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Distribution and geochemical significance of alkylbenzenes for crude oil with different depositional environments and thermal maturities

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Petroleum Science 2024年第2期21卷 777-790页

作者： Bing-Kun Meng Dao-Fu Song Yuan Chen Sheng-Bao Shi School of Petroleum engineering and Environmental engineering Yan'an UniversityYan'an716000ShaanxiChina State Key Laboratory of Petroleum Resources and Prospecting College of GeosciencesChina University of PetroleumBeijing102249China

A total of 45 alkylbenzenes were detected and identified in crude oils with different depositional environments and thermal maturities from the Tarim Basin,Beibuwan Basin,and Songliao Basin using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry(GC×GCTOFMS).By analyzing the distribution characteristics of C0-C5alkylbenzenes,it is found that the content of some alkylbenzenes varies greatly in crude *** on the distribution characteristics of 1,2,4,5-tetramethylbenzene(Te MB)and 1,2,3,4-Te MB,the ratio of 1,2,4,5-Te MB to 1,2,3,4-Te MB is proposed to indicate the organic matter origin and depositional environment of ancient *** samples originated mainly from lower hydrobiont,algae,bacteria and source rocks deposited under reducing/anoxic conditions have low 1,2,4,5-/1,2,3,4-Te MB values(less than 0.6),while oil samples originated mainly from terrestrial higher plants and source rocks deposited under oxic/sub-oxic conditions have higher 1,2,4,5-/1,2,3,4-Te MB values(greater than 1.0).The significant difference of 1,2,4,5-/1,2,3,4-Te MB values is controlled by 1,2,4,5-Te MB content.1,2,4,5-Te MB content in oils derived from source rocks deposited in oxidized sedimentary environment(greater than 1.0 mg/g whole oil)is higher than that in oils from source rocks deposited in reduced sedimentary environment(less than 1.0 mg/g whole oil).1,2,4,5-/1,2,3,4-Te MB ratio might not or slightly be affected by evaporative fractionation,biodegradation and thermal maturity.1,2,4,5-/1,2,3,4-Te MB ratio and 1,2,4,5-Te MB content can be used as supplementary parameter for the identification of sedimentary environment and organic matter *** should be noted that compared to the identification of organic matter sources,the 1,2,4,5-/1,2,3,4-Te MB parameter is more effective in identifying sedimentary environments.

关键词： 1 2 4 5-Tetramethylbenzene GC×GC-TOFMS Organic matter origin Depositional environment

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Effects of freeze-thaw cycles on sandstone in sunny and shady slopes

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Journal of Rock Mechanics and Geotechnical engineering 2024年第7期16卷 2503-2515页

作者： Dian Xiao Xiaoyan Zhao Corrado Fidelibus Roberto Tomás Qiu Lu Hongwei Liu Academy of Railway Sciences Corporation Limited BeijingChina faculty of geosciences and Environmental engineering Southwest Jiaotong UniversityChengduChina Department of Civil engineering University of AlicanteAlicanteSpain Department of Innovation engineering University of SalentoLecceItaly Department of Earth and Environmental Sciences University of Milano BicoccaMilanItaly

A growing rock engineering activity in cold regions is facing the threat of freeze-thaw(FT)weathering,especially in high mountains where the sunny-shady slope effects strongly control the difference in weathering behavior of *** this paper,an investigation of the degradation of petrophysical characteristics of sandstone specimens subjected to FT cycle tests to simulate the sunny-shady slope effects is *** this aim,non-destructive and repeatable testing techniques including weight,ultrasonic waves,and nuclear magnetic resonance methods on standard specimens were *** the sunny slope specimens,accompanied by the enlargement of small pores,100 FT cycles caused a significant decrease in P-wave velocity with an average of 23%,but a consistent rise of 0.18%in mass loss,34%in porosity,67%in pore geometrical mean radius,and a remarkable 14.5-fold increase in ***,slight changes with some abnormal trends in physical parameters of the shady slope specimens were observed during FT cycling,which can be attributed to superficial granular disaggregation and pore throat *** shocks enhance rock weathering on sunny slopes during FT cycles,while FT weathering on shady slopes is restricted to the small pores and the superficial *** two factors are primarily responsible for the differences in FT weathering intensity between sunny and shady *** conclusions derived from the interpretation of the experimental results may provide theoretical guidance for the design of slope-failure prevention measures and the selection of transportation routes in cold mountainous regions.

关键词： Sunny-shady slope Freeze and thaw Pore structure Tight rocks Talus slope Cold regions

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Quaternary Activity Characteristics and Regional Tectonic Significance of the Jiulong Fault in Jiujiang,Jiangxi Province,china

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Journal of Earth Science 2024年第4期35卷 1107-1117页

作者： Xin Qi Yuyong Jiao Qinghua Li Bin Li faculty of engineering China University of GeosciencesWuhan430074China Wuhan Center China Geological SurveyWuhan430205China Institute of Geological Survey China University of GeosciencesWuhan430074China

Obtaining geological and landform dislocation features,as well as the measured stratigraphic activity age,provides direct evidence to evaluate fault activity,which is more difficult to do in areas with low tectonic activity,such as eastern and central china.A detailed investigation of the fault activity,trenching,drilling joint geological profile,geological survey,and chronological analysis were used to obtain the spatial geometry,fault kinematics,and activity chronology of the Jiulong *** conclusions are as follows:(1)The Jiulong fault was a fracture zone composed of four branch faults,with a width of around 30–40 m and good extendibility,while the maximum surface rupture length was 373 m.(2)The Jiulong fault has many strata dislocations,and the dislocation distance decreased from bottom to top,demonstrating synsedimentary structure characteristics,with a maximum stratigraphic dislocation distance of 18.2 m.(3)Preliminary analysis suggested the Jiulong fault as a secondary fracture of the Xiangfan-Guangji fault zone and provided evidence of the southeastward extension of the Xiangfan-Guangji fault.A preliminary hypothesis purported the Xiangfan-Guangji fault as the seismogenic fault of the Ms 5.0 magnitude earthquake in 1911.(4)According to OSL and ESR dating analyses,the upper breakpoint of the Jiulong fault cuts into the Late Pleistocene Xingang Formation(Qp3x)strata,and the latest active age of the Jiulong fault was 57.6 *** chronology analysis confirmed an active fault from the Late Pleistocene and identified a weak tectonic in Jiujiang Province,which represents the largest active fault outcrop uncovered in the area so *** study provides evidence and research materials for the evaluation of fault activity and seismic stability in this region.

关键词： active fault regional tectonic earthquakes seismic intensity tectonics

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First Record of Cyclocarya from the Early Oligocene Qaidam Basin,North Tibet:Implications for the Paleogeography and Paleoecology

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Journal of Earth Science 2024年第1期35卷 201-211页

作者： Yafei Hou Bowen Song Xiangchuan Li Fang Han Xu Zhang Kexin Zhang Institute of Geological Survey China University of GeosciencesWuhan 430074China faculty of Materials Science and Chemistry China University of GeosciencesWuhan 430074China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430074China College of Earth Sciences and Resources&Key Laboratory of Western Mineral Resources and Geological engineering of the Ministry of Education Chang'an UniversityXi'an 710054China State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and PalaeontologyChinese Academy of SciencesNanjing 210008China School of Earth Sciences East China University of TechnologyNanchang 330013China

As the largest intermontane basin in the northeastern Tibetan Plateau(TP),the Qaidam Basin provides unique insight into paleoclimatic change and its relationship with global change and uplift on the *** this study,based on morphological comparison,fossil fruit of Cyclocarya from the Early Oligocene Shangganchaigou Formation in the Qaidam Basin is assigned as Cyclocarya *** discovery of Cyclocarya *** demonstrates the occurrence of Cyclocarya in the Oligocene sediment in Qaidam *** is the first record of Cyclocarya fossil of Early Oligocene Age in china and indicates that Cyclocarya has existed on the northeastern TP since at least the Early *** living analogues of the current fossil now lives in sub-tropical china,where the East Asian Monsoon is *** the new fossils and previously reported fossil remains of plants and fishes,it can be inferred that the Early Oligocene Qaidam Basin was primarily influenced by westerly circulation and had a relatively warm and humid climate,which was in sharp contrast to the present-day climate in Qaidam Basin.

关键词： biostratigraphy climate change winged-fruit fossil Qaidam Basin Early Oligocene paleoclimate paleogeography

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Swelling behaviors of heterogeneous red-bed mudstone subjected to different vertical stresses

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Journal of Rock Mechanics and Geotechnical engineering 2024年第5期16卷 1847-1863页

作者： Kang Huang Zhangjun Dai Chengzeng Yan Fei Yu Wei Zhang Shanxiong Chen State Key Laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China university of Chinese Academy of Sciences Beijing100049China faculty of engineering China University of GeosciencesWuhanChina International Joint Research Center for Deep Earth Drilling and Resource Development China University of GeosciencesWuhan430074China

In this study,the axial swelling strain of red-bed mudstone under different vertical stresses are measured by swell-under-load method,and the microstructure of mudstone after hygroscopic swelling is studied by mercury intrusion porosimetry(MIP).The weakening coefficient and Weibull distribution function are introduced into the coupling model of mudstone moisture diffusion-swelling deformation-fracture based on finite-discrete element method(FDEM).The weakening effect of moisture on mudstone's mechanical parameters,as well as the heterogeneity of swelling deformation and stress distribution,is *** microcrack behavior and energy evolution of mudstone during hygroscopic swelling deformation under different vertical stresses are *** results show that the axial swelling strain of mudstone decreases with increase of the vertical *** low vertical stresses,moisture absorption in mudstone leads to formation of cracks caused by hydration-induced *** high vertical stresses,a muddy sealing zone forms on the mudstone surface,preventing further water *** simulation results of mudstone swelling deformation also demonstrate that it involves both swelling of the mudstone matrix and swelling caused by crack ***,crack expansion plays a dominant role in mudstone *** increasing vertical stress,the cracks in mudstone change from tensile cracks to shear cracks,resulting in a significant reduction in the total number of *** the evolution of mudstone kinetic energy shows similarities under different vertical stresses,the evolution of strain energy varies significantly due to the presence of different types of cracks in the *** findings provide a theoretical basis for understanding the hygroscopic swelling deformation mechanism of red-bed mudstone at various depths.

关键词： Heterogeneous red-bed mudstone Self-sealing band Matric swelling and crack expansion FDEM Microcracks Energy evolution

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Interannual evolution of the chemical composition,sources and processes of PM_(2.5)in Chengdu,china:Insights from observations in four winters

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Journal of Environmental Sciences 2024年第4期138卷 32-45页

作者： Junke Zhang Jiaqi Li Yunfei Su Chunying Chen Luyao Chen Xiaojuan Huang Fangzheng Wang Yawen Huang Gehui Wang faculty of geosciences and Environmental engineering Southwest Jiaotong UniversityChengdu 611756China Department of Environmental Science&engineering Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP3)Fudan UniversityShanghai 200438China Key Lab of Geographic Information Science of the Ministry of Education School of Geographic SciencesEast China Normal UniversityShanghai 200241China

The air quality in china has improved significantly in the last decade and,correspondingly,the characteristics of PM_(2.5)have also *** studied the interannual variation of PM_(2.5)in Chengdu,one of the most heavily polluted megacities in southwest china,during the most polluted season(winter).Our results show that the mass concentrations of PM_(2.5)decreased significantly year-by-year,from 195.8±91.0μg/m~3in winter 2016 to 96.1±39.3μg/m^(3)in winter *** mass concentrations of organic matter(OM),SO_()4^(2-),NH_(4)^(+)and NO_(3)^(-)decreased by 49.6%,57.1%,49.7% and 28.7%,*** differential reduction in the concentrations of chemical components increased the contributions from secondary organic carbon and NO_(3)^(-)and there was a larger contribution from mobile *** contribution of OM and NO_(3)^(-)not only increased with increasing levels of pollution,but also increased year-by-year at the same level of *** sources of PM_(2.5)were identified:combustion sources,vehicular emissions,dust and secondary *** aerosols made the highest contribution and increased year-by-year,from 40.6%in winter 2016 to 46.3% in winter *** contrast,the contribution from combustion sources decreased from 14.4% to 8.7%.Our results show the effectiveness of earlier pollution reduction policies and emphasizes that priority should be given to key pollutants(e.g.,OM and NO_(3)^(-))and sources(secondary aerosols and vehicular emissions)in future policies for the reduction of pollution in Chengdu during the winter months.

关键词： PM_(2.5) Chemical composition Sources Interannual evolution Winter Chengdu

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Insight into the Permeability and Microstructure Evolution Mechanism of the Sliding Zone Soil: A Case Study from the Huangtupo Landslide, Three Gorges Reservoir, china

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Journal of Earth Science 2024年第3期35卷 941-954页

作者： Qianyun Wang Huiming Tang Pengju An Kun Fang Junrong Zhang Minghao Miao Qingwen Tan Lei Huang Shengming Hu Badong National Observation and Research Station of Geohazards China University of GeosciencesWuhan 430074China faculty of engineering China University of GeosciencesWuhan 430074China Institute of Rock Mechanics Ningbo UniversityNingbo 315211China National and Provincial Joint engineering Laboratory for the Hydraulic engineering Safety and Efficient Utilization of Water Resources of Poyang Lake Basin Nanchang Institute of TechnologyNanchang 330099China

A large number of laboratory investigations related to the permeability have been conducted on the sliding *** little attention has been paid to the particular sliding zones of the slideprone Badong ***,we experimentally investigate the permeability nature and the mechanism of seepage in the viscous sliding zone of the Huangtupo *** seepage tests have been performed first with consideration of six dry densities and thirteen hydraulic gradients,in conjunction with the mercury intrusion porosimetry test and scanning electron microscopy test for the microstructure analysis after *** results show that seepage in the sliding zone soil does not follow Darcy’s Law,since there is a threshold hydraulic gradient(i0)below which no flow is observed and a critical hydraulic gradient(icr)over which the hydraulic conductivity(K)tends to be *** percentage of bound water could be responsible for the occurrence of i0 and ***,pore size distributions(PSD)less than 0.6µm and between 10 and 90µm exhibit positive and negative correlations with the i0,respectively,indicating that the i0 is related to the *** mechanism accounting for this result is that pore water pressure forces fine clay particles into the surrounding large pores and converts arranged particles to discretely distributed ones,thereby weakening the connectivity of *** seepages in the sliding zones behave differently from that in the sliding mass and sliding bed in response to the permeability.

关键词： reservoir landslides sliding zone soil permeability microstructure seepage.

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Geochemistry and origins of hydrogen-containing natural gases in deep Songliao Basin,china:Insights from continental scientific drilling

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Petroleum Science 2024年第2期21卷 741-751页

作者： Shuang-Biao Han Chao-Han Xiang Xin Du Lin-Feng Xie Jie Huang Cheng-Shan Wang College of Geoscience and Surveying engineering China University of Mining and TechnologyBeijing100083China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesBeijing100083China

The different reservoirs in deep Songliao Basin have non-homogeneous lithologies and include multiple layers with a high content of hydrogen *** gas composition and stable isotope characteristics vary significantly,but the origin analysis of different gas types has previously been *** on the geochemical parameters of gas samples from different depths and the analysis of geological settings,this research covers the diverse origins of natural gas in different *** gas components are mainly methane with a small amount of C_(2+),and non-hydrocarbon gases,including nitrogen(N_(2)),hydrogen(H_(2)),carbon dioxide(CO_(2)),and helium(He).At greater depth,the carbon isotope of methane becomes heavier,and the hydrogen isotope points to a lacustrine sedimentary *** increasing depth,the origins of N_(2)and CO_(2)change gradually from a mixture of organic and inorganic to *** origins of hydrogen gas are complex and include organic sources,water radiolysis,water-rock(Fe^(2+)-containing minerals)reactions,and *** shales of Denglouku and Shahezi Formations,as source rocks,provide the premise for generation and occurrence of organic ***,the deep faults and fluid activities in Basement Formation control the generation and migration of mantle-derived *** discovery of a high content of H_(2)in study area not only reveals the organic and inorganic association of natural-gas generation,but also provides a scientific basis for the exploration of deep hydrogen-rich gas.

关键词： Gas compositions Stable isotopes Gas origins Hydrogen gas Songliao Basin

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Predicting dynamic compressive strength of frozen-thawed rocks by characteristic impedance and data-driven methods

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Journal of Rock Mechanics and Geotechnical engineering 2024年第7期16卷 2591-2606页

作者： Shengtao Zhou Zong-Xian Zhang Xuedong Luo Yifan Huang Zhi Yu Xiaowei Yang faculty of engineering China University of GeosciencesWuhan430074China Oulu Mining School University of OuluOulu90570Finland Zijin School of Geology and Mining Fuzhou UniversityFuzhou350116China Department of Earth Science&engineering Imperial College LondonLondonSW72AZUK

In cold regions,the dynamic compressive strength(DCS)of rock damaged by freeze-thaw weathering significantly influences the stability of rock ***,testing the dynamic strength under freeze-thaw weathering conditions is often both time-consuming and ***,this study considers the effect of characteristic impedance on DCS and aims to quickly determine the DCS of frozen-thawed rocks through the application of machine-learning ***,a database of DCS for frozen-thawed rocks,comprising 216 rock specimens,was *** external load parameters(freeze-thaw cycle number,confining pressure,and impact pressure)and two rock parameters(characteristic impedance and porosity)were selected as input variables,with DCS as the predicted *** research optimized the kernel scale,penalty factor,and insensitive loss coefficient of the support vector regression(SVR)model using five swarm intelligent optimization algorithms,leading to the development of five hybrid *** addition,a statistical DCS prediction equation using multiple linear regression techniques was *** performance of the prediction models was comprehensively evaluated using two error indexes and two trend indexes.A sensitivity analysis based on the cosine amplitude method has also been *** results demonstrate that the proposed hybrid SVR-based models consistently provided accurate DCS *** these models,the SVR model optimized with the chameleon swarm algorithm exhibited the best performance,with metrics indicating its effectiveness,including root mean square error(RMSE)?3.9675,mean absolute error(MAE)?2.9673,coefficient of determination(R2)?0.98631,and variance accounted for(VAF)?*** suggests that the chameleon swarm algorithm yielded the most optimal results for enhancing SVR ***,impact pressure and characteristic impedance emerged as the two most influential parameters in DCS *** research is ant

关键词： Freeze-thaw cycle Characteristic impedance Dynamic compressive strength Machine learning Support vector regression

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Centrifuge modeling of unreinforced and multi-row stabilizing piles reinforced landslides subjected to reservoir water level fluctuation

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Journal of Rock Mechanics and Geotechnical engineering 2024年第5期16卷 1600-1614页

作者： Chenyang Zhang Yueping Yin Hui Yan Sainan Zhu Ming Zhang Luqi Wang Department of Civil engineering The University of Hong KongHong KongChina china Institute of Geo-environment Monitoring BeijingChina Chongqing 107 Municipal Construction engineering Co. Ltd.ChongqingChina faculty of engineering China University of GeosciencesWuhanChina School of Civil engineering Chongqing UniversityChongqingChina

With the construction of the Three Gorges Reservoir dam,frequent reservoir landslide events have been *** recent years,multi-row stabilizing piles(MRSPs)have been used to stabilize massive reservoir landslides in *** this study,two centrifuge model tests were carried out to study the unreinforced and MRSP-reinforced slopes subjected to reservoir water level(RWL)operation,using the Taping landslide as a *** results indicate that the RWL rising can provide lateral support within the submerged zone and then produce the inward seepage force,eventually strengthening the slope ***,a rapid RWL drawdown may induce outward seepage forces and a sudden debuttressing effect,consequently reducing the effective soil normal stress and triggering partial pre-failure within the RWL fluctuation ***,partial deformation and subsequent soil structure damage generate excess pore water pressures,ultimately leading to the overall failure of the reservoir *** study also reveals that a rapid increase in the downslope driving force due to RWL drawdown significantly intensifies the lateral earth pressures exerted on the ***,the MRSPs possess a considerable reinforcement effect on the reservoir landslide,transforming the overall failure into a partial deformation and failure situated above and in front of the *** mechanical transfer behavior observed in the MRSPs demonstrates a progressive alteration in relation to RWL *** the RWL rises,the mechanical states among MRSPs exhibit a growing *** shear force transfer factor(*** ratio of shear forces on pile of the n th row to that of the first row)increases significantly with the RWL *** indicates that the mechanical states among MRSPs tend toward an enhanced *** insights gained from this study contribute to a more comprehensive understanding of the failure mechanisms of reservoir landslides and the mechanical behavior of M

关键词： Reservoir landslide Failure mechanism Multi-row stabilizing piles Mechanical behavior

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