International Journal of Coal Geology最新文献

{"title":"Modeling the spatial distribution of REEs and Li within two coal ash impoundments","authors":"Kalyn J. Tew ,&nbsp;Rona J. Donahoe ,&nbsp;Ibrahim G. Okunlola","doi":"10.1016/j.coal.2025.104826","DOIUrl":"10.1016/j.coal.2025.104826","url":null,"abstract":"<div><div>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, the composition of the ash is more variable and randomly distributed throughout the impoundment, resulting in poorly constrained models. At Site 2, the models better represent the spatial distributions of REYSc, Ce, La, Nd, and Li within the coal ash, which vary systematically from east to west, as well as with depth. These results demonstrate that EBK 3D offers a distinct and effective approach for modeling elemental concentrations in coal ash impoundments with limited sampling. Unlike traditional interpolation methods, EBK 3D accounts for spatial uncertainty and variability in three dimensions. It is particularly useful when ash remains undisturbed, the coal source is consistent, or the coal source transitions gradually. This approach introduces a novel methodology for evaluating the resource potential of impounded coal ash as an unconventional feedstock for critical elements.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"307 ","pages":"Article 104826"},"PeriodicalIF":5.6,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrated stratigraphy of an upper miocene lignite-bearing succession based on wireline log, seismic and organic petrographic data in the Tiszapalkonya-1 core section, NE Hungary","authors":"Katalin Sári ,&nbsp;Mária Hámor-Vidó ,&nbsp;Ernő Takács ,&nbsp;Márton Bauer ,&nbsp;Richard William McIntosh ,&nbsp;Zoltán Püspöki","doi":"10.1016/j.coal.2025.104825","DOIUrl":"10.1016/j.coal.2025.104825","url":null,"abstract":"<div><div>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 lignite and hydrocarbon research of very different scales. The Tiszapalkonya-1 long core traversing the lignite-bearing succession across 1300 m enabled this data integration, as (i) it was measured by wireline logs, (ii) its lignite samples were subjected to laboratory and coal petrological analyses and (iii) the logs can be correlated with seismic sections.</div><div>Three lignite-bearing units were identified in the section. According to lithological and organic petrological data, the lower represents mostly floodplain conditions with intermediate complex and marsh. The middle indicates a change from aquatic to unbalanced wet forest swamp, floodplain. In the upper unit more stable, balanced accumulation could develop. The density log proved to be a reliable proxy on the occurrence and ash content of peat-forming environments, and the lignite-bearing units occur as autonomous seismic facies based on their higher seismic amplitude. These enable the basin-scale tracking of the identified lignite-bearing units. A log-based multi-proxy time-series analysis revealed regular cycles in the succession but raised some necessity of re-consideration of the existing magnetostratigraphy of the section. The density log gained eminent cyclostratigraphic potential due to the sensitivity of the “coal window” to climate changes.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"307 ","pages":"Article 104825"},"PeriodicalIF":5.6,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evidence of solid bitumen and hydrocarbons in low thermal maturity Menilite shales from the Polish part of the Outer Carpathians","authors":"M. Waliczek,&nbsp;A. Zakrzewski,&nbsp;G. Machowski,&nbsp;G. Ząbek","doi":"10.1016/j.coal.2025.104830","DOIUrl":"10.1016/j.coal.2025.104830","url":null,"abstract":"<div><div>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, and to understand the hydrocarbon generation in low thermal maturity rocks. The OM dispersed in the analyzed Menilite Formation is mainly represented by alginite and bituminite-rich, oil-prone kerogen. The reflectance measurements of vitrinite (VR_o %), solid bitumen (BR_o %), and the values of the maturity biomarker parameter indicator revealed that the analyzed samples contain immature to early mature organic matter in terms of hydrocarbon generation. Three types of solid bitumen (SB) were noticed: dark brown, almost black in reflected white light with a scratchy or granular surface bitumen (GR), as well as two types of homogenous SB. One reflected shades of brown-orange when observed under UV light, while the other was a non-fluorescent, lighter gray in reflected white light. Solid bitumen appears in samples where the reflectance of vitrinite is equal to at least 0.43 % VR_o and has the ability to reflect light from 0.26 to 0.32 % BR_o. A strong correlation was found between lighter homogenous solid bitumen reflectance with vitrinite reflectance, CPI 25–31, and dinosterane distribution. The lack of a broad interrelation between geochemical parameters and vitrinite reflectance values was linked with different kerogen mixtures within the analyzed strata. Higher content of bacterial Type II kerogen prompted the generation of early-mature hydrocarbons, while higher input of Type I and/or III kerogen leads to a decrease in the scale of the phenomenon of early-mature hydrocarbons. In Menilite shales, the hydrocarbons are generated in the forms of oil droplets and oil exudates.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"307 ","pages":"Article 104830"},"PeriodicalIF":5.6,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144337816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanoporosity of graptolite periderm by atomic force microscopy (AFM): A case study from the Baltic Basin, Poland","authors":"Rafał Morga ,&nbsp;Roman Wrzalik","doi":"10.1016/j.coal.2025.104816","DOIUrl":"10.1016/j.coal.2025.104816","url":null,"abstract":"<div><div>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 reflectance equivalent VRE = 1.11–1.50 %) in the Silurian shales of the Baltic Basin (northern Poland) were investigated by atomic force microscopy (AFM). The size of the 200 × 200 nm measurement area was chosen to allow observation of pores with diameters ≥1.4 nm. The graptolite periderm shows a very low porosity (0.16–0.28 %), which increases with increasing thermal maturity and decreases the mean equivalent pore diameter and surface roughness. With the onset of the gas window (at GR ≥ 1.58 %; VRE ≥ 1.31 %), limited secondary porosity develops, and percentage of pores &lt;5 nm in size significantly increases. Elliptical or roundish micropores appear within the granular fragments, and sparse pores &lt;5 nm in size emerge within the non-granular fabric. The ability of the graptolite periderm to generate gaseous hydrocarbons at the beginning of the gas window is poor. Granular type is more generative compared to non-granular type. The ratio between the two types of fabric is not significant for the overall source and reservoir potential of the host formation at the maturity level considered in this study. However, it can be important at higher maturities. Changes in the pore system and roughness parameters align with the alteration of the chemistry and microstructure of graptolite periderm. The development of secondary porosity can depend on thermal degradation of the graptolite periderm during and after burial.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"307 ","pages":"Article 104816"},"PeriodicalIF":5.6,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144243228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Organic petrography and geochemistry of the Lower-Carboniferous coals from the Ekibastuz Basin, Kazakhstan","authors":"Majid Safaei-Farouji ,&nbsp;David Misch ,&nbsp;Reinhard F. Sachsenhofer ,&nbsp;Johannes Weitz ,&nbsp;Ivan Kojic ,&nbsp;Ksenija Stojanović ,&nbsp;Serik Tursyngaliyev ,&nbsp;Medet Junussov ,&nbsp;Milovan Fustic","doi":"10.1016/j.coal.2025.104813","DOIUrl":"10.1016/j.coal.2025.104813","url":null,"abstract":"<div><div>The Bogatyr Komin open-pit mine in the Ekibastuz Basin, located in north-east Kazakhstan, is one of the largest coal mines in the world. It is based on three Lower Carboniferous seams (from bottom to top: seams 3, 2, and 1), which together form a 150 m thick, uniform seam complex. At the study site on the western basin edge, the seams dip steeply. Organic petrological and geochemical investigations have been performed to determine the maturity and depositional environment of these exceptionally thick seams.</div><div>Vitrinite reflectance (0.8–1.1 %Rr) classifies the coal as high-volatile bituminous A coal, which is also supported by Tmax values and maturity-related biomarker ratios. Vitrinite reflectance patterns prove pre-deformational coalification and a relatively high paleo-heat flow, likely caused by magmatic activity.</div><div>High ash yields and relatively low sulfur contents indicate that the coal accumulated in low-lying mires without marine influence. The input of detrital minerals decreased during peat accumulation. Relatively high concentrations of sulfur-bearing aromatic compounds, particularly in the lower part of seam 3, may reflect volcanic activity, which is also evidenced by the presence of distinct ash layers (“kaolinitic beds”) and kaolinite in coal samples.</div><div>Thick wood-forming plants were rare in the peat-forming vegetation. However, samples from seams 1 and 3 contain higher concentrations of aromatic compounds derived from lignin-bearing arborescent cordiaite-conifer-pteridosperm vegetation. Enhanced bacterial activity during deposition of the upper part of seam 2 and seam 1 is indicated by elevated hopane concentrations.</div><div>The exceptional thickness of the coal complex indicates a geodynamic setting with high subsidence rates.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104813"},"PeriodicalIF":5.6,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiproxy-based evidence of wildfire occurrence in the Lower Permian coal-bearing Rio Bonito Formation, Paraná Basin, Brazil","authors":"M.M. Bicca ,&nbsp;W. Kalkreuth ,&nbsp;T.F. Silva ,&nbsp;M. Guerra-Sommer ,&nbsp;I. Degani-Schmidt ,&nbsp;C.M. Felix ,&nbsp;D.R. Boardman ,&nbsp;P.A. Souza","doi":"10.1016/j.coal.2025.104810","DOIUrl":"10.1016/j.coal.2025.104810","url":null,"abstract":"<div><div>Coals from southern Brazil are preserved in the Lower Permian postglacial Rio Bonito Formation of the Paraná Basin. Previous studies on the Candiota Coalfield have shown intervals with significant accumulations of inertinite macerals in the Banco Louco and S9 coal seams. Aiming to understand the causes of these anomalous inertinite accumulations, this study analyzed coal samples from the anomalous inertinite-rich interval and underlying carbonaceous siltites from the top of the Candiota Coal Superior (CCS), Banco Louco (BL), S9, and overlying S8 seams (post-anomalous) obtained from two borehole cores. The samples were analyzed using organic petrology, SEM, palynology, and biomarker (PAH) techniques. The results indicate that inertinite macerals accumulated in the paleoswamp in alternating small cycles, with general inertinite enrichment (fusinite, semifusinite, and inertodetrinite) towards the top of each coal seam analyzed. Macrocharcoal was present in all coal seams as charred wood, leaf fragments, and one reproductive structure. The peak of the inertinite-rich interval occurs at the S9 seam with the dominance of microcharcoal dispersed in fine-grained sediments and completely black palynomorphs, suggesting a significant wildfire event affecting the interval. Inertinite reflectance measurements indicated the predominance of ground and surface fire events with the rare occurrence of crown fires. Combustion of organic matter is also marked by the dominant presence of 3–5 ring PAHs and local occurrence of 6-ring PAHs (including coronene). The peatland flora was mainly composed of hygrophilous lycopsids and filicopsids, with subordinate elements represented by sphenopsids, mesophilous glossopterids, and meso-xerophilous conifers. The frequent oscillations in the vegetation composition were potentially related to climate changes and related environmental conditions, varying from hygrophilous to meso-hygrophilous and mesophilous, indicating that the vegetation composition adapted to environmental/climate changes as recognized by the alteration in the pollen-spore-producing flora towards the top of BL seam and their expansion in the overlying seams at the top of the anomalous interval. In the middle of the S9 seam, the completely dark palynomorphs and phytoclasts, plus a high abundance of pyrogenic biomarkers including 6-ring PAHs, point to significant fire events linked to the peak of the inertinite-rich interval during drier, warming intervals, which contributed to modifying the paleoecological patterns of the peatland. The paleo-wildfires of the Asselian age (ca. 298 Ma) Candiota Coalfield are the oldest record of wildfires in peat-forming environments of southern Brazil, being coeval with a warming period at the end of the Late Paleozoic Ice Age in Western Gondwana.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104810"},"PeriodicalIF":5.6,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144069774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of biocoke behaviour in a ferromanganese smelting pilot furnace: A petrographic approach","authors":"M. Wojtaszek-Kalaitzidi ,&nbsp;M. Rejdak ,&nbsp;M. Książek ,&nbsp;S.Y. Larsen ,&nbsp;S. Rørvik ,&nbsp;R. Muzyka ,&nbsp;S. Drewniak","doi":"10.1016/j.coal.2025.104791","DOIUrl":"10.1016/j.coal.2025.104791","url":null,"abstract":"<div><div>This study presents a pioneering investigation into the behaviour of biocoke, particularly its biogenic component (biochar), during ferromanganese production. Employing μCT scanning, micro-Raman spectrometry, and organic petrology, the research explores the transformation of organic matter throughout different zones of a pilot ferroalloy furnace. The results reveal that the degradation of biocoke and its biocomponent varies significantly depending on the relevant position within the furnace and the temperature conditions. Notably, the biocoke with a 20 % charcoal addition maintained structural integrity and functioned effectively as a reducing agent, contrary to concerns about premature gasification due to the high reactivity of biochar. Microscopic analysis confirmed the presence of partially preserved biochar even at the furnace's lowest levels, indicating active participation in the reduction process. Furthermore, the study provides compelling evidence of partial graphitisation within both the coke matrix and the biogenic component, most likely facilitated by catalytic effects from molten and/or vaporised metals such as iron and manganese at temperatures exceeding 1500 °C. The occurrence of semi-graphitic structures was confirmed by Raman spectroscopy. The work also advocates for a distinct classification of organic inerts of biomass origin, acknowledging their unique gasification and thermal behaviours. This classification should be refined through broader studies involving diverse biochar sources and interlaboratory comparisons. The findings validate the viability of biocoke as a sustainable and economically feasible reductant in ferroalloy production, as demonstrated through the Biocoke4FAI research project.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104791"},"PeriodicalIF":5.6,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143923677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Near surface lithium isotopic fractionation and lithium enrichment in coal-hosted Li-rich clays from the South China Block","authors":"Rongjie Wang ,&nbsp;Shifeng Dai ,&nbsp;David French ,&nbsp;Ian T. Graham ,&nbsp;Victor P. Nechaev ,&nbsp;Robert B. Finkelman","doi":"10.1016/j.coal.2025.104803","DOIUrl":"10.1016/j.coal.2025.104803","url":null,"abstract":"<div><div>Surficial low-temperature sedimentary clay-type Li deposit is one of three major types of Li deposits in the world; however, its formation and corresponding Li isotope fractionation mechanisms are still unclear. In this study, we demonstrate an unusually high Li concentration (89.1 ppm to 520 ppm) within a Late Triassic coal-hosted clay Li deposit from the Sichuan Basin, China. In-situ mapping of the Li distribution combined with isotopic analysis of Li occurring as clay-hosted ion-exchangeable and structurally bound Li was carried out to investigate low temperature Li migration and enrichment processes near the Earth's surface. The in-situ mapping shows that the dominant host of Li is fracture-fill and vermicular chlorite, while massive illite aggregate and fracture-fill paragonite contains lesser amounts of Li. Kaolinite and chlorite also absorbed a part of Li on surface/interlayer sites. The Li enrichment processes involve a contribution from detrital clastics (aggregate illite and kaolinite), especially felsic pyroclastics (vermicular-kaolinite) from collisional- and subduction setting, as well as the water-rock interactions during peat accumulation/burial stage between the acidic groundwater and primary Li-bearing clays. The primary kaolinite and illite was replaced with chlorite and paragonite accompanied with Li isotopic fractionation (Δ⁷Li: +2.67 ‰ to +15.4 ‰).</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104803"},"PeriodicalIF":5.6,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143942437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitigation of geothermal energy drilling risks in the presence of hydrocarbons: A basin scale approach applied to the eastern Swiss Plateau area (Schlattingen-1, Herdern-1 and St. Gallen-GT-1 geothermal transect)","authors":"S. Omodeo-Salé ,&nbsp;T. Cassola ,&nbsp;A. Moscariello","doi":"10.1016/j.coal.2025.104806","DOIUrl":"10.1016/j.coal.2025.104806","url":null,"abstract":"<div><div>Geothermal exploration can be complicated by the presence of hydrocarbons in the subsurface. This is a well-known issue in Switzerland, where geothermal projects were affected by the consequences of an unexpected finding of hydrocarbons during drilling operations. This was the case of the Schlattingen-1 well in 2011 and the St. Gallen-GT-1 well in 2013, both located in the north-eastern part of the Swiss Plateau. To confidently predict the potential of hydrocarbon occurrence in the subsurface, a 2D basin and petroleum system modelling (BPSM) was performed along a regional geological section of the eastern sector of the Swiss Plateau, including the Schlattingen-1, Herdern-1 and St. Gallen-GT-1 wells.</div><div>The BPSM reconstructs the temperature history of the basin by considering the geodynamic, structural and stratigraphic evolution of the basin. The modelling results were calibrated with present-day borehole temperature, porosity and vitrinite reflectance data. To calculate the hydrocarbon generation and accumulation potential in the studied area, the source rocks were geochemically and petrographically characterized. In the southern part of the section, gas accumulations are predicted by the model at the top of the Permo-Carboniferous graben, just beneath the St. Gallen GT-1 well. In the northern part, around the Schlattingen-1 and Herdern-1 well sites, the model indicates the migration and accumulation of hydrocarbons within the Mesozoic units. Migration to the uppermost Molasse units also occurs along faults, thrust planes and permeable units, when present.</div><div>The main uncertainties of the modelling results include: i) distribution and characteristics of faults; ii) thickness and hydrocarbon potential of the source rocks; iii) lithological and petrophysical properties of potential reservoir and seal units; iv) calibration data with big ranges and not uniformly measured. To refine the assumptions and enhance the understanding of the basin's evolution, further data should be collected and existing data reanalysed. Building risk analysis and probabilistic models would also help to plan drilling mitigation measures aimed at reducing these uncertainties. The workflow presented in this study can be highly valuable to geothermal projects. It allows more effective planning of the drilling procedure, thus reducing the operational risks and contributing to the overall project success.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104806"},"PeriodicalIF":5.6,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solid bitumen formation and resulting differential porosity development in the Mesoproterozoic Xiamaling shale during artificial thermal maturation","authors":"Ji Chen ,&nbsp;Jingwen Zheng ,&nbsp;Daxiang He ,&nbsp;Peng Cheng ,&nbsp;Qin Zhou ,&nbsp;Tengfei Li ,&nbsp;Haifeng Gai","doi":"10.1016/j.coal.2025.104812","DOIUrl":"10.1016/j.coal.2025.104812","url":null,"abstract":"<div><div>Solid bitumen constitutes a predominant organic component in thermally mature source rocks, yet its role in shale reservoirs remains poorly constrained. This study integrated hydrocarbon expulsion simulation via sequential solvent extraction with isothermal pyrolysis experiments conducted on an early mature bituminite-rich shale sample from the Mesoproterozoic Xiamaling Formation in North China. Organic petrography and gas adsorption were applied to characterize the solid bitumen and pore structure in pyrolysis residues, respectively. The primary objective was to advance the understanding of the solid bitumen formation and its influence on the porosity development of shales within the dry gas window. Quantitative petrographic evidence confirms that the composition of retained extractable organic matter exerts fundamental control over the yield and properties of solid bitumen. Notably, the polar fraction (e.g., asphaltene component) exhibits superior solid bitumen-generating capacity, indicating that expulsion-driven compositional fractionation of residual hydrocarbons serves as the primary determinant of intraformational solid bitumen heterogeneity. Furthermore, empirical data demonstrate an inverse relationship between solid bitumen content and porosity development of shales across the investigated maturity spectrum (vitrinite reflectance 1.02 %–3.62 %), manifested through depressed specific surface area and diminished pore volume metrics. Our findings suggest that provenance-controlled variations in solid bitumen occurrence and subsequent pore architecture may induce complex reservoir quality modifications, potentially accounting for divergent porosity trends observed in natural shale systems. While this investigation provides fundamental insights into organo-petrophysical relationships, the general applicability of these conclusions warrants further validation through subsequent research.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104812"},"PeriodicalIF":5.6,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}