Applied Geochemistry最新文献

{"title":"Dissolution behavior of calcium uranate under oxidizing and reducing conditions","authors":"Yuto Kato ,&nbsp;Takayuki Sasaki ,&nbsp;Ryutaro Tonna ,&nbsp;Taishi Kobayashi ,&nbsp;Yoshihiro Okamoto","doi":"10.1016/j.apgeochem.2024.106196","DOIUrl":"10.1016/j.apgeochem.2024.106196","url":null,"abstract":"<div><div>Calcium uranate solid phase is a secondary mineral found in geological environments. It may form in the residues of high-level radioactive liquid waste and in the fuel debris of the TEPCO's Fukushima Daiichi Nuclear Power Plant under high-temperature conditions. To assess the chemical stability of CaUO₄ in different aqueous environments, static immersion tests were performed under various redox conditions and carbonate ion concentrations. pH and Eh values, as well as concentrations of uranium, calcium, and total carbonate in the solutions, were measured after the supernatants were filtered through a membrane with a 10 kDa molecular weight cutoff. The components of the solid phase were also evaluated using X-ray diffraction and X-ray absorption fine structure analyses. The dissolution mechanism of CaUO₄ was examined using data from solid and liquid analyses, along with chemical thermodynamic calculations. Under reducing conditions and without carbonate, U(VI) in CaUO₄ was reduced to U(V) and the mineral was converted into non-stoichiometric CaUO_{4−<em>x</em>}. The dissolved uranium was then further reduced to U(IV) in the aqueous media, forming UO₂(am), which controlled the U solubility. Under oxidizing conditions and in the absence of carbonate, dissolved uranium formed metaschoepite ((UO₃)·2H₂O(cr)) at pH ≤ 7 and sodium diuranate (Na₂U₂O₇·H₂O(cr)) at pH &gt; 7, which controlled uranium solubility. In oxidizing conditions with carbonate present, the apparent solubility of U was lower than predicted by the solid-phase solubility calculations. The concentration of U was constrained to levels similar to that of calcium when the calcium concentration reached saturation with CaCO₃. Additionally, the dissolution of calcium from CaUO₄ influenced uranium dissolution.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"175 ","pages":"Article 106196"},"PeriodicalIF":3.1,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Catalytic oxidation of Mn(II) on ferrihydrite and goethite surfaces and the subsequent oxidation and immobilization of coexisting Cr(III)","authors":"Rongrong Su ,&nbsp;Chunhui Li ,&nbsp;Minyu He ,&nbsp;Kangsheng Hu ,&nbsp;Zhangjie Qin ,&nbsp;Shuai Lan","doi":"10.1016/j.apgeochem.2024.106195","DOIUrl":"10.1016/j.apgeochem.2024.106195","url":null,"abstract":"<div><div>Semiconductor iron oxides, which are distributed in soils, always catalyze Mn(II) oxidation to produce various Fe–Mn binary oxides. They affect the migration and transformation of heavy metals, <em>i.e.</em>, Cr(III). However, the specific effect mechanisms of different catalytic oxidation pathways (<em>i.e.</em>, electrochemical or interfacial catalysis) of Mn(II) catalyzed by minerals possessing different characteristics on the oxidation of coexisting Cr(III) remains elusive. Therefore, this study aims to explore different Mn(II) oxidation processes on ferrihydrite and goethite surfaces as well as the subsequent oxidation of coexisting Cr(III) and Cr(VI) immobilization. Herein, long-time aging oxidation tests were performed combined with solution chemical analysis and various spectroscopic techniques such as X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), to explore the Mn(II) catalytic oxidation behaviors on ferrihydrite and goethite surfaces under different pHs and initial Mn(II) reaction concentrations, as well as the oxidation products of Fe–Mn binary oxides. Subsequently, the oxidation mechanisms of Cr(III) by these different generated Fe–Mn binary oxides were studied. Results indicated that higher pH and initial reaction concentration of Mn(II) were more favorable for Mn(II) oxidation yielding more Mn oxides containing higher valence Mn. Additionally, goethite, which has better conductivity, showed stronger electrochemical catalysis effect for Mn(II) oxidation than ferrihydrite. Thus, more Mn(III) oxides were generated in goethite systems than in ferrihydrite systems. Fe–Mn binary oxides formed from higher Mn(II) oxidation rates and degrees exhibited more improved oxidative properties for Cr(III) and higher Cr(VI) fixation efficiencies than those obtained from lower reactions. These phenomena depended on the stronger oxidation and fixation effect of Mn(II) oxidation products with higher Mn valence states of Mn(III/IV) on Cr(III) and Cr(VI), respectively. Moreover, Mn(III) in Fe–Mn binary oxides exhibited considerably higher oxidation efficiency for Cr(III) than Mn(IV). In summary, high pH, higher initial Mn(II) concentration, and iron oxides with stronger electrochemical catalytic effect are more conducive to the oxidation of Mn(II) as well as the subsequent oxidation of coexisting Cr(III) and the immobilization of formed Cr(IV).</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"175 ","pages":"Article 106195"},"PeriodicalIF":3.1,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of geochemically induced permeability alteration in geothermal reservoirs and its implications for sustainable geothermal energy production","authors":"Taylor Smith ,&nbsp;Adedapo N. Awolayo ,&nbsp;Stephen E. Grasby ,&nbsp;Benjamin M. Tutolo","doi":"10.1016/j.apgeochem.2024.106193","DOIUrl":"10.1016/j.apgeochem.2024.106193","url":null,"abstract":"<div><div>Geothermal resources constitute a significant portion of the world's low-carbon, renewable energy potential, with about 75% classified as low-temperature. One such potential resource exists in Precambrian basement rocks underlying the Williston Basin in southern Saskatchewan, Canada, with a reservoir temperature of 120 °C. However, geochemically induced permeability alteration in these highly reactive low-temperature granitoid resources poses a significant risk to long-term heat production. To assess and potentially mitigate this risk, we conducted a geochemical and mineralogical study of both altered and unaltered samples. Our findings facilitated the parameterization of geochemical simulations of water-rock interactions to predict mineral volume changes and, by extension, draw inferences on porosity and permeability changes resulting from these interactions. The simulations indicate an increased mineral volume in both samples, yet geothermal alteration of the unaltered, and thus more reactive, rocks induced relative mineral volume changes about 30% greater than those in the altered rocks. The resulting absolute change in porosity is 0.5 vol% for the unaltered rocks and 0.35 vol% for the altered rocks. Utilizing an empirical porosity-permeability relationship, the computed change in permeability indicates that the unaltered basement rock experienced a greater change in total permeability than the altered basement rocks. Additional calculations demonstrate the sensitivity of the porosity-permeability equation to critical porosity and power exponent, forecasting various scenarios with permeability changes ranging from 1.0 × 10⁻¹³ to 1 × 10⁻²⁰ m². Consequently, we infer that altered, permeable zones of the examined Precambrian basement rocks are likely to offer favourable conditions for sustained, multi-decade heat production, and thus should be targeted over less altered zones to justify initial capital expenditures. Globally, geothermal heat extraction from these rocks remains an underexplored yet promising resource for generating reliable, low-carbon renewable energy, crucial in our efforts to decarbonize the global economy.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"175 ","pages":"Article 106193"},"PeriodicalIF":3.1,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selenium interaction with iron minerals: Quantitative comparison of sorption and coprecipitation impacts on mobility","authors":"Enrica Balboni ,&nbsp;Sol-chan Han ,&nbsp;Mavrik Zavarin","doi":"10.1016/j.apgeochem.2024.106194","DOIUrl":"10.1016/j.apgeochem.2024.106194","url":null,"abstract":"<div><div>Given the significance of selenium (Se) as a micronutrient, the radioactive nature of some of its isotopes, and its affinity to iron (Fe) minerals, extensive research has been conducted on the sorption mechanisms between Se and these minerals. Here, we employ sorption data sourced from the L-SCIE database and coprecipitation data from available literature to achieve the following objectives: i) establish coherence between adsorption and coprecipitation processes, ii) quantitatively evaluate the importance of these processes in nuclear waste repository science, and iii) propose a forward-looking approach for integrating coprecipitation into reactive transport models. Our findings indicate that a correlation between Se adsorption and coprecipitation can be established using the <em>λ</em> formalism. The comparable log(λ_Se(IV)/λ_Se(VI)) ratios derived from adsorption and coprecipitation experiments suggest that these processes can be quantitatively compared and evaluated using our numerical approach. Across all iron oxide phases examined, coprecipitation leads to significantly greater immobilization of Se compared to adsorption. Specifically, for hydrous ferric oxide, hematite, and goethite, coprecipitation is predicted to result in 100–1000 times more Se immobilization compared to adsorption, irrespective of the Se oxidation state (Se(IV) or Se(VI)); notably stronger immobilization potential via coprecipitation was observed for magnetite. The modeling approach and quantitative analysis presented herein clearly highlight the importance of including coprecipitation processes when simulating Se (and other elements) transport, particularly under conditions where mineral compositions are transient or evolving with time. Neglecting coprecipitation in models is likely to lead to significant overestimates of migration.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"175 ","pages":"Article 106194"},"PeriodicalIF":3.1,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High resolution concentration-discharge relationships in managed watersheds: A 30+ year analysis","authors":"M.A. Diaz ,&nbsp;S.K. Fortner ,&nbsp;W. Berry Lyons","doi":"10.1016/j.apgeochem.2024.106192","DOIUrl":"10.1016/j.apgeochem.2024.106192","url":null,"abstract":"<div><div>Concentration-discharge (C-Q) relationships provide insight into solute transport and biogeochemical processes for watersheds. A 30+ year, high-resolution dataset from the North Appalachian Experimental Watershed (NAEW) offers an unparalleled opportunity to explore land use and land management impacts on C-Q relationships for small watersheds of varying land management histories (agricultural to forested). The NAEW was among the few hydrologic research sites where storm event runoff was sampled using proportional sampling. This method captures the concentration-discharge behavior associated with land use more effectively than instantaneous sampling, which favors rising limb or falling limb dynamics. In this study, we explore C-Q relationships by investigating baseflow and storm event flow across their total behavior. We also build a systems-understanding by comparing chemostatic behavior to soil geochemistry and land use history. Highly managed agricultural watersheds with no associated stream baseflow demonstrate near-chemostatic behavior for most solutes, while mixed use and forested watersheds with associated streams are more mutable depending on whether primary sources of water were groundwater or surface water. Using this unique high-resolution dataset, we show that concentration-discharge relationships are influenced by soil and baseflow geochemistry, pore fluid concentration, and land type/land use legacy effects.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"175 ","pages":"Article 106192"},"PeriodicalIF":3.1,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reactive transport model of the long-term geochemical evolution in a HLW repository in granite at the disposal cell scale: Variants, sensitivities, and model simplifications","authors":"Javier Samper,&nbsp;Alba Mon,&nbsp;Luis Montenegro","doi":"10.1016/j.apgeochem.2024.106188","DOIUrl":"10.1016/j.apgeochem.2024.106188","url":null,"abstract":"<div><div>The assessment of the long-term performance of the engineered barrier systems of high-level radioactive waste (HLW) repositories requires the use of reactive transport models. Montenegro et al. (2023) presented a non-isothermal reactive transport model of the long-term geochemical evolution of a HLW disposal cell in a granitic host rock corresponding to a generic reference concept. The model accounted for the vitrified waste, the carbon-steel canister, the bentonite buffer and the reference granitic rock. Here we extend their model by considering model variants (V), sensitivity cases (SC) and model abstractions (MA). Variants V1, V2 and V3 consist of considering MX-80 bentonite instead of FEBEX bentonite (V1), a larger groundwater flux through the granite (V2) and the Czech reference crystalline rock as a host rock (V3). Cases SC1 and SC2 consider a decrease of the silica concentration threshold value in the glass dissolution rate (SC1) and an earlier canister failure time (SC2), respectively. Runs MA1 to MA4 consider smectite as an unreactive mineral phase (MA1), the porosity feedback effect on chemical and transport parameters (MA2), a time-varying corrosion rate (MA3), and a coarser finite element grid (MA4), respectively. Model results of V1 show a larger pH, a smaller precipitation of magnetite, siderite and greenalite and a slightly smaller dissolution of ISG and smectite than the base run of Montenegro et al. (2023). Model predictions are very sensitive to the increase in the groundwater flow through the granitic host rock (V2). However, predictions are not sensitive to the chemical composition of the granite porewater (V3). The decrease in the silica saturation threshold from 1·10⁻³ to 5·10⁻⁴ mol/L in SC1 leads to a significant decrease in glass dissolution. Glass dissolution after 50,000 years in SC2 (earlier canister failure) is much larger than that of the base run. Model results are not sensitive to considering smectite as an unreactive mineral phase (MA1). However, model results are very sensitive to the porosity feedback effect (MA2). A 60% volume fraction of Fe(s) remains uncorroded after 50,000 years when a variable corrosion rate is considered in MA3. In this case the precipitation of corrosion products is much smaller than that of the base run. The general patterns of the numerical results in MA4 (coarser grid) are similar to those of the base case.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"175 ","pages":"Article 106188"},"PeriodicalIF":3.1,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142416495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization and solubility measurement of synthetic uranophane and sklodowskite under oxic groundwater conditions","authors":"Wansik Cha,&nbsp;Junghwan Park,&nbsp;Euo Chang Jung,&nbsp;Hye Ran Noh,&nbsp;Hee-Kyung Kim,&nbsp;Hye-Ryun Cho","doi":"10.1016/j.apgeochem.2024.106191","DOIUrl":"10.1016/j.apgeochem.2024.106191","url":null,"abstract":"<div><div>Naturally occurring uranyl silicates can serve as solubility-limiting solid phases (SLSPs) of U(VI) in the oxic environment of granitic groundwater, which is likely to occur in crystalline host rock media in Korea. In this study, two synthetic uranyl silicates, uranophane (Ca[UO₂SiO₃OH]₂·5H₂O) and sklodowskite (Mg[UO₂SiO₃OH]₂·6H₂O) were prepared and used to measure the U(VI) solubility in simulated groundwater (sGW), mimicking the composition of samples collected from the underground research tunnel at the Korea Atomic Energy Research Institute (KAERI). The solid- and solution-phase species involved were examined in detail using various characterization methods. According to the powder X-ray diffraction pattern and elemental analysis results, the synthetic mineral phases, which were identified as uranophane-α and sklodowskite having layered crystal structures, were retained intact in sGW; however, in 0.1 M NaClO₄, emergence of other solid phases was observed. Enhanced FTIR and Raman spectroscopic data, particularly in the regions of 790–860 and 940–1020 cm⁻¹ for the UO₂²⁺ and SiO₄⁴⁻ ions, respectively, enable monitoring the changes in the solid phases. Ternary Ca–U(VI)-tricarbonato complexes were identified as the dominant dissolved U(VI) species in sGW using time-resolved laser-induced luminescence spectroscopy. Furthermore, the solubility constant of uranophane was calculated (log <em>K</em>_s,0° = 10.3 ± 0.4) and compared with the predicted values based on our geochemical modeling analysis and previously reported ones.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"175 ","pages":"Article 106191"},"PeriodicalIF":3.1,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142416490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lithium isotope systematics in an endorheic saline lacustrine system: Insights from Qinghai Lake, China","authors":"Yin Li ,&nbsp;Yang-Yang Wang ,&nbsp;Fancui Kong ,&nbsp;Haicheng Wei ,&nbsp;Jack Geary Murphy ,&nbsp;Dong-Bo Tan ,&nbsp;Jing Chen ,&nbsp;Jing Lei ,&nbsp;Yigan Lu ,&nbsp;Cheng-Long Yu ,&nbsp;Yilin Xiao","doi":"10.1016/j.apgeochem.2024.106190","DOIUrl":"10.1016/j.apgeochem.2024.106190","url":null,"abstract":"<div><div>The study of lithium isotopic (δ⁷Li) signatures in sedimentary deposits has become a powerful tool to infer past silicate weathering regimes, thus informing our knowledge of the geological carbon cycle and paleoclimate evolution. Sediments from Qinghai Lake, the largest saltwater lake in China (4625 km²), offer an unparalleled archive for investigating the climatic history of the Qinghai-Tibet Plateau. However, prior to leveraging the δ⁷Li proxy in this context, it is imperative to unravel the mechanisms of lithium (Li) isotope fractionation and elemental cycling within the lake's aqueous and sedimentary systems. In this study, we collected and analyzed samples of Qinghai Lake's water, sediments, and recharge waters (rivers, groundwater, and rainfall) to investigate the processes controlling the δ⁷Li value recorded in Qinghai Lake sediments.</div><div>Our data reveal subtle variances in Qinghai Lake water Li concentration ([Li]), ranging from 652 to 873 ng/g, suggesting interactions with iron oxides or suspended matter. The δ⁷Li signature, however, exhibits remarkable uniformity across the lake at 32.1‰ (±0.4‰). Near the estuary of the Buha River, there is a swift homogenization of [Li] and δ⁷Li, stabilizing within just 3 km of the inflow. Lake sediments exhibit δ⁷Li values ranging from 1.5‰ to 6.6‰, exceeding those of the upper continental crust (∼0‰ ± 4‰), yet approximately 30‰ lower than those in lake waters. This significant discrepancy between the δ⁷Li of lake water and sediments is likely due to the preferential incorporation of ⁶Li over ⁷Li during the neoformation of clay minerals.</div><div>Lithium mass balance modeling for Qinghai Lake, incorporating inputs from river and groundwater (∼46.5 t/a with δ⁷Li ∼18.3‰) and outputs via clay mineral uptake (∼44 t/a with δ⁷Li ∼5.1‰), indicates that the lake's Li system is currently out of steady state. The model predicts a gradual rise in the lake's Li inventory, estimated to achieve steady state within 1.2 ka and the δ⁷Li value of lake water will increase until reaching ∼45‰ assuming constant climate conditions.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"175 ","pages":"Article 106190"},"PeriodicalIF":3.1,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142416494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dissolution kinetics and heterogeneous evolution of dolomite with different pore structures","authors":"Jiayi Ma ,&nbsp;Shuyun Xie ,&nbsp;Min She ,&nbsp;Tianfu Zhang ,&nbsp;Anjiang Shen ,&nbsp;Zhiwei Kuang ,&nbsp;Yue Zhou ,&nbsp;Zhengyu Bao","doi":"10.1016/j.apgeochem.2024.106186","DOIUrl":"10.1016/j.apgeochem.2024.106186","url":null,"abstract":"<div><div>Mesogenetic dissolution is a critical process in the evolution and preservation of pore spaces in carbonate reservoirs. While limestone dissolution has been extensively studied, there is a lack of research on the dissolution kinetics of dolomite reservoirs, particularly regarding differences in dissolution mechanisms and heterogeneity evolution across various pore structures. This study aims to investigate diagenesis processes and heterogeneity evolution patterns in dolomites with different pore structures by simulating reservoir dissolution using organic acids generated during kerogen cracking. Flow system dissolution experiments were conducted on four dolomites with varying pore structures in 0.2% acetic acid under high-temperature (T = 40–160 °C) and high-pressure (P = 10–50 MPa) conditions. The chemical composition of the fluid and pore structure images were analyzed using ICP-OES and X-ray computed microtomography, respectively. Pore size distribution and evolution were assessed through digital cores based on Micro-CT analysis, while fractal and multifractal analyses were employed to quantify the evolution of pore structure heterogeneity. The findings highlight the importance of an effective combination of early material base and subsequent organic acid dissolution in the formation and maintenance of deep, high-quality dolomite reservoirs.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"175 ","pages":"Article 106186"},"PeriodicalIF":3.1,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142416489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using benzonaphthothiophenes to trace paleo-oil migration directions in the Ediacaran-Cambrian reservoirs of the central Sichuan Basin","authors":"Zhi Chai ,&nbsp;Zhonghong Chen ,&nbsp;Moïse Luemba","doi":"10.1016/j.apgeochem.2024.106189","DOIUrl":"10.1016/j.apgeochem.2024.106189","url":null,"abstract":"<div><div>Benzonaphthothiophenes (BNTs) are important organosulfur compounds in oil, and their concentrations and [2,1]/([2,1] + [1,2])BNT ratio have been used as migration tracers. Here we focus on the applicability of BNTs as migration tracers for abnormally heat-altered paleo-oil reservoirs. For this purpose, 57 pyrobitumen samples from the Ediacaran to Cambrian dolomite reservoirs in the central Sichuan Basin were collected and detected by gas chromatography-mass spectrometry. The results showed that most pyrobitumens of the studied samples are characterized by high concentrations of unsubstituted polycyclic aromatic hydrocarbons (PAHs), high values of fluoranthene/PAHs, pyrene/PAHs, fluoranthene/(fluoranthene + pyrene), benzofluoranthene/(benzofluoranthene + benzopyrene), and unsubstituted-to-methylated aromatic ratios due to the alteration by abnormal heating. These pyrobitumens have high concentrations of BNTs, and their three isomers show a pattern of [2,1] &gt; [1,2] &gt; [2,3]BNT. The BNTs concentrations display a good positive relationship with the concentrations of the abnormal heating-related PAH, while [2,1]/([2,1] + [1,2])BNT ratio has no correlation with the abnormal heating-related indices, suggesting that abnormal heating of the paleo-oil reservoirs lead to the enrichment of BNTs but has a limited effect on [2,1]/([2,1] + [1,2])BNT ratio. Moreover, [2,1]/([2,1] + [1,2])BNT ratio seem to be not affected by kerogen type and depositional environment, but increases with source rock maturity. Therefore, the [2,1]/([2,1]+[1,2])BNT is still an effective migration tracer for abnormally heated reservoirs. This ratio was applied as migration tracer in the studied area. The result suggests that the paleo-oil primarily migrated from west depression to east bulges, followed by the direction from northwest to southeast, which is congruent with the geological setting and exploration practice, demonstrating the applicability of this parameter for abnormally heat-altered oil reservoirs.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"175 ","pages":"Article 106189"},"PeriodicalIF":3.1,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}