Determining the degree of maturation and thermal evolution in kerogen is vital to the hydrocarbons industry. This study evaluates the thermal maturation of source rock sections in sedimentary basins. Its determination makes it possible to estimate whether a sample from a given depth in an oil well falls within the window of oil or natural gas generation or remains immature. The Spore Coloration Index

Methane release into mine workings and the atmosphere poses a serious environmental and safety risks. This study examines the composition and stable isotope geochemistry of coalbed methane in a hard coal mine of the Upper Silesian Coal Basin (Poland), with emphasis on gas migration pathways from the coal seam through mine workings and ventilation shaft to the atmosphere. Methane concentrations decrease

The Daqingshan Coalfield in Inner Mongolia takes the CP2 coal section (Shuanmazhuang Formation) as its primary mineable layer, with the CP4 coal section (Zahuaigou Formation) as a local mineable layer. These coal sections contain abundant claystone resources. This study presents a systematic analysis of claystone samples from the CP2 seam in the Adaohai Mine, integrating mineralogical and geochemical

Carboniferous–Permian coals in North China are widely recognized for their enrichment in critical metals, yet the enrichment within their adjacent rocks has received comparatively less attention. Recent investigations have identified rare earth elements and yttrium (REY)-enriched coal-measure kaolins, occurring as partings and floor of coal seams in the southeastern Datong Coalfield. These REY anomalies

The behavior of trace elements (TEs) during coal combustion is highly temperature-dependent, presenting a dual challenge of environmental risk and resource potential. However, the strategic utilization and effective pollution control of coal ash are hindered by insufficient understanding of how combustion temperature differentially governs the fate of critical and harmful elements. Combining combustion

The identification of sweet spots in shale is crucial for ensuring energy security and the economic development of gas resources. However, the pronounced heterogeneity of laminae and lithofacies presents substantial challenges in the accurate identification of sweet spots, particularly in shale formations deposited across the Early Silurian, which was significantly affected by episodic volcanism. To

Organic Matter (OM) thermal maturity plays a critical role in hydrocarbon generation within unconventional systems, controlling the transformation of kerogen to oil, and from oil to gas/condensate, thereby defining the fluid type in place. Reliable maturity evaluation underpins resource assessment, sweet-spot mapping, landing-zone selection, and calibration across geochemical, petrographic, and spectroscopic

The rapid expansion of the new energy industry has resulted in a significant shift in the demand structure for specific lanthanides and yttrium (REY) and an overall increase in demand, thereby accelerating the depletion of conventional sources and driving the exploration of unconventional sources such as coal-based resources. This study established a comprehensive database of REY in Chinese coal, calculated

Hydrocarbons have been known in Sicily for centuries from oil seeps and bitumen-impregnated limestones, which were exploited in the 19th and early 20th centuries. In the 1950s, several shallow wells were drilled in the Sicilian Foreland with the aim of hydrocarbon production. The study focuses on oil and bitumen seeps in Sicily, southern Italy. The oil seeps occur on the surface in Madonna dell’Olio

The abundance of elements in coal is important not only because it provides a solid scientific and practical foundation for various geochemical comparisons, but also because it helps address broader questions in Earth Sciences. In this study, data on major and trace elements in global coals comprising hundreds of thousands of coal samples were compiled from peer-reviewed journal articles, books, various

Titanium oxides (predominantly rutile) constitute critical reservoirs of niobium within coal-bearing strata, yet their provenance discrimination remains methodologically challenging. This study establishes a robust rutile provenance discrimination framework for Nb-rich sequences (coal, tonstein, mudstone) in the Ordos Basin through integrated machine learning and rutile trace element geochemistry.

This study provides an extensive investigation of the origin, morphological evolution, pore structure, and flow behavior of organic matter (OM)-hosted pore systems in the overmature Wufeng–Longmaxi (W–L) shales of the Sichuan Basin, SW China, with implications for shale gas storage and production. Eleven core samples from the Wufeng and Longmaxi formations, spanning a wide range of total organic carbon

As the world deal with the global climate and energy crises and energy transition, studies related to coal are still needed because, despite de phasing out of coal, the recognition of the environmental legacy left by fossil fuels is important to identify the influence of its use in the carbon cycle and to meet the main commitments of the European Green Deal. This study aims to identify the fingerprint

Barremian organic-rich black shales are significant source rocks in the eastern Tethyan Qiangtang Basin. Based on petrological, inorganic and organic geochemistry analyses, the black shales are divided into three units from bottom to top. Unit 1 micritic limestones exhibit high total organic carbon (TOC) contents and Type II₂ kerogen, indicating a mixture of marine microalgae and land plants. Unit

The carbon dioxide removal (CDR) potential of biochar is determined by the long-term stability of its biogenic carbon, derived from atmospheric CO₂ fixed by photosynthesis and stabilized in solid form. This stability (carbon permanence) is commonly assessed using decay models to evaluate resistance to re-emission as greenhouse gases. However, these models are limited, as they focus primarily on short-term

Evaluation of thermal maturity in vitrinite-free or vitrinite-deficient sediments via fluorescence microspectrometry can provide relevant information related to petroleum exploration and thermal history assessment. However, variation in spectral fluorescence properties of alginite macerals with increasing thermal maturity is largely underexplored. Here, authors of this study have applied confocal laser-scanning

Coal-based graphite deposits developed in Lutang, Hunan Province, China, provide an opportunity to investigate the petrographic characteristics of graphitic carbon. Optical microscopy and microphotometry were employed to observe the morphology, microstructure, occurrence and reflectance of graphitic carbon and thus classify its type. The results indicated that the evolutionary stage of the coal-based

Graptolites are widely presented in the Ordovician–Silurian Wufeng–Longmaxi Formations and other Lower Paleozoic marine shales throughout the world, and their reflectance is regarded as an effective index for the thermal maturity assessment of the graptolite-bearing shales devoid of vitrinite. Graptolites display distinct optically biaxial features, and the optical characteristics and reflectance of

This study aimed to investigate the quality and rank of the Tatapani-Ramkola coal and decipher the paleoclimate and depositional conditions during coal formation, explicitly focusing on vegetation sources, detrital contributions, and paleomire conditions. The studied coals exhibit a moisture between 4.0 % and 12.8 % and a volatile matter yield in the range of 28.8–49.5 wt% (dry ash–free basis), classifying

Understanding the mechanical response of organic-rich shales to CO2 adsorption is critical for optimising CO2 sequestration and enhanced gas recovery operations. However, these responses are often highly complex and demand a thorough understanding of the underlying sorptive poromechanical mechanisms involved. This study examines the sorptive poromechanical response of Beetaloo shale to CO2 adsorption

Fine-grained successions, traditionally interpreted as continuous archives, contain cryptic hiatuses that are critical for evaluating stratigraphic completeness and paleoenvironmental evolution but remain difficult to resolve, especially in deep-water black shales. This study identifies six hiatuses (H1–H6) in the Lower Silurian Longmaxi Formation through integrated sedimentology, cyclostratigraphy

Coal seam gas (CSG) is an unconventional gas resource in the global energy supply. A key factor in predicting and evaluating methane production in coalbeds is coal relative permeability. This study explores the effects of an enzyme-based surfactant, GreenZyme (GZ), on coal relative permeability through drainage unsteady-state core flooding experiments. Initial measurements of interfacial tension (IFT)

As peat deposits represent significant terrestrial carbon sinks, the processes of peatland initiation, evolution and termination are important components of the global carbon cycle. Research on recent peatlands leaves many questions unanswered concerning peatland evolution and the driving mechanisms for changes in peat forming environments in deep-time. Using a combination of sedimentology, coal petrology

Coal mineralogy and trace element composition provide vital insights into the geological coal formation processes, depositional environments, and potential resource valorization. However, there is limited knowledge and understanding of the geochemical and mineralogical composition of coal discards from the Witbank Coalfield. Thus, the coal discards remain underexplored, limiting effective management

Oxidant stimulation has emerged as a promising supplementary approach to enhance gas recovery from coal seams, targeting coal organic matter more directly than acid stimulation, which affects mineral components. However, the reactivity of different coal maceral subtypes to oxidants, particularly under reservoir conditions, remains poorly understood. In this study, sodium hypochlorite (NaClO) was used

Uranium enrichment in coal is of great significance for understanding metallogenic processes and assessing resource potential. Numerous studies have investigated the geochemical behavior and modes of occurrence of U in super-high-organic‑sulfur coals from Southern China. However, the Huanghebei Coalfield in Shandong, a major high‑sulfur coal-bearing region in North China, yet remains largely unidentified

The enrichment of trace elements in coals is of significant economic importance because of the growing demand for the critical elements. Several enrichment processes have been identified and in this paper the role of palaeosalinity is evaluated using published data from the East Pennine Coalfield (UK). The coal and associated mudrocks for which comprehensive ICP- AES and ICP-MS analyses are available

Natural radioactive radiation emitted by uranium (U) in sedimentary basins continuously transforms organic matter and thus its degrading impact overprints the burial-related thermal maturation process. However, the systematic pathway for irradiated alteration of sedimentary organic matter and its influence remain poorly understood. This omission hinders a comprehensive understanding of organic matter

Soluble organic matter (SOM) in low- to middle-rank coal can be categorized into free (FSOM), mineral-associated (MSOM) and chemical-associated (CSOM) states. However, the characteristics of these different types of SOM remain poorly understood in tar-rich coal research, primarily due to the long-standing perception of coal as a conventional gas source rock. This paper investigates the geochemical

Compared to shallow coal seams, deep coalbed methane (CBM) reservoirs exhibit significantly higher formation water salinity. During deep CBM extraction or CO2 sequestration, salt precipitation induced by water evaporation and salt crystal migration via gas flow blocks channels, causing reservoir damage. This study integrates high-resolution scanning electron microscopy (SEM) imaging to characterize

The coal-bearing succession associated with the Ashoka Coal Mine in the North Karanpura Basin has been studied to ascertain the palaeovegetation, palaeoecology and depositional settings. The basin contains an excellently preserved diverse plant fossil assemblage of Lower Gondwana successions. The megafossil assemblage retrieved from sediments shows rich floral diversity comprising 3 genera (Gangamopteris

Coalbed methane plays a critical role in both energy resource potential and environmental and mine safety strategies. Despite much research has been done on coalbed gas origin, the combined effects of coal maturity, gas migration processes, and mine ventilation in an active mining environment are still not fully understood. This study combined molecular and stable carbon and hydrogen isotope analyses

The Qinshui Basin is renowned for its thick, laterally extensive coal seams, high thermal maturity, and significant coalbed methane (CBM) potential. However, reservoir heterogeneity resulting from multi-stage tectonic activity leads to pronounced variability in CBM enrichment, posing challenges for efficient development. This study examines the influence of individual and coupled tectonic, roof–floor

The October sub-basin is one of the largest oil fields in Egypt, situated within the central Gulf of Suez petroleum province. Four wells were studied to investigate the petroleum system using integrated geochemical and petrographic techniques. This gives valuable information on the source rock potentialities, which may help in new hydrocarbon discoveries in the October sub-basin. Organic-rich pre-rift

The organic-rich shales in the Upper Permian Longtan Formation (LF) and Dalong Formation (DF) are important hydrocarbon source rocks and have become key targets for shale gas exploration in the Yangtze area, South China. To investigate the provenance, tectonic setting, paleoenvironmental conditions, and mechanisms of organic matter (OM) accumulation, this study presents an integrated petrological and

Critical elements in coal have attracted global attention in recent years due to a substantial increase in demand driven by economic development and defense security needs. Understanding their geochemical distribution patterns is crucial for the future strategic management and effective utilization of these metals. As the world's largest coal-producing country which has a complex condition of coal

Long-term industrial operations fueled by coal and oil have the potential to significantly impact surrounding ecosystems, particularly in the past when environmental regulations were less stringent. In this study, organic contamination was investigated in soils surrounding a former industrial complex and coal mining area on the Portuguese Atlantic coastline, active from the 19th century through the

There are numerous asphaltite veins in southeastern Anatolia, Turkey. The Avgamasya, Anılmış, Harbul, Silip, and Üçkardeşler veins, which are the focus of this study, are enriched in elements such as As, Cd, Mo, Ni, Sb (except in Harbul), U, V, Zn, and Hg. Commonly detected minerals across all samples include dolomite, calcite, apatite, pyrite, sphalerite, alkali feldspar, quartz, illite, and iron

The up to 30-m-thick Brezhani coal seam in the Pirin deposit (SW Bulgaria) is the only coal of early Oligocene age on the territory of Bulgaria, providing important insights into peat-forming environments during that period. The coal seam was investigated using organic petrography, bulk organic geochemistry and biomarker analysis.

The coalification process and maceral composition influence the molecular structure of the organic matter, yet their precise effects remain a significant challenge in coal geology studies. This investigation focused on sub-bituminous and bituminous coal from the Cretaceous-Paleogene Guaduas Formation in the Colombian Andes, concurrently creating an extensive database of FTIR spectral signatures with

Understanding secondary hydrocarbon generation from organic matter is critical for assessing source rock potential in thermally complex basins. This study investigates the hydrocarbon generation kinetics of immature to low-maturity kerogen types (Type I, II, III) using open-system pyrolysis experiments on oil shale and coal samples from the Minhe and Meihe Basins, China. Results show that Type I kerogen

The increasing demand and utilization of rare earth elements (REE or REY, if yttrium is included) in numerous sectors have led to the consideration of secondary resources for their recovery. The worldwide research has been focused on coal beds that may have potential recovery of REE or REY. Despite India's extensive coal reserves, the complex geochemistry of REE in its coalfields remains underexplored

As the promising critical metal elements in coal, rare earth elements and yttrium (REY) can occur in minerals or complex with organic matter. Some differences have been observed in the modes of occurrence of REY in coals with different ranks, which raises interesting questions on their variation characteristic and mechanism during complex coalification. In this study, the modes of occurrence of REY

Thermal maturity assessment in sedimentary basins often relies on thermal indicators of varying quality and sensitivity, frequently available in an uneven distribution across wells. To improve interpretative reliability and reduce the influence of local statistical variability, we apply a joint inversion approach to thermal maturity data from three wells situated in contrasting geological settings

Continental hypersaline lacustrine basins constitute critical repositories of unconventional shale oil resources, often hosting source rocks with primary exploration value. The hydrocarbon generation potential and organic matter accumulation within the Qianjiang Formation of Jianghan Basin, however, remain elucidated inadequately. This study targets the third member of the Qianjiang Formation (Eq3)

In the Elephant Game Reserve (EGR) in Mozambiquan Maputaland, several small peatlands have been developed between dunes. The aim of the study is to determine the peat-forming conditions and elucidate the evolution of the peatlands. Herbaceous vegetation (reeds and sedges) thrive on the surface of the mires. Fifty-five organic and inorganic samples were picked up from nine manually-retrieved cores up

This study presents the results of microscopic and geochemical analyses of the Menilite Formation from the Polish part of the Outer Carpathians. Twelve Oligocene shales from the Central Carpathian Synclinorium of the Silesian Nappe were examined to evaluate the petrological characterization of the solid bitumen and other organic matter (OM), identify the hydrocarbon evidence in the analyzed samples

The upper Permian Newcastle Coal Measures (NCM) host world-class coal resources in coastal New South Wales, Australia. They formed close to the foredeep axis of a developing retroarc foreland basin associated with the Hunter-Bowen contractional event. In addition to the typical coal-bearing lithological suite of mudrocks, heteroliths, sandstones, and coals (with several beds of volcanic ash), the NCM

Historical and newly acquired data are used to model the spatial variability of rare earth elements (REE), Sc, Y, and Li concentrations in two coal ash impoundments. Samples were collected using a limited sampling scheme and modeled in ArcGIS Pro for total REYSc, Ce, La, Sc, Y, Nd, and Li using 3-dimensional empirical Bayesian Kriging (EBK 3D). Although a higher sample density was modeled at Site 1

An intriguing problem of the Upper Miocene stratigraphy in the Pannonian Basin is the correlation of marginal lignite-bearing units to the thick siliciclastic succession in the basin centre; however, it is inevitable in the stratigraphic investigation of the Jászság Basin, necessitated by a regional scale hydrogeological study. An essential precondition of this investigation is integrating data from

To date, the pore system of graptolite periderm in shales with thermal maturity at the transition phase from the oil to the gas window has been poorly researched and understood. It was also not clear whether the graptolite periderm develops secondary pores. Therefore, porosity, pore characteristics, and surface roughness of the graptolite periderm (graptolite reflectance GR = 1.30–1.83 %; vitrinite

Point counting is a widely used quantitative technique in microscopic analysis for estimating the volume percentage of target constituents within a sample. Its application in coal petrography has been standardized through international guidelines such as ISO 7404 and ASTM D2797/D2799, which were primarily developed for the analysis of carbonaceous materials such as coal and peat. These standards have

The benefits of coalbed gas (CBG) development are directly affected by the production capacity level. Previous studies of CBG productivity response have mainly focused on the hydrogeochemical characteristics of produced water, and paid less attention to the correlation between microbial communities and productivity. This study focuses on nine CBG wells in the Liulin Block of the eastern Ordos Basin