Fire is a fundamental ecological driver shaping natural vegetation patterns.In the semi-arid southern Espinal-Monte ecotone of Argentina,the spatiotemporal patterns of fire occurrence related to and modulated by clima...Fire is a fundamental ecological driver shaping natural vegetation patterns.In the semi-arid southern Espinal-Monte ecotone of Argentina,the spatiotemporal patterns of fire occurrence related to and modulated by climatic gradients and antecedent conditions are not well researched.This study examined fire occurrence in the semi-arid southern Espinal-Monte ecotone(southeastern La Pampa,northeastern Río Negro,and southwestern Buenos Aires with an area of 68×103 km2)of Argentina,a key environmental transition zone with pronounced climatic and vegetation gradients.The objective was to identify the spatiotemporal patterns of fire occurrence and their relationship with climatic variables.Thermal anomaly(TA)data from the MODIS(Moderate Resolution Imaging Spectrometer;MOD14)sensor(November 2000–March 2020)with confidence levels>65.0%were analyzed.Climatic variables(rainfall isohyets and aridity indices)were obtained from the WorldClim datasets,and annual meteorological conditions(rainfall and potential evapotranspiration)were calculated using the climatic research unit(CRU)database.Monthly data and moving averages of rainfall and aridity indices from distinct periods(two and three years preceding fire events)were integrated.Spatial analysis was conducted using kernel density estimation on a 10 km×10 km grid to correlate TA with climatic gradients,while linear regression examined relationships between summer TA and meteorological variables over different periods.Results showed that the highest fire occurrence was recorded in summer,with peaks in December and January.Spatially,55.0%of TA occurred in areas with annual rainfall of 300–400 mm,and 64.5%in areas with an aridity index of 0.3–0.4,forming an arc-like distribution in the center of the ecotone.The highest TA densities were observed in southeastern La Pampa and northeastern Río Negro,decreasing toward southwestern Buenos Aires.Significant correlations(R2>0.700)were found among TA accumulation,aridity index values,and cumulative rainfall from previous two and three years,at both vegetation unit and provincial levels.Summer was the critical season for fire occurrence,with spatial distribution primarily determined by the interaction between climatic conditions and woody biomass availability.The lower fire incidence in southwestern Buenos Aires was linked to sparse woody vegetation and agricultural expansion,which reduced fuel load.These findings reinforce that fuel availability,modulated by climatic conditions from previous years,is a key limiting factor for fire dynamics in this area,and that human activities such as agriculture and grazing alter fire regimes by affecting fuel structure and continuity.展开更多
The pore structure of shale oil reservoir significantly affects the occurrence and mobility of hydrocarbons.The potential of a new type of alkaline lake shale oil has been demonstrated,but there are few reports on the...The pore structure of shale oil reservoir significantly affects the occurrence and mobility of hydrocarbons.The potential of a new type of alkaline lake shale oil has been demonstrated,but there are few reports on the pore system of alkaline lake shale,which restricts the efficient exploration and development of shale oil.This study investigates the Fengcheng Formation shale in the Mahu sag of the Junggar Basin,employing methods such as low-temperature nitrogecn adsorption(LTNA),mercury intrusion capillary pressure(MICP),and nuclear magnetic resonance(NMR)to quantitatively characterize the multi-scale pore structure and fractal characteristics of shale,while evaluating the applicability of these methods.Based on a comprehensive analysis of material composition,different pore types,and fractal dimensions,the controlling factors for the development of different pore types and their seepage capacity are discussed.The results indicate that inorganic mineral pores are the main development in alkaline lake shale,with the pore morphology being characterized by slit-like and ink-bottle shapes.The multi-scale pore size distribution(PSD)shows that Ⅱ-micropores(10-100 nm)and mesopores(100–1000 nm)are the main contributors to the pore system.The development of Ⅱ-micropores is associated with feldspar and calcareous minerals,the development of Ⅰ-micropores(<10 nm)and mesopores is related to quartz content,while large pores are mainly found in interlayer fissures of clay minerals.The development of Ⅰ-micropores increases the roughness of pore surface and enhances the adsorption capacity of the pores,while the development of Ⅱ-micropores associated with calcareous minerals hinders pore seepage capacity.Mesopores and macropores(>1000 nm)exhibit good flowability.The high content of siliceous minerals plays a positive role in the pore system of alkaline lake shale.The shale with higher fractal dimension Dmin exhibits greater adsorption capacity,which hinders the accumulation of free-state shale oil.Different types of pore space play different roles in the occurrence of shale oil,with free-state shale oil primarily occurring in micro-fractures and inorganic mineral pores,and the pore size is exceeding 10 nm.展开更多
Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the o...Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.展开更多
Background Cotton crop is infested by numerous arthropod pests from sowing to harvesting,causing substantial direct and indirect yield losses.Knowledge of seasonal population trends and the relative occurrence of pest...Background Cotton crop is infested by numerous arthropod pests from sowing to harvesting,causing substantial direct and indirect yield losses.Knowledge of seasonal population trends and the relative occurrence of pests and their natural enemies is required to minimize the pest population and yield losses.In the current study,analysis of the seasonal population trend of pests and natural enemies and their relative occurrence on cultivars of three cotton species in Central India has been carried out.Results A higher number and diversity of sucking pests were observed during the vegetative cotton growth stage(60 days after sowing),declining as the crop matured.With the exception of cotton jassid(Amrasca biguttula biguttula Ishida),which caused significant crop damage mainly from August to September;populations of other sucking insects seldom reached economic threshold levels(ETL)throughout the studied period.The bollworm complex populations were minimal,except for the pink bollworm(Pectinophora gossypiella Saunders),which re-emerged as a menace to cotton crops during the cotton cropping season 2017–2018 due to resistance development against Bt-cotton.A reasonably good number of predatory arthropods,including coccinellids,lacewings,and spiders,were found actively preying on the arthropod pest complex of the cotton crop during the early vegetative growth stage.Linear regression indicates a significant relationship between green boll infestations and pink bollworm moths in pheromone traps.Multiple linear regression analyse showed mean weekly weather at one-or two-week lag periods had a significant impact on sucking pest population(cotton aphid,cotton jassid,cotton whitefly,and onion thrips)fluctuation.Gossypium hirsutum cultivars RCH 2 and DCH 32,and G.barbadense cultivar Suvin were found susceptible to cotton jassid and onion thrips.Phule Dhanvantary,an G.arboreum cotton cultivar,demonstrated the highest tolerance among all evaluated cultivars against all sucking pests.Conclusion These findings have important implications for pest management in cotton crops.Susceptible cultivars warrant more attention for plant protection measures,making them more input-intensive.The choice of appropriate cultivars can help minimize input costs,thereby increasing net returns for cotton farmers.展开更多
Alkaline lacustrine shale is highly heterogeneous,and the complex relationship between the organicinorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and developm...Alkaline lacustrine shale is highly heterogeneous,and the complex relationship between the organicinorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and development.Herein,we investigated the Fengcheng Formation(P_(1)f)in Mahu Sag.This study integrated geochemistry,Soxhlet extraction,scanning electron microscopy,gas adsorption,and nuclear magnetic resonance T_(1)-T_(2)spectroscopy to elucidate the microscopic oil occurrence mechanisms in shales.Results indicate the presence of felsic shale,dolomitic shale,lime shale,and mixed shale within the P_(1)f.Matrix pores and microfractures associated with inorganic minerals are the predominant pore types in P_(1)f.Adsorbed oil primarily resides on the surfaces of organic matter and clay minerals,while free oil predominantly occupies inorganic pores and microfractures with larger pore sizes.Variations exist in the quantity and distribution of shale oil accumulation across different scales,where free oil and adsorbed oil are governed by dominant pores with diameters exceeding 10 nm and ineffective pores with diameters below 10 nm,respectively.Shale oil occurrence characteristics are influenced by organic matter,pore structure,and mineral composition.Felsic shale exhibits a high abundance of dominant pores,possesses the highest oil content,predominantly harbors free oil within these dominant pores,and demonstrates good mobility.Fluid occurrence in dolomitic shale and lime shale is intricate,with low oil content and a free oil to adsorbed oil ratio of 1:1.Mixed shale exhibits elevated clay mineral content and a scarcity of dominant pores.Moreover,ineffective pores contain increased bound water,resulting in medium oil content and limited mobility predominantly due to adsorption.Presently,shale oil mainly occurs in the dominant pores with a diameter larger than 10 nm in a free state.During the exploration and development of alkaline lacustrine shale oil resources,emphasis should be placed on identifying sweet spots within the felsic shale characterized by dominant pores.展开更多
In this study we review the occurrence of different types (A, B, C, M, and X classes) of solar flares during different solar cycle phases from 1996 to 2019 covering the solar cycles 23 and 24. During this period, a to...In this study we review the occurrence of different types (A, B, C, M, and X classes) of solar flares during different solar cycle phases from 1996 to 2019 covering the solar cycles 23 and 24. During this period, a total of 19,126 solar flares were observed regardless the class: 3548 flares in solar cycle 23 (SC23) and 15,668 flares in solar cycle 24 (SC24). Our findings show that the cycle 23 has observed the highest occurrences of M-class and X-class flares, whereas cycle 24 has pointed out a predominance of B-class and C-class flares throughout its different phases. The results indicate that the cycle 23 was magnetically more intense than cycle 24, leading to more powerful solar flares and more frequent geomagnetic storms, capable of generating significant electromagnetic emissions that can affect satellites and GPS signals. The decrease in intense solar flares during cycle 24 compared to cycle 23 reflects an evolution in solar activity patterns over time.展开更多
0 INTRODUCTION The Andean orogenic belt,a globally significant active continental margin(Lamb et al.,1997),extends in a north-south direction along the western coast of South America.The Colombian Andes,located in the...0 INTRODUCTION The Andean orogenic belt,a globally significant active continental margin(Lamb et al.,1997),extends in a north-south direction along the western coast of South America.The Colombian Andes,located in the northern segment of this orogen,constitute a vital component and host abundant Au-Cu resources.Three principal Au-Cu metallogenic belts(Chocó,Middle Cauca,and Antioquia)are developed from west to east across Colombia(Lesage et al.,2013;Sillitoe,2008;Figure 1a).展开更多
Due to the limitations of widely used energy spectrum and spectral analyses for the determination of trace elements in coal,the modes of occurrence of Li still remains unclear.This study investigated the distribution ...Due to the limitations of widely used energy spectrum and spectral analyses for the determination of trace elements in coal,the modes of occurrence of Li still remains unclear.This study investigated the distribution of Li in selected bulk samples and in-situ kaolinite particles in the No.6 Li-rich coals from the Haerwusu Mine of the Jungar Coalfield using ICP-MS and LA-ICP-MS.The results reveal an elevated Li concentration in the lower section of the No.6 coal with high Sr/Ba ratio compared to the upper section with more terrigenous mudstone along the vertical profile.LA-ICP-MS mapping and spot analyses results showed that Li was concentrated in kaolinite but occur in variations in the concentrations of Li among different types of kaolinite.The concentration of Li in kaolinite is ranked as follows:cryptocrystalline kaolinite(2225.83 ppm)>vermicular kaolinite(651.49 ppm)>altered K-bearing kaolinite(593.44 ppm)>clastic kaolinite(478.68 ppm).The in-situ concentration of Li in kaolinite is much higher than that of the bulk samples,indicating that kaolinite is the dominant host mineral for Li as well.The Al2O3/TiO2 and Nb/Yb-Zr/TiO2 ratios indicate that Li in No.6 coal primarily originated from Paleoproterozoic granite in the Yinshan Mountain and felsic volcanic ash.Seawater leaching has a critical influence on the redistribution of Li in the coal from the Haerwusu Mine or even the whole Jungar Coalfield.展开更多
Tailings produced by mining and ore smelting are a major source of soil pollution.Understanding the speciation of heavy metals(HMs)in tailings is essential for soil remediation and sustainable development.Given the co...Tailings produced by mining and ore smelting are a major source of soil pollution.Understanding the speciation of heavy metals(HMs)in tailings is essential for soil remediation and sustainable development.Given the complex and time-consuming nature of traditional sequential laboratory extraction methods for determining the forms of HMs in tailings,a rapid and precise identification approach is urgently required.To address this issue,a general empirical prediction method for HM occurrence was developed using machine learning(ML).The compositional information of the tailings,properties of the HMs,and sequential extraction steps were used as inputs to calculate the percentages of the seven forms of HMs.After the models were tuned and compared,extreme gradient boosting,gradient boosting decision tree,and categorical boosting methods were found to be the top three performing ML models,with the coefficient of determination(R^(2))values on the testing set exceeding 0.859.Feature importance analysis for these three optimal models indicated that electronegativity was the most important factor affecting the occurrence of HMs,with an average feature importance of 0.4522.The subsequent use of stacking as a model integration method enabled the ability of the ML models to predict HM occurrence forms to be further improved,and resulting in an increase of R^(2) to 0.879.Overall,this study developed a robust technique for predicting the occurrence forms in tailings and provides an important reference for the environmental assessment and recycling of tailings.展开更多
Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and m...Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and moving pattern of REEs from rock to products are still unclear,which limits separation and enrichment of REEs from phosphorite.Mappings of scanning electron microscope(SEM) and electron probe X-ray micro-analyzer(EPMA) of REEs are highly consistent with those of calcium and phosphorus,and complementary with that of magnesium,which indicates that fluorapatite(Fap) is the main host mineral of REEs.The results of flotation and leaching experiments further indicate that REEs are enriched along with Fap from phosphorite to products.Occupied sites and occupation number of REEs were obtained by X-ray diffraction(XRD) refinement based on the Rietveld method.La,Ce,Nd,and Y can occupy both Ca1 and Ca2 sites.The ratios of La,Ce,Nd,and Y at Ca2 and Cal sites are 4.20,3.70,3.00,and 1.33,showing a decreasing trend,indicating that La,Ce,and Nd tend to occupy Ca2 sites,while Y tends to occupy Ca1 sites.X-ray absorption fine structure(XAFS) shows that REEs mainly form coordinate structures with oxygen and fluorine,which is a direct evidence that REEs replace calcium(Ⅱ) in phosphorite in an isomorphism form.Coordination structure and polyhedral configuration analysis indicate that substitution degree of La,Ce,Nd,and Y is Y> La> Ce≈Nd from easy to difficult at Cal and Ca2 sites.The research enriches the mineralization theory of REEs-bearing phosphorite and provides certain theoretical guidance for selective enrichment of REEs from phosphorite.展开更多
Due to the complexity of the lithofacies associated with shale oil in saline lacustrine basins,the differences of shale oil occurrence state and its controlling factors in different lithofacies are not completely clea...Due to the complexity of the lithofacies associated with shale oil in saline lacustrine basins,the differences of shale oil occurrence state and its controlling factors in different lithofacies are not completely clear.This hinders efficient shale oil exploration and development.We investigated the shale oil in the Permian Lucaogou Formation in the Jimusar Sag,Junggar Basin,China,based mainly on sequential solvent extraction,petrological,organic geochemical,and nuclear magnetic resonance techniques.The fluidity of extractable organic matter decreased from the first extract to the fourth extract,which was caused by the gradual decrease in the contents of saturated and aromatic hydrocarbons,and gradual increase in the contents of NSO compounds and asphaltenes.The contents of free hydrocarbons(the first and second extracts)and adsorbed hydrocarbons(the third and fourth extracts)are very different among the lithofacies.The free hydrocarbon ratios in the siltstones and carbonate rocks are>70%and the main pore throats are>1μm in size,corresponding to the best sweet spots.The contents of free hydrocarbons in the laminated silty mudstones and shales with bedding fractures are>50%,which are also available.The free hydrocarbons in the siltstones and carbonates are saturated with migrated hydrocarbons,with the contents being more affected by the physical properties of rocks.In contrast,the free hydrocarbons in the mudstones are mainly self-generated and-stored,and their contents are controlled by total organic carbon contents and maturity.For the adsorbed hydrocarbons,the contents in all lithofacies are controlled mainly by the total organic carbon contents.The biomarker parameters record a slight increase in maturity from the fourth to the first extract.The ∑C22-/∑C23+values of n-alkanes in the third extract are the lowest,because carbonate minerals tend to capture long-chain n-alkanes.The sequential solvent extraction method provides new insights into the occurrence state and molecular geochemical characteristics of lacustrine shale oil in different lithofacies.Future exploration should focus on siltstones and carbonate rocks with a relatively high proportion of the first extract(free hydrocarbons occurring in large pores and fractures),and mudstones with a relatively high proportion of the second extract(free to adsorbed hydrocarbons occurring in matrix pores)that are suitable for hydraulic fracturing to aid production.展开更多
Neonicotinoid insecticides(NEOs)have become an integral part of the global insecticide market due to their high efficiency and low toxicity.However,their environmental persistence has raised significant ecological con...Neonicotinoid insecticides(NEOs)have become an integral part of the global insecticide market due to their high efficiency and low toxicity.However,their environmental persistence has raised significant ecological concerns.Dongting Lake represents a vital freshwater lake in China,and its ecosystem health directly affects regional ecological balance and people’s livelihoods.This study systematically investigated the occurrence characteristics and ecological risks of NEOs in water bodies and sediments across the Dongting Lake basin.Based on surface water and sediment samples collected from 26 representative sampling sites,this study quantified nine NEOs using liquid chromatography triple quadrupole mass spectrometry.Furthermore,it assessed ecological risks posed by the NEOs using the risk quotient(RQ)method and fugacity modeling.The results revealed the presence of six NEOs in the water bodies:imidacloprid(IMI),acetamiprid(ACE),clothianidin(CLO),thiamethoxam(THIA),flonicamid(FLO),and dinotefuran(DIN).The total concentrations of these six NEOs averaged 275.11 ng/L.Five predominant NEOs(i.e.,IMI,THIA,ACE,CLO,and DIN)were identified in the sediments,with a mean concentration of 0.31 ng/g.The NEO concentrations in the water bodies across the Dongting Lake basin increased in the order of the Xiangjiang,Zishui,Yuanjiang,and Lishui rivers(collectively referred to as the Four Rivers),the mainstream of Dongting Lake,the Xinqiang River,the Miluo River,and the Hudu,Ouchi,and Songzi rivers(collectively referred to as the Three Outlets).Sediments from tributaries progressively accumulate in the lake.The ecological risk assessment identified IMI and DIN as the highest-risk compounds(RQ>1),with high-risk areas concentrated in the mainstream of Dongting Lake and the Ouchi,Miluo,and Hudu rivers.The fugacity model showed that IMI,ACE,and THIA are prone to diffuse from sediments to water bodies in most areas,with fugacity fractions(ff)values of greater than 0.5.In contrast,the mainstream of Dongting Lake acts as a sink of CLO and DIN(ff values:<0.5).Sediments at the lake’s outlet emerge as an important sink of NEOs.Based on the results of this study,it is advisable to strengthen the supervision of NEO applications in agricultural areas and to implement zonal control strategies.These measures will help reduce ecological risks and protect the safety of water ecosystems in the Dongting Lake region.展开更多
The microscopic occurrence characteristics primarily constrain the enrichment and mobility of shale oil.This study collected the lacustrine shales from the Palaeogene Funing Formation in the Gaoyou Sag, Subei Basin. C...The microscopic occurrence characteristics primarily constrain the enrichment and mobility of shale oil.This study collected the lacustrine shales from the Palaeogene Funing Formation in the Gaoyou Sag, Subei Basin. Conventional and multistage Rock-Eval, scanning electron microscopy, and nuclear magnetic resonance(NMR) T1-T2were performed to analyze the contents and occurrence characteristics of shale oil. Low-temperature nitrogen adsorption-desorption(LTNA/D) experiments were conducted on the shales before and after extraction. The relationships between shale oil occurrence with organic matter and pore structures were then discussed. Predominantly, the shale oil in the Funing Formation is found within fractures, with secondary occurrences in interparticle pores linked to brittle minerals and sizeable intraparticle pores associated with clay minerals. The selected shales can be categorized into two types based on the nitrogen isotherms. Type A shales are characterized by high contents of felsic and calcareous minerals but low clay minerals, with larger TOC and shale oil values. Conversely, Type B shales are marked by abundant clay minerals but diminished TOC and shale oil contents. The lower BET specific surface area(SSA), larger average pore diameter, and simpler pore surfaces and pore structures lead to the Type A shales being more conducive to shale oil enrichment and mobility. Shale oil content is predominantly governed by the abundance of organic matter, while an overabundance of organic matter typically equates to a reduced ratio of free oil and diminished fluidity. The BET SSA, volumes of pores less than 25 and 100 nm at extracted state all correlate negatively with total and adsorbed oil contents but display no correlation with free oil, while they have positive relationships with capillary-bound water.Consequently, pore water is mainly saturated in micropores(<25 nm) and minipores(25-100 nm), as well as adsorbed oil, while free oil, i.e., bound and movable oil, primarily exists in mesopores(100-1000 nm) and macropores(>1000 nm). These findings may enhance the understanding of the microscopic occurrence characteristics of shale oil and will contribute to guide resource estimation and shale oil sweet spot exploitation in the Gaoyou Sag, Subei Basin.展开更多
The occurrence types and controlling factors of organic matter in the sepiolite-containing successions of the first member of Mid-Permian Maokou Formation(Mao-1 Member for short)in the Eastern Sichuan Basin,SW China,h...The occurrence types and controlling factors of organic matter in the sepiolite-containing successions of the first member of Mid-Permian Maokou Formation(Mao-1 Member for short)in the Eastern Sichuan Basin,SW China,have been investigated through outcrop section measurement,core observation,thin section identification,argon ion polishing-field scanning electron microscopy,energy spectrum analysis,X-ray diffraction,total organic carbon content(TOC),major and trace element analysis.Finally,the symbiotic adsorption model of sepiolite for organic matter enrichment has been established.The results show that the sepiolite-containing successions of the Mao-1 Member are composed of the rhythmite of mudstone,argillaceous limestone and limestone,with five depositional intervals vertically and the organic matter mostly developed in the mudstone and argillaceous limestone layers within the lower three intervals.The organic matter occurrence types are mostly layered or nodular in macro to meso-scale,blocky-vein-like under a microscope,but scattered,interstitial or adsorbed at a mesoscopic scale.It underwent transition processes from lower to higher salinity,from oxygen-poor and anoxic reduction to oxygen-poor and localized oxygen enrichment on the palaeo-environment of the Mao-1 Member.The first two intervals of the early depositional phase of Mao-1 Member constitute the cyclothems of mudstone,argillaceous limestone and limestone and quantities of fibrous-feathered sepiolite settle down within the Tongjiang-Changshou sag with continuous patchy organic matter from adsorption of alginate by sepiolite in intercrystalline,bedding surfaces and interlayer pores.The third and fourth intervals in the mid-depositional phase are mostly composed of the mudstone and argillaceous limestone alternations with the continuous patchy or banded organic matter in the surface and inter-crystalline pores of fibrous,feathered and flaky sepiolite.And the fifth interval in the late depositional phase of the Mao-1 Member comprises the cyclothems of extremely thin layered argillaceous limestone and thick-layered limestone with the fibrous sepiolite depositing in the argillaceous limestone and irregular organic matter dispersing around the sepiolite.Therefore,the symbiotic adsorption between organic matter and sepiolite effectively enhances the preservation efficiency of organic matter and improves the source rock quality of the Mao-1 Member,which enhances our understanding on the enrichment model of the depositional organic matter.展开更多
Understanding the occurrence state of shale oil is crucial for the effective development of shale oil resources.Although the second member of the Kongdian Formation(Ek2)is a key interval for lacustrine shale oil produ...Understanding the occurrence state of shale oil is crucial for the effective development of shale oil resources.Although the second member of the Kongdian Formation(Ek2)is a key interval for lacustrine shale oil production in the Cangdong Sag,Bohai Bay Basin,the occurrence state and controlling factors of shale oil in this formation remain poorly understood.This study established a multi-step programmed pyrolysis,combined with a light hydrocarbon recovery scheme,to quantitatively characterize the shale oil in different occurrence states.An integrated approach utilizing Rock-Eval pyrolysis,pyrolysis-gas chromatography,and crude oil gas chromatography was employed.Factors influencing the shale oil occurrence state were analyzed from petrology and organic geochemistry perspectives.The study revealed significant variations of shale oil occurrence states within the Ek2,attributed to differences in sedimentary organic matter,mineral compositions,sedimentary structures,and thermal maturity.Felsic laminae are the primary reservoir space for oil in laminated shales,and the frequent interbedding of felsic and organic-rich laminae facilitates the retention of free oil.The contents of free and adsorbed oil are primarily influenced by organic matter content and shale storage capacity,both of which exhibit distinct occurrence patterns.Based on the shale reservoir quality classification using the pyrolysis values of S1-1+S1-2 and(S1-1+S1-2)×100/TOC,the Ek2 shale demonstrates significant exploitation potential,with the first-level reservoirs comprising 66%,second-level reservoirs 11%,and third-level reservoirs 23%.These findings provide new insights into the geological accumulation and production of shale oil.展开更多
Pore structure characteristics,gas content,and micro-scale gas occurrence mechanisms were investigated in the Shan_(2)^(3)sub-member marine-continental transitional shale of the southeastern margin of the Ordos Basin ...Pore structure characteristics,gas content,and micro-scale gas occurrence mechanisms were investigated in the Shan_(2)^(3)sub-member marine-continental transitional shale of the southeastern margin of the Ordos Basin using scanning electron microscope images,lowtemperature N_(2)/CO_(2)adsorption and high-pressure mercury intrusion,methane isothermal adsorption experiments,and CH4-saturated nuclear magnetic resonance(NMR).Two distinct shale types were identified:organic pore-rich shale(Type OP)and microfracture-rich shale(Type M).The Type OP shale exhibited relatively well-developed organic matter pores,while the Type M shale was primarily characterized by a high degree of microfracture development.An experimental method combining methane isothermal adsorption on crushed samples and CH4-saturated NMR of plug samples was proposed to determine the adsorbed gas,free gas,and total gas content under high temperature and pressure conditions.There were four main research findings.(1)Marine-continental transitional shale exhibited substantial total gas content in situ,ranging from 2.58 to 5.73 cm^(3)/g,with an average of 4.35 cm^(3)/g.The adsorbed gas primarily resided in organic matter pores through micropore filling and multilayer adsorption,followed by multilayer adsorption in clay pores.(2)The changes in adsorbed and free pore volumes can be divided into four stages.Pores of<5 nm exclusively contain adsorbed gas,while those of 5-20 nm have a high proportion of adsorbed gas alongside free gas.Pores ranging from 20 to 100 nm have a high proportion of free gas and few adsorbed gas,while pores of>100 nm and microfractures are almost predominantly free gas.(3)The proportion of adsorbed gas in Type OP shale exceeds that in Type M,reaching 66%.(4)Methane adsorbed in Type OP shale demonstrates greater desorption capability,suggesting a potential for enhanced stable production,which finds support in existing production well data.However,it must be emphasized that high-gas-bearing intervals in both types present valuable opportunities for exploration and development.These data may support future model validations and enhance confidence in exploring and developing marine-continental transitional shale gas.展开更多
基金funded by the National University of Río Negro Research Project (40-C-658)
文摘Fire is a fundamental ecological driver shaping natural vegetation patterns.In the semi-arid southern Espinal-Monte ecotone of Argentina,the spatiotemporal patterns of fire occurrence related to and modulated by climatic gradients and antecedent conditions are not well researched.This study examined fire occurrence in the semi-arid southern Espinal-Monte ecotone(southeastern La Pampa,northeastern Río Negro,and southwestern Buenos Aires with an area of 68×103 km2)of Argentina,a key environmental transition zone with pronounced climatic and vegetation gradients.The objective was to identify the spatiotemporal patterns of fire occurrence and their relationship with climatic variables.Thermal anomaly(TA)data from the MODIS(Moderate Resolution Imaging Spectrometer;MOD14)sensor(November 2000–March 2020)with confidence levels>65.0%were analyzed.Climatic variables(rainfall isohyets and aridity indices)were obtained from the WorldClim datasets,and annual meteorological conditions(rainfall and potential evapotranspiration)were calculated using the climatic research unit(CRU)database.Monthly data and moving averages of rainfall and aridity indices from distinct periods(two and three years preceding fire events)were integrated.Spatial analysis was conducted using kernel density estimation on a 10 km×10 km grid to correlate TA with climatic gradients,while linear regression examined relationships between summer TA and meteorological variables over different periods.Results showed that the highest fire occurrence was recorded in summer,with peaks in December and January.Spatially,55.0%of TA occurred in areas with annual rainfall of 300–400 mm,and 64.5%in areas with an aridity index of 0.3–0.4,forming an arc-like distribution in the center of the ecotone.The highest TA densities were observed in southeastern La Pampa and northeastern Río Negro,decreasing toward southwestern Buenos Aires.Significant correlations(R2>0.700)were found among TA accumulation,aridity index values,and cumulative rainfall from previous two and three years,at both vegetation unit and provincial levels.Summer was the critical season for fire occurrence,with spatial distribution primarily determined by the interaction between climatic conditions and woody biomass availability.The lower fire incidence in southwestern Buenos Aires was linked to sparse woody vegetation and agricultural expansion,which reduced fuel load.These findings reinforce that fuel availability,modulated by climatic conditions from previous years,is a key limiting factor for fire dynamics in this area,and that human activities such as agriculture and grazing alter fire regimes by affecting fuel structure and continuity.
基金financially supported by the National Natural Science Foundation of China(Nos.42272137,42202160)AAPG Foundation Grants-in-Aid and the Strategic Cooperation Technology Projecti of CNPC and CUPB(No.ZLZX2020-01-05)。
文摘The pore structure of shale oil reservoir significantly affects the occurrence and mobility of hydrocarbons.The potential of a new type of alkaline lake shale oil has been demonstrated,but there are few reports on the pore system of alkaline lake shale,which restricts the efficient exploration and development of shale oil.This study investigates the Fengcheng Formation shale in the Mahu sag of the Junggar Basin,employing methods such as low-temperature nitrogecn adsorption(LTNA),mercury intrusion capillary pressure(MICP),and nuclear magnetic resonance(NMR)to quantitatively characterize the multi-scale pore structure and fractal characteristics of shale,while evaluating the applicability of these methods.Based on a comprehensive analysis of material composition,different pore types,and fractal dimensions,the controlling factors for the development of different pore types and their seepage capacity are discussed.The results indicate that inorganic mineral pores are the main development in alkaline lake shale,with the pore morphology being characterized by slit-like and ink-bottle shapes.The multi-scale pore size distribution(PSD)shows that Ⅱ-micropores(10-100 nm)and mesopores(100–1000 nm)are the main contributors to the pore system.The development of Ⅱ-micropores is associated with feldspar and calcareous minerals,the development of Ⅰ-micropores(<10 nm)and mesopores is related to quartz content,while large pores are mainly found in interlayer fissures of clay minerals.The development of Ⅰ-micropores increases the roughness of pore surface and enhances the adsorption capacity of the pores,while the development of Ⅱ-micropores associated with calcareous minerals hinders pore seepage capacity.Mesopores and macropores(>1000 nm)exhibit good flowability.The high content of siliceous minerals plays a positive role in the pore system of alkaline lake shale.The shale with higher fractal dimension Dmin exhibits greater adsorption capacity,which hinders the accumulation of free-state shale oil.Different types of pore space play different roles in the occurrence of shale oil,with free-state shale oil primarily occurring in micro-fractures and inorganic mineral pores,and the pore size is exceeding 10 nm.
基金supported by the National Natural Science Foundation of China(No.22276219)the foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)+1 种基金the major program Natural Science Foundation of Hunan Province of China(No.2021JC0001)the Fundamental Research Funds for the Central Universities of Central South University(No.2024ZZTS0063).
文摘Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.
基金Funding support for the Crop Pest Surveillance and Advisory Project(CROPSAP)。
文摘Background Cotton crop is infested by numerous arthropod pests from sowing to harvesting,causing substantial direct and indirect yield losses.Knowledge of seasonal population trends and the relative occurrence of pests and their natural enemies is required to minimize the pest population and yield losses.In the current study,analysis of the seasonal population trend of pests and natural enemies and their relative occurrence on cultivars of three cotton species in Central India has been carried out.Results A higher number and diversity of sucking pests were observed during the vegetative cotton growth stage(60 days after sowing),declining as the crop matured.With the exception of cotton jassid(Amrasca biguttula biguttula Ishida),which caused significant crop damage mainly from August to September;populations of other sucking insects seldom reached economic threshold levels(ETL)throughout the studied period.The bollworm complex populations were minimal,except for the pink bollworm(Pectinophora gossypiella Saunders),which re-emerged as a menace to cotton crops during the cotton cropping season 2017–2018 due to resistance development against Bt-cotton.A reasonably good number of predatory arthropods,including coccinellids,lacewings,and spiders,were found actively preying on the arthropod pest complex of the cotton crop during the early vegetative growth stage.Linear regression indicates a significant relationship between green boll infestations and pink bollworm moths in pheromone traps.Multiple linear regression analyse showed mean weekly weather at one-or two-week lag periods had a significant impact on sucking pest population(cotton aphid,cotton jassid,cotton whitefly,and onion thrips)fluctuation.Gossypium hirsutum cultivars RCH 2 and DCH 32,and G.barbadense cultivar Suvin were found susceptible to cotton jassid and onion thrips.Phule Dhanvantary,an G.arboreum cotton cultivar,demonstrated the highest tolerance among all evaluated cultivars against all sucking pests.Conclusion These findings have important implications for pest management in cotton crops.Susceptible cultivars warrant more attention for plant protection measures,making them more input-intensive.The choice of appropriate cultivars can help minimize input costs,thereby increasing net returns for cotton farmers.
基金financially supported by the State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Efficient Development(33550000-22-ZC0613-0006)National Natural Science Foundation of China(42202133)+2 种基金CNPC Innovation Fund(2022DQ02-0106)Strategic Cooperation Technology Projects of the CNPC and CUPB(ZLZX2020-01-05)Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences),Ministry of Education,China(TPR-2023-05)。
文摘Alkaline lacustrine shale is highly heterogeneous,and the complex relationship between the organicinorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and development.Herein,we investigated the Fengcheng Formation(P_(1)f)in Mahu Sag.This study integrated geochemistry,Soxhlet extraction,scanning electron microscopy,gas adsorption,and nuclear magnetic resonance T_(1)-T_(2)spectroscopy to elucidate the microscopic oil occurrence mechanisms in shales.Results indicate the presence of felsic shale,dolomitic shale,lime shale,and mixed shale within the P_(1)f.Matrix pores and microfractures associated with inorganic minerals are the predominant pore types in P_(1)f.Adsorbed oil primarily resides on the surfaces of organic matter and clay minerals,while free oil predominantly occupies inorganic pores and microfractures with larger pore sizes.Variations exist in the quantity and distribution of shale oil accumulation across different scales,where free oil and adsorbed oil are governed by dominant pores with diameters exceeding 10 nm and ineffective pores with diameters below 10 nm,respectively.Shale oil occurrence characteristics are influenced by organic matter,pore structure,and mineral composition.Felsic shale exhibits a high abundance of dominant pores,possesses the highest oil content,predominantly harbors free oil within these dominant pores,and demonstrates good mobility.Fluid occurrence in dolomitic shale and lime shale is intricate,with low oil content and a free oil to adsorbed oil ratio of 1:1.Mixed shale exhibits elevated clay mineral content and a scarcity of dominant pores.Moreover,ineffective pores contain increased bound water,resulting in medium oil content and limited mobility predominantly due to adsorption.Presently,shale oil mainly occurs in the dominant pores with a diameter larger than 10 nm in a free state.During the exploration and development of alkaline lacustrine shale oil resources,emphasis should be placed on identifying sweet spots within the felsic shale characterized by dominant pores.
文摘In this study we review the occurrence of different types (A, B, C, M, and X classes) of solar flares during different solar cycle phases from 1996 to 2019 covering the solar cycles 23 and 24. During this period, a total of 19,126 solar flares were observed regardless the class: 3548 flares in solar cycle 23 (SC23) and 15,668 flares in solar cycle 24 (SC24). Our findings show that the cycle 23 has observed the highest occurrences of M-class and X-class flares, whereas cycle 24 has pointed out a predominance of B-class and C-class flares throughout its different phases. The results indicate that the cycle 23 was magnetically more intense than cycle 24, leading to more powerful solar flares and more frequent geomagnetic storms, capable of generating significant electromagnetic emissions that can affect satellites and GPS signals. The decrease in intense solar flares during cycle 24 compared to cycle 23 reflects an evolution in solar activity patterns over time.
基金supported by the National Natural Science Foundation of China(No.42572076)the Continental Gold Ltd.,Colombian Branch(No.CG-EXP-041-23).
文摘0 INTRODUCTION The Andean orogenic belt,a globally significant active continental margin(Lamb et al.,1997),extends in a north-south direction along the western coast of South America.The Colombian Andes,located in the northern segment of this orogen,constitute a vital component and host abundant Au-Cu resources.Three principal Au-Cu metallogenic belts(Chocó,Middle Cauca,and Antioquia)are developed from west to east across Colombia(Lesage et al.,2013;Sillitoe,2008;Figure 1a).
基金supported by the National Key R&D Program of China(No.2021YFC2902003)National Natural Science Foundation of China(No.42302193No.42272201).
文摘Due to the limitations of widely used energy spectrum and spectral analyses for the determination of trace elements in coal,the modes of occurrence of Li still remains unclear.This study investigated the distribution of Li in selected bulk samples and in-situ kaolinite particles in the No.6 Li-rich coals from the Haerwusu Mine of the Jungar Coalfield using ICP-MS and LA-ICP-MS.The results reveal an elevated Li concentration in the lower section of the No.6 coal with high Sr/Ba ratio compared to the upper section with more terrigenous mudstone along the vertical profile.LA-ICP-MS mapping and spot analyses results showed that Li was concentrated in kaolinite but occur in variations in the concentrations of Li among different types of kaolinite.The concentration of Li in kaolinite is ranked as follows:cryptocrystalline kaolinite(2225.83 ppm)>vermicular kaolinite(651.49 ppm)>altered K-bearing kaolinite(593.44 ppm)>clastic kaolinite(478.68 ppm).The in-situ concentration of Li in kaolinite is much higher than that of the bulk samples,indicating that kaolinite is the dominant host mineral for Li as well.The Al2O3/TiO2 and Nb/Yb-Zr/TiO2 ratios indicate that Li in No.6 coal primarily originated from Paleoproterozoic granite in the Yinshan Mountain and felsic volcanic ash.Seawater leaching has a critical influence on the redistribution of Li in the coal from the Haerwusu Mine or even the whole Jungar Coalfield.
基金financially supported by the Natural Science Foundation of Hunan Province,China(No.2024JJ2074)the National Natural Science Foundation of China(No.22376221)the Young Elite Scientists Sponsorship Program by CAST,China(No.2023QNRC001).
文摘Tailings produced by mining and ore smelting are a major source of soil pollution.Understanding the speciation of heavy metals(HMs)in tailings is essential for soil remediation and sustainable development.Given the complex and time-consuming nature of traditional sequential laboratory extraction methods for determining the forms of HMs in tailings,a rapid and precise identification approach is urgently required.To address this issue,a general empirical prediction method for HM occurrence was developed using machine learning(ML).The compositional information of the tailings,properties of the HMs,and sequential extraction steps were used as inputs to calculate the percentages of the seven forms of HMs.After the models were tuned and compared,extreme gradient boosting,gradient boosting decision tree,and categorical boosting methods were found to be the top three performing ML models,with the coefficient of determination(R^(2))values on the testing set exceeding 0.859.Feature importance analysis for these three optimal models indicated that electronegativity was the most important factor affecting the occurrence of HMs,with an average feature importance of 0.4522.The subsequent use of stacking as a model integration method enabled the ability of the ML models to predict HM occurrence forms to be further improved,and resulting in an increase of R^(2) to 0.879.Overall,this study developed a robust technique for predicting the occurrence forms in tailings and provides an important reference for the environmental assessment and recycling of tailings.
基金Project supported by Guizhou Provincial Basic Research Program (Natural Science)(Qian Ke He Basic-ZK 2024 General 626)National Natural Science Foundation of China (52164018)Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology (13210025)。
文摘Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and moving pattern of REEs from rock to products are still unclear,which limits separation and enrichment of REEs from phosphorite.Mappings of scanning electron microscope(SEM) and electron probe X-ray micro-analyzer(EPMA) of REEs are highly consistent with those of calcium and phosphorus,and complementary with that of magnesium,which indicates that fluorapatite(Fap) is the main host mineral of REEs.The results of flotation and leaching experiments further indicate that REEs are enriched along with Fap from phosphorite to products.Occupied sites and occupation number of REEs were obtained by X-ray diffraction(XRD) refinement based on the Rietveld method.La,Ce,Nd,and Y can occupy both Ca1 and Ca2 sites.The ratios of La,Ce,Nd,and Y at Ca2 and Cal sites are 4.20,3.70,3.00,and 1.33,showing a decreasing trend,indicating that La,Ce,and Nd tend to occupy Ca2 sites,while Y tends to occupy Ca1 sites.X-ray absorption fine structure(XAFS) shows that REEs mainly form coordinate structures with oxygen and fluorine,which is a direct evidence that REEs replace calcium(Ⅱ) in phosphorite in an isomorphism form.Coordination structure and polyhedral configuration analysis indicate that substitution degree of La,Ce,Nd,and Y is Y> La> Ce≈Nd from easy to difficult at Cal and Ca2 sites.The research enriches the mineralization theory of REEs-bearing phosphorite and provides certain theoretical guidance for selective enrichment of REEs from phosphorite.
基金funded by the National Natural Science Foundation of China(Grant Nos.42230808 and 41830425)PetroChina Science and Technology Major Project(Grant No.2021DJ0108).
文摘Due to the complexity of the lithofacies associated with shale oil in saline lacustrine basins,the differences of shale oil occurrence state and its controlling factors in different lithofacies are not completely clear.This hinders efficient shale oil exploration and development.We investigated the shale oil in the Permian Lucaogou Formation in the Jimusar Sag,Junggar Basin,China,based mainly on sequential solvent extraction,petrological,organic geochemical,and nuclear magnetic resonance techniques.The fluidity of extractable organic matter decreased from the first extract to the fourth extract,which was caused by the gradual decrease in the contents of saturated and aromatic hydrocarbons,and gradual increase in the contents of NSO compounds and asphaltenes.The contents of free hydrocarbons(the first and second extracts)and adsorbed hydrocarbons(the third and fourth extracts)are very different among the lithofacies.The free hydrocarbon ratios in the siltstones and carbonate rocks are>70%and the main pore throats are>1μm in size,corresponding to the best sweet spots.The contents of free hydrocarbons in the laminated silty mudstones and shales with bedding fractures are>50%,which are also available.The free hydrocarbons in the siltstones and carbonates are saturated with migrated hydrocarbons,with the contents being more affected by the physical properties of rocks.In contrast,the free hydrocarbons in the mudstones are mainly self-generated and-stored,and their contents are controlled by total organic carbon contents and maturity.For the adsorbed hydrocarbons,the contents in all lithofacies are controlled mainly by the total organic carbon contents.The biomarker parameters record a slight increase in maturity from the fourth to the first extract.The ∑C22-/∑C23+values of n-alkanes in the third extract are the lowest,because carbonate minerals tend to capture long-chain n-alkanes.The sequential solvent extraction method provides new insights into the occurrence state and molecular geochemical characteristics of lacustrine shale oil in different lithofacies.Future exploration should focus on siltstones and carbonate rocks with a relatively high proportion of the first extract(free hydrocarbons occurring in large pores and fractures),and mudstones with a relatively high proportion of the second extract(free to adsorbed hydrocarbons occurring in matrix pores)that are suitable for hydraulic fracturing to aid production.
基金jointly supported by project of the China Geological Survey(DD20243375,DD20230478)the Key Research and Development Program of Hunan Province(2023SK2066)the Natural Science Foundation of Hunan Province(2024JJ7620).
文摘Neonicotinoid insecticides(NEOs)have become an integral part of the global insecticide market due to their high efficiency and low toxicity.However,their environmental persistence has raised significant ecological concerns.Dongting Lake represents a vital freshwater lake in China,and its ecosystem health directly affects regional ecological balance and people’s livelihoods.This study systematically investigated the occurrence characteristics and ecological risks of NEOs in water bodies and sediments across the Dongting Lake basin.Based on surface water and sediment samples collected from 26 representative sampling sites,this study quantified nine NEOs using liquid chromatography triple quadrupole mass spectrometry.Furthermore,it assessed ecological risks posed by the NEOs using the risk quotient(RQ)method and fugacity modeling.The results revealed the presence of six NEOs in the water bodies:imidacloprid(IMI),acetamiprid(ACE),clothianidin(CLO),thiamethoxam(THIA),flonicamid(FLO),and dinotefuran(DIN).The total concentrations of these six NEOs averaged 275.11 ng/L.Five predominant NEOs(i.e.,IMI,THIA,ACE,CLO,and DIN)were identified in the sediments,with a mean concentration of 0.31 ng/g.The NEO concentrations in the water bodies across the Dongting Lake basin increased in the order of the Xiangjiang,Zishui,Yuanjiang,and Lishui rivers(collectively referred to as the Four Rivers),the mainstream of Dongting Lake,the Xinqiang River,the Miluo River,and the Hudu,Ouchi,and Songzi rivers(collectively referred to as the Three Outlets).Sediments from tributaries progressively accumulate in the lake.The ecological risk assessment identified IMI and DIN as the highest-risk compounds(RQ>1),with high-risk areas concentrated in the mainstream of Dongting Lake and the Ouchi,Miluo,and Hudu rivers.The fugacity model showed that IMI,ACE,and THIA are prone to diffuse from sediments to water bodies in most areas,with fugacity fractions(ff)values of greater than 0.5.In contrast,the mainstream of Dongting Lake acts as a sink of CLO and DIN(ff values:<0.5).Sediments at the lake’s outlet emerge as an important sink of NEOs.Based on the results of this study,it is advisable to strengthen the supervision of NEO applications in agricultural areas and to implement zonal control strategies.These measures will help reduce ecological risks and protect the safety of water ecosystems in the Dongting Lake region.
基金supported by the National Natural Science Foundation of China(42302160)the Sanya City Science and Technology Innovation Project(2022KJCX51)the Support Plan for Outstanding Youth Innovation Team in Shandong Higher Education Institutions(2022KJ060).
文摘The microscopic occurrence characteristics primarily constrain the enrichment and mobility of shale oil.This study collected the lacustrine shales from the Palaeogene Funing Formation in the Gaoyou Sag, Subei Basin. Conventional and multistage Rock-Eval, scanning electron microscopy, and nuclear magnetic resonance(NMR) T1-T2were performed to analyze the contents and occurrence characteristics of shale oil. Low-temperature nitrogen adsorption-desorption(LTNA/D) experiments were conducted on the shales before and after extraction. The relationships between shale oil occurrence with organic matter and pore structures were then discussed. Predominantly, the shale oil in the Funing Formation is found within fractures, with secondary occurrences in interparticle pores linked to brittle minerals and sizeable intraparticle pores associated with clay minerals. The selected shales can be categorized into two types based on the nitrogen isotherms. Type A shales are characterized by high contents of felsic and calcareous minerals but low clay minerals, with larger TOC and shale oil values. Conversely, Type B shales are marked by abundant clay minerals but diminished TOC and shale oil contents. The lower BET specific surface area(SSA), larger average pore diameter, and simpler pore surfaces and pore structures lead to the Type A shales being more conducive to shale oil enrichment and mobility. Shale oil content is predominantly governed by the abundance of organic matter, while an overabundance of organic matter typically equates to a reduced ratio of free oil and diminished fluidity. The BET SSA, volumes of pores less than 25 and 100 nm at extracted state all correlate negatively with total and adsorbed oil contents but display no correlation with free oil, while they have positive relationships with capillary-bound water.Consequently, pore water is mainly saturated in micropores(<25 nm) and minipores(25-100 nm), as well as adsorbed oil, while free oil, i.e., bound and movable oil, primarily exists in mesopores(100-1000 nm) and macropores(>1000 nm). These findings may enhance the understanding of the microscopic occurrence characteristics of shale oil and will contribute to guide resource estimation and shale oil sweet spot exploitation in the Gaoyou Sag, Subei Basin.
基金Supported by National Natural Science Foundation of China(42572132,U24B6001,41872150,42230310,U2344209).
文摘The occurrence types and controlling factors of organic matter in the sepiolite-containing successions of the first member of Mid-Permian Maokou Formation(Mao-1 Member for short)in the Eastern Sichuan Basin,SW China,have been investigated through outcrop section measurement,core observation,thin section identification,argon ion polishing-field scanning electron microscopy,energy spectrum analysis,X-ray diffraction,total organic carbon content(TOC),major and trace element analysis.Finally,the symbiotic adsorption model of sepiolite for organic matter enrichment has been established.The results show that the sepiolite-containing successions of the Mao-1 Member are composed of the rhythmite of mudstone,argillaceous limestone and limestone,with five depositional intervals vertically and the organic matter mostly developed in the mudstone and argillaceous limestone layers within the lower three intervals.The organic matter occurrence types are mostly layered or nodular in macro to meso-scale,blocky-vein-like under a microscope,but scattered,interstitial or adsorbed at a mesoscopic scale.It underwent transition processes from lower to higher salinity,from oxygen-poor and anoxic reduction to oxygen-poor and localized oxygen enrichment on the palaeo-environment of the Mao-1 Member.The first two intervals of the early depositional phase of Mao-1 Member constitute the cyclothems of mudstone,argillaceous limestone and limestone and quantities of fibrous-feathered sepiolite settle down within the Tongjiang-Changshou sag with continuous patchy organic matter from adsorption of alginate by sepiolite in intercrystalline,bedding surfaces and interlayer pores.The third and fourth intervals in the mid-depositional phase are mostly composed of the mudstone and argillaceous limestone alternations with the continuous patchy or banded organic matter in the surface and inter-crystalline pores of fibrous,feathered and flaky sepiolite.And the fifth interval in the late depositional phase of the Mao-1 Member comprises the cyclothems of extremely thin layered argillaceous limestone and thick-layered limestone with the fibrous sepiolite depositing in the argillaceous limestone and irregular organic matter dispersing around the sepiolite.Therefore,the symbiotic adsorption between organic matter and sepiolite effectively enhances the preservation efficiency of organic matter and improves the source rock quality of the Mao-1 Member,which enhances our understanding on the enrichment model of the depositional organic matter.
基金supported by the National Natural Science Foundation of China(No.41830431)the Shandong Provincial Key Research and Development Program(No.2020ZLYS08).
文摘Understanding the occurrence state of shale oil is crucial for the effective development of shale oil resources.Although the second member of the Kongdian Formation(Ek2)is a key interval for lacustrine shale oil production in the Cangdong Sag,Bohai Bay Basin,the occurrence state and controlling factors of shale oil in this formation remain poorly understood.This study established a multi-step programmed pyrolysis,combined with a light hydrocarbon recovery scheme,to quantitatively characterize the shale oil in different occurrence states.An integrated approach utilizing Rock-Eval pyrolysis,pyrolysis-gas chromatography,and crude oil gas chromatography was employed.Factors influencing the shale oil occurrence state were analyzed from petrology and organic geochemistry perspectives.The study revealed significant variations of shale oil occurrence states within the Ek2,attributed to differences in sedimentary organic matter,mineral compositions,sedimentary structures,and thermal maturity.Felsic laminae are the primary reservoir space for oil in laminated shales,and the frequent interbedding of felsic and organic-rich laminae facilitates the retention of free oil.The contents of free and adsorbed oil are primarily influenced by organic matter content and shale storage capacity,both of which exhibit distinct occurrence patterns.Based on the shale reservoir quality classification using the pyrolysis values of S1-1+S1-2 and(S1-1+S1-2)×100/TOC,the Ek2 shale demonstrates significant exploitation potential,with the first-level reservoirs comprising 66%,second-level reservoirs 11%,and third-level reservoirs 23%.These findings provide new insights into the geological accumulation and production of shale oil.
基金the Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance,China(No.2020CX030101)the National Natural Science Foundation of China(No.42222209)the Scientific Research and Technological Development Program of CNPC,China(No.2023ZZ0801).
文摘Pore structure characteristics,gas content,and micro-scale gas occurrence mechanisms were investigated in the Shan_(2)^(3)sub-member marine-continental transitional shale of the southeastern margin of the Ordos Basin using scanning electron microscope images,lowtemperature N_(2)/CO_(2)adsorption and high-pressure mercury intrusion,methane isothermal adsorption experiments,and CH4-saturated nuclear magnetic resonance(NMR).Two distinct shale types were identified:organic pore-rich shale(Type OP)and microfracture-rich shale(Type M).The Type OP shale exhibited relatively well-developed organic matter pores,while the Type M shale was primarily characterized by a high degree of microfracture development.An experimental method combining methane isothermal adsorption on crushed samples and CH4-saturated NMR of plug samples was proposed to determine the adsorbed gas,free gas,and total gas content under high temperature and pressure conditions.There were four main research findings.(1)Marine-continental transitional shale exhibited substantial total gas content in situ,ranging from 2.58 to 5.73 cm^(3)/g,with an average of 4.35 cm^(3)/g.The adsorbed gas primarily resided in organic matter pores through micropore filling and multilayer adsorption,followed by multilayer adsorption in clay pores.(2)The changes in adsorbed and free pore volumes can be divided into four stages.Pores of<5 nm exclusively contain adsorbed gas,while those of 5-20 nm have a high proportion of adsorbed gas alongside free gas.Pores ranging from 20 to 100 nm have a high proportion of free gas and few adsorbed gas,while pores of>100 nm and microfractures are almost predominantly free gas.(3)The proportion of adsorbed gas in Type OP shale exceeds that in Type M,reaching 66%.(4)Methane adsorbed in Type OP shale demonstrates greater desorption capability,suggesting a potential for enhanced stable production,which finds support in existing production well data.However,it must be emphasized that high-gas-bearing intervals in both types present valuable opportunities for exploration and development.These data may support future model validations and enhance confidence in exploring and developing marine-continental transitional shale gas.
