International Journal of Coal Geology最新文献

{"title":"Gas-water flow in fractured coal revealed by multimodal imaging","authors":"Wen Xi ,&nbsp;Aaron Uthaia Kumaran ,&nbsp;Yaser Hadi Gholami ,&nbsp;Ryan T. Armstrong ,&nbsp;Yu Jing ,&nbsp;Joan Esterle ,&nbsp;Klaus Regenauer Lieband ,&nbsp;Peyman Mostaghimi","doi":"10.1016/j.coal.2024.104586","DOIUrl":"10.1016/j.coal.2024.104586","url":null,"abstract":"<div><p>This research presents a new method for studying gas-water two-phase flow in fractured coal, integrating cutting-edge imaging techniques. We combine dynamic positron emission tomography (PET), high-resolution X-ray micro-computed tomography (micro-CT), and unsteady-state fluid flow experiments. First, micro-CT under reservoir pressure conditions maps the sample's fracture structure at high-resolution. Then, helium injection into a water-saturated sample simulates gas flow in a coal seam during production. Real-time PET monitoring captures the dynamic displacement process within the fractures. This approach yields crucial data on gas injection volume, pressure variations, and water production, enabling relative permeability curve prediction. Finally, multi-scale image analysis merges high-resolution micro-CT with dynamic PET images, overlaying the flow path onto the fracture network. This innovative method leverages the strengths of both PET and micro-CT, offering unprecedented visualization of gas-water flow behaviour in fractured coal. PET images play a crucial role in providing both spatial and temporal water saturation profiles since the activity mapping directly correlates with water volume distribution in the fractures. The consistency between the initial activity profile along the sample from PET and the fracture volume distribution calculated from micro-CT images confirms the reliability of PET data. The workflow proposed in this paper can be used to monitor two phase flow displacement in unconventional rocks such as coal and be applied for determination of relative permeability curves.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"293 ","pages":"Article 104586"},"PeriodicalIF":5.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142041325","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":"Kerogen kinetics and the effect of rock matrix: Insights from Western Greece","authors":"Vagia Ioanna Makri ,&nbsp;Ioannis Oikonomopoulos ,&nbsp;David Muirhead ,&nbsp;Nikos Pasadakis","doi":"10.1016/j.coal.2024.104585","DOIUrl":"10.1016/j.coal.2024.104585","url":null,"abstract":"<div><p>The importance of kerogen kinetics extends beyond hydrocarbon generation, encompassing thermal modeling, organic matter heterogeneity, and the assessment of thermal decomposition. Our study focuses on analyzing the organic and inorganic signatures of source rock intervals, by integrating also literature maceral compositions, to identify potential correlations between kinetics and the mineral matrix. To achieve this, nineteen samples from proved Mesozoic source rock intervals in Western Greece were analyzed. Rock-Eval 6 pyrolysis experiments identified thermally immature to slightly mature, mainly type II, and mixed I-II kerogens. X-ray fluorescence and X-ray diffraction analysis revealed a predominance of carbonate over silicate minerals, indicating a carbonate-dominated source rock character and predominantly reducing marine depositional conditions. High sulfur contents, primarily observed in the Late Triassic – Early Jurassic interval, suggest euxinic conditions and the presence of II(S) kerogens. Bulk rock kinetic analysis revealed activation energy distributions mainly ranging from 43 to 60 kcal/mol. The Late Triassic – Early Jurassic and Early – Mid Jurassic intervals show greater heterogeneity with broad distributions, while the Mid – Late Jurassic and Early Cretaceous intervals exhibit more homogeneity, with two to three principal activation energy peaks. Kerogen isolation revealed differences in activation energies and frequency factors between the bulk rock and the kerogen, with the mineral matrix potentially having a minimal effect in the reaction rate. This research offers insights into the bulk kinetics of marine source rocks linked with global oceanic anoxic events, with broader implications to the hydrocarbon exploration in the fold and thrust belt of Western Greece, and to analogue geological settings worldwide.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"292 ","pages":"Article 104585"},"PeriodicalIF":5.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141915357","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":"Radiological risks and excess lifetime cancer risk of the topsoil around the coal-fired Plomin thermal power plant (Istria, Croatia) and long-term effects after ceasing use of the coal with elevated radionuclides activities","authors":"Ivanka Lovrenčić Mikelić ,&nbsp;Gorana Ernečić ,&nbsp;Delko Barišić","doi":"10.1016/j.coal.2024.104576","DOIUrl":"10.1016/j.coal.2024.104576","url":null,"abstract":"<div><p>Radiological and health risks arising from ²²⁶Ra, ²³²Th, and ⁴⁰K in topsoil due to coal combustion in Plomin thermal power plant were assessed: outdoor absorbed dose rate in air (<em>D</em>), annual outdoor effective dose rate (<em>D</em>_ef), external hazard index (<em>H</em>_ex), internal hazard index (<em>H</em>_in), and excess lifetime cancer risk outdoors (<em>ELCR</em>_out). Spatial distribution of risks around the plant was studied and relative contributions of ²²⁶Ra, ²³²Th, and ⁴⁰K to <em>D</em> (applies to <em>D</em>_ef and <em>ELCR</em>_out as well), <em>H</em>_ex, and <em>H</em>_in were determined. The risks were studied at two soil depths (A: 0–10 cm, B: 10–25 cm), radially around the plant at 1 km, 5 km, and 10 km distances from the plant, and in a downwind (SW) profile at 0.1–1 km distance from the plant. Elevated <em>D</em>, <em>D</em>_ef, <em>H</em>_in, and <em>ELCR</em>_out were determined, while <em>H</em>_ex was not elevated. Almost all <em>D</em>, <em>D</em>_ef, and <em>ELCR</em>_out values were above the world average for soils (58 nGy/h, 0.07 mSv/y, and 0.29 × 10⁻³, respectively). <em>D</em>, <em>D</em>_ef, and <em>ELCR</em>_out were: 32–338 nGy/h (mean value: 116 nGy/h), 0.039–0.414 mSv/y (mean value: 0.142 mSv/y), and 0.17 × 10⁻³–1.79 × 10⁻³ (mean value: 0.61 × 10⁻³), respectively. <em>H</em>_ex was in the 0.18–1.98 range (mean value: 0.69), with only two extreme values above the recommended limit of 1. <em>H</em>_in was in the 0.22–3.67 range (mean value: 1.02), with most of the values above the recommended limit of 1 in the downwind profile and at one station with extremes (1 km from the plant). A “hot spot” was determined for all risks at 1 km distance from the plant in the wind direction (SW from the plant). The next highest, elevated, risks were observed in the downwind profile stations. The most important parameters influencing spatial distribution of risks are ²²⁶Ra activities in soil, wind direction, and distance from the plant. ²²⁶Ra is generally the most important contributor to risks in soils, while ⁴⁰K is the least important. ²²⁶Ra and ²³²Th were found to be the most significant and comparable contributors to <em>D</em>, <em>D</em>_ef, <em>H</em>_ex, and <em>ELCR</em>_out. Only ²²⁶Ra was found as the most significant contributor to <em>H</em>_in in the studied area. Elevated risks are partially from the natural source (carbonate bedrock) and partially from the power plant (coal combustion and handling, ash deposition on soil).</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"291 ","pages":"Article 104576"},"PeriodicalIF":5.6,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141838768","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":"Chemical characteristics, formation mechanisms, and geological evolution processes of high-salinity coal reservoir water in the Binchang area of the southern Ordos Basin, China","authors":"Yabing Lin ,&nbsp;Shuangming Wang ,&nbsp;Junwei Qiao ,&nbsp;Hui Zhang ,&nbsp;Ermeng Zhang ,&nbsp;Yue Ma ,&nbsp;Yutong Hao","doi":"10.1016/j.coal.2024.104574","DOIUrl":"10.1016/j.coal.2024.104574","url":null,"abstract":"<div><p>The chemical characteristics of coal reservoir water are important for studying the formation and enrichment of biogenic coalbed methane (BCM). Based on geological and sampling test data, this paper studied the geochemical characteristics and formation mechanisms of high-salinity coal reservoir water (CRW) in the Jurassic Yan'an Formation of the Binchang area in the southern Ordos Basin. The results show that the TDS contents of the CRW in the Binchang area are between 7577.38 and 15,138.61 mg/L (av. 13,268.95 mg/L), which is high-salinity brackish water. The ion types of CRW are mainly Na⁺, Cl⁻ and HCO₃⁻, and the correlations between TDS and Na⁺ and Cl⁻ are close to 1. The Piper trilinear diagram indicates that the evolution direction of the CRW is deep concentrated brine, and the hydrochemical type is the Na<img>Cl type. The ¹²⁷I concentrations of CRW are between 285 and 484 μg/L, which are much higher than the values of 55.88 μg/L for seawater. The results of ¹²⁹I dating show that the minimum age of the CRW in the study area is between 6.7 Ma and 39.97 Ma, which is much younger than the actual geological age of the Yan'an Formation. The hydrogen and oxygen isotope results show that the CRW in the study area experiences an apparent oxygen drift, indicating that the coal reservoir of the Yan'an Formation has good sealing and a long retention time for the CRW. The hydrodynamic factors show that the hydrodynamic conditions of the coal reservoir are weak, and the primary ions in the CRW originated from the dissolution of salt rocks. The main ion differentiation indices show that high-salinity coal seam water is mainly formed by evaporation, and the ion exchange between CRW and the surrounding rock and the alternating adsorption of cations in water are very weak. Evaporation and diagenesis lead to an increase in the contents of Na⁺, Cl⁻ and I⁺ in coalbed water, which in turn leads to an increase in the total dissolved solids contents of CRW and its evolution toward concentrated brine. The genesis and evolution of the CRW in the study area are affected by the combination of the relationships among the paleoclimate, aquifers and aquifuges, and tectonic evolution processes. The CRW in the study area has experienced five evolution stages, i.e., sedimentary water and diagenetic water, high-salinity infiltration water, primary mixed water, paleoatmospheric precipitation recharge water, and secondary mixed water. The above understanding can provide a basis for studying the formation period and accumulation mechanism of BCM and provide a hydrogeological basis for water resource utilisation and pollution prevention and the control of high-salinity water.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"291 ","pages":"Article 104574"},"PeriodicalIF":5.6,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141836826","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":"Understanding organic matter supply in the Eocene to Miocene Lark Formation, Danish North Sea","authors":"Zhiheng Zhou, Henrik Ingermann Petersen, Niels Hemmingsen Schovsbo, Arka Rudra, Hamed Sanei","doi":"10.1016/j.coal.2024.104575","DOIUrl":"https://doi.org/10.1016/j.coal.2024.104575","url":null,"abstract":"The significance of the Lark Formation is underscored by the variations in regional depositional environments and climatic conditions that characterized the late Cenozoic sedimentary flux into the Danish North Sea basin. This study marks the first systematic investigation of sedimentary organic matter in the Lark Formation. A total of 391 drill cuttings from 7 wells in the Danish North Sea were collected and analyzed. All 391 samples were analyzed by pyrolysis geochemistry, and thirty-eight were examined petrographically using reflected light to document maceral composition. This allowed the investigation into spatial and temporal variations in the distribution and properties of organic matter within the Danish North Sea Basin from the latest Eocene to the Middle Miocene. The results reveal that the organic matter comprises primarily Type III kerogen and is thermally immature, as indicated by thermal indicators (T < 430 °C, mean HRo = 0.3%, mean R/G = 0.51). The kerogen is predominantly composed of huminite (abundant), liptinite (less abundant), and inertinite (trace quantity) macerals.","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"24 1","pages":""},"PeriodicalIF":5.6,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141836825","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":"Understanding organic matter supply in the Eocene to Miocene Lark Formation, Danish North Sea","authors":"Zhiheng Zhou ,&nbsp;Henrik Ingermann Petersen ,&nbsp;Niels Hemmingsen Schovsbo ,&nbsp;Arka Rudra ,&nbsp;Hamed Sanei","doi":"10.1016/j.coal.2024.104575","DOIUrl":"10.1016/j.coal.2024.104575","url":null,"abstract":"<div><p>The significance of the Lark Formation is underscored by the variations in regional depositional environments and climatic conditions that characterized the late Cenozoic sedimentary flux into the Danish North Sea basin. This study marks the first systematic investigation of sedimentary organic matter in the Lark Formation. A total of 391 drill cuttings from 7 wells in the Danish North Sea were collected and analyzed. All 391 samples were analyzed by pyrolysis geochemistry, and thirty-eight were examined petrographically using reflected light to document maceral composition. This allowed the investigation into spatial and temporal variations in the distribution and properties of organic matter within the Danish North Sea Basin from the latest Eocene to the Middle Miocene. The results reveal that the organic matter comprises primarily Type III kerogen and is thermally immature, as indicated by thermal indicators (T_max &lt; 430 °C, mean HRo = 0.3%, mean R/G = 0.51). The kerogen is predominantly composed of huminite (abundant), liptinite (less abundant), and inertinite (trace quantity) macerals.</p><p>The increasing trend in total organic carbon (TOC) commenced mainly in the northeastern part of the basin (F-1 well) in the late Oligocene. From the late Oligocene to the Early and Middle Miocene, there was a progressive clockwise shift in this increasing trend of sedimentary organic carbon content towards the southernmost part of the Danish North Sea basin (Adda-3, E-1, Dany-1X and Jens-1 wells). The results of the analysis further demonstrate that this rise in sedimentary organic carbon is primarily driven by the increased content of huminite and inertinite.</p><p>Given the immaturity of the organic matter and its consistent preservation conditions, the spatial and temporal increase in the abundance of huminite and inertinite is attributed to the influx of allochthonous organic matter from terrestrial sources. This influx was primarily influenced by climatic changes and subsequent alterations in runoff. Lower runoff during cooler and drier climates from the latest Eocene to the late Oligocene resulted in a low influx of allochthonous organic matter. Conversely, higher runoff during warmer and more humid conditions in the Early Miocene and earliest Middle Miocene markedly increased its influx. The distribution of allochthonous organic matter in the study area depended on the positioning of basin entrances and depocenters, which respectively determined the supply routes and accumulation sites. This further contributed to the relatively higher abundance of allochthonous organic matter in the areas near the corresponding stratum depocenters.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"291 ","pages":"Article 104575"},"PeriodicalIF":5.6,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141841363","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":"Geochemical and biological evidence for the presence of secondary microbial gas in anthracite: A case study in the songta block, northern Qinshui Basin, China","authors":"Haijiao Fu ,&nbsp;Kangjun Yang ,&nbsp;Yueguo Li ,&nbsp;Detian Yan ,&nbsp;Zhan Zhou ,&nbsp;Tuo Deng ,&nbsp;Xianbo Su ,&nbsp;Gang Wang ,&nbsp;Shuguang Yang","doi":"10.1016/j.coal.2024.104564","DOIUrl":"10.1016/j.coal.2024.104564","url":null,"abstract":"&lt;div&gt;&lt;p&gt;In general, the bioavailability of organic matter in coal decreases with increasing coal rank, and the current coalbed gas (CBG) present in anthracite (&lt;em&gt;R&lt;/em&gt;&lt;sub&gt;&lt;em&gt;o&lt;/em&gt;&lt;/sub&gt; &lt;em&gt;&gt;&lt;/em&gt; 2.5%) is typically classified as a thermogenic gas. Recently, gas-production simulation experiments have revealed that native microorganisms could degrade complex organic matter in anthracite and then generate a certain amount of microbial gases. Therefore, the possibility of secondary microbial gas formation in anthracite under the current coal seam conditions requires further investigation. This study aimed to investigate the presence of secondary microbial gas in anthracite by analyzing and interpreting gas and water samples from the Songta (ST) block of the northern Qinshui Basin using geochemical and biological evidence. The study indicates that the coalbed water is primarily recharged by surface freshwater, and the oxidation/reduction potential (ORP) and closed coefficient values indicate a relatively reductive coalbed water environment, and the low concentrations of NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt;, SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2−&lt;/sup&gt;, and Fe&lt;sup&gt;3+&lt;/sup&gt; indicate complete denitrification, sulfate reduction, and iron reduction, respectively, and these conditions can provide a favorable environment for microbial methanogenesis. The majority of the water samples are located to the left of the global meteoric water line (GMWL), and the formation of secondary microbial gas is likely responsible for this leftward shift. The geochemical characteristics of the gas samples indicate that the CBG in anthracite is predominantly thermogenic in origin, but its δ&lt;sup&gt;13&lt;/sup&gt;C-CH&lt;sub&gt;4&lt;/sub&gt; value is significantly lighter than the theoretical δ&lt;sup&gt;13&lt;/sup&gt;C value of the thermogenic CH&lt;sub&gt;4&lt;/sub&gt;, which may be influenced by the mixing of microbial CH&lt;sub&gt;4&lt;/sub&gt;. In the ST block, geochemical evidence for the presence of secondary microbial gas in anthracite is directly provided by the observation of the positive δ&lt;sup&gt;13&lt;/sup&gt;C values of gas-phase CO&lt;sub&gt;2&lt;/sub&gt; (ranging from +8.19‰ to +20.21‰) and dissolved inorganic carbon (DIC) (ranging from +17.65‰ to +27.1‰) in the coalbed water. The microbial community composition indicates the presence of hydrolyzing bacteria, acidogenic bacteria, hydrogen-producing acetogenic bacteria, and CO&lt;sub&gt;2&lt;/sub&gt;-reducing methanogens in the coalbed water, and these microorganisms are capable of cooperatively completing the conversion of anthracite to microbial gas, thereby providing the biological evidence for the presence of secondary microbial gas. Additional studies indicate that metabolic activities with different functions may be separated from each other in underground coal seams (e.g., methanogenesis and methane oxidation) and jointly involved in the cycling of carbon, nitrogen, and sulfur, which can reform the early thermogenic CBG in anthracite, and that secondary microbial gas exists mainly as by-products of metabolic act","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"291 ","pages":"Article 104564"},"PeriodicalIF":5.6,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141732329","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":"Molecular characterization of biochar and the relation to carbon permanence","authors":"Arka Rudra ,&nbsp;Henrik I. Petersen ,&nbsp;Hamed Sanei","doi":"10.1016/j.coal.2024.104565","DOIUrl":"10.1016/j.coal.2024.104565","url":null,"abstract":"<div><p>Molecular compounds present in biochar carbon structure are studied from biochar produced from forest, food, and agricultural wastes and sewage sludge using pyrolysis gas chromatography mass spectrometry (Py-GC/MS). The results show that with increasing biochar production temperature (PT), the total pyrolysis yield decreases, and the macromolecular structure becomes more condensed with the aromatic linkages becoming less alkylated, hence indicating a stable carbon structure. These highly stable biochar samples consist predominantly of inertinite and have the entire random reflectance (R_o) distributions above the inertinite benchmark (IBR_o2%). The results are aligned with high carbon stability of high-temperature biochar. In contrast, biochar samples that were insufficiently carbonized and comprised of mainly semi-inertinitic biochar contain alkane traces, volatile compounds, and higher degrees of alkylation with aromatic linkages in their molecular structure. This indicates the more proneness to oxidative and microbial breakdown, and therefore a less condensed and less stable carbon structure. Additionally, occurrence of these compounds in inertinitic biochar indicate retention of free hydrocarbons within the biochar carbon structure. Complimenting microscopic and bulk geochemical data, Py-GC/MS data is additionally advantageous to assess the stability conditions of the biochar samples.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"291 ","pages":"Article 104565"},"PeriodicalIF":5.6,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141693896","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":"A Multidisciplinary approach to facies analysis and paleoenvironmental reconstruction of the Cretaceous Second White Specks Formation, Eastern Margin of the Western Interior Seaway, Canada","authors":"Somayeh H. Mohebati ,&nbsp;Per K. Pedersen ,&nbsp;Thomas Gentzis ,&nbsp;Fariborz Goodarzi","doi":"10.1016/j.coal.2024.104563","DOIUrl":"10.1016/j.coal.2024.104563","url":null,"abstract":"&lt;div&gt;&lt;p&gt;The Cenomanian-Turonian strata of the Second White Specks (2WS) Formation on the cratonic margin of the Western Interior Seaway (WIS) are comprised of organic-rich, carbonate-siliciclastic successions. This study focuses on a carbonate-siliciclastic succession of the 2WS in two cored wells located on the eastern margin of the Cretaceous Interior Seaway. Based on sedimentary facies and organic/inorganic geochemistry representing distal and proximal sections of the 2WS, it was possible to interpret factors, including productivity, preservation, and dilution of the Organic Matter (OM). The results revealed eight subfacies and three main facies associations, including deep shelf calcareous mudstones and marlstones, and shallow shelf bioclastic limestones. The carbonaceous mudstones have high type II immature kerogen content and the bioclastic limestones have low organic content dominated by type III and degraded type II kerogen. The 2WS mineralogy primarily consists of calcite, clay minerals, and quartz, and is characterized by a low degree of physical and chemical diagenesis. Based on mineralogical analysis, carbonate is the dominant component, and its proportion is inversely associated with terrigenous silica content. There is a general increase in carbonates and a decrease in siliciclastics from the distal to the proximal sections within the study area. Lateral changes in physical and chemical properties of similar facies associations are mainly controlled by changes in water depth. The 2WS was deposited during a long-lived transgression comprised of higher order parasequences. Core logging data from multiple drillholes show that these parasequences have a general coarsening upward trend with an upward shift from pelagic (i.e., planktonic foraminifera and coccoliths) to benthic (i.e., &lt;em&gt;Inoceramus&lt;/em&gt;) carbonate productivity. During deposition of the mudstone/marlstone facies association, a clear and oxygenated water column allowed for a high photosynthetic activity to occur within the photic zone, which is reflected in OM enrichment and higher micronutrient content, such as Zn and Ni, predominance of fecal aggregates, and planktonic foraminifera. In the mudstone/marlstone facies, oxygen deficient pore water conditions, which are reflected in the high redox-sensitive trace element concentrations such as V, contributed to the high degree of OM preservation. The 2WS along the eastern margin of the WIS was deposited on a low gradient carbonate ramp environment. The oxygenated broad ramp accommodated the bioclastic limestones, which are characterized by high benthic carbonate dilution rate that resulted in lower OM preservation potential. The shallow shelf setting was characterized by restricted wave energy and minimal fluvial input from the adjacent craton under temperate climatic conditions. This study contributes to our understanding about paleo-oceanography and hydrocarbon exploration in analogous epeiric seas and mixed siliciclastic‑ca","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"292 ","pages":"Article 104563"},"PeriodicalIF":5.6,"publicationDate":"2024-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141705398","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":"Influence of thermal intrusion on the Alum Shale from south central Sweden","authors":"Anji Liu ,&nbsp;Xiaowei Zheng ,&nbsp;Niels H. Schovsbo ,&nbsp;Qingyong Luo ,&nbsp;Ningning Zhong ,&nbsp;Hamed Sanei","doi":"10.1016/j.coal.2024.104560","DOIUrl":"https://doi.org/10.1016/j.coal.2024.104560","url":null,"abstract":"<div><p>This study investigates the geochemical and petrological characteristics of solid bitumen in the DBH15/73 core from the Furongian (upper Cambrian) and Miaolingian (middle Cambrian) Alum Shale in Billingen, south central Sweden. At Billingen a &gt; 30 m thick Permian diabase (dolerite sill) intruded approximately 100 m above the Alum Shale that promoting the formation of solid bitumen in the uppermost half of the Alum Shale due to enhanced heat flow. The bitumen has been classified into bituminite/diagenetic solid bitumen (DSB), initial-oil solid bitumen (IOSB), and primary-oil solid bitumen (POSB) based on their genesis, morphology and random solid bitumen reflectance (BR_o). The Miaolingian shale, constituting the lower part of the Alum Shale, is immature and contains solely bituminite and DSB, with measured BR_o ranging from 0.40% to 0.48%. In contrast, the Furongian shale exhibits enrichment in IOSB and POSB and range from marginally mature to peak oil generation with towards the top of the section. Characteristics of uneven heating is seen in the IOSB (BR_o: 0.97–1.08%) including oxidation rims and abnormally high maturity surrounding fractures. The POSB (BR_o: 0.63–2.01%) is present not only in the Alum Shale but also in the overlying Ordovician Latorp limestone and the underlying Kakeled Limestone Bed, and shows flow structures which is further evidence for migration. The abundance of POSB and IOSB is determined through maceral point counting, revealing POSB as the dominant bitumen type (1.54–7.13 vol%), while IOSB constitutes the minority (0.05–0.31 vol%) within the Furongian shale. This distribution suggests rapid thermal evolution of organic matter within the oil generation window. Additionally, a reduction in free hydrocarbons (Rock-Eval S1), potential hydrocarbons (Rock-Eval S2), and unexpectedly low T_max was observed in the Furongian shale. Results indicate that hydrocarbon generation resulting from thermal intrusion contributes to the relatively low S2. Migration of POSB and generated oil to adjacent layers leads to the loss of S1, while the reduced Tmax may be attributed to high uranium content which weakens carbon chain bond energy. These anomalies result in an underestimation when evaluating thermal maturity and kerogen type conversion based on Rock Eval data alone.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"290 ","pages":"Article 104560"},"PeriodicalIF":5.6,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141606161","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}