International Journal of Coal Geology最新文献

{"title":"In situ coal permeability and favorable development methods for coalbed methane (CBM) extraction in China: From real data","authors":"Shida Chen ,&nbsp;Shu Tao ,&nbsp;Dazhen Tang","doi":"10.1016/j.coal.2024.104472","DOIUrl":"10.1016/j.coal.2024.104472","url":null,"abstract":"<div><p>Permeability plays a significant role in the economic viability of coalbed methane (CBM) development. In China, in situ permeability obtained from injection fall-off tests range from 0.0001 to 41 mD at depths of 130–1728 m, with the majority (78%) falling between 0.01 and 1 mD. Coal reservoirs with high rank, common cleat mineralization, and depth-dependent high stress may result in extremely low permeability. Low-rank coal and cataclastic coal exhibit more favorable permeability conditions at shallow depths. Heterogeneity in coal rank, coal texture, and stress magnitude results in a discrete distribution of permeability both regionally and vertically. Most deep seams are highly compressed with extremely low permeability (&lt;0.1 mD) as high stress levels. Multilateral horizontal wells work best with high permeability seams, while vertical wells with conventional hydraulic fracturing demonstrate limited adaptability to deep and low-permeability seams due to insufficient proppant-supported fractures. With increasing depth, both vertical and horizontal wells should employ larger fracturing scales to create effectively supported zones with higher fracture conductivity and reduced stress sensitivity to enhance CBM productivity. Horizontal wells with large-scale volume fracturing demonstrate superior performance compared to vertical wells in extracting CBM from deep, low-permeability, and high gas saturation reservoirs.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"284 ","pages":"Article 104472"},"PeriodicalIF":5.6,"publicationDate":"2024-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139916371","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":"Advancements in machine learning techniques for coal and gas outburst prediction in underground mines","authors":"Angelina Anani ,&nbsp;Sefiu O. Adewuyi ,&nbsp;Nathalie Risso ,&nbsp;Wedam Nyaaba","doi":"10.1016/j.coal.2024.104471","DOIUrl":"10.1016/j.coal.2024.104471","url":null,"abstract":"<div><p>Coal and gas outbursts are a major cause of fatalities in underground coal mines and pose a threat to coal power generation worldwide. Among the current mitigation efforts include monitoring methane gas levels using sensors, employing geophysical surveys to identify geological structures and zones prone to outbursts, and using empirical modeling for outburst predictions. However, in the wake of industry 4.0 technologies, several studies have been conducted on applying artificial intelligence methods to predict outbursts. The proposed models and their results vary significantly in the literature. This study reviews the application of machine learning (ML) to predict coal and gas outbursts in underground mines using a mixed-method approach. Most of the available literature, with a focus on ML applications in coal and gas outburst prediction, was investigated in China. Findings indicate that researchers proposed diverse ML models mostly combined with different optimization algorithms, including particle swarm optimization (PSO), genetic algorithm (GA), rough set (RS), and fruit fly optimization algorithm (IFOA) for outburst prediction. The number and type of input parameters used for prediction differed significantly, with initial gas velocity being the most dominant parameter for gas outbursts, and coal seam depth as the dominant parameter for coal outbursts. The datasets for training and testing the proposed ML models in the literature varied significantly but were mostly insufficient - which questions the reliability of some of the applied ML models. Future research should investigate the effect of data size and input parameters on coal and gas outburst prediction.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"285 ","pages":"Article 104471"},"PeriodicalIF":5.6,"publicationDate":"2024-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139878460","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":"Geochemistry and petrology of Early Permian lacustrine shales in the Lodève Basin, Southern France: Depositional history, organic matter accumulation and thermal maturity","authors":"Zhongrui Wu,&nbsp;Sebastian Grohmann,&nbsp;Ralf Littke","doi":"10.1016/j.coal.2024.104469","DOIUrl":"https://doi.org/10.1016/j.coal.2024.104469","url":null,"abstract":"<div><p>The lacustrine shales in the Lodève Basin, southern France, serve as excellent archives of paleo-lake development as well as climatic evolution during the Early Permian. In this study, an extensive dataset is presented encompassing organic petrographic data, major and trace element quantification, bulk and molecular organic geochemical proxies, as well as compound-specific stable carbon isotope data derived from the analysis of 36 black shale outcrop samples originating from the Usclas-St. Privat Formation (USPF), Tuilières-Loiras Formation (TLF), and Viala Formation (VF). All sample are thermally oil-mature, as evident from a vitrinite reflectance (VR_r) of around 0.8%. The lower section of the USPF, characterized by notably higher total sulfur (TS) concentrations, displays total organic carbon (TOC) and TS contents spanning from 2.69 to 7.83 (avg. 4.28) wt% and 0.42–1.55 (avg. 1.09) wt%, respectively. In contrast, the upper section of the USPF (average TOC of 2.59 wt%), TLF (average TOC of 2.66 wt%), and VF (average TOC of 3.17 wt%) exhibit considerably lower TS contents of 0.26 wt%, 0.22 wt%, and 0.17 wt%, respectively. The lower section of the USPF, characterized by the lowest pristane/phytane (Pr/Ph) ratio and the highest TS/TOC ratios and chemical index of alteration (CIA) values, was deposited in oxygen-depleted and saline lacustrine environments. These conditions prevailed under more humid climatic conditions and were probably related to marine incursions. In contrast, the upper section of the USPF, the TLF, and the VF display elevated Pr/Ph ratios but reduced TS/TOC and CIA values, signifying deposition within oxic-dysoxic and freshwater-brackish bottom water conditions with a significant change towards arid conditions. All samples are characterized by low vitrinite and inertinite contents together with consistently similar average values of Al₂O₃ and TiO₂. The biomarker analysis suggests that the organic matter (OM) in most samples mainly originates from planktonic/algal biomass with additional microbial OM. Only the lower section of the USPF displays a slightly enhanced contribution of terrestrial OM input and also more detrital elements. It is concluded that the structural evolution of the basin from narrow deep towards wider and shallower settings as well as the postulated marine transgressive events during early stages played a crucial role in shaping the deposition environments of the two distinct sets of lacustrine shales, thereby influencing the OM accumulation mechanisms. In contrast, the substantial climatic aridification seems to have a relatively minor impact on the sources of OM and the conditions prevailing within the water column.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"284 ","pages":"Article 104469"},"PeriodicalIF":5.6,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0166516224000260/pdfft?md5=4398c5ed62ad13d95aafae2b30fdd20d&pid=1-s2.0-S0166516224000260-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139743298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical and petrographic evaluation of hydrous pyrolysis experiments on core plugs of Lower Toarcian Posidonia Shale: Comparison of artificial and natural thermal maturity series","authors":"A. Arysanto,&nbsp;L. Burnaz,&nbsp;T. Zheng,&nbsp;R. Littke","doi":"10.1016/j.coal.2024.104459","DOIUrl":"10.1016/j.coal.2024.104459","url":null,"abstract":"<div><p>Semi-closed hydrous pyrolysis (HP) of whole-rock cuboids is a relatively novel technique aimed at improving the knowledge of the geochemical and petrographic alteration of petroleum source rocks. This study evaluates the comparability of observations on petroleum generation and migration in a natural maturation sequence and after HP in the same source rock. Two artificially matured samples of the Lower Jurassic (Toarcian) Posidonia Shale from the Hils Syncline (Lower Saxony Basin) were subjected to 24 h-HP experiments at 280 °C, 300 °C, 320 °C, 330 °C and 340 °C. The samples were subsequently analyzed with respect to changes in Rock-Eval pyrolysis parameters, molecular organic geochemistry, and organic petrography. After HP at 280 °C and 300 °C, organic geochemical composition and organic petrographic characterization show only minor changes. Significant geochemical and petrological changes occur at 320 °C: <em>Tasmanales</em> and <em>Leiosperidales</em> phytoclasts show weakened fluorescence and volume loss, accompanied by a pronounced decrease in the Rock-Eval S2 yield of the sample, indicating conversion of kerogen to petroleum products. Optical changes are even more pronounced at 330 °C and 340 °C, when very high transformation ratios are reached, exceeding those under natural conditions. The majority of aliphatic molecular geochemical proxies for thermal maturation show systematic changes with increasing vitrinite reflectance, similar to maturation trends observed in the natural maturation sequence. However, some hopanoid thermal maturity proxies (e.g. moretane/C₃₀ hopane) show unexpected inverse trends, whereas aromatic hydrocarbon ratios hardly change with increasing HP temperatures. These observations suggest that the reactions leading to changes in these parameters require considerably more time than C<img>C bond breaking (cracking) within the kerogen structure. A large part of the organic carbon remaining in the cuboids after HP at 330 °C and 340 °C is soluble in dichloromethane and should, therefore, be classified as bitumen rather than kerogen.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"284 ","pages":"Article 104459"},"PeriodicalIF":5.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0166516224000168/pdfft?md5=aecc8eb0d24546996d2158b171f2197b&pid=1-s2.0-S0166516224000168-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139656009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fossil cutin of Karinopteris (Middle Pennsylvanian pteridosperm) from the “paper” coal of Indiana, U.S.A.","authors":"José A. D'Angelo ,&nbsp;James C. Hower ,&nbsp;Gerardo Camí","doi":"10.1016/j.coal.2024.104460","DOIUrl":"10.1016/j.coal.2024.104460","url":null,"abstract":"<div><p>For the first time, a cutin-like, highly chemically resistant macropolymer has been isolated from rachises of <em>Karinopteris</em> sp. (lyginopteridalean pteridosperm, Middle Pennsylvanian). Samples are obtained from a cuticular or “paper” coal-shale, i.e., an organic-rich and highly clastic rock associated with the Upper Block Coal Member of the Brazil Formation, Parke County, west-central Indiana, U.S.A. <em>Karinopteris</em> specimens are preserved as naturally oxidized compressions, termed “fossilized cuticles”, and possibly represent vegetation of mineral substrate environments. Employing laboratory oxidation reactions, the fossilized cuticle of <em>Karinopteris</em> rachises is used to obtain the cuticle. After additional and long-term oxidation treatment, the cuticle yields the cutin-like macropolymer, here referred to as “cutin” for simplicity. The fossilized cuticle, cuticle, and cutin samples of <em>Karinopteris</em> sp. are chemically analyzed using semi-quantitative Fourier transform infrared (FTIR) spectroscopy. Cutin IR spectra of <em>Karinopteris</em> rachises are characterized by (a) a predominantly aliphatic composition as indicated by intense aliphatic (CH_al) C<img>H stretching peaks at 3000–2700 cm⁻¹, which are assigned to methylene (CH₂) and methyl (CH₃) groups; (b) carbonyl (C=O) groups at 1730–1640 cm⁻¹, and aromatic carbon (C=C) absorption bands at 1600–1500 cm⁻¹. A comparison with the cuticle, the cutin stands out due to relatively higher values of CH₂/CH₃ and C=O/C=C, while displaying notably low values of CH_al/C=O and C<img>C contribution. Specifically, the relatively low value of CH_al/C=O ratio obtained for the cutin of <em>Karinopteris</em> rachises is consistent with those found in the cutin of extant and fossil leaves. This lower CH_al/C=O ratio indicates the important role likely played by C<img>O groups in creating a deformable and flexible structure in both the cutin and the cuticle. Such a reduced rigidity suggests a high level of rachis flexibility of the once-living <em>Karinopteris</em> plant, supporting the interpretation of a climbing or liana habit. Cutin isolation and its chemical characterization shed light on the probable biomechanical (flexibility) properties of <em>Karinopteris</em> rachises, thereby enhancing our understanding of the plant growth habit.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"284 ","pages":"Article 104460"},"PeriodicalIF":5.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139655955","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":"Advancements in machine learning techniques for coal and gas outburst prediction in underground mines","authors":"A. Anani, S. Adewuyi, Nathalie Risso, W. Nyaaba","doi":"10.1016/j.coal.2024.104471","DOIUrl":"https://doi.org/10.1016/j.coal.2024.104471","url":null,"abstract":"","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"28 5","pages":""},"PeriodicalIF":5.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139818698","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":"Impact of goaf gas drainage from surface vertical boreholes on goaf explosive gas zones","authors":"Yuehan Wang ,&nbsp;Guangyao Si ,&nbsp;Bharath Belle ,&nbsp;David Webb ,&nbsp;Liang Zhao ,&nbsp;Joung Oh","doi":"10.1016/j.coal.2024.104461","DOIUrl":"10.1016/j.coal.2024.104461","url":null,"abstract":"<div><p>Goaf gas drainage is extensively employed in Australian gassy underground coal mines to manage safety and productivity and to mitigate gas emissions. As mining operations reach greater depths and produce higher levels of gas emissions, narrower spacing between adjacent vertical goaf boreholes and higher suction pressure are increasingly being adopted. While this proactive goaf gas drainage design enhances gas extraction efficiency, there is a concern that an increased amount of ventilation air might be drawn back into the deep goaf, potentially resulting in the formation of an explosive gas zone (EGZ) composed of methane-air mixtures. Extensive goaf gas drainage data from various Australian coal mines have undergone detailed analysis in preceding back analysis studies (Wang et al., 2022a, 2023). These findings serve as crucial validation input for a CFD model of the goaf, providing ventilation engineers with visualization of an otherwise inaccessible environment. In this paper, the simulation outcomes of the CFD model were integrated with Coward's triangle to demarcate potential EGZ within the active goaf areas. It indicated that the EGZ was pushed far away from the longwall face under the impact of intensive goaf gas drainage compared to the EGZ without the active goaf boreholes, exhibiting a ‘U-shaped’ distribution. Furthermore, this study delves into the gas drainage factors influencing EGZs in the goaf, emphasising the impact of various gas drainage designs on gas explosion risks within the goaf. Factors such as the number of active boreholes and completion depth are assessed, with the size of EGZ serving as a quantitative evaluation criterion. Therefore, this paper plays a pivotal role in optimising goaf gas drainage efficiency, striving to minimise gas emissions into the atmosphere while upholding the priority of mining and worker safety.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"284 ","pages":"Article 104461"},"PeriodicalIF":5.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139660201","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":"Hyperspectral imaging of coal core: A focus on the visible-near-shortwave infrared (VN-SWIR) region","authors":"W.M. Langa ,&nbsp;C. Ndou ,&nbsp;L. Zieger ,&nbsp;P. Harris ,&nbsp;N. Wagner","doi":"10.1016/j.coal.2024.104456","DOIUrl":"10.1016/j.coal.2024.104456","url":null,"abstract":"<div><p>Analytical technology is constantly being developed, refined, and applied to different materials. A key objective is to develop technologies that are non-destructive, rapid, and improve data accuracy. Hyperspectral imaging (HSI) is a non-destructive analytical technique that measures the spectral response of molecular bonds within mineral crystals or organic matter, caused by their excitation by light. The technique has a potential to save time and money for the coal exploration and mining companies. Typically, minerals within borehole cores are characterised based on their unique spectral properties within specific infrared ranges and presented as a function of reflectance versus wavelength. to examine spectra generated on coal core samples using HSI. The HSI spectral data were compared to traditional approaches X-ray fluorescence, X-ray diffraction, proximate data, and Fourier-transform infrared spectroscopy (FTIR). A coal core from Witbank Coalfield, South Africa (Medium Rank C bituminous, inertinite-rich, generally high ash), was examined within the visible-near infrared (VNIR) (350–1000 nm) and shortwave infrared (SWIR) (1000–2500 nm) regions. The HSI coal spectra exhibit positive slopes with low reflectance values within the VNIR region and gradual increase of reflectance values in the SWIR region. The spectra are influenced by very-fine grained clay and Fe-rich minerals (pyrite and siderite) included in the coal; the latter was verified by XRD as pyrite and siderite. The spectra with higher amounts of organic matter are flat and the absorption features are weaker due to the absorbing nature of the carbon. The identified absorption features for coal functional groups within VN-SWIR are 1700 nm (C<img>H), 2200–2206 nm (CH₂, C<img>C, C<img>O) and ∼ 2310 nm (CH₃), which were confirmed by FTIR data. However, the absorption features between 2200 and 2450 nm are affected by overlapping bands of inorganic phases, resulting in uncertainty. The bright banded coal (vitrinite-rich) can be adequately separated from the dull coal (inertinite-rich) through the extraction (D) of D2200 and the deepest feature between D2100 - D2450. The technique can also distinguish the carbonaceous shale from coal, demonstrating the ability to differentiate rock types based on the mineral composition and proportions.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"284 ","pages":"Article 104456"},"PeriodicalIF":5.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0166516224000132/pdfft?md5=0fd5edba47afeee15727cf92195383bf&pid=1-s2.0-S0166516224000132-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139655957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Origin of organic matter pore heterogeneity in oil mature Triassic Chang-7 mudstones, Ordos Basin, China","authors":"Yingzhu Wang ,&nbsp;Jijin Yang","doi":"10.1016/j.coal.2024.104458","DOIUrl":"10.1016/j.coal.2024.104458","url":null,"abstract":"<div><p><span>Organic matter (OM)-hosted pores play a crucial role in hydrocarbon storage and migration in unconventional shale oil<span> and gas systems. An accurate identification of different OM compositions is critical to understanding the origin of heterogeneity in OM-hosted pore development, which remains challenging due to the lack of apparent intrinsic connection between them. This study correlates light-electron-Raman spectroscopy to investigate various OM maceral<span> types and their molecular structures with respect to the pore characteristics in an oil mature Triassic Chang-7 lacustrine mudstone from the Ordos Basin, China. Moreover, the occurrence and distribution of soluble bitumen and its effect on OM-hosted pore development were directly characterized by comparison of a stitched large SEM image mosaic (∼1 mm</span></span></span>²<span><span>) before and after organic solvent extraction. Results show that terrestrial OM including </span>inertinite<span> and vitrinite<span> fragments display well-preserved biological structure and high reflectance intensity in light microscopy. They often are nonporous under SEM, and have no change before and after solvent extraction. Solid bitumen is the predominant maceral of the examined mudstone, and shows two general populations: 1) nonporous or weakly porous solid bitumen (SB1) that often occurs in large-sized and structured accumulation; 2) porous solid bitumen (SB2) that is filled or dispersed in mineral matrix. After extraction, SB2 was completely removed and have a noticeable recovery of pores, while SB1 changed slightly. The heterogenous pore characteristics can be related to the varying OM molecular structure which shows a decreasing trend of aromaticity in the order of terrestrial macerals, SB1, and SB2 as indicated by Raman parameters. A relatively higher pore abundance in SB2 may be attributed to chromatographic fractionation which led to more mobile and compliant components of SB2.</span></span></span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"283 ","pages":"Article 104458"},"PeriodicalIF":5.6,"publicationDate":"2024-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139523118","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":"Tracing the geochemical imprints of Maastrichtian black shales in southern Tethys, Egypt: Assessing hydrocarbon source potential and environmental signatures","authors":"Douaa Fathy ,&nbsp;Alireza Baniasad ,&nbsp;Ralf Littke ,&nbsp;Mabrouk Sami","doi":"10.1016/j.coal.2024.104457","DOIUrl":"10.1016/j.coal.2024.104457","url":null,"abstract":"<div><p><span><span>This study conducted comprehensive bulk and molecular geochemical analyses, as well as elemental investigations, on seventeen black shale<span> samples collected from the Upper Cretaceous sediments on the western margin of the Red Sea. The primary objective is to assess the </span></span>hydrocarbon generation<span><span> potential, maturity, source input, biodegradation levels, and depositional environment characteristics within the Lower </span>Maastrichtian<span> interval near the Safaga area. Lower Maastrichtian black shales demonstrate very good to excellent source rock generative potential based on pyrolysis data. The prevalent kerogen type in the older black shale at the Heweitat mine is Type II, whereas within the younger units at the Queih mine, it predominantly exhibits Type II/III kerogen. These Maastrichtian black shales remain thermally immature, as evidenced by </span></span></span>vitrinite reflectance (VRr &lt; 0.5%), pyrolysis data, and biomarker proxies.</p><p><span>The studied black shales show that the organic matter input comprises bacterial and algal biomass<span> with minor terrigenous contributions. Additionally, there is no evidence of significant biodegradation in the studied samples based on molecular fossils data. Microscopic analysis and various bulk and molecular characteristics, in conjunction with major and trace element profiles, collectively indicate a marine depositional environment with oxygen-deficient bottom water conditions during </span></span>source rock deposition<span><span>. The presence of isorenieratene and aryl isoprenoids suggests persistent and episodic </span>photic zone<span> anoxia during the Maastrichtian period. Elevated nutrient inputs and paleobioproductivity were recorded in the older black shale at the Heweitat mine compared to the younger one at the Queih mine. Paleoproductivity and oxygen depletion emerge as pivotal factors influencing the accumulation and preservation of organic matter within the black shales. These findings provide valuable insights into the environmental conditions prevailing during the deposition of Maastrichtian sediments in the Eastern Desert.</span></span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"283 ","pages":"Article 104457"},"PeriodicalIF":5.6,"publicationDate":"2024-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139523115","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}