International Journal of Coal Geology最新文献

{"title":"Pore systems and their correlation with oil enrichment in various lithofacies of saline lacustrine shale strata","authors":"Yan Cao ,&nbsp;Zhijun Jin ,&nbsp;Rukai Zhu ,&nbsp;Kouqi Liu","doi":"10.1016/j.coal.2024.104444","DOIUrl":"10.1016/j.coal.2024.104444","url":null,"abstract":"<div><p><span>The potential of China's saline lacustrine shale oil<span> resources is enormous. Currently, the storage space of saline lacustrine shale oil remains unclear, posing significant challenges for commercial development. In this study, we selected the samples from the typical saline lacustrine shale strata of the Lucaogou Formation, Jimusar Sag, Junggar Basin and investigated the pore systems and their relationship with oil content S</span></span>₁<span> of different lithofacies. The pore structures were quantified by using the combination of low-pressure N</span>₂<span> adsorption and mercury intrusion. TOC<span> assessment, rock pyrolysis, and XRD were utilized for characterizing the organic geochemical and mineralogical parameters. The results showed that the organic matter comprising type III mainly appears in the clay-enriched lithofacies (types I</span></span>₂, II₁ and III₂), while the organic matter types I, II₁ and II₂<span> can be found in other lithofacies. Regarding the nine lithofacies, siltstone has the highest oil content S</span>₁, followed by the felsic-enriched lithofacies (types III₃ and III₁<span>). The enrichment of oil in siltstone, carbonate rocks, and felsic-enriched lithofacies (types III</span>₃ and III₁<span>) is primarily attributed to macropores. Conversely, in clay-enriched lithofacies (types I</span>₂, II₁ and III₂), the oil content S₁<span> is attributed to both the mesopore fractal dimensions (D</span>₁ and D₂) and the TOC content. Moreover, the higher the complexity of the mesoporous structure (D₂) and the larger the macropore surface area in clayey carbonate felsic shale (II₃), the greater the oil content S₁. It is further observed that, macropores with size range between approximately 60 nm and 3000 nm are abundant in siltstone and felsic mineral-enriched lithofacies (i.e., carbonate felsic shale III₃ and felsic shale III₁). Furthermore, the siltstone shows the widest oil-rich macropore size range (range of 70–1000 nm), followed by felsic shale (III₁) (range of 150–1000) and carbonate felsic shale (III₃) (range of 100–110 nm). Siltstones and felsic-enriched shales are optimal for exploiting saline lacustrine shale deposits.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139396193","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":"Recognition and (semi-)quantitative analysis of REE-bearing minerals in coal using automated scanning electron microscopy","authors":"Biao Fu ,&nbsp;Guorong Xu ,&nbsp;James C. Hower ,&nbsp;Yijun Cao ,&nbsp;Yukun Huang ,&nbsp;Liang Si ,&nbsp;Li Xian ,&nbsp;Guangqian Luo ,&nbsp;Guijian Liu ,&nbsp;Guangqing Hu ,&nbsp;Hong Yao","doi":"10.1016/j.coal.2023.104443","DOIUrl":"10.1016/j.coal.2023.104443","url":null,"abstract":"<div><p><span>The recognition and quantification of rare earth and yttrium (REY) minerals in coal is extremely important for understanding their geological origin and developing high-efficiency extraction techniques. This study developed an automated image analysis by scanning electron microscopy (AIA-SEM) method for characterizing REY minerals in coal. Carbon and copper were used as grey-scale calibration standard to assure the consistency per experiment and differentiate organic matter and minerals with different brightness. Two critical issues in determining REY including rapid recognition of fine REY-bearing particles and accurate classification and quantification of REY minerals in coal are resolved by (1) establishing grey threshold standard to locate REY-bearing grains and a two-step image scan; (2) developing classification criteria supplemented with spot- and EDS-mapping analysis for questionable particles. By using the established method, a total of 166 REY-bearing mineral grains were identified from 12,930 particles in a medium-volatile </span>bituminous coal<span> (REY concentration: 149.21 ppm; ash yield: 21.25%). It is found that Ca-REE flurocarbonates, monazite<span>, and (Sc, Y)-bearing zircon<span><span> are the dominant REY species in the studied coal sample. REE-aluminophosphates are also important hosts for REE<span> in coal, with total amounts being &gt;10%. REY minerals are fine in particle size. Over 50% of monazite, xenotime, Ca-REE flurocarbonate, and REE-aluminophosphate have particle size below 5 μm and monazite occurs mostly as submicron particle. Most REY minerals (&gt; 60%) are embedded into </span></span>coal macerals as included minerals. About 80% of REY-bearing phosphates and zircon are partly or completely encapsulated in clay minerals, whereas more than half of Ca-REY-fluorocarbonates mineral grains is free of other minerals.</span></span></span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139101497","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 containment risks assessment for subsurface CO2 storage: Overburden analysis and top seal integrity study, offshore Norway","authors":"Md Jamilur Rahman ,&nbsp;Manzar Fawad ,&nbsp;Nazmul Haque Mondol","doi":"10.1016/j.coal.2023.104440","DOIUrl":"10.1016/j.coal.2023.104440","url":null,"abstract":"<div><p>This study summarizes the OASIS (Overburden Analysis and Seal Integrity Study for CO₂ Sequestration in the North Sea) project that focuses on assessing the containment risks associated with the geological carbon sequestration (CCS) of the Northern Lights project. CCS is viewed as one of the most effective solutions for reducing carbon emissions, as it captures carbon dioxide from point sources and permanently stores it in suitable geological formations. However, injecting CO₂ into the subsurface may have mechanical consequences, including fault reactivation, top seal fracturing, surface heave, etc. This study proposes an interdisciplinary workflow to characterize the caprock, faults, and overburden associated with CCS projects in the Horda Platform area, to improve injection-induced containment risk assessment. Our findings show that the proposed workflows and tools effectively characterize stress-related mechanical hazards. However, due to the complex nature of rocks, it is challenging to evaluate the top seal integrity using a single method. Therefore, the proposed interdisciplinary approach is more effective for any fluid injection site's characterization, given the complex nature of the subsurface and its behavior under injection-induced stress changes. This research paper adds knowledge about the top seal integrity assessment and the reliability of injected CO₂, making CCS projects more reliable and safer. Although this study focuses on the northern North Sea, the proposed methods are equally applicable globally to characterize subsurface CO₂ storage sites. Apart from CCS projects, these research results can benefit other subsurface injection projects, such as water injection for reservoir management, wastewater injection for disposal, hydrogen storage, and hydraulic fracturing for unconventional hydrocarbon resources.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0166516223002586/pdfft?md5=220a45195ba928debf6d0eb5221b96bd&pid=1-s2.0-S0166516223002586-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139101484","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":"Association and textural-compositional evolution of pyrite-organic matter in coals of the Tarakan, Barito, and Pasir Basins, Kalimantan, Indonesia","authors":"Aulia Agus Patria ,&nbsp;Renaldi Suhendra ,&nbsp;Ferian Anggara ,&nbsp;Andrea Agangi ,&nbsp;Stephen P. Obrochta ,&nbsp;Iwan Setiawan","doi":"10.1016/j.coal.2023.104442","DOIUrl":"10.1016/j.coal.2023.104442","url":null,"abstract":"<div><p><span><span><span><span>The Barito, Pasir, and Tarakan Basins in Kalimantan Island is the most extensive coal-bearing sedimentary basin in Indonesia, mined since 1989. The coal is notable in having high </span>sulfur coal content, exceeding &gt;10% in some cases, contributed by the presence of pyrite. The latter issue contributed to interest in the coal, forming economic </span>mineral deposits<span> hosted by the sedimentary pyrite and organic matter. Novel findings of this research providing valuable information of trace element behavior during the diagenetic conditions. This paper documents the textural and compositional evolution of pyrite-organic matter of coals using coal petrographic, proximate, ultimate, total sulfur content, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), </span></span>electron probe micro analyser (EPMA), and </span>Raman spectroscopy<span>. Coals from Kalimantan are mainly characterized by medium-high sulfur content (&gt;3%) and the maximum temperatures reached by organic matter during diagenesis<span> are 166 ± 10 °C for the Pasir Basin, 136 ± 11 °C for the Barito Basin, and 132 ± 12 °C for the Tarakan Basin. Pyrite is mainly found as large size framboids (mostly &gt;5 μm), indicating formation in the sedimentary layer with dysoxic bottom water conditions during early–late diagenetic stages. The framboidal pyrite was preferably formed in detrovitrinite and gelovitrinite under topogenous mire<span> conditions, due to the degradation of macerals and biochemical gelification, which provided the organic templates. High concentrations of trace elements (TEs) of framboidal pyrite, such as 1) Cu, Ni, and Co in the Pasir Basin and 2) As in the Barito Basin, likely reflect the local sedimentary provenance and underlying basement rocks. Pyrite texture evolved with increasing diagenetic temperatures from 1) framboidal pyrite, 2) recrystallized framboidal pyrite rims, and 3) anhedral, anhedral-euhedral pyrite transition, and euhedral massive pyrite. This study shows a similar average TE concentrations of various pyrite textures, suggesting that the TEs are not remobilized during the evolution of pyrite at the diagenetic stages.</span></span></span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139081999","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":"Geological factors for the enrichment of critical elements within the Lopingian (Late Permian) coal-bearing strata in western Guizhou, Southwestern China: Constrained with whole-rock and zircon geochemistry","authors":"Tianyang Yang ,&nbsp;Yulin Shen ,&nbsp;Lu Lu ,&nbsp;Jun Jin ,&nbsp;Wen Huang ,&nbsp;Fayue Li ,&nbsp;Yunfei Zhang ,&nbsp;Jiangchen Hu ,&nbsp;Lijun Zeng","doi":"10.1016/j.coal.2023.104441","DOIUrl":"10.1016/j.coal.2023.104441","url":null,"abstract":"<div><p><span><span>A number of volcanic ash-bearing layers deposited in the Upper Permian<span> coal-bearing strata on the southwestern margin of the Yangtze Craton are well preserved, and some layers show the enrichment of critical elements such as an assemblage of Zr(Hf)–Nb(Ta)–Ga–REE (REE, rare earth elements). Based on previous work, we studied the source of the Upper Permian volcanic ash-bearing layers widely distributed in western to northwestern Guizhou and the geological factors for the enrichment of critical elements. This article provides a detailed analysis of the mineralogical and geochemical characteristics of the Upper Permian volcanic ash-bearing layers. The </span></span>mineralogy<span><span><span> of the samples is dominated by clay minerals, quartz, anatase, plagioclase, and pyrite, with a few containing K-feldspar, </span>calcite<span><span>, dolomite, and siderite. The clay minerals are mainly composed of mixed-layer illite/smectite (I/S) and </span>kaolinite. The whole </span></span>rock geochemistry (Al</span></span>₂O₃/TiO₂, Nb/Ta vs. Zr/Hf, Nb/Al₂O₃ vs. Zr/Al₂O₃, and Th/Al₂O₃ vs. Zr/Al₂O₃<span><span><span><span>) and zircon trace elements (Th/Nb vs. Hf/Th, Nb/Yb vs. U/Yb, Ta vs. Nb, and Yb/Sm vs. Y) were used to help determine the source. The results indicate that the sources of the samples include Emeishan high-Ti </span>basalt<span><span>, intraplate volcanic ash from the Emeishan large igneous province (ELIP), and arc volcanic ash. The critical elements (Zr[Hf]–Nb[Ta]–REE) are mainly derived from the syndepositional intraplate volcanic ash erupted from the ELIP. The results of zircon trace elements and Hf </span>isotope ratios suggest that the </span></span>magma from the ELIP has gradually evolved from the mantle to the crust, and became more enriched in critical elements such as Nb and Ta. The intraplate volcanic ash from ELIP is the main supplier of critical elements and plays a crucial role in their enrichment through the Late Permian in southwestern China. The </span>paleoenvironment<span> controlled the deposition of volcanic ashes, and most of the critical element enrichment layers developed in weak hydrodynamic<span><span> environments. The paleogeography and acid rain influenced the migration of critical elements such as Nb, Ta, </span>REE, and Y in some layers. The enrichment of critical elements is also controlled by the regularity and intensity of intraplate volcanic activity.</span></span></span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139081839","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":"Effect of ScCO2-H2O treatment duration on the microscopic structure of coal reservoirs: Implications for CO2 geological sequestration in coal","authors":"Yarui Guan ,&nbsp;Zhe Zhou ,&nbsp;Zhaolong Ge ,&nbsp;Qinglin Deng ,&nbsp;Yunzhong Jia ,&nbsp;Shan Huang ,&nbsp;Changjiang Chen ,&nbsp;Shihui Gong","doi":"10.1016/j.coal.2023.104439","DOIUrl":"10.1016/j.coal.2023.104439","url":null,"abstract":"<div><p><span>The microstructure of coal reservoirs, especially the pore structure, alters as a result of physicochemical reactions between the CO</span>₂ acidic fluid and coals. However, it is still unclear what controls this process and how the pore structure properties of coal alter by the action of CO₂<span><span> acid fluids change over time. The objective of this study is to identify the underlying mechanism by analyzing the changes in the mineral composition, surface roughness<span>, as well as micropore and mesopore structure of </span></span>anthracite<span> and bituminous coal<span> when exposed to supercritical CO</span></span></span>₂ (ScCO₂)-H₂<span>O. The results indicate that coal reservoirs primarily undergo processes of adsorption expansion and mineral dissolution/precipitation. Among these, adsorption expansion concluded or weakened after 7 days, with mineral precipitation gradually becoming the dominant factor, which results in more secure geological CO</span>₂ storage (GCS). Furthermore, comparative analysis of anthracite and bituminous coal with untreated and long-term treatment demonstrates that anthracite exhibits higher CO₂<span><span> storage capacity and greater wettability. Consequently, anthracite is more suitable as a target reservoir for GCS compared to bituminous coal. These results, therefore, offer a theoretical foundation and a guide for choosing GCS sites in deep un-minable </span>coal seams.</span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2023-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139060798","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":"Modes of occurrence of gallium in Al-Ga-rich coals in the Jungar Coalfield, Ordos Basin, China: Insights from LA-ICP-MS data","authors":"Bo Jiu ,&nbsp;Zhijun Jin ,&nbsp;Zhaoguo Wang ,&nbsp;Runchao Liu ,&nbsp;Qitu Hu","doi":"10.1016/j.coal.2023.104436","DOIUrl":"10.1016/j.coal.2023.104436","url":null,"abstract":"<div><p><span><span><span>Owing to the concern about supply of Ga, it has been attracted much attention for the modes of occurrence of Ga in Al-Ga-rich coal-hosted deposits. However, the modes of occurrence of Ga in coal were mainly investigated using indirect methods, which may cause uncertainties. In this study, laser ablation </span>inductively coupled plasma mass </span>spectrometry<span> (LA-ICP-MS) spot and mapping analysis were used to directly characterize the concentration of Ga within the host minerals including kaolinite<span><span> and boehmite, and to investigate the distribution of Ga in organic matter in the Carboniferous Al-Ga-rich coal from the Haerwusu Mine in the Jungar Coalfield of the Ordos Basin, North China. Microscope observation and scanning </span>electron microscope<span> - energy dispersive spectrometry (SEM-EDS) analysis were performed, along with petrographical and mineralogical investigations. Eight types of kaolinite and three types of boehmite particles from coal, erosional-sourced mudstone, and tonstein were identified, classified, and selected for the determination of </span></span></span></span><em>in-situ</em><span> elemental compositions.</span></p><p>The results showed that the concentration of Ga in the selected minerals varies, with the following order from highest to lowest: colloidal boehmite (90.38 ppm), low-Al (Al₂O₃/SiO₂<span>) clastic kaolinite (84.67 ppm), high-Al clastic kaolinite (55.49 ppm), Na-bearing kaolinite (49.94 ppm), fine-grained boehmite (47.13 ppm), high-Al cryptocrystalline<span> kaolinite (40.25 ppm), low-Al cryptocrystalline kaolinite (38.78 ppm), and low-Al vermicular kaolinite (29.67 ppm), high-Al vermicular kaolinite (28.37 ppm), K-bearing kaolinite (19.44 ppm), and clastic boehmite and cell-filling kaolinite (below detection limit). LA-ICP-MS mapping demonstrated that a certain proportion of Ga could be associated with organic matter, concentrating on vitrinite. Notably, the concentration of Ga in clastic kaolinite and colloidal boehmite was found to be substantially higher compared to the whole-rock coal and erosional-sourced mudstone samples, indicative of their dominant host minerals for Ga. Conversely, the concentration of Ga in K-bearing or Na-bearing kaolinite which had experienced transformation from primary kaolinite is much lower than that in clastic kaolinite, while the concentration of Ga in fine-grained boehmite, which had altered from kaolinite, surpassed that of its corresponding kaolinite layer. These findings suggest that gallium could have undergone migration during the evolution or alteration of clay minerals.</span></span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139060009","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 geochemistry and organic petrology of Oligocene and Miocene lignites, subbituminous and high volatile bituminous coals and carbonaceous shales in northern and central Trinidad","authors":"Anastasia A. Baboolal ,&nbsp;Ralf Littke ,&nbsp;Laura Zieger","doi":"10.1016/j.coal.2023.104437","DOIUrl":"10.1016/j.coal.2023.104437","url":null,"abstract":"<div><p>The so far unstudied Oligocene<span> and Miocene<span><span> organic matter–rich deposits of the Cunapo and Nariva Formation of northern and central Trinidad, western tropical Atlantic Ocean have been investigated using organic geochemical and organic petrological techniques to assess the </span>thermal maturity<span><span> and paleoenvironmental conditions during peat accumulation. Twenty samples were collected along various sections within the Cunapo and Nariva formations. Evaluation based on organic petrological analyses and Rock-Eval pyrolysis reveals that the coals and carbonaceous shales are thermally immature in the </span>lignite<span> and subbituminous rank for Cunapo Formation and mature in the subbituminous to high-volatile bituminous rank for Nariva Formation. The respective maturities correspond to high volatile matter contents.</span></span></span></span></p><p><span>Petrographically, the Cunapo Formation coals are dominated by huminite with minor amounts of inertinite<span><span> and liptinite<span>, and the Nariva Formation coals contain high amounts of vitrinite, with moderate to low liptinite and low inertinite contents. The detailed petrographic data for Cunapo and Nariva coals indicate predominantely limnic conditions and a herbaceous </span></span>origin of organic matter. Further conclusions are deduced from petrographic ratios such as gelification-, tissue preservation-, vegetation- and groundwater</span></span>_AC<span> indices, ash- and sulfur contents<span>, iso- and n-alkane distribution, and 17α(H)-homohopane ratio. In summary, the data supports that both the Cunapo and Nariva coals formed in a tropical peat environment, partly influenced by very high microbial activity<span> and ± in case of Nariva coals - partly grading into ombrogenic mires. The Cunapo coals were influenced by the development of the Orinoco River system during the Miocene and exposure to marine water during transgressive phases in a tidal, coastal environment.</span></span></span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139059438","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":"Multi-tracer approach to constrain groundwater flow and geochemical baseline assessments for CO2 sequestration in deep sedimentary basins","authors":"Harald Hofmann ,&nbsp;Julie K. Pearce ,&nbsp;Phil Hayes ,&nbsp;Sue D. Golding ,&nbsp;Nick Hall ,&nbsp;Kim A. Baublys ,&nbsp;Matthias Raiber ,&nbsp;Axel Suckow","doi":"10.1016/j.coal.2023.104438","DOIUrl":"10.1016/j.coal.2023.104438","url":null,"abstract":"<div><p>Geological storage of gases will be necessary in the push to net zero and the energy transition to reduce carbon emissions to atmosphere. These include CO₂ geological storage in suitable sandstone reservoirs. Understanding groundwater flow, connectivity and hydrogeochemical processes in aquifer and storage systems is vital to prevent risk and protect important water resources, such as the Great Artesian Basin. Here, we provide a ‘tool-box’ of geochemical assessment methods to provide information on flow patterns through the basin's aquifers (changes in chemistry along flow path), stagnant versus flowing conditions (cosmogenic isotopes and noble gases), inter-aquifer connectivity and seal properties (major ions, Sr and stable isotopes), water quality (major ions and metals) and general assessments on residence times of groundwater (cosmogenic isotopes and noble gases). This information can be used with reservoir and groundwater models to inform on possible changes in the above-mentioned processes and serve as input parameters for CO₂ injection impact modelling. We demonstrate the use and interpretation on an example of a potential CO₂ storage geological sequestration site in the Surat Basin, part of the Great Artesian Basin, and the aquifers that overly the reservoir. The stable water isotopes are depleted compared to average rainfall and most likely indicate greater contributions from monsoonal rain events from the northern monsoonal troughs, where amount and rainout effects lead to the depletion rather than colder recharge climates. This is supported by the modern recharge temperatures from noble gases. Inter-aquifer mixing between the Precipice Sandstone reservoir and the Hutton Sandstone aquifer seems unlikely as the Sr isotope ratios are distinctly different suggesting that the Evergreen Formation is a seal in the locations sampled. Mixing, however, occurs on the edges of the basin, especially in the south-east and east where the Surat Basin transitions into the Clarence-Moreton Basin. Groundwater flow appears to be to the south in the Precipice Sandstone, with a component of flow east to the Clarence-Morton Basin. The cosmogenic isotopes and noble gases strongly indicate very long residence times of groundwater in the central south Precipice Sandstone around a proposed storage site. ¹⁴C values below analytical uncertainty, R³⁶Cl ratios at secular equilibrium as well as high He concentrations and high ⁴⁰Ar/³⁶Ar ratios support the argument that groundwater flow in this area is extremely slow or groundwater is stagnant. The results of this study reflect the geological and hydrogeological complexities of sedimentary basins and that baseline studies, such as this one, are paramount for management strategies.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0166516223002562/pdfft?md5=789c48b3ac6bf0b012217ea4726fbbb6&pid=1-s2.0-S0166516223002562-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139059661","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":"Factors controlling the heterogeneity of shale pore structure and shale gas production of the Wufeng–Longmaxi shales in the Dingshan plunging anticline of the Sichuan Basin, China","authors":"Yijun Zheng ,&nbsp;Yuhong Liao ,&nbsp;Jie Wang ,&nbsp;Yongqiang Xiong ,&nbsp;Yunpeng Wang ,&nbsp;Ping’an Peng","doi":"10.1016/j.coal.2023.104434","DOIUrl":"10.1016/j.coal.2023.104434","url":null,"abstract":"<div><p><span><span>Shale gas exploration in the Dingshan plunging </span>anticline of the Sichuan Basin, China, has uncovered substantial Wufeng–Longmaxi shale reserves. However, substantial variations exist in shale gas content and production among the wells in this region. We investigated the geological factors and mechanisms influencing shale pore structure heterogeneity and shale gas content and production in the area. We conducted comprehensive analyses of </span>mineralogy<span><span><span>, geochemical characteristics, and petrophysical properties on the Late Ordovician<span> Wufeng Formation–Early Silurian Longmaxi </span></span>Formation shales. Shale samples were collected from a shallow well, Anwen-1, located in proximity to the Qiyueshan </span>thrust fault<span><span><span> within the Dingshan plunging anticline. Additionally, samples from Dingye (DY) 1 and DY 3 wells, located at varying distances from the thrust fault, were examined. We also integrated previously published data from two correlative sections in the southeastern margin of the Sichuan Basin, each at different distances from the thrust fault. The pore volume, specific surface area, and porosity of the shales were positively correlated with their total organic content (TOC). However, strong lateral compressive stress, often occurring near the regional thrust fault, attenuated the linear relationship between </span>TOC<span> and pore volume/porosity. Lateral compressive stress did not significant affect shale porosity and pore structure when the distance from the regional thrust fault exceeded approximately 15 km. The specific surface area of the shale was less affected by compressive stress. Moreover, carbonate cementation<span> reduced porosity by sealing shale matrix pores and natural microfractures, reducing </span></span></span>nanopore connectivity. Consequently, shale gas production is not solely influenced by shale gas content but is also significantly affected by carbonate cementation. Therefore, shale reservoirs located at relatively long tectonic distances from regional thrust faults (approximately 15 km) within the Dingshan plunging anticline exhibit high pore volume, porosity, and shale gas content, rendering them favorable for shale gas exploration.</span></span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2023-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139041605","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}