inorganic fluid–rock interactions. The effects of lamina-scale diagenetic processes are superimposed to exert on lithofacies-scale diagenetic sequences, which further impose on the entire diagenetic system of a shale reservoir. Organic acids from kerogen maturation are indispensable components in diagenetic reaction. However

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 sample

The local and/or global environmental effects on the organic matter (OM) enrichment in ancient sediments has long received extensive attention. The Upper Cretaceous Nenjiang lacustrine shale (K2n) is one of the most essential hydrocarbon source rocks in NE China with massive OM deposition across the Santonian–Campanian boundary interval, which can be correlated with the terminal stage of the last oceanic

The ratio of aromatic to aliphatic (AR/AL) hydrocarbons was used to investigate migration pathways in tight unconventional reservoirs. Analytical methods, including organic petrography and geochemistry, programmed pyrolysis, solid bitumen reflectance, and liptinite autofluorescence, were employed to generate regional thermal maturity maps. While AR/AL ratios are known to increase with thermal maturity

The present study aims to illustrate the paradigms of saturated and aromatic biomarker distributions in the lithotypes of Lower Gondwana bituminous coals (R̄r = 0.50–0.68%), perhaps for the first time. The coal samples were collected from the Early Permian Barakar Formation of the Rajmahal Basin, India. These coals mostly comprise three lithotypes, i.e., vitrain, durain, and fusain. The durain shows

Prospecting for trace and rare earth elements will only increase in the coming decades as the world expands into sustainable energy and the use of digital technology. A key component of finding these resources is understanding how they are distributed, mobilized and emplaced. The coal beds in Shanxi Province in China have already been identified as a resource with elevated trace elements, especially

Although shale heterogeneity has recently emerged as a key topic in unconventional petroleum systems, hydrocarbon (HC) retention and pore evolution in organic-rich shales still remain poorly constrained. In this study, an organic-rich Eagle Ford Shale sample (EqVRo = 0.92%) from a shale-oil prospecting well in South Texas was selected for gold-tube pyrolysis experiments to investigate organic matter

We sampled and studied a borehole located at the southern part of Maritsa Iztok lignite field (Bulgaria) which comprises Late Miocene-Pliocene sediments of Maritsa Formation. The current report of Troyanovo-3 Mine sequence is the first to our knowledge. It represents a lignite- mudstone succession with variations in organic matter (OM) maturity. Thirty eight coal and mudstone core samples showed predictable

Pre-evaporitic Messinian deposits, consisting of a cyclic alternation of diatomites with lime mudstones, and laminated marls, crop out all over the Mediterranean area, representing important archives of deteriorating environmental conditions. The peculiar section of Torrente Vaccarizzo (Sicily) shows several intervals of organic-rich shales, exceptionally rich in lipid biomarkers, interbedded mostly

The Zhengzhuang Field is a new developing coalbed methane (CBM) field in the southern Qinshui Basin. To disclose the high interwell heterogeneity in production, we provide a detailed investigation of local structural controls on the gas accumulation in the Zhengzhuang Field. The Zhengzhuang Field is a northwest-dipping homocline that contains abundant normal faults, and several secondary folds, karst

Laminae are the most typical and representive sedimentary feature in organic-rich shales, and revealing their influences on the reservoir physical properties is vital to understand the oil enrichment mechanisms of lacustrine shale. This study investigated the laminae characteristics and their effects on the physical properties of the shales from the Second Member of the Kongdian Formation (Ek2). The

Rare earth elements and yttrium (REYs) are critical elements and valuable commodities due to their limited availability and high demand in a wide range of applications and especially in high-technology products. The increased demand and geopolitical pressures motivate the search for alternative sources of REYs, and coal, coal waste, and coal ash are considered as new sources for these critical elements

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 coal measures

The hierarchical clustering algorithm, especially Pearson correlation coefficient, along with other statistical approach, is used statistical approach for determining the toxic elements affinities in coal, and this method is one of the common approaches due to the correlations between some elements with minerals that cannot be chemically affiliated. This study aims to correlate geochemical and mineralogical

Total organic carbon (TOC) content is significant for “sweet spots” prediction and resource calculation. Traditional physical methods and machine learning methods, however, only use labeled samples (core TOC samples and well logging data) to predict TOC, resulting in a performance bottleneck. Meanwhile, many oilfields have considerable unlabeled data (well logging data). Therefore, this paper proposed

This study presents the first organic and inorganic geochemical characterization of a non-over mature section of the Permian Longtan Shale as it can be found in the southwestern Guizhou Province, China. Compared to previous studies, the here analyzed interval lies in the oil window, which allows a more detailed and precise interpretation of the original kerogen quality, the depositional conditions

A rise in global energy demand has led to an increase in coal consumption. Consequently, global coal fly ash production has increased creating a pressing need for recycling and utilisation of coal fly ash. Since coal fly ash is enriched with rare earth elements one application is to extract rare earth elements from this waste material. There has been a rise in demand for rare earth elements over the

The organic matter-rich mudstones of the Middle Jurassic Dameigou Formation in the northern Qaidam Basin are regarded as the principal petroleum source rocks for unconventional resource exploration in China. In this study, a detailed investigation on the organic petrography, inorganic geochemistry as well as bulk and molecular organic geochemistry is presented. Three different source rock units were

To reveal the impact of biomass input (marine algae, terrestrial plants and lacustrine Botryococcus braunii) on the composition of high molecular weight organooxygen and organonitrogen compounds (Ox, Ny and NyOx), solvent extracts of immature–early mature rock and coal samples were systematically characterized by Fourier transform ion cyclotron resonance mass spectrometry using different ionization

The petrographic, palynologic, and geochemical character of the high volatile A bituminous Pennsylvanian (Bashkerian, Duckmantian) Pond Creek coal was evaluated for a series of mine samples in the Lick Creek and Jamboree 7 ½’ quadrangles in Pike County, Kentucky. In its prime years of production, the Pond Creek coal was among the most important coal resources in the leading coal producing state in

The degradation of coal into CH4 by microorganisms is a multi-stage process involving a variety of bacteria and archaea. However, little understood about the coupling between in-situ coalbed water geochemical signature and microbial communities involved in different degradation processes. Here, the relation is made between the geochemical signature of the in-situ coalbed water (pH, anions, light metal

Abundant pyrobitumen related to an abnormal thermal event has been observed in the Ediacaran-lower Cambrian reservoirs of the central Sichuan Basin. Using reflected light microscopy, this study classified reservoir pyrobitumen in the Ediacaran-lower Cambrian into three groups: isotropic, mosaic, and fibrous; the mosaic pyrobitumen was further subdivided into fine-grained, medium-grained, and coarse-grained

The Tabas Basin is in the Tabas Block in the central part of Iran, and it contains Iran’s largest coal deposits, mostly in the Parvadeh Coalfield. The basin is structurally characterised by regional scale thrust faults and orthogonal strike-slip faults that segregate the coalfields into different areas namely Parvadeh (P) I to IV. The coals under study are in the upper Triassic Nayband Formation. Samples

In the past few years, scientific research related to the hydrocarbon potential in Greece has been focused on the formations of the Ionian Unit in the western areas of the country, where oil-seepages are well known. In contrast, Parnassos-Ghiona geotectonic Unit (PGU), Central Mainland Greece, has mainly been studied for the presence of bauxite ores. However, Upper-Cretaceous organic-rich strata, including

Oxidative potential (OP) is considered to be an efficient indicator of particulate matter (PM) to induce oxidative stress in the lungs and is increasingly considered to be a relevant health metric. In this study, two complementary OP assays were deployed, including dithiothreitol (DTT) and ascorbic acid (AA) assays, to investigate the potential toxicity (as generators of oxidative stress) of respirable

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 lacustrine

Secondary biogenic coalbed gas (CBG) is the gas generated by the microbial degradation of coal or wet gas components after freshwater recharge events. However, in situ microorganisms in deep coalbed water with high total dissolved solids (TDS) content may be overlooked. The evolution of the community structure and gene function of in situ microorganisms and their contributions to secondary biogenic

Changes in the bulk modulus of coal induced by sorbing gases occur during gas production and CO2 sequestration processes in coal seams. Understanding these changes, however, remains a challenge due to the complexity of coupled sorptive poromechanical processes. Some studies report that the bulk modulus of fractured coal reduces with gas adsorption, others state otherwise. In this study, we perform

Three sampling profiles (BA, BB, and BC) from, respectively, the A, B, and C sectors of the Çayırhan coalfield representing the working Tv and Tb splits of the Middle Miocene-age upper seam were investigated for mineralogical and elemental compositions. The Tv and Tb splits are mainly separated by a 70–100-cm thick tuffaceous clastic rock/marl parting in the study area, and the thickness of the Tv

Coal is both the most widely utilized traditional energy resource and a raw material for chemical industries. Uranium is an important nuclear fuel used to produce clear electric energy. The coal mine is widely distributed, while the uranium deposit is scarce. However, a large storage of both the two ore deposits, with the uranium deposit lying above the coal seam, was found in the Tarangaole coalfield

Under hot, deep-basin conditions, hydrogen-to-carbon ratios of residual kerogen are low. Whether ubiquitous water in sedimentary environments contributes hydrogen directly to hydrocarbon gas formation through organic-inorganic interactions is, therefore, critical for natural gas generation. Accordingly, we conducted laboratory experiments on immature to overmature kerogens at 300–600°C and 700 bar

Organic-rich black shale and dark-grey mudstone are widespread in the Seventh Member of the Yanchang Formation, Ordos Basin. There are obviously differences in geochemical characteristics and hydrocarbon generation potential between black shale and dark-grey mudstone. Based on the detailed organic geochemical examination, this paper reveals the differences in hydrocarbon generation processes and characteristics

With a low mechanical strength and high Poisson's ratio, coal can exhibit brittle or ductile deformation when exposed to lower levels of stress, strain rate, pressure, and temperature compared to the adjacent sedimentary rocks (sandstone, mudrock, and carbonate). The physical and optical properties of deformed coals have been extensively examined. However, it is still unclear if within the shallow

Abstract not available

Evaluating pore structure of unconventional shale reservoirs enables us to determine their productivity, allowing for better operational decisions. Despite extensive studies in this field, considering the complexity of shale plays, pore structure analysis of such formations still requires novelties and further research. In this study, 10 samples from the Qingshankou Formation (from 5 wells) were analyzed

In the Barito Basin of Borneo, there are extensive coal seams in the Miocene Warukin Formation. The net thickness of subbituminous C coal exceeds 100 m in the Tutupan mine. Three coal seams (from bottom to top: T110, T210, T300) were studied to explore the paleo-peat type and the factors controlling paleo-peat accumulation. The study is based on 93 coal and 7 non-coal samples, each representing a stratigraphic

The characterization of pore accessibility is essential for shale oil and gas reservoir evaluation. However, owing to the extremely low permeability and high heterogeneity of shale components, accurate nanoscale evaluation of pore accessibility remains challenging. In this study, a systematic investigation of nanoscale pore accessibility characteristics and their controlling factors was undertaken

Hydrocarbon exploration onshore Denmark has been unsuccessful with no commercial discoveries. Several potential plays have been identified of which the Zechstein carbonate play relying on organic-rich Zechstein (Z2) carbonates as source rock is considered the most promising. Additional source rocks might be lower Carboniferous calcareous and carbonaceous units. This study aims at documenting Palaeozoic

Organic-rich claystones and mudstones can be very good source rocks for hydrocarbons. Middle Jurassic organic-rich siliciclastic horizons are known from the Polish Basin area, however, there are no hydrocarbon accumulations associated with these horizons. The main scientific goal of this paper is to propose why these horizons did not produce significant hydrocarbons quantities. To deal with it, we

Organic matter-rich intervals in the Cretaceous succession of the large non-marine Songliao Basin in northeastern China (covered area ~ 87 × 103 km2), including the Turonian–Coniacian Qingshankou Formation (K2qn), offer unique records to study the role of global (e.g., climate, “limno-eustasy”) and regional (tectonics, basin geometry) controls on organic matter accumulation. A wealth of scientific

The composition of oil trapped in fluid inclusions (FI), occurring in mineral cements, can provide valuable insights into oil migration. Here, FI oils in a calcite vein (representing expelled fluids) and source rock (SR) extracts (representing retained bitumen) from the Hosszúhetény Calcareous Marl Formation (HCMF) in the Mecsek Mountains area of Hungary were investigated to assess how organic compounds

Despite the importance of natural fractures in shales, few techniques are currently available to examine their formation mechanism and effects on shale oil accumulation directly. The Middle Permian Lucaogou Formation in the Jimsar Sag of the Junggar Basin is a typical fractured shale. The Jimsar Sag has experienced multiple phases of tectonic movement since the Paleozoic Era, forming numerous natural

Soluble organic matter (SOM) in shale can be divided into free and adsorbed states. However, the characteristics and occurrence mode of different types of SOM remain unclear, which are of great significance to the unconventional oil and gas and hydrocarbon generation mechanism. This paper investigates the characteristics of different types of SOM, discusses the relationships between SOM and minerals

The lacustrine organic-rich fine-grained sedimentary rocks of the Early Cretaceous Bayingebi Formation are widely distributed in the Yin'e Basin and they have become important source rocks for oil and gas exploration. To reveal the influence of paleoclimate warming event on sedimentary environment evolution and organic matter sources, the petrological and molecular geochemical analyses of the upper

Organic matter (OM)-hosted pores play important roles in controlling the porosity and gas content of gas shales. However, the control of organic pore development and preservation remains poorly understood, partly because of the inability to distinguish OM types under the scanning electron microscope (SEM). In this study, seven over-mature Wufeng-Longmaxi Shale samples (equivalent vitrinite reflectance

Although the Jurassic features a considerable accumulation of coal worldwide, only a few tonsteins within coal seams in this coal-forming period have been investigated. This paper presents the detailed mineralogical and geochemical compositions of six tonstein layers from the Middle Jurassic Yan'an Formation, Ordos Basin, North China. Based on the typical evidence of the distinct field characteristics

Reliable prediction of methane emission sources and dynamics from adjacent strata of longwall coal mining is critical for developing efficient methane capture designs to maximise emission reduction and improve mining safety. This paper presents an integrated field monitoring study that has resulted in many new insights into mine methane emissions and dynamics in a relatively high permeability, multi-seam