This study aims to determine the variation and controlling factors of shale gas adsorption capacity in reservoirs in the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation(also referred to as ...This study aims to determine the variation and controlling factors of shale gas adsorption capacity in reservoirs in the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation(also referred to as the WF-LMX formations),South China.Based on data obtained using scanning helium ion microscopy(HIM)and nitrogen(N_(2))and methane(CH_(4))adsorption experiments,this study analyzed the organic pore heterogeneity of shales in the WF-LMX formations in well A and its effect on shale gas adsorption.Using the Frenkel-Halsey-Hill(FHH)model,data from N_(2) adsorption experiments were converted into fractal dimensions,which can reflect the complexity and heterogeneity of organic pores while also serving as a novel indicator for quantitatively assessing the pore structure complexity.The results indicate that shales in the WF-LMX formations in well A can be divided into two sections:(Ⅰ)the Wufeng Formation and the lower Longmaxi Formation(depths:ca.2871.0-2898.6 m),and(Ⅱ)the upper Longmaxi Formation(depths:<2871.0 m).Organic pores in Section Ⅰ typically exhibit complex internal structures,coarse surfaces,and interconnectivity,whereas those in Section Ⅱ are simple,smooth,and isolated.Moreover,the former possesses larger specific surface areas(SSAs)than the latter.A fractal analysis reveals that organic pores in the shale sequence can be classified into micropores(<2 nm),mesopores(2-10 nm),and macropores(>10 nm).The calculated fractal dimensions show greater heterogeneity of organic pores,especially macropores,in Section Ⅰ compared to Section Ⅱ.The results also reveal that organic macropores are the primary pores controlling the SSAs of organic pores in shale reservoirs in the WF-LMX formations.Organic pores in Section Ⅰ manifest a superior shale gas adsorption capacity compared to Section Ⅱ.The heterogeneity of organic pores might affect the adsorption capacity of shales in the formations.Generally,organic macropores in Section Ⅰ of the shale sequence exhibit more complex structures and larger SSAs,leading to a stronger absorption capacity of shale reservoirs in Section Ⅰ compared to Section Ⅱ.展开更多
A thermodynamics-based unsaturated hydro-mechanical-chemical(HMC)coupling model is developed to analyze the coupled response and stability of boreholes in chemically active gas formations.The newly coupled constitutiv...A thermodynamics-based unsaturated hydro-mechanical-chemical(HMC)coupling model is developed to analyze the coupled response and stability of boreholes in chemically active gas formations.The newly coupled constitutive relations are formulated by incorporating the chemical effect into the solid-gasliquid unsaturated framework to account for the interactions between rock deformation,gas-liquid two-phase flow,and chemical potential difference.Compared with previous models,the present model shows significant prediction differences in field variables and wellbore stability evolution.The maximum absolute difference of pore pressure,effective radial stress,effective tangential stress,and collapse pressure can reach 8.98 MPa,7.64 MPa,7.29 MPa,7.65 MPa,respectively.It is more conservative to select a long-term wellbore collapse pressure rather than a short-term one to guide drilling operations.The two-phase flow behavior,jointly controlled by wellbore pressure,capillary pressure,and chemical osmosis effect,provides a more realistic observation of the mud intrusion process.Compared with low salinity muds,high salinity muds can effectively impede the mud intrusion into the formation,which is more conducive to preventing wellbore collapse,but at the same time increases the risk of wellbore fracture.Sensitivity analysis shows that solute diffusion and reflection coefficients affect early wellbore stability through pore pressure and solute transport,while the chemical swelling coefficient has a long-term effect through chemically induced deformation.The results can provide theoretical guidance for quantitative optimization of mud parameters and prevention of wellbore instability when drilling in chemically active gas formations.展开更多
Surface hydrogen storage facilities are limited and costly,making subsurface hydrogen storage in geological formations a more viable alternative due to its substantial capacity,safety,and economic feasibility.This met...Surface hydrogen storage facilities are limited and costly,making subsurface hydrogen storage in geological formations a more viable alternative due to its substantial capacity,safety,and economic feasibility.This method is essential for large-scale hydrogen storage to support renewable energy integration,fuel cell technologies,and other applications aimed at mitigating global climate change.This review examines underground hydrogen storage(UHS)in geological formations,focusing on recent experiments,modeling and simulations,and field applications.Geological formations such as depleted oil reservoirs,salt caverns,and depleted natural gas reservoirs are identified as favorable candidates due to minimal interactions with hydrogen,leading to low hydrogen loss.Globally,80%of UHS projects utilize depleted natural gas and oil reservoirs,with over 50%focused on depleted natural gas and oil condensate reservoirs due to cost-effective existing infrastructure.Among storage options,salt caverns are the most advantageous,offering self-healing properties,low caprock permeability,large storage capacity,rapid injection and withdrawal rates,and low contamination risk.Additionally,hydrogen produced from coal is the cheapest option,costing 1.2e2 USD/kg,whereas hydrogen from renewable sources,such as water,is the most expensive at 3e13 USD/kg.Despite its higher cost,green hydrogen from water,characterized by low carbon emissions,requires further research to reduce production costs.This review highlights critical research gaps,challenges,and policy recommendations to advance UHS technologies,ensuring their role in combating climate change.展开更多
By comprehensively considering the influences of temperature and pressure on fluid density in high temperature and high pressure(HTHP)wells in deepwater fractured formations and the effects of formation fracture defor...By comprehensively considering the influences of temperature and pressure on fluid density in high temperature and high pressure(HTHP)wells in deepwater fractured formations and the effects of formation fracture deformation on well shut-in afterflow,this study couples the shut-in temperature field model,fracture deformation model,and gas flow model to establish a wellbore pressure calculation model incorporating thermo-hydro-mechanical coupling effects.The research analyzes the governing patterns of geothermal gradient,bottomhole pressure difference,drilling fluid pit gain,and kick index on casing head pressure,and establishes a shut-in pressure determination chart for HPHT wells based on coupled model calculation results.The study results show:geothermal gradient,bottomhole pressure difference,and drilling fluid pit gain exhibit positive correlations with casing head pressure;higher kick indices accelerate pressure rising rates while maintaining a constant maximum casing pressure;validation against field case data demonstrates over 95%accuracy in predicting wellbore pressure recovery after shut-in,with the pressure determination chart achieving 97.2%accuracy in target casing head pressure prediction and 98.3%accuracy in target shut-in time.This method enables accurate acquisition of formation pressure after HPHT well shut-in,providing reliable technical support for subsequent well control measures and ensuring safe and efficient development of deepwater and deep hydrocarbon reservoirs.展开更多
Existing studies indicate that gas hydrate-bearing formations exhibit notable seismic velocity dispersion and attenuation. The Shenhu area of the South China Sea hold significant gas hydrate resource potential;however...Existing studies indicate that gas hydrate-bearing formations exhibit notable seismic velocity dispersion and attenuation. The Shenhu area of the South China Sea hold significant gas hydrate resource potential;however, the relationship between seismic velocity dispersion, attenuation properties, and gas-hydrate saturation remains insufficiently understood. Furthermore, a significant mismatch exists between the real seismic angle gather near a well and the synthetic angle gather generated using the convolution method, and this discrepancy may arise from the seismic velocity dispersion and attenuation characteristics of the gas hydrate-bearing formations. In this paper, we develop a rock physics model that integrates White's and Dvorkin's models, accounting for varied types of gas-hydrate occurrence states,specifically tailored to the gas hydrate-bearing formations in the Shenhu area. This model is calibrated with well log data and employed to investigate how gas-hydrate saturation influences seismic velocity dispersion and attenuation. Numerical analysis reveals the coexistence of two types of gas-hydrate occurrence states in the region: high gas-hydrate saturation formations are dominated by loadbearing-type gas hydrate, and formations containing both gas hydrate and free gas may exhibit either load-bearing or pore-filling types. The seismic velocity dispersion and attenuation properties vary significantly depending on the gas-hydrate occurrence state. We further apply the proposed model to generate seismic velocity and attenuation logs at various frequencies. These logs are used in seismic forward modeling employing both the convolution method and the propagator matrix method. Well tie analysis indicates that the synthetic angle gather incorporating attenuation via the propagator matrix method aligns more closely with the real seismic angle gather than the convolution method. This study provides valuable insights into frequency-dependent amplitude versus offset(AVO) analysis and the seismic interpretation of gas hydrate-bearing formations in the South China Sea.展开更多
Due to complex geological structures and a narrow safe mud density window,offshore fractured formations frequently encounter severe lost circulation(LC)during drilling,significantly hindering oil and gas exploration a...Due to complex geological structures and a narrow safe mud density window,offshore fractured formations frequently encounter severe lost circulation(LC)during drilling,significantly hindering oil and gas exploration and development.Predicting LC risks enables the targeted implementation of mitigation strategies,thereby reducing the frequency of such incidents.To address the limitations of existing 3D geomechanical modeling in predicting LC,such as arbitrary factor selection,subjective weight assignment,and the inability to achieve pre-drilling prediction along the entire well section,an improved prediction method is proposed.This method integrates multi-source data and incorporates three LC-related sensitivity factors:fracture characteristics,rock brittleness,and in-situ stress conditions.A quantitative risk assessment model for LC is developed by combining the subjective analytic hierarchy process with the objective entropy weight method(EWM)to assign weights.Subsequently,3D geomechanical modeling is applied to identify regional risk zones,enabling digital visualization for pre-drilling risk prediction.The developed 3D LC risk prediction model was validated using actual LC incidents from drilled wells.Results were generally consistent with field-identified LC zones,with an average relative error of 19.08%,confirming its reliability.This method provides practical guidance for mitigating potential LC risks and optimizing drilling program designs in fractured formations.展开更多
The Bipindi iron ore district is located in the central section of the Nyong Complex at the northwestern margin of the Congo Craton in Southwest Cameroon.This iron district contains numerous iron mineralization hosted...The Bipindi iron ore district is located in the central section of the Nyong Complex at the northwestern margin of the Congo Craton in Southwest Cameroon.This iron district contains numerous iron mineralization hosted by the Mewongo,Bibole,Kouambo,and Zambi banded iron formations(BIFs).These BIFs contain magnetite as the main iron ore mineral associated with pyrite,and gangue minerals are quartz with minor chlorite and amphibole.The origin of iron ore from these BIFs was investigated using a combination of in-situ magnetite and whole-rock chemistry.The studied BIF ore samples have a narrow range of TFe between 30.90 wt.%and 43.20 wt.%,indicating a low-grade ore.The geochemical signatures of magnetite such as low contents of base metals(e.g.,Cu,Co,V,and Zn)and low Co/Zn ratios<0.85 indicate a hydrothermal origin.Combined with the geochemical features of these BIFs,e.g.,high Fe/Ti and Fe/Al ratios(mean>600 and>75,respectively),we suggest that magnetite was derived from a mixture of seawater and~0.1%low-temperature hydrothermal fluids in an oxidizing environment.Collectively,low-temperature hydrothermal and later metamorphic fluids were necessary for the transformation of the protolith Nyong Complex BIFs to iron ore.展开更多
Shales of the Wufeng-Longmaxi formations in the basin-margin transition zone of southeastern Chongqing,China are characterized by high organic matter content and a significant presence of pyrite development.By examini...Shales of the Wufeng-Longmaxi formations in the basin-margin transition zone of southeastern Chongqing,China are characterized by high organic matter content and a significant presence of pyrite development.By examining numerous scanning electron microscope(SEM)images and considering the crystal and aggregate characteristics of minerals,we identified four types of pyrite in the study area:euhedral crystals,irregular aggregates,framboidal aggregates,and metasomatized organisms.Among these types,framboidal aggregates are the most prevalent.The formation mechanism of framboidal pyrite can be categorized into inorganic and organic origins.As inferred from the pyrite characteristics in the study area,the formation mechanism of the metasomatized organisms aligns with the biologically induced mineralization mode of organic origin,whereas the framboidal aggregates are more associated with the biologically controlled mineralization mode of organic origin.This underscores a close relationship between the pyrite formation and organic matter,which in turn indicates that an organic origin is more consistent with the pyrite characteristics observed in this study area.The pyrite morphology can reflect reactive iron concentration.Euhedral pyrite crystals tend to form under a low reactive iron concentration,whereas the formation of framboidal pyrite requires a high reactive iron concentration.Additionally,the type and grain size of pyrite aggregates can reflect variations in the redox conditions of the depositional environment.Pyrite produces positive effects on reservoir storage space,with intercrystalline organic pores,intercrystalline pores,and mold pores associated with pyrite contributing greatly to the storage spaces.展开更多
XRF and EDX analyses were carried out on 18 batches of representative raw samples to determine the distribution of major chemical elements in the petroleum source rocks of Donga and Yogou formations of Termit sediment...XRF and EDX analyses were carried out on 18 batches of representative raw samples to determine the distribution of major chemical elements in the petroleum source rocks of Donga and Yogou formations of Termit sedimentary basin. The chemical composition of these formations is dominated by silicon (Si), aluminum (Al) and iron (Fe). This is consistent with the oxide composition, which is also dominated by silicon oxide (SiO2), aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) and iron monoxide (FeO). No less important chemical elements are calcium (Ca), potassium (K), sulfur (S), titanium (Ti), magnesium (Mg), manganese (Mn) and barium (Ba), as well as some of their oxides. All these major chemical elements are carried by silicate detrital minerals associated with pyrite and goethite and/or clay minerals such as kaolinite and interstratified illite, smectite and chlorite. This trend is illustrated by the values of the Si/Al and SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> ratios.展开更多
Hylocereus polyrhizus,also known as pitaya or dragon fruit,is a climbing cactus grown worldwide because of its excellent performance under drought stress and appealing red-purple fruits.In practice,accelerating flower...Hylocereus polyrhizus,also known as pitaya or dragon fruit,is a climbing cactus grown worldwide because of its excellent performance under drought stress and appealing red-purple fruits.In practice,accelerating flower formation and inducing more flowers usually result in higher yield.However,the genes for this purpose have not been well characterized in pitaya.Previously,FLOWERING BHLHs(FBHs)have been identified as positive regulators of flower formation.In the present work,a total of eight FBHs were identified in pitaya.This is a greater number than in beet and spinach,possibly because of the recent whole-genome duplication that occurred in the pitaya genome.The phylogenetic tree indicated that the FBHs could be divided into three groups.In TYPEⅡ,the genes of Caryophyllales encode atypical FBHs and are generated by dispersed duplication.The K_(a)/K_(s) ratios indicated that HpFBHs are under purifying selection.Promoter and expression analysis of HpFBHs revealed that they are spatiotemporally activated in flower-related tissues and responsive to multiple abiotic stresses.These results indicated that HpFBHs are involved in the flower formation of pitaya.Therefore,typical HpFBH1/3 from TYPEⅡI and an atypical HpFBH8 from TYPEⅡwere selected for functional verification.HpFBH3 was found to heterodimerize with HpFBH1 in the nucleus using subcellular localization,yeast two-hybrid and luciferase complementation assays.With bioinformatic analysis,all HpFBHs were predicted to transactivate downstream genes via binding to the E-boxes,which were frequently detected in the promoters of HpCOs,HpFTs and HpSOC1s.RNA-Seq datasets showed that these flowering accelerators were expressed in coordination with HpFBH3.Yeast one-hybrid and dual-luciferase reporter assays further verified that HpFBH3 transactivated HpCO7 by selectively binding to the E-boxes in the promoter.Moreover,ectopic overexpression of HpFBH3 accelerated flower formation in Arabidopsis.In summary,this study systematically characterized the typical HpFBHs,especially HpFBH3,as positive regulators of flower formation,which could be target genes for the genetic improvement of pitaya.展开更多
Superior strength and high-temperature performance make γ-TiAl vital for lightweight aero-engines. However, its inherent brittleness poses machining problems. This study employed Elliptical Ultrasonic Vibration Milli...Superior strength and high-temperature performance make γ-TiAl vital for lightweight aero-engines. However, its inherent brittleness poses machining problems. This study employed Elliptical Ultrasonic Vibration Milling (EUVM) to address these problems. Considering the influence of machining parameters on vibration patterns of EUVM, a separation time model was established to analyze the vibration evolutionary process, thereby instructing the cutting mechanism. On this basis, deep discussions regarding chip formation, cutting force, edge breakage, and subsurface layer deformation were conducted for EUVM and Conventional Milling (CM). Chip morphology showed the chip formation was rooted in the periodic brittle fracture. Local dimples proved that the thermal effect of high-speed cutting improved the plasticity of γ-TiAl. EUVM achieved a maximum 18.17% reduction in cutting force compared with CM. The force variation mechanism differed with changes in the cutting speed or the vibration amplitude, and its correlation with thermal softening, strain hardening, and vibratory cutting effects was analyzed. EUVM attained desirable edge breakage by achieving smaller fracture lengths. The fracture mechanisms of different phases were distinct, causing a surge in edge fracture size of γ-TiAl under microstructural differences. In terms of subsurface deformation, EUVM also showed strengthening effects. Noteworthy, the lamellar deformation patterns under the cutting removal state differed from the quasi-static, which was categorized by the orientation angles. Additionally, the electron backscattering diffraction provided details of the influence of microstructural difference on the orientation and the deformation of grains in the subsurface layer. The results demonstrate that EUVM is a promising machining method for γ-TiAl and guide further research and development of EUVM γ-TiAl.展开更多
Investigations into rail corrugation within metro systems have traditionally focused on specific mechanisms,thereby limiting the generalizability of proposed theories.Understanding the commonalities in rail corrugatio...Investigations into rail corrugation within metro systems have traditionally focused on specific mechanisms,thereby limiting the generalizability of proposed theories.Understanding the commonalities in rail corrugation across diverse metro lines remains pivotal for elucidating its underlying mechanisms.The present study conducted extensive field surveys and tracking tests across 14 Chinese metro lines.By employing t-distributed stochastic neighbor embedding(t-SNE)for dimensional reduction and employing the unsupervised clustering algorithm DBSCAN,the research redefines the classification of metro rail corrugation based on characteristic information.The analysis encompassed spatial distribution and temporal evolution of this phenomenon.Findings revealed that floating slab tracks exhibited the highest proportion of rail corrugation at 47%.Notably,ordinary monolithic bed tracks employing damping fasteners were more prone to inducing rail corrugation.Corrugation primarily manifested in curve sections with radii between 300 and 500 m,featuring ordinary monolithic bed track and steel-spring floating slab track structures,with wavelengths typically between 30 and 120 mm.Stick–slip vibrations of the wheel–rail system maybe led to short-wavelength corrugations(40–60 mm),while longer wavelengths(200–300 mm)exhibited distinct fatigue damage characteristics,mainly observed in steel-spring floating slab tracks and small-radius curve sections of ordinary monolithic bed tracks and ladder sleeper tracks.A classification system comprising 57 correlated features categorized metro rail corrugation into four distinct types.These research outcomes serve as critical benchmarks for validating various theories pertaining to rail corrugation formation.展开更多
The Early Cambrian Yuertusi Formation(Є_(1)y)in the Tarim Basin of China deposits a continuously developed suite of organic-rich black mudstones,which constitute an important source of oil and gas reservoirs in the Pa...The Early Cambrian Yuertusi Formation(Є_(1)y)in the Tarim Basin of China deposits a continuously developed suite of organic-rich black mudstones,which constitute an important source of oil and gas reservoirs in the Paleozoic.However,its hydrocarbon generation and evolution characteristics and resource potential have long been constrained by deeply buried strata and previous research.In this paper,based on the newly obtained ultra-deep well drilling data,the hydrocarbon generation and expulsion model ofЄ_(1)y shale was established by using data-driven Monte Carlo simulation,upon which the hydrocarbon generation,expulsion,and retention amounts were calculated by using the diagenetic method.The research indicates that theЄ_(1)y shale reaches the hydrocarbon generation and expulsion threshold at equivalent vitrinite reflectances of 0.46%and 0.72%,respectively.The cumulative hydrocarbon generation is 68.88×10^(10)t,the cumulative hydrocarbon expulsion is 35.59×10^(10)t,and the cumulative residual hydrocarbon is 33.29×10^(10)t.This paper systematically and quantitatively calculates the hydrocarbon expulsion at various key geological periods for theЄ_(1)y source rocks in the study area for the first time,more precisely confirming that the black shale of theЄ_(1)y is the most significant source rock contributing to the marine oil and gas resources in the Tarim Basin,filling the gap in hydrocarbon expulsion calculation in the study area,and providing an important basis for the formation and distribution of Paleozoic hydrocarbon reservoirs.The prospect of deep ultra-deep oil and gas exploration in the Tarim Basin is promising.Especially,the large area of dolomite reservoirs under the Cambrian salt and source rock interiors are the key breakthrough targets for the next exploration in the Tarim Basin.展开更多
Shaped charge has been widely used for penetrating concrete.However,due to the obvious difference between the propagation of shock waves and explosion products in water and air,the theory governing the formation of sh...Shaped charge has been widely used for penetrating concrete.However,due to the obvious difference between the propagation of shock waves and explosion products in water and air,the theory governing the formation of shaped charge jets in water as well as the underwater penetration effect of concrete need to be studied.In this paper,we introduced a modified forming theory of an underwater hemispherical shaped charge,and investigated the behavior of jet formation and concrete penetration in both air and water experimentally and numerically.The results show that the modified jet forming theory predicts the jet velocity of the hemispherical liner with an error of less than 10%.The underwater jets exhibit at least 3%faster and 11%longer than those in air.Concrete shows different failure modes after penetration in air and water.The depth of penetration deepens at least 18.75%after underwater penetration,accompanied by deeper crater with 65%smaller radius.Moreover,cracks throughout the entire target are formed,whereas cracks exist only near the penetration hole in air.This comprehensive study provides guidance for optimizing the structure of shaped charge and improves the understanding of the permeability effect of concrete in water.展开更多
Severe ground-level ozone(O_(3))pollution over major Chinese cities has become one of the most challenging problems,which have deleterious effects on human health and the sustainability of society.This study explored ...Severe ground-level ozone(O_(3))pollution over major Chinese cities has become one of the most challenging problems,which have deleterious effects on human health and the sustainability of society.This study explored the spatiotemporal distribution characteristics of ground-level O_(3) and its precursors based on conventional pollutant and meteorological monitoring data in Zhejiang Province from 2016 to 2021.Then,a high-performance convolutional neural network(CNN)model was established by expanding the moment and the concentration variations to general factors.Finally,the response mechanism of O_(3) to the variation with crucial influencing factors is explored by controlling variables and interpolating target variables.The results indicated that the annual average MDA8-90th concentrations in Zhejiang Province are higher in the northern and lower in the southern.When the wind direction(WD)ranges from east to southwest and the wind speed(WS)ranges between 2 and 3 m/sec,higher O_(3) concentration prone to occur.At different temperatures(T),the O_(3) concentration showed a trend of first increasing and subsequently decreasing with increasing NO_(2) concentration,peaks at the NO_(2) concentration around 0.02mg/m^(3).The sensitivity of NO_(2) to O_(3) formation is not easily affected by temperature,barometric pressure and dew point temperature.Additionally,there is a minimum IRNO_(2) at each temperature when the NO_(2) concentration is 0.03 mg/m^(3),and this minimum IRNO_(2) decreases with increasing temperature.The study explores the response mechanism of O_(3) with the change of driving variables,which can provide a scientific foundation and methodological support for the targeted management of O_(3) pollution.展开更多
Tectonic activities significantly impact deep reservoir properties via sedimentary and diagenetic processes,and this is particularly true for lacustrine rift basins.The tectonic-sedimentary-diageneticreservoir system ...Tectonic activities significantly impact deep reservoir properties via sedimentary and diagenetic processes,and this is particularly true for lacustrine rift basins.The tectonic-sedimentary-diageneticreservoir system is crucial in deep reservoir exploration.This study examined the first member and upper submember of the second member of the Dongying Formation in the Bodong Low Uplift in the Bohai Bay Basin(East China),documenting the petrologic features and physical properties of reservoirs in different tectonic sub-units through integrated analysis of log and rock data,along with core observation.A mechanism for deep reservoir formation in lacustrine rift basins was developed to elucidate the sedimentary and diagenetic processes in complex tectonic settings.The results show that tectonic activities result in the occurrence of provenances in multiple directions and the existence of reservoirs at varying burial depths,as well as the significant diversity in sedimentary and diagenetic processes.The grain sizes of the sandstones,influenced by transport pathways rather than the topography of the sedimentary area,exhibit spatial complexity due to tectonic frameworks,which determine the initial pore content of reservoirs.However,the burial depth,influenced by subsequent tectonic subsidence,significantly impacts pore evolution during diagenesis.Based on the significant differences of reservoirs in slope zone,low uplift and depression zone,we establish different tectonic-diagenetic models in deep complex tectonic units of lacustrine rift basins.展开更多
The morphology and dimension of W phases play an important role in determining mechanical properties of Mg-RE-Zn(where RE denotes rare earth elements)alloys.In this study,theγ′platelet and W particle occurred in the...The morphology and dimension of W phases play an important role in determining mechanical properties of Mg-RE-Zn(where RE denotes rare earth elements)alloys.In this study,theγ′platelet and W particle occurred in the aged Mg-2Dy-0.5Zn(at.%)alloys were investigated by aberration-corrected scanning transmission electron microscopy.A novel formation mechanism of W phase was proposed,and its effects on the morphology and dimension of W particle,as well as mechanical properties of Mg-2Dy-0.5Zn alloys,were also discussed particularly.Different from other Mg-RE-Zn alloys,the nucleation and growth of W particle in Mg-Dy-Zn alloys mainly depend on the precipitatedγ′platelet.Primarily,a mass of Dy and Zn solute atoms concentrated nearγ′platelet or between two adjacentγ′platelets can meet the composition requirement of W particle nucleation.Next,the smaller interfacial mismatch between W andγ′facilitates the nucleation and growth of W particle.Thirdly,the growth of W particle can be achieved by consuming the surroundingγ′platelets.The nucleation and growth mechanisms make W particles exhibit rectangular or leaf-like and remain at the nanoscale.The coexistence ofγ′platelets and nanoscale W particles,and some better interfacial relationships between phases,lead to a high strength-ductility synergy of alloy.The findings may provide some fundamental guidelines for the microstructure design and optimization of new-type Mg-based alloys.展开更多
The 7 ka old Qixiangzhan lava flow(QXZ,Tianchi volcano)represents the last eruptive event before the 946 CE,caldera-forming‘Millennium’eruption(ME).Petrographic,whole rock,mineral composition,Sr-Nd isotopic data on ...The 7 ka old Qixiangzhan lava flow(QXZ,Tianchi volcano)represents the last eruptive event before the 946 CE,caldera-forming‘Millennium’eruption(ME).Petrographic,whole rock,mineral composition,Sr-Nd isotopic data on QXZ show that:(a)the lava consists of two components,constituted by comenditic obsidian fragments immersed in a continuous,aphanitic component;(b)both components have the same geochemical and isotopic variations of the ME magma.The QXZ and ME comendites result from fractional crystallization and crustal assimilation processes.The temperature of the QXZ magma was about 790℃ and the depth of the magma reservoir around 7 km,the same values as estimated for ME.QXZ had a viscosity of 10^(5.5)-10^(9) Pa s and a velocity of 3-10 km/yr.The emplacement time was 0.5-1.6yr and the flow rate 0.48-1.50 m^(3)/s.These values lie within the range estimated for other rhyolitic flows worldwide.The QXZ lava originated through a mixed explosive-effusive activity with the obsidian resulting from the ascent of undercooling,degassing and the fragmentation of magma along the conduit walls,whereas the aphanitic component testifies to the less undercooled and segregated flow at the center of the conduit.The QXZ lava demonstrates the extensive history of the ME magma chamber.展开更多
Clarifying the mechanisms that control the evolution of territorial space patterns is essential for regulating and optimizing the geographical structure and processes related to sustainable development.Using the Guang...Clarifying the mechanisms that control the evolution of territorial space patterns is essential for regulating and optimizing the geographical structure and processes related to sustainable development.Using the Guangdong and Guangxi sections of the Pearl River Basin as examples,the transfer-matrix method and standard deviation ellipse model were applied to characterize the evolution of territorial space patterns from 1990 to 2020.A trend surface analysis and the Theil index were used to analyze regional differences in the evolution process,and geodetectors were used to identify the underlying mechanisms of the changes.There were three key results.(1)In these critical areas of the Pearl River Basin,agricultural and ecological spaces have rapidly declined due to urban expansion,with transfers between these spaces dominating the evolution of territorial space patterns.Spatial pattern changes in the Guangdong section were more intense than in the Guangxi section.(2)Regional differences in urban space have decreased,whereas differences in agricultural and ecological spaces have intensified.Driven by socio-economic growth,the cross-regional transfers of territorial space have created a“high in the east,while low in the west”inter-regional difference,and a“high in the south,while low in the north”intra-regional difference shaped by natural conditions.The regional differences in space patterns were greater in Guangdong than in Guangxi.(3)The evolution of watershed territorial space patterns resulted from scale changes,locational shifts,structural reorganizations,and directional changes driven by multiple factors.Natural environment,social life,economic development,and policy factors played foundational,leading,key driving,and guiding roles,respectively.Additionally,the regional differences in the evolution of watershed territorial space patterns originated from the differential transmission of the influence of various factors affecting spatial evolution.Enhancing urban space efficiency,restructuring agricultural space,and optimizing ecological space are key strategies for building a complementary and synergistic territorial space pattern in the basin.展开更多
基金funded by the National Natural Science Foundation Research of China(No.41902127,41802157)the Shandong Provincial Natural Science Foundation,China(No.ZR2018BD015).
文摘This study aims to determine the variation and controlling factors of shale gas adsorption capacity in reservoirs in the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation(also referred to as the WF-LMX formations),South China.Based on data obtained using scanning helium ion microscopy(HIM)and nitrogen(N_(2))and methane(CH_(4))adsorption experiments,this study analyzed the organic pore heterogeneity of shales in the WF-LMX formations in well A and its effect on shale gas adsorption.Using the Frenkel-Halsey-Hill(FHH)model,data from N_(2) adsorption experiments were converted into fractal dimensions,which can reflect the complexity and heterogeneity of organic pores while also serving as a novel indicator for quantitatively assessing the pore structure complexity.The results indicate that shales in the WF-LMX formations in well A can be divided into two sections:(Ⅰ)the Wufeng Formation and the lower Longmaxi Formation(depths:ca.2871.0-2898.6 m),and(Ⅱ)the upper Longmaxi Formation(depths:<2871.0 m).Organic pores in Section Ⅰ typically exhibit complex internal structures,coarse surfaces,and interconnectivity,whereas those in Section Ⅱ are simple,smooth,and isolated.Moreover,the former possesses larger specific surface areas(SSAs)than the latter.A fractal analysis reveals that organic pores in the shale sequence can be classified into micropores(<2 nm),mesopores(2-10 nm),and macropores(>10 nm).The calculated fractal dimensions show greater heterogeneity of organic pores,especially macropores,in Section Ⅰ compared to Section Ⅱ.The results also reveal that organic macropores are the primary pores controlling the SSAs of organic pores in shale reservoirs in the WF-LMX formations.Organic pores in Section Ⅰ manifest a superior shale gas adsorption capacity compared to Section Ⅱ.The heterogeneity of organic pores might affect the adsorption capacity of shales in the formations.Generally,organic macropores in Section Ⅰ of the shale sequence exhibit more complex structures and larger SSAs,leading to a stronger absorption capacity of shale reservoirs in Section Ⅰ compared to Section Ⅱ.
基金supported by the National Natural Science Foundation of China(Grant No.52474010)the Natural Science Foundation of Sichuan Province(Grant No.2024NSFSC0023)the Sichuan Science and Technology Program(Grant No.2020JDJQ0055).
文摘A thermodynamics-based unsaturated hydro-mechanical-chemical(HMC)coupling model is developed to analyze the coupled response and stability of boreholes in chemically active gas formations.The newly coupled constitutive relations are formulated by incorporating the chemical effect into the solid-gasliquid unsaturated framework to account for the interactions between rock deformation,gas-liquid two-phase flow,and chemical potential difference.Compared with previous models,the present model shows significant prediction differences in field variables and wellbore stability evolution.The maximum absolute difference of pore pressure,effective radial stress,effective tangential stress,and collapse pressure can reach 8.98 MPa,7.64 MPa,7.29 MPa,7.65 MPa,respectively.It is more conservative to select a long-term wellbore collapse pressure rather than a short-term one to guide drilling operations.The two-phase flow behavior,jointly controlled by wellbore pressure,capillary pressure,and chemical osmosis effect,provides a more realistic observation of the mud intrusion process.Compared with low salinity muds,high salinity muds can effectively impede the mud intrusion into the formation,which is more conducive to preventing wellbore collapse,but at the same time increases the risk of wellbore fracture.Sensitivity analysis shows that solute diffusion and reflection coefficients affect early wellbore stability through pore pressure and solute transport,while the chemical swelling coefficient has a long-term effect through chemically induced deformation.The results can provide theoretical guidance for quantitative optimization of mud parameters and prevention of wellbore instability when drilling in chemically active gas formations.
基金the Chinese Scholarship Council for their support(Grant No.2022GXZ005733).
文摘Surface hydrogen storage facilities are limited and costly,making subsurface hydrogen storage in geological formations a more viable alternative due to its substantial capacity,safety,and economic feasibility.This method is essential for large-scale hydrogen storage to support renewable energy integration,fuel cell technologies,and other applications aimed at mitigating global climate change.This review examines underground hydrogen storage(UHS)in geological formations,focusing on recent experiments,modeling and simulations,and field applications.Geological formations such as depleted oil reservoirs,salt caverns,and depleted natural gas reservoirs are identified as favorable candidates due to minimal interactions with hydrogen,leading to low hydrogen loss.Globally,80%of UHS projects utilize depleted natural gas and oil reservoirs,with over 50%focused on depleted natural gas and oil condensate reservoirs due to cost-effective existing infrastructure.Among storage options,salt caverns are the most advantageous,offering self-healing properties,low caprock permeability,large storage capacity,rapid injection and withdrawal rates,and low contamination risk.Additionally,hydrogen produced from coal is the cheapest option,costing 1.2e2 USD/kg,whereas hydrogen from renewable sources,such as water,is the most expensive at 3e13 USD/kg.Despite its higher cost,green hydrogen from water,characterized by low carbon emissions,requires further research to reduce production costs.This review highlights critical research gaps,challenges,and policy recommendations to advance UHS technologies,ensuring their role in combating climate change.
基金Supported by the Joint Fund Key Program of the National Natural Science Foundation of China(U21B2069)Key Research and Development Program of Shandong Province(2022CXGC020407)Basic Science Center Program of the National Natural Science Foundation of China(52288101)。
文摘By comprehensively considering the influences of temperature and pressure on fluid density in high temperature and high pressure(HTHP)wells in deepwater fractured formations and the effects of formation fracture deformation on well shut-in afterflow,this study couples the shut-in temperature field model,fracture deformation model,and gas flow model to establish a wellbore pressure calculation model incorporating thermo-hydro-mechanical coupling effects.The research analyzes the governing patterns of geothermal gradient,bottomhole pressure difference,drilling fluid pit gain,and kick index on casing head pressure,and establishes a shut-in pressure determination chart for HPHT wells based on coupled model calculation results.The study results show:geothermal gradient,bottomhole pressure difference,and drilling fluid pit gain exhibit positive correlations with casing head pressure;higher kick indices accelerate pressure rising rates while maintaining a constant maximum casing pressure;validation against field case data demonstrates over 95%accuracy in predicting wellbore pressure recovery after shut-in,with the pressure determination chart achieving 97.2%accuracy in target casing head pressure prediction and 98.3%accuracy in target shut-in time.This method enables accurate acquisition of formation pressure after HPHT well shut-in,providing reliable technical support for subsequent well control measures and ensuring safe and efficient development of deepwater and deep hydrocarbon reservoirs.
基金supported by National Natural Science Foundation of China(W2431028,42122029)SINOPEC Fundamental Research Program(P24258)CNPC Investigations on fundamental experiments and advanced theoretical methods in geophysical prospecting applications(2022DQ0604-02).
文摘Existing studies indicate that gas hydrate-bearing formations exhibit notable seismic velocity dispersion and attenuation. The Shenhu area of the South China Sea hold significant gas hydrate resource potential;however, the relationship between seismic velocity dispersion, attenuation properties, and gas-hydrate saturation remains insufficiently understood. Furthermore, a significant mismatch exists between the real seismic angle gather near a well and the synthetic angle gather generated using the convolution method, and this discrepancy may arise from the seismic velocity dispersion and attenuation characteristics of the gas hydrate-bearing formations. In this paper, we develop a rock physics model that integrates White's and Dvorkin's models, accounting for varied types of gas-hydrate occurrence states,specifically tailored to the gas hydrate-bearing formations in the Shenhu area. This model is calibrated with well log data and employed to investigate how gas-hydrate saturation influences seismic velocity dispersion and attenuation. Numerical analysis reveals the coexistence of two types of gas-hydrate occurrence states in the region: high gas-hydrate saturation formations are dominated by loadbearing-type gas hydrate, and formations containing both gas hydrate and free gas may exhibit either load-bearing or pore-filling types. The seismic velocity dispersion and attenuation properties vary significantly depending on the gas-hydrate occurrence state. We further apply the proposed model to generate seismic velocity and attenuation logs at various frequencies. These logs are used in seismic forward modeling employing both the convolution method and the propagator matrix method. Well tie analysis indicates that the synthetic angle gather incorporating attenuation via the propagator matrix method aligns more closely with the real seismic angle gather than the convolution method. This study provides valuable insights into frequency-dependent amplitude versus offset(AVO) analysis and the seismic interpretation of gas hydrate-bearing formations in the South China Sea.
基金supported by the National Natural Science Foundation of China(No.52074312)the CNPC Science and Technology Innovation Foundation(No.2021DQ02-0505)+1 种基金the Open Fund Project of the National Key Laboratory for the Enrichment Mechanism and Efficient Development of Shale Oil and Gas(No.36650000-24-ZC0609-0006)the Major Science and Technology Project of Karamay City(No.20232023zdzx0003).
文摘Due to complex geological structures and a narrow safe mud density window,offshore fractured formations frequently encounter severe lost circulation(LC)during drilling,significantly hindering oil and gas exploration and development.Predicting LC risks enables the targeted implementation of mitigation strategies,thereby reducing the frequency of such incidents.To address the limitations of existing 3D geomechanical modeling in predicting LC,such as arbitrary factor selection,subjective weight assignment,and the inability to achieve pre-drilling prediction along the entire well section,an improved prediction method is proposed.This method integrates multi-source data and incorporates three LC-related sensitivity factors:fracture characteristics,rock brittleness,and in-situ stress conditions.A quantitative risk assessment model for LC is developed by combining the subjective analytic hierarchy process with the objective entropy weight method(EWM)to assign weights.Subsequently,3D geomechanical modeling is applied to identify regional risk zones,enabling digital visualization for pre-drilling risk prediction.The developed 3D LC risk prediction model was validated using actual LC incidents from drilled wells.Results were generally consistent with field-identified LC zones,with an average relative error of 19.08%,confirming its reliability.This method provides practical guidance for mitigating potential LC risks and optimizing drilling program designs in fractured formations.
基金supported by the Central South University Postdoctoral Research Fund(No.22020084)。
文摘The Bipindi iron ore district is located in the central section of the Nyong Complex at the northwestern margin of the Congo Craton in Southwest Cameroon.This iron district contains numerous iron mineralization hosted by the Mewongo,Bibole,Kouambo,and Zambi banded iron formations(BIFs).These BIFs contain magnetite as the main iron ore mineral associated with pyrite,and gangue minerals are quartz with minor chlorite and amphibole.The origin of iron ore from these BIFs was investigated using a combination of in-situ magnetite and whole-rock chemistry.The studied BIF ore samples have a narrow range of TFe between 30.90 wt.%and 43.20 wt.%,indicating a low-grade ore.The geochemical signatures of magnetite such as low contents of base metals(e.g.,Cu,Co,V,and Zn)and low Co/Zn ratios<0.85 indicate a hydrothermal origin.Combined with the geochemical features of these BIFs,e.g.,high Fe/Ti and Fe/Al ratios(mean>600 and>75,respectively),we suggest that magnetite was derived from a mixture of seawater and~0.1%low-temperature hydrothermal fluids in an oxidizing environment.Collectively,low-temperature hydrothermal and later metamorphic fluids were necessary for the transformation of the protolith Nyong Complex BIFs to iron ore.
基金funded by SINOPEC(scientific research project P21087-6).
文摘Shales of the Wufeng-Longmaxi formations in the basin-margin transition zone of southeastern Chongqing,China are characterized by high organic matter content and a significant presence of pyrite development.By examining numerous scanning electron microscope(SEM)images and considering the crystal and aggregate characteristics of minerals,we identified four types of pyrite in the study area:euhedral crystals,irregular aggregates,framboidal aggregates,and metasomatized organisms.Among these types,framboidal aggregates are the most prevalent.The formation mechanism of framboidal pyrite can be categorized into inorganic and organic origins.As inferred from the pyrite characteristics in the study area,the formation mechanism of the metasomatized organisms aligns with the biologically induced mineralization mode of organic origin,whereas the framboidal aggregates are more associated with the biologically controlled mineralization mode of organic origin.This underscores a close relationship between the pyrite formation and organic matter,which in turn indicates that an organic origin is more consistent with the pyrite characteristics observed in this study area.The pyrite morphology can reflect reactive iron concentration.Euhedral pyrite crystals tend to form under a low reactive iron concentration,whereas the formation of framboidal pyrite requires a high reactive iron concentration.Additionally,the type and grain size of pyrite aggregates can reflect variations in the redox conditions of the depositional environment.Pyrite produces positive effects on reservoir storage space,with intercrystalline organic pores,intercrystalline pores,and mold pores associated with pyrite contributing greatly to the storage spaces.
文摘XRF and EDX analyses were carried out on 18 batches of representative raw samples to determine the distribution of major chemical elements in the petroleum source rocks of Donga and Yogou formations of Termit sedimentary basin. The chemical composition of these formations is dominated by silicon (Si), aluminum (Al) and iron (Fe). This is consistent with the oxide composition, which is also dominated by silicon oxide (SiO2), aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) and iron monoxide (FeO). No less important chemical elements are calcium (Ca), potassium (K), sulfur (S), titanium (Ti), magnesium (Mg), manganese (Mn) and barium (Ba), as well as some of their oxides. All these major chemical elements are carried by silicate detrital minerals associated with pyrite and goethite and/or clay minerals such as kaolinite and interstratified illite, smectite and chlorite. This trend is illustrated by the values of the Si/Al and SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> ratios.
基金supported by the National Natural Science Foundation of China(32160681 and 32060663)the National Guidance Foundation for Local Science and Technology Development of China(2023-009)+1 种基金the Guizhou Provincial Basic Research Program(Natural Science)(ZK[2022]YB132)the Foundation of Postgraduate of Guizhou Province,China(YJSKYJJ[2021]057)。
文摘Hylocereus polyrhizus,also known as pitaya or dragon fruit,is a climbing cactus grown worldwide because of its excellent performance under drought stress and appealing red-purple fruits.In practice,accelerating flower formation and inducing more flowers usually result in higher yield.However,the genes for this purpose have not been well characterized in pitaya.Previously,FLOWERING BHLHs(FBHs)have been identified as positive regulators of flower formation.In the present work,a total of eight FBHs were identified in pitaya.This is a greater number than in beet and spinach,possibly because of the recent whole-genome duplication that occurred in the pitaya genome.The phylogenetic tree indicated that the FBHs could be divided into three groups.In TYPEⅡ,the genes of Caryophyllales encode atypical FBHs and are generated by dispersed duplication.The K_(a)/K_(s) ratios indicated that HpFBHs are under purifying selection.Promoter and expression analysis of HpFBHs revealed that they are spatiotemporally activated in flower-related tissues and responsive to multiple abiotic stresses.These results indicated that HpFBHs are involved in the flower formation of pitaya.Therefore,typical HpFBH1/3 from TYPEⅡI and an atypical HpFBH8 from TYPEⅡwere selected for functional verification.HpFBH3 was found to heterodimerize with HpFBH1 in the nucleus using subcellular localization,yeast two-hybrid and luciferase complementation assays.With bioinformatic analysis,all HpFBHs were predicted to transactivate downstream genes via binding to the E-boxes,which were frequently detected in the promoters of HpCOs,HpFTs and HpSOC1s.RNA-Seq datasets showed that these flowering accelerators were expressed in coordination with HpFBH3.Yeast one-hybrid and dual-luciferase reporter assays further verified that HpFBH3 transactivated HpCO7 by selectively binding to the E-boxes in the promoter.Moreover,ectopic overexpression of HpFBH3 accelerated flower formation in Arabidopsis.In summary,this study systematically characterized the typical HpFBHs,especially HpFBH3,as positive regulators of flower formation,which could be target genes for the genetic improvement of pitaya.
基金co-supported by the Science Center for Gas Turbine Project, China(No. P2022-AB-IV-001-002)the National Natural Science Foundation of China (No. 91960203)+1 种基金the Fundamental Research Funds for the Central Universities (No. D5000230048)the Innovation Capability Support Program of Shaanxi (No. 2022TD-60)
文摘Superior strength and high-temperature performance make γ-TiAl vital for lightweight aero-engines. However, its inherent brittleness poses machining problems. This study employed Elliptical Ultrasonic Vibration Milling (EUVM) to address these problems. Considering the influence of machining parameters on vibration patterns of EUVM, a separation time model was established to analyze the vibration evolutionary process, thereby instructing the cutting mechanism. On this basis, deep discussions regarding chip formation, cutting force, edge breakage, and subsurface layer deformation were conducted for EUVM and Conventional Milling (CM). Chip morphology showed the chip formation was rooted in the periodic brittle fracture. Local dimples proved that the thermal effect of high-speed cutting improved the plasticity of γ-TiAl. EUVM achieved a maximum 18.17% reduction in cutting force compared with CM. The force variation mechanism differed with changes in the cutting speed or the vibration amplitude, and its correlation with thermal softening, strain hardening, and vibratory cutting effects was analyzed. EUVM attained desirable edge breakage by achieving smaller fracture lengths. The fracture mechanisms of different phases were distinct, causing a surge in edge fracture size of γ-TiAl under microstructural differences. In terms of subsurface deformation, EUVM also showed strengthening effects. Noteworthy, the lamellar deformation patterns under the cutting removal state differed from the quasi-static, which was categorized by the orientation angles. Additionally, the electron backscattering diffraction provided details of the influence of microstructural difference on the orientation and the deformation of grains in the subsurface layer. The results demonstrate that EUVM is a promising machining method for γ-TiAl and guide further research and development of EUVM γ-TiAl.
基金support extended by the Joint Funds of Beijing Municipal Natural Science Foundation and Fengtai Rail Transit Frontier Research(Grant No.L211006)the Fundamental Research Funds for the Central Universities(Science and technology leading talent team project,Grant No.2022JBXT010)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.2023YJS052)the National Natural Science Foundation of China(Grant No.52308426)。
文摘Investigations into rail corrugation within metro systems have traditionally focused on specific mechanisms,thereby limiting the generalizability of proposed theories.Understanding the commonalities in rail corrugation across diverse metro lines remains pivotal for elucidating its underlying mechanisms.The present study conducted extensive field surveys and tracking tests across 14 Chinese metro lines.By employing t-distributed stochastic neighbor embedding(t-SNE)for dimensional reduction and employing the unsupervised clustering algorithm DBSCAN,the research redefines the classification of metro rail corrugation based on characteristic information.The analysis encompassed spatial distribution and temporal evolution of this phenomenon.Findings revealed that floating slab tracks exhibited the highest proportion of rail corrugation at 47%.Notably,ordinary monolithic bed tracks employing damping fasteners were more prone to inducing rail corrugation.Corrugation primarily manifested in curve sections with radii between 300 and 500 m,featuring ordinary monolithic bed track and steel-spring floating slab track structures,with wavelengths typically between 30 and 120 mm.Stick–slip vibrations of the wheel–rail system maybe led to short-wavelength corrugations(40–60 mm),while longer wavelengths(200–300 mm)exhibited distinct fatigue damage characteristics,mainly observed in steel-spring floating slab tracks and small-radius curve sections of ordinary monolithic bed tracks and ladder sleeper tracks.A classification system comprising 57 correlated features categorized metro rail corrugation into four distinct types.These research outcomes serve as critical benchmarks for validating various theories pertaining to rail corrugation formation.
基金supported by the CNPC Science and Technology Major Project of the Fourteenth Five-Year Plan(2021DJ0101)the National Natural Science Foundation of China(U19B600302,41872148)。
文摘The Early Cambrian Yuertusi Formation(Є_(1)y)in the Tarim Basin of China deposits a continuously developed suite of organic-rich black mudstones,which constitute an important source of oil and gas reservoirs in the Paleozoic.However,its hydrocarbon generation and evolution characteristics and resource potential have long been constrained by deeply buried strata and previous research.In this paper,based on the newly obtained ultra-deep well drilling data,the hydrocarbon generation and expulsion model ofЄ_(1)y shale was established by using data-driven Monte Carlo simulation,upon which the hydrocarbon generation,expulsion,and retention amounts were calculated by using the diagenetic method.The research indicates that theЄ_(1)y shale reaches the hydrocarbon generation and expulsion threshold at equivalent vitrinite reflectances of 0.46%and 0.72%,respectively.The cumulative hydrocarbon generation is 68.88×10^(10)t,the cumulative hydrocarbon expulsion is 35.59×10^(10)t,and the cumulative residual hydrocarbon is 33.29×10^(10)t.This paper systematically and quantitatively calculates the hydrocarbon expulsion at various key geological periods for theЄ_(1)y source rocks in the study area for the first time,more precisely confirming that the black shale of theЄ_(1)y is the most significant source rock contributing to the marine oil and gas resources in the Tarim Basin,filling the gap in hydrocarbon expulsion calculation in the study area,and providing an important basis for the formation and distribution of Paleozoic hydrocarbon reservoirs.The prospect of deep ultra-deep oil and gas exploration in the Tarim Basin is promising.Especially,the large area of dolomite reservoirs under the Cambrian salt and source rock interiors are the key breakthrough targets for the next exploration in the Tarim Basin.
基金supported by the National Science Foundation of China(Grant Nos.12372361,12102427,12372335 and 12102202)the Fundamental Research Funds for the Central Universities(Grant No.30923010908)Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX23_0520).
文摘Shaped charge has been widely used for penetrating concrete.However,due to the obvious difference between the propagation of shock waves and explosion products in water and air,the theory governing the formation of shaped charge jets in water as well as the underwater penetration effect of concrete need to be studied.In this paper,we introduced a modified forming theory of an underwater hemispherical shaped charge,and investigated the behavior of jet formation and concrete penetration in both air and water experimentally and numerically.The results show that the modified jet forming theory predicts the jet velocity of the hemispherical liner with an error of less than 10%.The underwater jets exhibit at least 3%faster and 11%longer than those in air.Concrete shows different failure modes after penetration in air and water.The depth of penetration deepens at least 18.75%after underwater penetration,accompanied by deeper crater with 65%smaller radius.Moreover,cracks throughout the entire target are formed,whereas cracks exist only near the penetration hole in air.This comprehensive study provides guidance for optimizing the structure of shaped charge and improves the understanding of the permeability effect of concrete in water.
基金supported by the National Key Research and Development Program of China (Nos.2022YFC3702000 and 2022YFC3703500)the Key R&D Project of Zhejiang Province (No.2022C03146).
文摘Severe ground-level ozone(O_(3))pollution over major Chinese cities has become one of the most challenging problems,which have deleterious effects on human health and the sustainability of society.This study explored the spatiotemporal distribution characteristics of ground-level O_(3) and its precursors based on conventional pollutant and meteorological monitoring data in Zhejiang Province from 2016 to 2021.Then,a high-performance convolutional neural network(CNN)model was established by expanding the moment and the concentration variations to general factors.Finally,the response mechanism of O_(3) to the variation with crucial influencing factors is explored by controlling variables and interpolating target variables.The results indicated that the annual average MDA8-90th concentrations in Zhejiang Province are higher in the northern and lower in the southern.When the wind direction(WD)ranges from east to southwest and the wind speed(WS)ranges between 2 and 3 m/sec,higher O_(3) concentration prone to occur.At different temperatures(T),the O_(3) concentration showed a trend of first increasing and subsequently decreasing with increasing NO_(2) concentration,peaks at the NO_(2) concentration around 0.02mg/m^(3).The sensitivity of NO_(2) to O_(3) formation is not easily affected by temperature,barometric pressure and dew point temperature.Additionally,there is a minimum IRNO_(2) at each temperature when the NO_(2) concentration is 0.03 mg/m^(3),and this minimum IRNO_(2) decreases with increasing temperature.The study explores the response mechanism of O_(3) with the change of driving variables,which can provide a scientific foundation and methodological support for the targeted management of O_(3) pollution.
基金funded by the Open Fund of Key Laboratory of Marine Geology and Environment,Chinese Academy of Sciences(Grant No.MGE2020KG10)the Open Fund of Key Laboratory of Submarine Geosciences,Ministry of Natural Resources(Grant No.KLSG 2208)+2 种基金the Natural Science Basic Research Program of Shaanxi(Grant No.2024JC-YBMS-227,2023-JC-QN-0287)the Postgraduate Innovation and Practice Ability Development Fund of Xi'an Shiyou University(No.YCS23113046)the National Natural Science Foundation of China(Grant No.41802128,42076219)。
文摘Tectonic activities significantly impact deep reservoir properties via sedimentary and diagenetic processes,and this is particularly true for lacustrine rift basins.The tectonic-sedimentary-diageneticreservoir system is crucial in deep reservoir exploration.This study examined the first member and upper submember of the second member of the Dongying Formation in the Bodong Low Uplift in the Bohai Bay Basin(East China),documenting the petrologic features and physical properties of reservoirs in different tectonic sub-units through integrated analysis of log and rock data,along with core observation.A mechanism for deep reservoir formation in lacustrine rift basins was developed to elucidate the sedimentary and diagenetic processes in complex tectonic settings.The results show that tectonic activities result in the occurrence of provenances in multiple directions and the existence of reservoirs at varying burial depths,as well as the significant diversity in sedimentary and diagenetic processes.The grain sizes of the sandstones,influenced by transport pathways rather than the topography of the sedimentary area,exhibit spatial complexity due to tectonic frameworks,which determine the initial pore content of reservoirs.However,the burial depth,influenced by subsequent tectonic subsidence,significantly impacts pore evolution during diagenesis.Based on the significant differences of reservoirs in slope zone,low uplift and depression zone,we establish different tectonic-diagenetic models in deep complex tectonic units of lacustrine rift basins.
基金supported by Natural Science Foundation of Liaoning Province of China under Grant No.2020-MS-085。
文摘The morphology and dimension of W phases play an important role in determining mechanical properties of Mg-RE-Zn(where RE denotes rare earth elements)alloys.In this study,theγ′platelet and W particle occurred in the aged Mg-2Dy-0.5Zn(at.%)alloys were investigated by aberration-corrected scanning transmission electron microscopy.A novel formation mechanism of W phase was proposed,and its effects on the morphology and dimension of W particle,as well as mechanical properties of Mg-2Dy-0.5Zn alloys,were also discussed particularly.Different from other Mg-RE-Zn alloys,the nucleation and growth of W particle in Mg-Dy-Zn alloys mainly depend on the precipitatedγ′platelet.Primarily,a mass of Dy and Zn solute atoms concentrated nearγ′platelet or between two adjacentγ′platelets can meet the composition requirement of W particle nucleation.Next,the smaller interfacial mismatch between W andγ′facilitates the nucleation and growth of W particle.Thirdly,the growth of W particle can be achieved by consuming the surroundingγ′platelets.The nucleation and growth mechanisms make W particles exhibit rectangular or leaf-like and remain at the nanoscale.The coexistence ofγ′platelets and nanoscale W particles,and some better interfacial relationships between phases,lead to a high strength-ductility synergy of alloy.The findings may provide some fundamental guidelines for the microstructure design and optimization of new-type Mg-based alloys.
基金funded by the National Natural Science Foundation of China(Grant Nos.41972313 and 41790453)the Engineering Research Center of Geothermal Resources Development Technology and Equipment,Ministry of Education,Jilin University。
文摘The 7 ka old Qixiangzhan lava flow(QXZ,Tianchi volcano)represents the last eruptive event before the 946 CE,caldera-forming‘Millennium’eruption(ME).Petrographic,whole rock,mineral composition,Sr-Nd isotopic data on QXZ show that:(a)the lava consists of two components,constituted by comenditic obsidian fragments immersed in a continuous,aphanitic component;(b)both components have the same geochemical and isotopic variations of the ME magma.The QXZ and ME comendites result from fractional crystallization and crustal assimilation processes.The temperature of the QXZ magma was about 790℃ and the depth of the magma reservoir around 7 km,the same values as estimated for ME.QXZ had a viscosity of 10^(5.5)-10^(9) Pa s and a velocity of 3-10 km/yr.The emplacement time was 0.5-1.6yr and the flow rate 0.48-1.50 m^(3)/s.These values lie within the range estimated for other rhyolitic flows worldwide.The QXZ lava originated through a mixed explosive-effusive activity with the obsidian resulting from the ascent of undercooling,degassing and the fragmentation of magma along the conduit walls,whereas the aphanitic component testifies to the less undercooled and segregated flow at the center of the conduit.The QXZ lava demonstrates the extensive history of the ME magma chamber.
基金National Social Science Foundation Program,No.22VRC163National Natural Science Foundation of China,No.42061043+1 种基金Postgraduate Research&Practice Innovation Program of Jiangsu Province,No.KYCX24_1008Innovation Project of Guangxi Graduate Education,No.YCSW2024473。
文摘Clarifying the mechanisms that control the evolution of territorial space patterns is essential for regulating and optimizing the geographical structure and processes related to sustainable development.Using the Guangdong and Guangxi sections of the Pearl River Basin as examples,the transfer-matrix method and standard deviation ellipse model were applied to characterize the evolution of territorial space patterns from 1990 to 2020.A trend surface analysis and the Theil index were used to analyze regional differences in the evolution process,and geodetectors were used to identify the underlying mechanisms of the changes.There were three key results.(1)In these critical areas of the Pearl River Basin,agricultural and ecological spaces have rapidly declined due to urban expansion,with transfers between these spaces dominating the evolution of territorial space patterns.Spatial pattern changes in the Guangdong section were more intense than in the Guangxi section.(2)Regional differences in urban space have decreased,whereas differences in agricultural and ecological spaces have intensified.Driven by socio-economic growth,the cross-regional transfers of territorial space have created a“high in the east,while low in the west”inter-regional difference,and a“high in the south,while low in the north”intra-regional difference shaped by natural conditions.The regional differences in space patterns were greater in Guangdong than in Guangxi.(3)The evolution of watershed territorial space patterns resulted from scale changes,locational shifts,structural reorganizations,and directional changes driven by multiple factors.Natural environment,social life,economic development,and policy factors played foundational,leading,key driving,and guiding roles,respectively.Additionally,the regional differences in the evolution of watershed territorial space patterns originated from the differential transmission of the influence of various factors affecting spatial evolution.Enhancing urban space efficiency,restructuring agricultural space,and optimizing ecological space are key strategies for building a complementary and synergistic territorial space pattern in the basin.
