The physical properties of hydrocarbon reservoirs are important factors affecting the percolation ability of the reservoirs.Tight-sand reservoirs exhibit complex pore throat connectivity due to the extensive developme...The physical properties of hydrocarbon reservoirs are important factors affecting the percolation ability of the reservoirs.Tight-sand reservoirs exhibit complex pore throat connectivity due to the extensive development of micro-and nano-scale pore and throat systems.Characterizing the microscopic properties of these reservoirs using nondestructive,quantitative methods serves as an important means to determine the characteristics of microscopic pores and throats in tight-sand reservoirs and the mechanism behind the influence of these characteristics on reservoir porosity and permeability.In this study,a low-permeability sandstone sample and two tight sandstone samples collected from the Ordos Basin were nondestructively tested using high-resolution nano-CT technology to quantitively characterize their microscopic pore throat structures and model them three-dimensionally(in 3D)based on CT threshold differences and gray models.A thorough analysis and comparison reveal that the three samples exhibit a certain positive correlation between their porosity and permeability but the most important factor affecting both porosity and permeability is the microscopic pore throat structure.Although the number of pores in tight sandstones shows a minor impact on their porosity,large pores(more than 20μm)contribute predominantly to porosity,suggesting that the permeability of tight sandstones is controlled primarily by large pore throats.For these samples,higher permeability corresponds to larger average throat sizes.Therefore,throats with average radii greater than 2μm can significantly improve the permeability of tight sandstones.展开更多
Tuojiang River Basin is a first-class tributary of the upper reaches of the Yangtze River—which is the longest river in China.As phytoplankton are sensitive indicators of trophic changes inwater bodies,characterizing...Tuojiang River Basin is a first-class tributary of the upper reaches of the Yangtze River—which is the longest river in China.As phytoplankton are sensitive indicators of trophic changes inwater bodies,characterizing phytoplankton communities and their growth influencing factors in polluted urban rivers can provide new ideas for pollution control.Here,we used direct microscopic count and environmental DNA(eDNA)metabarcoding methods to investigate phytoplankton community structure in Tuojiang River Basin(Chengdu,Sichuan Province,China).The association between phytoplankton community structure and water environmental factors was evaluated by Mantel analysis.Additional environmental monitoring data were used to pinpoint major factors that influenced phytoplankton growth based on structural equation modeling.At the phylum level,the dominant phytoplankton taxa identified by the conventional microscopic method mainly belonged to Bacillariophyta,Chlorophyta,and Cyanophyta,in contrast with Chlorophyta,Dinophyceae,and Bacillariophyta identified by eDNA metabarcoding.Inα-diversity analysis,eDNA metabarcoding detected greater species diversity and achieved higher precision than the microscopic method.Phytoplankton growth was largely limited by phosphorus based on the nitrogen-to-phosphorus ratios>16:1 in all water samples.Redundancy analysis and structural equation modeling also confirmed that the nitrogen-to-phosphorus ratio was the principal factor influencing phytoplankton growth.The results could be useful for implementing comprehensive management of the river basin environment.It is recommended to control the discharge of point-and surface-source pollutants and the concentration of dissolved oxygen in areas with excessive nutrients(e.g.,Jianyang-Ziyang).Algae monitoring techniques and removal strategies should be improved in 201 Hospital,Hongrihe Bridge and Colmar Town areas.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
The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is si...The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC.In this work,the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB,and have provided new evidence for the regional tectonic evolution.The(U-Th)/He chronological data states the weighted ages of 240‒235 Ma,141 Ma with the peak distribution of 244 Ma,219 Ma,173 Ma,147‒132 Ma.The thermal evolution,geochronological data,and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2)the Late Triassic-Early Jurassic;(3)the Late Jurassic-Early Cretaceous;(4)the Late Cretaceous-Early Paleogene.It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB.Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.展开更多
The middle reaches of the Yellow River represent a critically ecologically sensitive and fragile area within the Yellow River Basin(YRB),holding significant scientific value for ecological security assessment and envi...The middle reaches of the Yellow River represent a critically ecologically sensitive and fragile area within the Yellow River Basin(YRB),holding significant scientific value for ecological security assessment and environmental management strategies.This study comprehensively evaluates the evolution of the eco-environment in the“Two Mountains,Seven Rivers,and One Basin”(TSO)area of Shanxi Province from 2000 to 2020 based on fraction vegetation cover(FVC)derived from the Normalized Difference Vegetation Index(NDVI),net primary productivity(NPP)calculated via the Carnegie–Ames–Stanford approach(CASA),and the remote sensing ecological index(RSEI).The results indicate a significant improvement in the TSO’s eco-environment from 2000 to 2020,with the RSEI values increased from 0.34 in 2000 to 0.41 in 2020(an increase of 17.76%).Both FVC and NPP demonstrated notable upward trends,with FVC increasing by 22.74%and NPP by 53.11%.Spatially,FVC rose by 21.84%,19.72%and 26.06%,respectively in the Two Mountains,Seven Rivers,and the YRB in Shanxi Province.Similarly,the NPPs increased by 51.60%,48.60%,and 61.65%in these regions over the past 21 years.Both FVC and NPP exhibited decreasing patterns from southeast to northwest,with significant eco-environmental improvements in the northern region and slower recovery in the southern region.Precipitation was the primary causes influencing vegetation recovery,showing positive trends in the central and northern TSO regions,while this trend reversed in the southern.The RSEI value indicate substantial eco-environment improvements in the central and northern areas(Sanggan,Daqing and Hutuo River Basins),whereas the southern regions(e.g.,Zhang,Qin,Fen and Sushui River Basins)remain in poor grade.Human activities,particularly land use/cover changes marked by increased forestation and urbanization alongside decreased cultivated land,significantly affected vegetation cover patterns.This study provides scientific references for formulating policies on ecological construction and high-quality development in the YRB.展开更多
The tight sandstone reservoirs in the first sub-member of Chang 7 member(Chang 71)of Triassic Yanchang Formation in the Jiyuan area,Ordos Basin,show significant variations in microscopic pore-throat structure(PTS)and ...The tight sandstone reservoirs in the first sub-member of Chang 7 member(Chang 71)of Triassic Yanchang Formation in the Jiyuan area,Ordos Basin,show significant variations in microscopic pore-throat structure(PTS)and fluid mobility due to the influences of the northeast and northwest dual provenance systems.This study performed multiple experimental analyses on nine samples from the area to determine the petrological and petrophysical properties,as well as the PTS characteristics of reservoirs in different provenance-controlled regions.On this basis,the pore-throat size distribution(PSD)obtained from high-pressure mercury injection(HPMI)was utilized to convert the NMR movable fluid T2spectrum,allowing for quantitative characterization of the full PSD and the occurrence characteristics of movable fluids.A systematic analysis was conducted on the primary controlling factors affecting fluid mobility in the reservoir.The results indicated that the lithology in the eastern and western regions is lithic arkose.The eastern sandstones,being farther from the provenance,exhibit higher contents of feldspar and lithic fragments,along with the development of more dissolution pores.The reservoir possesses good petrophysical properties,low displacement pressure,and high pore-throat connectivity and homogeneity,indicating strong fluid mobility.In contrast,the western sandstones,being nearer to the provenance,exhibit poor grain sorting,high contents of lithic fragments,strong compaction and cementation effects,resulting in poor petrophysical properties,and strong pore-throat heterogeneity,revealing weak fluid mobility.The range of full PSD in the eastern reservoir is wider than that in the western reservoir,with relatively well-developed macropores.The macropores are the primary space for occurrence of movable fluids,and controls the fluid mobility of the reservoir.The effective porosity of movable fluids(EPMF)quantitatively represents the pore space occupied by movable fluids within the reservoir and correlates well with porosity,permeability,and PTS parameters,making it a valuable parameter for evaluating fluid mobility.Under the multi-provenance system,the eastern and western reservoirs underwent different sedimentation and diagenesis processes,resulting in differential distribution of reservoir mineral components and pore types,which in turn affects the PTS heterogeneity and reservoir quality.The composition and content of reservoir minerals are intrinsic factors influencing fluid mobility,while the microscopic PTS is the primary factor controlling it.Low clay mineral content,welldeveloped macropores,and weak pore-throat heterogeneity all contribute to the storage and seepage of reservoir fluids.展开更多
Source properties and stress fields are critical to understand fundamental mechanisms for fluid-induced earthquakes.In this study,we identify the focal mechanism solutions(FMSs)of 360 earthquakes with local magnitude ...Source properties and stress fields are critical to understand fundamental mechanisms for fluid-induced earthquakes.In this study,we identify the focal mechanism solutions(FMSs)of 360 earthquakes with local magnitude M_(L)≥1.5 in the Changning shale gas field from January 2016 to May 2017 by fitting three-component waveforms.We then constrain the directions of the maximum horizontal stress(σ_(H_(max)))for four dense earthquake clusters using the stress tensor inversion method.The stress drops of 121 earthquakes with M_(L)≥1.5 are calculated using the spectral ratio method.We examine the spatiotemporal heterogeneity of stress field,and discuss the cause of non-double-couple(non-DC)components in seismicity clusters.Following the Mohr-Coulomb criterion,we estimate the fluid overpressure thresholds from FMS for different seismic clusters,providing insights into potential physical mechanisms for induced seismicity.The FMS results indicate that shallow reverse earthquakes,with steep dip angles,characterize most events.The source mechanisms of earthquakes with M_(L)≥1.5 are dominated by DC components(>70%),but several earthquakes with M_(L)>3.0 and the microseismic events nearby during injection period display significant non-DC components(>30%).Stress inversion results reveal that the σ_(H_(max)) direction ranges from 120°to 128°.Stress drops of earthquakes range between 0.10 and 64.49 MPa,with high values occurring on reverse faults situated at a greater distance from the shale layer,accompanied by a moderate rotation(≤25°)in the trend of σ_(H_(max)).The seismic clusters close to the shale layer exhibit low fluid overpressure thresholds,prone to being triggered by high pore-pressure fluid.The integrated results suggest that the diffusion of high pore pressures is likely to be the primary factor for observed earthquakes.The present results are expected to offer valuable insights into the origin of anomalous seismicity near the shale gas sites.展开更多
Wetlands play a critical role in the global environment.The Middle Yangtze River Basin(MYRB),known for its abundant wetland resources,has experienced notable changes resulting from the complex interplay of environment...Wetlands play a critical role in the global environment.The Middle Yangtze River Basin(MYRB),known for its abundant wetland resources,has experienced notable changes resulting from the complex interplay of environmental factors.Therefore,we investigated the spatiotemporal characteristics of wetland ecological quality in the MYRB from 2001 to 2020.Utilizing the random forest(RF)regression algorithm and patch-generated land-use simulation(PLUS)model,we forecasted variations in wetland habitat quality and their determinants under the Shared Socioeconomic Pathway-Representative Concentration Pathway(SSPRCP)framework from 2035 to 2095.The main findings are as follows:(1)The RF algorithm was optimal for land-use and land-cover(LULC)classification in the MYRB from 2001 to 2020,when notable changes were observed in water bodies and buildings.However,the forested area exhibited an increase and decrease of 3.9%and 1.2%under the SSP1-2.6 and SSP5-8.5 scenarios,respectively,whereas farmland exhibited a diminishing trend.(2)Wetlands were primarily concentrated in the central and eastern MYRB,with counties in the southwest exhibiting superior ecological-environmental quality from 2001 to 2020.Notably,wetland coverage revealed significantly high level,significant changes,frequent but relatively minor changes under the SSP1-2.6,SSP2-4.5,and SSP 5-8.5 scenarios,respectively.(3)Regions with lower habitat quality were primarily concentrated in urbanized areas characterized by frequent human activities,indicating a clear degradation in habitat quality across different scenarios.In conclusion,we established a foundational framework for future investigations into the eco-hydrological processes and ecosystem quality of watersheds.展开更多
China has abundant resources of hot dry rocks.However,due to the fact that the evaluation methods for favorable areas are mainly qualitative,and the evaluation indicators and standards are inconsistent,which restrict ...China has abundant resources of hot dry rocks.However,due to the fact that the evaluation methods for favorable areas are mainly qualitative,and the evaluation indicators and standards are inconsistent,which restrict the evaluation efficiency and exploration process of dry hot rocks.This paper is based on the understanding of the geologic features and genesis mechanisms of hot dry rocks in China and abroad.By integrating the main controlling factors of hot dry rock formation,and using index grading and quantification,the fuzzy hierarchical comprehensive method is applied to establish an evaluation system and standards for favorable areas of hot dry rocks.The evaluation system is based on four indicators:heat source,thermal channel,thermal reservoir and cap rock.It includes 11 evaluation parameters,including time of magmatic/volcanic activity,depth of molten mass or magma chamber,distribution of discordogenic faults,burial depth of thermal reservoir,cap rock type and thickness,surface thermal anomaly,heat flow,geothermal gradient,Moho depth,Curie depth,Earthquake magnitude and focal depth.Each parameter is divided into 3 levels.Applying this evaluation system to assess hot dry rock in central Inner Mongolia revealed that Class I favorable zones cover approximately 494 km^(2),while Class II favorable zones span about 5.7×10^(4) km^(2).The Jirgalangtu Sag and Honghaershute Sag in the Erlian Basin,along with Reshuitang Town in Keshiketeng Banner,Reshui Town in Ningcheng County,and Reshuitang Town in Aohan Banner of Chifeng City,are identified as Class I favorable zones for hot dry rock resources.These areas are characterized by high-temperature subsurface molten bodies or magma chambers serving as high-quality heat sources,shallow thermal reservoir depths,and overlying thick sedimentary rock layers acting as caprock.The establishment and application of the evaluation system for favorable areas of hot dry rock are expected to provide new approaches and scientific basis for guiding the practice of selecting hot dry rock areas in China.展开更多
Gas-bearing shales have become a major source of future natural gas production worldwide.It has become increasingly urgent to develop a reliable prediction model and corresponding workflow for identifying shale gas sw...Gas-bearing shales have become a major source of future natural gas production worldwide.It has become increasingly urgent to develop a reliable prediction model and corresponding workflow for identifying shale gas sweet spots.The formation of gas-bearing shales is closely linked to relative sealevel changes,providing an important approach to predicting sweet spots in the Wufeng-Longmaxi shale in the southern Sichuan Basin,China.Three types of marine shale gas sweet spots are identified in the shale based on their formation stages combined with relative sea-level changes:early,middle,and late transgression types.This study develops a prediction model and workflow for identifying shale gas sweet spots by analyzing relative sea-level changes and facies sequences.Predicting shale gas sweet spots in an explored block using this model and workflow can provide a valuable guide for well design and hydraulic fracturing,significantly enhancing the efficiency of shale gas exploration and development.Notably,the new prediction model and workflow can be utilized for the rapid evaluation of the potential for shale gas development in new shale gas blocks or those with low exploratory maturity.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
Climate change is significantly impacting cotton production in the Tarim River Basin.The study investigated the climate change characteristics from 2021 to 2100 using climate change datasets simulated per the coupled ...Climate change is significantly impacting cotton production in the Tarim River Basin.The study investigated the climate change characteristics from 2021 to 2100 using climate change datasets simulated per the coupled model inter-comparison project phase six(CMIP6)climatic patterns under the shared socioeconomic pathways SSP2-4.5 and SSP5-8.5.The DSSAT-CROPGROCotton model,along with stepwise multiple regression analyses,was used to simulate changes in the potential yield of seed cotton due to climate change.The results show that while future temperatures in the Tarim River Basin will rise significantly,changes in precipitation and radiation during the cotton-growing season are minimal.Seed cotton yields are more sensitive to low temperatures than to precipitation and radiation.The potential yield of seed cotton under the SSP2-4.5 scenario would increase by 14.8%,23.7%,29.0%,and 29.4%in the 2030S,2050S,2070S,and 2090S,respectively.In contrast,under the SSP5-8.5 scenario,the potential yield of seed cotton would see increases of 17.5%,27.1%,30.1%,and 22.6%,respectively.Except for the 2090s under the SSP5-8.5 scenario,future seed cotton production can withstand a 10%to 20%deficit in irrigation.These findings will help develop climate change adaptation strategies for cotton cultivation.展开更多
Gas hydrate(GH)is an unconventional resource estimated at 1000-120,000 trillion m^(3)worldwide.Research on GH is ongoing to determine its geological and flow characteristics for commercial produc-tion.After two large-...Gas hydrate(GH)is an unconventional resource estimated at 1000-120,000 trillion m^(3)worldwide.Research on GH is ongoing to determine its geological and flow characteristics for commercial produc-tion.After two large-scale drilling expeditions to study the GH-bearing zone in the Ulleung Basin,the mineral composition of 488 sediment samples was analyzed using X-ray diffraction(XRD).Because the analysis is costly and dependent on experts,a machine learning model was developed to predict the mineral composition using XRD intensity profiles as input data.However,the model’s performance was limited because of improper preprocessing of the intensity profile.Because preprocessing was applied to each feature,the intensity trend was not preserved even though this factor is the most important when analyzing mineral composition.In this study,the profile was preprocessed for each sample using min-max scaling because relative intensity is critical for mineral analysis.For 49 test data among the 488 data,the convolutional neural network(CNN)model improved the average absolute error and coefficient of determination by 41%and 46%,respectively,than those of CNN model with feature-based pre-processing.This study confirms that combining preprocessing for each sample with CNN is the most efficient approach for analyzing XRD data.The developed model can be used for the compositional analysis of sediment samples from the Ulleung Basin and the Korea Plateau.In addition,the overall procedure can be applied to any XRD data of sediments worldwide.展开更多
Based on the experimental results of casting thin section,low temperature nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance T2 spectrum,contact angle and oil-water interfacial tension,the ...Based on the experimental results of casting thin section,low temperature nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance T2 spectrum,contact angle and oil-water interfacial tension,the relationship between pore throat structure and crude oil mobility characteristics of full particle sequence reservoirs in the Lower Permian Fengcheng Formation of Mahu Sag,Junggar Basin,are revealed.(1)With the decrease of reservoir particle size,the volume of pores connected by large throats and the volume of large pores show a decreasing trend,and the distribution and peak ranges of throat and pore radius shift to smaller size in an orderly manner.The upper limits of throat radius,porosity and permeability of unconventional reservoirs in Fengcheng Formation are approximately 0.7μm,8%and 0.1×10^(−3)μm^(2),respectively.(2)As the reservoir particle size decreases,the distribution and peak ranges of pores hosting retained oil and movable oil are shifted to a smaller size in an orderly manner.With the increase of driving pressure,the amount of retained and movable oil of the larger particle reservoir samples shows a more obvious trend of decreasing and increasing,respectively.(3)With the increase of throat radius,the driving pressure of reservoir with different particle levels presents three stages,namely rapid decrease,slow decrease and stabilization.The oil driving pressures of various reservoirs and the differences of them decrease with the increase of temperature and obviously decrease with the increase of throat radius.According to the above experimental analysis,it is concluded that the deep shale oil of Fengcheng Formation in Mahu Sag has great potential for production under geological conditions.展开更多
The Upper Cretaceous of Tantou Basin in western Henan has yielded many vertebrate fossils,which are featured by several non-avian dinosaurs.Meanwhile,studies on their eggs were yet inadequate though many eggshells hav...The Upper Cretaceous of Tantou Basin in western Henan has yielded many vertebrate fossils,which are featured by several non-avian dinosaurs.Meanwhile,studies on their eggs were yet inadequate though many eggshells have been reported.The newly discovered material 41HⅤ0199 was excavated from the Upper Cretaceous Qiupa Formation in 2021.The block preserves eight complete eggs arranged in two partial rings that form a partial clutch,and there are some scattered eggshells preserved closely with the block,showing a concave-up to concave-down ratio of 54.5:45.5,which indicates that the scattered eggshells come from the clutch and the clutch had been partially broken before it was buried.Based on morphological and microstructural characteristics,the eggs and eggshells can be assigned to Macroolithus yaotunensis(Elongatoolithidae),an oospecies known to be related to oviraptorids,which leads Yulong mini to be its probable producer.Besides,some eggshells show microstructural signs indicating egg retention,which marks the second example of egg retention in the oofamily Elongatoolithidae.展开更多
This report is about the first record of non-avian dinosaur eggs in the Hefei Basin,Anhui Province,China.Based on the combination of elongated egg body,linear ridges on the outer surface and two structure layer,the eg...This report is about the first record of non-avian dinosaur eggs in the Hefei Basin,Anhui Province,China.Based on the combination of elongated egg body,linear ridges on the outer surface and two structure layer,the eggs can be referred to Elongatoolithidae.The gradual boundary between the cone and the column layers as well as the relative thin eggshell(less than 1 mm)indicates its affinity within Elongatoolithus.The eggs are identified as Elongatoolithus oosp.,as they were severely compressed and experienced erosion on both inner and outer surfaces.The discovery of egg fossil in the Hefei Basin offers evidence for stratum comparison in this region and supplements the diversity of egg fossils in Anhui.Meanwhile,this discovery also enriches the paleogeographic distribution of elongatoolithids.展开更多
In 2015,the discovery of mammalian fossils,paleolithic artifacts,and burned bones in the Maoershan Cave of the Guilin Basin,northeastern Guangxi,indicated that it is a late Middle Pleistocene Paleolithic site.In 2021,...In 2015,the discovery of mammalian fossils,paleolithic artifacts,and burned bones in the Maoershan Cave of the Guilin Basin,northeastern Guangxi,indicated that it is a late Middle Pleistocene Paleolithic site.In 2021,stratigraphic sectioning and the systematic screening of small mammal sand samples were conducted.This paper presents a comprehensive account of the new material of the fruit bat Rousettus leschenaultii,accompanied by a concise overview of the non-volant micromammals that coexisted with it in the Quaternary sediments of the Maoershan Cave.This finding marks the second occurrence of fruit bat fossils in China,contributing to our understanding of the dental morphology and past geographical distribution of Rousettus.The micromammalian assemblage of the Maoershan Cave is composed of 3 orders,9 families,26 genera,and 30 species,and exhibits notable similarities with those of the late Middle Pleistocene Yumi Cave,Xinglong Cave,Yanhui Cave,Mawokou Cave,Zhongliangshan,and Chuan Cave faunas.The biochronology of the micromammalian assemblage from the Maoershan Cave has been determined to be consistent with the late Middle Pleistocene,providing a new assemblage in the Pleistocene mammalian faunal sequence in southern China.The presence of abundant oriental forested elements indicates that the Guilin Basin used to be a humid and warm subtropical forest paleoenvironment similar to the contemporary environment during the late Middle Pleistocene.展开更多
Based on the analysis of surface geological survey,exploratory well,gravity-magnetic-electric and seismic data,and through mapping the sedimentary basin and its peripheral orogenic belts together,this paper explores s...Based on the analysis of surface geological survey,exploratory well,gravity-magnetic-electric and seismic data,and through mapping the sedimentary basin and its peripheral orogenic belts together,this paper explores systematically the boundary,distribution,geological structure,and tectonic attributes of the Ordos prototype basin in the geological historical periods.The results show that the Ordos block is bounded to the west by the Engorwusu Fault Zone,to the east by the Taihangshan Mountain Piedmont Fault Zone,to the north by the Solonker-Xilamuron Suture Zone,and to the south by the Shangnan-Danfeng Suture Zone.The Ordos Basin boundary was the plate tectonic boundary during the Middle Proterozoic to Paleozoic,and the intra-continental deformation boundary in the Meso-Cenozoic.The basin survived as a marine cratonic basin covering the entire Ordos block during the Middle Proterozoic to Ordovician,a marine-continental transitional depression basin enclosed by an island arc uplift belt at the plate margin during the Carboniferous to Permian,a unified intra-continental lacustrine depression basin in the Triassic,and an intra-continental cratonic basin circled by a rift system in the Cenozoic.The basin scope has been decreasing till the present.The large,widespread prototype basin controlled the exploration area far beyond the present-day sedimentary basin boundary,with multiple target plays vertically.The Ordos Basin has the characteristics of a whole petroleum(or deposition)system.The Middle Proterozoic wide-rift system as a typical basin under the overlying Phanerozoic basin and the Cambrian-Ordovician passive margin basin and intra-cratonic depression in the deep-sited basin will be the important successions for oil and gas exploration in the coming years.展开更多
文摘The physical properties of hydrocarbon reservoirs are important factors affecting the percolation ability of the reservoirs.Tight-sand reservoirs exhibit complex pore throat connectivity due to the extensive development of micro-and nano-scale pore and throat systems.Characterizing the microscopic properties of these reservoirs using nondestructive,quantitative methods serves as an important means to determine the characteristics of microscopic pores and throats in tight-sand reservoirs and the mechanism behind the influence of these characteristics on reservoir porosity and permeability.In this study,a low-permeability sandstone sample and two tight sandstone samples collected from the Ordos Basin were nondestructively tested using high-resolution nano-CT technology to quantitively characterize their microscopic pore throat structures and model them three-dimensionally(in 3D)based on CT threshold differences and gray models.A thorough analysis and comparison reveal that the three samples exhibit a certain positive correlation between their porosity and permeability but the most important factor affecting both porosity and permeability is the microscopic pore throat structure.Although the number of pores in tight sandstones shows a minor impact on their porosity,large pores(more than 20μm)contribute predominantly to porosity,suggesting that the permeability of tight sandstones is controlled primarily by large pore throats.For these samples,higher permeability corresponds to larger average throat sizes.Therefore,throats with average radii greater than 2μm can significantly improve the permeability of tight sandstones.
基金supported by the National Natural Science Foundation of China (No.72091511)the Science Fund for Distinguished Young Scholars of Hebei Province (No.E2022402064).
文摘Tuojiang River Basin is a first-class tributary of the upper reaches of the Yangtze River—which is the longest river in China.As phytoplankton are sensitive indicators of trophic changes inwater bodies,characterizing phytoplankton communities and their growth influencing factors in polluted urban rivers can provide new ideas for pollution control.Here,we used direct microscopic count and environmental DNA(eDNA)metabarcoding methods to investigate phytoplankton community structure in Tuojiang River Basin(Chengdu,Sichuan Province,China).The association between phytoplankton community structure and water environmental factors was evaluated by Mantel analysis.Additional environmental monitoring data were used to pinpoint major factors that influenced phytoplankton growth based on structural equation modeling.At the phylum level,the dominant phytoplankton taxa identified by the conventional microscopic method mainly belonged to Bacillariophyta,Chlorophyta,and Cyanophyta,in contrast with Chlorophyta,Dinophyceae,and Bacillariophyta identified by eDNA metabarcoding.Inα-diversity analysis,eDNA metabarcoding detected greater species diversity and achieved higher precision than the microscopic method.Phytoplankton growth was largely limited by phosphorus based on the nitrogen-to-phosphorus ratios>16:1 in all water samples.Redundancy analysis and structural equation modeling also confirmed that the nitrogen-to-phosphorus ratio was the principal factor influencing phytoplankton growth.The results could be useful for implementing comprehensive management of the river basin environment.It is recommended to control the discharge of point-and surface-source pollutants and the concentration of dissolved oxygen in areas with excessive nutrients(e.g.,Jianyang-Ziyang).Algae monitoring techniques and removal strategies should be improved in 201 Hospital,Hongrihe Bridge and Colmar Town areas.
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This study was jointly supported by the Science&Technology Fundamental Resources Investigation Program(2022FY101800)National Science Foundation(92162212)+1 种基金the project from the Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences,Wuhan)(TPR-2022-22)the International Geoscience Programme(IGCP-675)。
文摘The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC.In this work,the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB,and have provided new evidence for the regional tectonic evolution.The(U-Th)/He chronological data states the weighted ages of 240‒235 Ma,141 Ma with the peak distribution of 244 Ma,219 Ma,173 Ma,147‒132 Ma.The thermal evolution,geochronological data,and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2)the Late Triassic-Early Jurassic;(3)the Late Jurassic-Early Cretaceous;(4)the Late Cretaceous-Early Paleogene.It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB.Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.
基金This research was supported by the Fundamental Research Program of Shanxi Province(202203021212497,20210302123265)the Shanxi Normal University School Fund(Research Project on Major Issues of High-Quality Development in Shanxi Province,GZLFZ2327).
文摘The middle reaches of the Yellow River represent a critically ecologically sensitive and fragile area within the Yellow River Basin(YRB),holding significant scientific value for ecological security assessment and environmental management strategies.This study comprehensively evaluates the evolution of the eco-environment in the“Two Mountains,Seven Rivers,and One Basin”(TSO)area of Shanxi Province from 2000 to 2020 based on fraction vegetation cover(FVC)derived from the Normalized Difference Vegetation Index(NDVI),net primary productivity(NPP)calculated via the Carnegie–Ames–Stanford approach(CASA),and the remote sensing ecological index(RSEI).The results indicate a significant improvement in the TSO’s eco-environment from 2000 to 2020,with the RSEI values increased from 0.34 in 2000 to 0.41 in 2020(an increase of 17.76%).Both FVC and NPP demonstrated notable upward trends,with FVC increasing by 22.74%and NPP by 53.11%.Spatially,FVC rose by 21.84%,19.72%and 26.06%,respectively in the Two Mountains,Seven Rivers,and the YRB in Shanxi Province.Similarly,the NPPs increased by 51.60%,48.60%,and 61.65%in these regions over the past 21 years.Both FVC and NPP exhibited decreasing patterns from southeast to northwest,with significant eco-environmental improvements in the northern region and slower recovery in the southern region.Precipitation was the primary causes influencing vegetation recovery,showing positive trends in the central and northern TSO regions,while this trend reversed in the southern.The RSEI value indicate substantial eco-environment improvements in the central and northern areas(Sanggan,Daqing and Hutuo River Basins),whereas the southern regions(e.g.,Zhang,Qin,Fen and Sushui River Basins)remain in poor grade.Human activities,particularly land use/cover changes marked by increased forestation and urbanization alongside decreased cultivated land,significantly affected vegetation cover patterns.This study provides scientific references for formulating policies on ecological construction and high-quality development in the YRB.
文摘The tight sandstone reservoirs in the first sub-member of Chang 7 member(Chang 71)of Triassic Yanchang Formation in the Jiyuan area,Ordos Basin,show significant variations in microscopic pore-throat structure(PTS)and fluid mobility due to the influences of the northeast and northwest dual provenance systems.This study performed multiple experimental analyses on nine samples from the area to determine the petrological and petrophysical properties,as well as the PTS characteristics of reservoirs in different provenance-controlled regions.On this basis,the pore-throat size distribution(PSD)obtained from high-pressure mercury injection(HPMI)was utilized to convert the NMR movable fluid T2spectrum,allowing for quantitative characterization of the full PSD and the occurrence characteristics of movable fluids.A systematic analysis was conducted on the primary controlling factors affecting fluid mobility in the reservoir.The results indicated that the lithology in the eastern and western regions is lithic arkose.The eastern sandstones,being farther from the provenance,exhibit higher contents of feldspar and lithic fragments,along with the development of more dissolution pores.The reservoir possesses good petrophysical properties,low displacement pressure,and high pore-throat connectivity and homogeneity,indicating strong fluid mobility.In contrast,the western sandstones,being nearer to the provenance,exhibit poor grain sorting,high contents of lithic fragments,strong compaction and cementation effects,resulting in poor petrophysical properties,and strong pore-throat heterogeneity,revealing weak fluid mobility.The range of full PSD in the eastern reservoir is wider than that in the western reservoir,with relatively well-developed macropores.The macropores are the primary space for occurrence of movable fluids,and controls the fluid mobility of the reservoir.The effective porosity of movable fluids(EPMF)quantitatively represents the pore space occupied by movable fluids within the reservoir and correlates well with porosity,permeability,and PTS parameters,making it a valuable parameter for evaluating fluid mobility.Under the multi-provenance system,the eastern and western reservoirs underwent different sedimentation and diagenesis processes,resulting in differential distribution of reservoir mineral components and pore types,which in turn affects the PTS heterogeneity and reservoir quality.The composition and content of reservoir minerals are intrinsic factors influencing fluid mobility,while the microscopic PTS is the primary factor controlling it.Low clay mineral content,welldeveloped macropores,and weak pore-throat heterogeneity all contribute to the storage and seepage of reservoir fluids.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.U20A20266 and 12302503)Scientific and technological research projects in Sichuan province(Grant No.2024NSFSC0973).
文摘Source properties and stress fields are critical to understand fundamental mechanisms for fluid-induced earthquakes.In this study,we identify the focal mechanism solutions(FMSs)of 360 earthquakes with local magnitude M_(L)≥1.5 in the Changning shale gas field from January 2016 to May 2017 by fitting three-component waveforms.We then constrain the directions of the maximum horizontal stress(σ_(H_(max)))for four dense earthquake clusters using the stress tensor inversion method.The stress drops of 121 earthquakes with M_(L)≥1.5 are calculated using the spectral ratio method.We examine the spatiotemporal heterogeneity of stress field,and discuss the cause of non-double-couple(non-DC)components in seismicity clusters.Following the Mohr-Coulomb criterion,we estimate the fluid overpressure thresholds from FMS for different seismic clusters,providing insights into potential physical mechanisms for induced seismicity.The FMS results indicate that shallow reverse earthquakes,with steep dip angles,characterize most events.The source mechanisms of earthquakes with M_(L)≥1.5 are dominated by DC components(>70%),but several earthquakes with M_(L)>3.0 and the microseismic events nearby during injection period display significant non-DC components(>30%).Stress inversion results reveal that the σ_(H_(max)) direction ranges from 120°to 128°.Stress drops of earthquakes range between 0.10 and 64.49 MPa,with high values occurring on reverse faults situated at a greater distance from the shale layer,accompanied by a moderate rotation(≤25°)in the trend of σ_(H_(max)).The seismic clusters close to the shale layer exhibit low fluid overpressure thresholds,prone to being triggered by high pore-pressure fluid.The integrated results suggest that the diffusion of high pore pressures is likely to be the primary factor for observed earthquakes.The present results are expected to offer valuable insights into the origin of anomalous seismicity near the shale gas sites.
基金National Natural Science Foundation of China,No.42207078CUG Scholar-Scientific Research Funds at China University of Geosciences(Wuhan),No.2022166+1 种基金China Scholarship Council,No.202306410026Opening Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,China Institute of Water Resources and Hydropower Research,No.IWHR-SKL-KF202217。
文摘Wetlands play a critical role in the global environment.The Middle Yangtze River Basin(MYRB),known for its abundant wetland resources,has experienced notable changes resulting from the complex interplay of environmental factors.Therefore,we investigated the spatiotemporal characteristics of wetland ecological quality in the MYRB from 2001 to 2020.Utilizing the random forest(RF)regression algorithm and patch-generated land-use simulation(PLUS)model,we forecasted variations in wetland habitat quality and their determinants under the Shared Socioeconomic Pathway-Representative Concentration Pathway(SSPRCP)framework from 2035 to 2095.The main findings are as follows:(1)The RF algorithm was optimal for land-use and land-cover(LULC)classification in the MYRB from 2001 to 2020,when notable changes were observed in water bodies and buildings.However,the forested area exhibited an increase and decrease of 3.9%and 1.2%under the SSP1-2.6 and SSP5-8.5 scenarios,respectively,whereas farmland exhibited a diminishing trend.(2)Wetlands were primarily concentrated in the central and eastern MYRB,with counties in the southwest exhibiting superior ecological-environmental quality from 2001 to 2020.Notably,wetland coverage revealed significantly high level,significant changes,frequent but relatively minor changes under the SSP1-2.6,SSP2-4.5,and SSP 5-8.5 scenarios,respectively.(3)Regions with lower habitat quality were primarily concentrated in urbanized areas characterized by frequent human activities,indicating a clear degradation in habitat quality across different scenarios.In conclusion,we established a foundational framework for future investigations into the eco-hydrological processes and ecosystem quality of watersheds.
基金Supported by PetroChina Prospective and Basic Technological Project(2022DJ5503).
文摘China has abundant resources of hot dry rocks.However,due to the fact that the evaluation methods for favorable areas are mainly qualitative,and the evaluation indicators and standards are inconsistent,which restrict the evaluation efficiency and exploration process of dry hot rocks.This paper is based on the understanding of the geologic features and genesis mechanisms of hot dry rocks in China and abroad.By integrating the main controlling factors of hot dry rock formation,and using index grading and quantification,the fuzzy hierarchical comprehensive method is applied to establish an evaluation system and standards for favorable areas of hot dry rocks.The evaluation system is based on four indicators:heat source,thermal channel,thermal reservoir and cap rock.It includes 11 evaluation parameters,including time of magmatic/volcanic activity,depth of molten mass or magma chamber,distribution of discordogenic faults,burial depth of thermal reservoir,cap rock type and thickness,surface thermal anomaly,heat flow,geothermal gradient,Moho depth,Curie depth,Earthquake magnitude and focal depth.Each parameter is divided into 3 levels.Applying this evaluation system to assess hot dry rock in central Inner Mongolia revealed that Class I favorable zones cover approximately 494 km^(2),while Class II favorable zones span about 5.7×10^(4) km^(2).The Jirgalangtu Sag and Honghaershute Sag in the Erlian Basin,along with Reshuitang Town in Keshiketeng Banner,Reshui Town in Ningcheng County,and Reshuitang Town in Aohan Banner of Chifeng City,are identified as Class I favorable zones for hot dry rock resources.These areas are characterized by high-temperature subsurface molten bodies or magma chambers serving as high-quality heat sources,shallow thermal reservoir depths,and overlying thick sedimentary rock layers acting as caprock.The establishment and application of the evaluation system for favorable areas of hot dry rock are expected to provide new approaches and scientific basis for guiding the practice of selecting hot dry rock areas in China.
文摘Gas-bearing shales have become a major source of future natural gas production worldwide.It has become increasingly urgent to develop a reliable prediction model and corresponding workflow for identifying shale gas sweet spots.The formation of gas-bearing shales is closely linked to relative sealevel changes,providing an important approach to predicting sweet spots in the Wufeng-Longmaxi shale in the southern Sichuan Basin,China.Three types of marine shale gas sweet spots are identified in the shale based on their formation stages combined with relative sea-level changes:early,middle,and late transgression types.This study develops a prediction model and workflow for identifying shale gas sweet spots by analyzing relative sea-level changes and facies sequences.Predicting shale gas sweet spots in an explored block using this model and workflow can provide a valuable guide for well design and hydraulic fracturing,significantly enhancing the efficiency of shale gas exploration and development.Notably,the new prediction model and workflow can be utilized for the rapid evaluation of the potential for shale gas development in new shale gas blocks or those with low exploratory maturity.
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.
基金supported by the Science and Technology Program of Xinjiang Construction Corps(No.2024AB064)the National Natural Science Foundation of China(Nos.41975044,42001314)。
文摘Climate change is significantly impacting cotton production in the Tarim River Basin.The study investigated the climate change characteristics from 2021 to 2100 using climate change datasets simulated per the coupled model inter-comparison project phase six(CMIP6)climatic patterns under the shared socioeconomic pathways SSP2-4.5 and SSP5-8.5.The DSSAT-CROPGROCotton model,along with stepwise multiple regression analyses,was used to simulate changes in the potential yield of seed cotton due to climate change.The results show that while future temperatures in the Tarim River Basin will rise significantly,changes in precipitation and radiation during the cotton-growing season are minimal.Seed cotton yields are more sensitive to low temperatures than to precipitation and radiation.The potential yield of seed cotton under the SSP2-4.5 scenario would increase by 14.8%,23.7%,29.0%,and 29.4%in the 2030S,2050S,2070S,and 2090S,respectively.In contrast,under the SSP5-8.5 scenario,the potential yield of seed cotton would see increases of 17.5%,27.1%,30.1%,and 22.6%,respectively.Except for the 2090s under the SSP5-8.5 scenario,future seed cotton production can withstand a 10%to 20%deficit in irrigation.These findings will help develop climate change adaptation strategies for cotton cultivation.
基金supported by the Gas Hydrate R&D Organization and the Korea Institute of Geoscience and Mineral Resources(KIGAM)(GP2021-010)supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.2021R1C1C1004460)Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korean government(MOTIE)(20214000000500,Training Program of CCUS for Green Growth).
文摘Gas hydrate(GH)is an unconventional resource estimated at 1000-120,000 trillion m^(3)worldwide.Research on GH is ongoing to determine its geological and flow characteristics for commercial produc-tion.After two large-scale drilling expeditions to study the GH-bearing zone in the Ulleung Basin,the mineral composition of 488 sediment samples was analyzed using X-ray diffraction(XRD).Because the analysis is costly and dependent on experts,a machine learning model was developed to predict the mineral composition using XRD intensity profiles as input data.However,the model’s performance was limited because of improper preprocessing of the intensity profile.Because preprocessing was applied to each feature,the intensity trend was not preserved even though this factor is the most important when analyzing mineral composition.In this study,the profile was preprocessed for each sample using min-max scaling because relative intensity is critical for mineral analysis.For 49 test data among the 488 data,the convolutional neural network(CNN)model improved the average absolute error and coefficient of determination by 41%and 46%,respectively,than those of CNN model with feature-based pre-processing.This study confirms that combining preprocessing for each sample with CNN is the most efficient approach for analyzing XRD data.The developed model can be used for the compositional analysis of sediment samples from the Ulleung Basin and the Korea Plateau.In addition,the overall procedure can be applied to any XRD data of sediments worldwide.
基金Supported by Leading Talent Program of Autonomous Region(2022TSYCLJ0070)PetroChina Prospective and Basic Technological Project(2021DJ0108)Natural Science Foundation for Outstanding Young People in Shandong Province(ZR2022YQ30).
文摘Based on the experimental results of casting thin section,low temperature nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance T2 spectrum,contact angle and oil-water interfacial tension,the relationship between pore throat structure and crude oil mobility characteristics of full particle sequence reservoirs in the Lower Permian Fengcheng Formation of Mahu Sag,Junggar Basin,are revealed.(1)With the decrease of reservoir particle size,the volume of pores connected by large throats and the volume of large pores show a decreasing trend,and the distribution and peak ranges of throat and pore radius shift to smaller size in an orderly manner.The upper limits of throat radius,porosity and permeability of unconventional reservoirs in Fengcheng Formation are approximately 0.7μm,8%and 0.1×10^(−3)μm^(2),respectively.(2)As the reservoir particle size decreases,the distribution and peak ranges of pores hosting retained oil and movable oil are shifted to a smaller size in an orderly manner.With the increase of driving pressure,the amount of retained and movable oil of the larger particle reservoir samples shows a more obvious trend of decreasing and increasing,respectively.(3)With the increase of throat radius,the driving pressure of reservoir with different particle levels presents three stages,namely rapid decrease,slow decrease and stabilization.The oil driving pressures of various reservoirs and the differences of them decrease with the increase of temperature and obviously decrease with the increase of throat radius.According to the above experimental analysis,it is concluded that the deep shale oil of Fengcheng Formation in Mahu Sag has great potential for production under geological conditions.
文摘The Upper Cretaceous of Tantou Basin in western Henan has yielded many vertebrate fossils,which are featured by several non-avian dinosaurs.Meanwhile,studies on their eggs were yet inadequate though many eggshells have been reported.The newly discovered material 41HⅤ0199 was excavated from the Upper Cretaceous Qiupa Formation in 2021.The block preserves eight complete eggs arranged in two partial rings that form a partial clutch,and there are some scattered eggshells preserved closely with the block,showing a concave-up to concave-down ratio of 54.5:45.5,which indicates that the scattered eggshells come from the clutch and the clutch had been partially broken before it was buried.Based on morphological and microstructural characteristics,the eggs and eggshells can be assigned to Macroolithus yaotunensis(Elongatoolithidae),an oospecies known to be related to oviraptorids,which leads Yulong mini to be its probable producer.Besides,some eggshells show microstructural signs indicating egg retention,which marks the second example of egg retention in the oofamily Elongatoolithidae.
文摘This report is about the first record of non-avian dinosaur eggs in the Hefei Basin,Anhui Province,China.Based on the combination of elongated egg body,linear ridges on the outer surface and two structure layer,the eggs can be referred to Elongatoolithidae.The gradual boundary between the cone and the column layers as well as the relative thin eggshell(less than 1 mm)indicates its affinity within Elongatoolithus.The eggs are identified as Elongatoolithus oosp.,as they were severely compressed and experienced erosion on both inner and outer surfaces.The discovery of egg fossil in the Hefei Basin offers evidence for stratum comparison in this region and supplements the diversity of egg fossils in Anhui.Meanwhile,this discovery also enriches the paleogeographic distribution of elongatoolithids.
文摘In 2015,the discovery of mammalian fossils,paleolithic artifacts,and burned bones in the Maoershan Cave of the Guilin Basin,northeastern Guangxi,indicated that it is a late Middle Pleistocene Paleolithic site.In 2021,stratigraphic sectioning and the systematic screening of small mammal sand samples were conducted.This paper presents a comprehensive account of the new material of the fruit bat Rousettus leschenaultii,accompanied by a concise overview of the non-volant micromammals that coexisted with it in the Quaternary sediments of the Maoershan Cave.This finding marks the second occurrence of fruit bat fossils in China,contributing to our understanding of the dental morphology and past geographical distribution of Rousettus.The micromammalian assemblage of the Maoershan Cave is composed of 3 orders,9 families,26 genera,and 30 species,and exhibits notable similarities with those of the late Middle Pleistocene Yumi Cave,Xinglong Cave,Yanhui Cave,Mawokou Cave,Zhongliangshan,and Chuan Cave faunas.The biochronology of the micromammalian assemblage from the Maoershan Cave has been determined to be consistent with the late Middle Pleistocene,providing a new assemblage in the Pleistocene mammalian faunal sequence in southern China.The presence of abundant oriental forested elements indicates that the Guilin Basin used to be a humid and warm subtropical forest paleoenvironment similar to the contemporary environment during the late Middle Pleistocene.
基金Supported by the National Natural Science Foundation of China(42330810)Major Science and Technology Project of PetroChina Changqing Oilfield Company(ZDZX2021-01).
文摘Based on the analysis of surface geological survey,exploratory well,gravity-magnetic-electric and seismic data,and through mapping the sedimentary basin and its peripheral orogenic belts together,this paper explores systematically the boundary,distribution,geological structure,and tectonic attributes of the Ordos prototype basin in the geological historical periods.The results show that the Ordos block is bounded to the west by the Engorwusu Fault Zone,to the east by the Taihangshan Mountain Piedmont Fault Zone,to the north by the Solonker-Xilamuron Suture Zone,and to the south by the Shangnan-Danfeng Suture Zone.The Ordos Basin boundary was the plate tectonic boundary during the Middle Proterozoic to Paleozoic,and the intra-continental deformation boundary in the Meso-Cenozoic.The basin survived as a marine cratonic basin covering the entire Ordos block during the Middle Proterozoic to Ordovician,a marine-continental transitional depression basin enclosed by an island arc uplift belt at the plate margin during the Carboniferous to Permian,a unified intra-continental lacustrine depression basin in the Triassic,and an intra-continental cratonic basin circled by a rift system in the Cenozoic.The basin scope has been decreasing till the present.The large,widespread prototype basin controlled the exploration area far beyond the present-day sedimentary basin boundary,with multiple target plays vertically.The Ordos Basin has the characteristics of a whole petroleum(or deposition)system.The Middle Proterozoic wide-rift system as a typical basin under the overlying Phanerozoic basin and the Cambrian-Ordovician passive margin basin and intra-cratonic depression in the deep-sited basin will be the important successions for oil and gas exploration in the coming years.
