Effective management of mining areas in the Luo River Basin,located in the eastern Qinling Mountains,is vital for the integrated protection and restoration needed to support the high-quality development of the Yellow ...Effective management of mining areas in the Luo River Basin,located in the eastern Qinling Mountains,is vital for the integrated protection and restoration needed to support the high-quality development of the Yellow River Basin.Using the‘cupball'model,this study analyzes the limiting factors and restoration characteristics across four mining areas and proposes a conceptual model for selecting appropriate restoration approaches.A second conceptual model is then introduced to address regional development needs,incorporating ecological conservation,safety protection,and people's wellbeing.The applicability of the integrated model selection framework is demonstrated through a case study on the south bank of the Qinglongjian River.The results indicate that:(1)The key limiting factors are similar across cases,but the degree of ecological degradation varies.(2)Mildly degraded areas are represented by a shallower and narrower‘cup',where natural recovery is the preferred approach,whereas moderately and severely degraded systems call for assisted regeneration and ecological reconstruction,respectively.(3)When the restoration models determined based on limiting factors and development needs are consistent,the model is directly applicable;if they differ,the option involving less artificial intervention is preferred;(4)Monitoring of the restored mining area on the Qinglongjian River's south bank confirms significant improvements in soil erosion control and vegetation coverage.This study provides a transferable methodology for balancing resource extraction with ecosystem conservation,offering practical insights for other ecologically vulnerable mining regions.展开更多
It is an important standard to judge the flood disaster in the basin whether the rainfall at the flood-inducing interface is reached.In this paper,the Xin'anjiang model,Topmodel model and SCS model were selected t...It is an important standard to judge the flood disaster in the basin whether the rainfall at the flood-inducing interface is reached.In this paper,the Xin'anjiang model,Topmodel model and SCS model were selected to calculate and compare the rainfall at the flood-inducing interface in the Zhanghe Reservoir basin in Hubei Province.The results showed that average relative error and average absolute error of Xin'anjiang model were-3.36%and-21.46×10^(5)m^(3),which were the minimum,followed by Topmodel model with 5.72%and 26.22×10^(5)m^(3),SCS model with 11.33%and 58.13×10^(5)m^(3).The minimum absolute error of the three hydrological models in calculating the rainfall at the critical interface was 3.26 mm,while the maximum was 49.24 mm.When the initial water level exceeded 120 m,the difference among the three models in calculating the rainfall at the critical interface became more and more obvious.When the reservoir water level was lower than 120 m,it mainly referred to the calculation results of Xin'anjiang model.When the reservoir water level was higher than 120 m,it mainly referred to the calculation results of Topmodel model.The research conclusion can provide reference for small and medium-sized basins selecting hydrological model to calculate the rainfall at the flood-inducing interface.展开更多
The stretching process of some Tertiary rift basins in eastern China is characterized by multiphase rifting. A multiple instantaneous uniform stretching model is proposed in this paper to simulate the formation of the...The stretching process of some Tertiary rift basins in eastern China is characterized by multiphase rifting. A multiple instantaneous uniform stretching model is proposed in this paper to simulate the formation of the basins as the rifting process cannot be accurately described by a simple (one episode) stretching model. The study shows that the multiphase stretching model, combined with the back-stripping technique, can be used to reconstruct the subsidence history and the stretching process of the lithosphere, and to evaluate the depth to the top of the asthenosphere and the deep thermal evolution of the basins. The calculated results obtained by applying the quantitative model to the episodic rifting process of the Tertiary Qiongdongnan and Yinggehai basins in the South China Sea are in agreement with geophysical data and geological observations. This provides a new method for quantitative evaluation of the geodynamic process of multiphase rifting occurring during the Tertiary in eastern China.展开更多
The geologic conditions of superimposed basins in China are very complicated. This is mainly shown by multi-phase structural evolution, multiple sets of source-reservoir-cap rock combinations, multiple stages of hydro...The geologic conditions of superimposed basins in China are very complicated. This is mainly shown by multi-phase structural evolution, multiple sets of source-reservoir-cap rock combinations, multiple stages of hydrocarbon generation and expulsion from source rocks, multi-cycle hydrocarbon enrichment and accumulation, and multi-phase reservoir adjustment and reconstruction. The enrichment, accumulation and distribution of hydrocarbon is mainly controlled by the source rock kitchen, paleo- anticline, regional cap rock and intensity of tectonic movement. In this paper, the T-BCMS model has been developed to predict favorable areas of hydrocarbon accumulation in complicated superimposed basins according to time and spatial relationships among five key factors. The five factors include unconformity surface representing tectonic balancing （B）, regional cap rock representing hydrocarbon protection （C）, paleo-anticline representing hydrocarbon migration and accumulation （M）, source rock kitchen representing hydrocarbon generation and expulsion （S） and geological time （T）. There are three necessary conditions to form favorable areas of hydrocarbon accumulation. First, four key factors BCMS should be strictly in the order of BCMS from top to bottom. Second, superimposition of four key factors BCMS in the same area is the most favorable for hydrocarbon accumulation. Third, vertically ordered combination and superimposition in the same area of BCMS should occur at the same geological time. The model has been used to predict the most favorable exploration areas in Ordovician in the Tarim Basin in the main hydrocarbon accumulation periods. The result shows that 95% of the discovered Ordovician hydrocarbon reservoirs are located in the predicted areas, which indicates the feasibility and reliability of the key factor matching T-BCMS model for hydrocarbon accumulation and enrichment.展开更多
Three series of sandbox modeling experiments were performed to study the fault-increment pattern in extensional basins. Experimental results showed that the tectonic action mode of boundaries and the shape of major bo...Three series of sandbox modeling experiments were performed to study the fault-increment pattern in extensional basins. Experimental results showed that the tectonic action mode of boundaries and the shape of major boundary faults control the formation and evolution of faults in extensional basins. In the process of extensional deformation, the increase in the number and length of faults was episodic, and every ＇episode＇ experienced three periods, strain-accumulation period, quick fault-increment period and strain-adjustment period. The more complex the shape of the boundary fault, the higher the strain increment each ＇episode＇ experienced. Different extensional modes resulted in different fault-increment patterns. The horizontal detachment extensional mode has the ＇linear＇ style of fault-increment pattern, while the extensional mode controlled by a listric fault has the ＇stepwise＇ style of fault-increment pattern, and the extensional mode controlled by a ramp-flat boundary fault has the ＇stepwise-linear＇ style of fault-increment pattern. These fault-increment patterns given above could provide a theoretical method of fault interpretation and fracture prediction in extensional basins.展开更多
The Carboniferous prototype sedimentary basin in the Tazhong (Central Tarimbasin) area is recognized as a compressive intracratonic depressional one. Three type Ⅰ sequenceboundaries and three type Ⅱ sequence boundar...The Carboniferous prototype sedimentary basin in the Tazhong (Central Tarimbasin) area is recognized as a compressive intracratonic depressional one. Three type Ⅰ sequenceboundaries and three type Ⅱ sequence boundaries can be identified in the CarboniferousSystem, which can accordingly be divided into five sedimentary sequences. These sequencespossess stratigraphic characters of the standard sequence and correspond to the depositionalstratigraphic unit of a third-order eustatic cycle. They can be regionally or globally correlatedwith each other. The framework of sequence stratigraphy of the intracratonict basin in thestudy area distinctly differs from that of the passive continental-margin basin in the lack ofdepositional systems of early-middle lowstand, poor development of the deeply incised valleyand condensed section of the maximum sea-flood, good development of type Ⅱ sequenceboundaries and coastal plain depositional systems coexisting with shelf-type fan deltas underwet climatic conditions, Which consequently led to the formation of a paralic lithofacies frame-work.展开更多
Hydrocarbon expulsion features and resource potential evaluation of source rocks are crucial for the petroleum exploration.High-maturity marine source rocks have not exhibited a hydrocarbon expulsion mode owing to the...Hydrocarbon expulsion features and resource potential evaluation of source rocks are crucial for the petroleum exploration.High-maturity marine source rocks have not exhibited a hydrocarbon expulsion mode owing to the lack of low-maturity source rocks in deep petroliferous basins.We considered the Ediacaran microbial dolomite in the Sichuan Basin,the largest high-maturity marine gas layer in China,to exhibit a method that quantitatively characterizes the hydrocarbon expulsion of high-maturity marine source rocks.The experiment of fluid inclusion,rock pyrolysis,and vitrinite reflectance(Ro)of 119 microbial dolomite core samples obtained from the Dengying Formation were performed.A hydrocarbon expulsion model of high-maturity source rock was established,and its resource potential was evaluated.The results showed that the Ediacaran microbial dolomite in the Sichuan Basin is a good source rock showing vast resource potential.The hydrocarbon expulsion threshold is determined to be vitrinite reflectance at 0.92%.The hydrocarbon expulsion intensities in the geologic history is high with maximum of 1.6×10^(7)t/km^(2).The Ediacaran microbial dolomite expelled approximately 1.008×10^(12)t of hydrocarbons,and the recoverable resource was 1.5×10^(12)m^(3).The region can be categorized into areasⅠ,Ⅱ,Ⅲ,andⅣ,in decreasing order of hydrocarbon expulsion intensity.Areas with a higher hydrocarbon expulsion intensity have a lower drilling risk and should be prioritized for exploration in the orderⅠ>Ⅱ>Ⅲ>Ⅳ.Two areas,northern and central parts of Ediacaran in the Sichuan Basin,were selected as prospects which had the drilling priority in the future gas exploration.The production data of 55 drilled wells verified the high reliability of this method.This model in this study does not require low-maturity samples and can be used for evaluating high-maturity marine source rocks,which has broad applicability in deep basins worldwide.展开更多
A large quantity of drilling core, paleontology, geochemistry and geophysics data revealed several features of the Jiyang subbasin during the deposition of the Ekl-ES4x members： （1） the paleotopography of the gentl...A large quantity of drilling core, paleontology, geochemistry and geophysics data revealed several features of the Jiyang subbasin during the deposition of the Ekl-ES4x members： （1） the paleotopography of the gentle slope belt had an extremely low gradient; （2） the paleoclimate frequently alternated between dry and wet periods in a generally arid setting; （3） there was strong weathering around the periphery of the basin; （4） the lake was very shallow; （5） the lake level frequently rose and fell; and （6） the sedimentary environment of the gentle slope belt was an over- flooding lake. All of these factors provided favorable geological conditions for the development of an over-flooding lake delta. The lithologies of the continental over-flooding lake delta deposits are complex and diverse. The compositional maturity is moderate to low, and the grain size distribution curves and sedimentary structures indicate the presence of both gravity and traction currents. The sedimentary microfacies associations consist of a combination of ordered superposition of flood channels, distributary channels and sheet sands. The delta exhibits a weak foreset seismic reflection. The over-flooding lake delta deposits are laterally extensive. The sandstone content is high, and the individual sandstone beds are thin. The flood channel and distributary channel deposits exhibit evidence of bifurcation and lateral migration. The distribution of the sandbodies and the oxidation color of the mudstones provide evidence of cyclic deposition. The paleoclimate was the dominant factor controlling the development of the over-flooding lake delta. Due to the frequently alternating wet and dry paleoclimates, the over-flooding lake delta is characterized by the development of a broad upper plain and a lower delta plain. The upper delta plain is characterized by flood channel deposits, whereas the lower delta plain is represented by distributary channel deposits. The transition zone is characterized by the interaction of flood channels and distributary channels. Due to fault activity, the sandbodies of the over-flooding lake delta were juxtaposed against hydrocarbon source rocks, which was favorable for the development of lithologic reservoirs or structural-lithologic reservoirs. The lower delta plain deposits comprise the most favorable reservoirs.展开更多
The northwestern margin of Junggar Basin is the region with the richest oil sand resources in China.For better understanding the enrichment rules and deployment of exploration and development of regional oil sand,it i...The northwestern margin of Junggar Basin is the region with the richest oil sand resources in China.For better understanding the enrichment rules and deployment of exploration and development of regional oil sand,it is of great scientific significance to study the accumulation conditions of oil sand in different strata and mining areas of the Junggar Basin.Through a large number of field investigations,drilling verification and sampling tests,it is found that the oil sand in the region covers an area of 2000 km^(2),with shallow and thick reservoir,and predicted resource of 180 million tons.The oil sand resources are mainly distributed in four geological strata,namely the Middle Triassic Karamay Formation,Early Jurassic Badaowan Formation,Late Jurassic Qigu Formation,and Early Cretaceous Qingshuihe Formation.The reservoir is mainly composed of sandstone with high porosity and permeability,and the reservoir space is mainly intergranular pores with a medium average oil content.The oil sand deposit in the region is a typical destructive oil reservoir.The crude oil in the oil sand layer is degraded and thickened from the deep to the shallow,the content of saturated hydrocarbon decreased,and the content of aromatic hydrocarbon,non-hydrocarbon and asphaltene increased.The oil source comes from the deep Permian hydrocarbon-generating depression.Unconformities,faults and marginal fan delta-braided river depositional systems constitute effective migration and storage systems.Caprocks of the Upper Triassic Baijiantan Formation,Lower Jurassic Sangonghe Formation and Lower Cretaceous Hutubihe Formation were formed by three large scale lake transgressions.The Indosinian,Yanshan and Late Yanshan movements are the main driving forces for the migration of deep oil and gas to the shallow edge to form oil sand deposits.It is considered that the oil sand in the northwestern margin of Junggar Basin is of a slope complex migration type.展开更多
This study systematically reviews the development history and key technological breakthroughs of large gas fields in the Ordos Basin,and summarizes the development models of three gas reservoir types,low-permeability ...This study systematically reviews the development history and key technological breakthroughs of large gas fields in the Ordos Basin,and summarizes the development models of three gas reservoir types,low-permeability carbonate,low-permeability sandstone and tight sandstone,as well as the progress in deep coal-rock gas development.The current challenges and future development directions are also discussed.Mature development models have been formed for the three representative types of gas reservoirs in the Ordos Basin:(1)Low-permeability carbonate reservoir development model featuring groove fine-scale characterization and three-dimensional vertical succession between Upper and Lower Paleozoic formations.(2)Low-permeability sandstone reservoir development model emphasizing horizontal well pressure-depletion production and vertical well pressure-controlled production.(3)Tight sandstone gas reservoir development model focusing on single-well productivity enhancement and well placement optimization.In deep coal-rock gas development,significant progress has been achieved in reservoir evaluation,sweet spot prediction,and geosteering of horizontal wells.The three types of reservoirs have entered the mid-to-late stages of the development,when the main challenge lies in accurately characterizing residual gas,evaluating secondary gas-bearing layers,and developing precise potential-tapping strategies.In contrast,for the early-stage development of deep coal-rock gas,continuous technological upgrades and cost reduction are essential to achieving economically viable large-scale development.Four key directions of future research and technological breakthroughs are proposed:(1)Utilizing dual-porosity(fracture-matrix)modeling techniques in low-permeability carbonate reservoirs to delineate the volume and distribution of remaining gas in secondary pay zones,supporting well pattern optimization and production enhancement of existing wells.(2)Integrating well-log and seismic data to characterize reservoir spatial distribution of successive strata,enhancing drilling success rates in low-permeability sandstone reservoirs.(3)Utilizing the advantages of horizontal wells to penetrate effective reservoirs laterally,achieving meter-scale quantification of small-scale single sand bodies in tight gas reservoirs,and applying high-resolution 3D geological models to clarify the distribution of remaining gas and guide well placement optimization.(4)Further strengthening the evaluation of deep coal-rock gas in terms of resource potential,well type and pattern,reservoir stimulation,single-well performance,and economic viability.展开更多
Based on petroleum exploration and new progress of oil and gas geology study in the Qiongdongnan Basin,combined with seismic,logging,drilling,core,sidewall coring,geochemistry data,a systematic study is conducted on t...Based on petroleum exploration and new progress of oil and gas geology study in the Qiongdongnan Basin,combined with seismic,logging,drilling,core,sidewall coring,geochemistry data,a systematic study is conducted on the source,reservoir-cap conditions,trap types,migration and accumulation characteristics,enrichment mechanisms,and reservoir formation models of ultra-deep water and ultra-shallow natural gas,taking the Lingshui 36-1 gas field as an example.(1)The genetic types of the ultra-deep water and ultra-shallow natural gas in the Qiongdongnan Basin include thermogenic gas and biogenic gas,and dominated by thermogenic gas.(2)The reservoirs are mainly composed of the Quaternary deep-water submarine fan sandstone.(3)The types of cap rocks include deep-sea mudstone,mass transport deposits mudstone,and hydrate-bearing formations.(4)The types of traps are mainly lithological,and also include structural-lithological traps.(5)The migration channels include vertical transport channels such as faults,gas chimneys,fracture zones,and lateral transport layers such as large sand bodies and unconformity surfaces,forming a single or composite transport framework.A new natural gas accumulation model is proposed for ultra-deep water and ultra-shallow layers,that is,dual source hydrocarbon supply,gas chimney and submarine fan composite migration,deep-sea mudstone-mass transport deposits mudstone-hydrate-bearing strata ternary sealing,late dynamic accumulation,and large-scale enrichment at ridges.The new understanding obtained from the research has reference and enlightening significance for the next step of deepwater and ultra-shallow layers,as well as oil and gas exploration in related fields or regions.展开更多
Based on the comprehensive analysis of data from petrology and mineralogy,well logging,seismic surveys,paleontology,and geochemistry,a detailed research was conducted on paleoenvironmental and paleoclimatic conditions...Based on the comprehensive analysis of data from petrology and mineralogy,well logging,seismic surveys,paleontology,and geochemistry,a detailed research was conducted on paleoenvironmental and paleoclimatic conditions,and modeling of the source rocks in the second member of the Eocene Wenchang Formation(Wen 2 Member)in the Northern Shunde Subsag at the southwestern margin of the Pearl River Mouth Basin.The Wen 2 Member hosts excellent,thick lacustrine source rocks with strong longitudinal heterogeneity and an average total organic carbon(TOC)content of over 4.9%.The Wen 2 Member can be divided into three units(I,II,III)from bottom to top.Unit I features excellent source rocks with Type I organic matters(average TOC of 5.9%)primarily sourced from lake organisms;Unit II hosts source rocks dominated by Type II2 organic matters(average TOC of 2.2%),which are originated from mixed sources dominated by terrestrial input.Unit III contains good to excellent source rocks dominated by Type II1 organic matters(average TOC of 4.9%),which are mainly contributed by lake organisms and partially by terrestrial input.Under the background of rapid subsidence and limited source supply during intense rifting period in the Eocene,excellent source rocks were developed in Wen 2 Member in the Northern Shunde Subsag under the coordinated control of warm and humid climate,volcanic activity,and deep-water reducing conditions.During the deposition of Unit I,the warm and humid climate and volcanic activity promoted the proliferation of lake algaes,primarily Granodiscus,resulting in high initial productivity,and deep-water reducing conditions enabled satisfactory preservation of organic matters.These factors jointly controlled the development and occurrence of excellent source rocks.During the deposition of Unit II,a transition from warm to cool and semi-arid paleoclimatic conditions led to a decrease in lake algaes and initial productivity.Additionally,enhanced terrestrial input and shallow-water,weakly oxidizing water conditions caused a significant dilution and decomposition of organic matters,degrading the quality of source rocks.During the deposition of Unit III,when the paleoclimatic conditions are cool and humid,Pediastrum and Botryococcus began to thrive,leading to an increase in productivity.Meanwhile,the reducing environment of semi-deep water facilitated the preservation of excellent source rocks,albeit slightly inferior to those in Unit I.The study results clarify the differential origins and development models of various source rocks in the Shunde Sag,offering valuable guidance for evaluating source rocks and selecting petroleum exploration targets in similar marginal sags.展开更多
Taking the second member of the Xujiahe Formation of the Upper Triassic in the Xinchang structural belt as an example,based on data such as logging,production,seismic interpretation and test,a systematic analysis was ...Taking the second member of the Xujiahe Formation of the Upper Triassic in the Xinchang structural belt as an example,based on data such as logging,production,seismic interpretation and test,a systematic analysis was conducted on the structural characteristics and evolution,reservoir diagenesis and densification processes,and types and stages of faults/fractures,and revealing the multi-stage and multi-factor dynamic coupled enrichment mechanisms of tight gas reservoirs.(1)In the early Yanshan period,the paleo-structural traps were formed with low-medium maturity hydrocarbons accumulating in structural highs driven by buoyancy since reservoirs were not fully densified in this stage,demonstrating paleo-structure control on traps and early hydrocarbon accumulation.(2)In the middle-late Yanshan period,the source rocks became mature to generate and expel a large quantity of hydrocarbons.Grain size and type of sandstone controlled the time of reservoir densification,which restricted the scale of hydrocarbon charging,allowing for only a small-scale migration through sand bodies near the fault/fracture or less-densified matrix reservoirs.(3)During the Himalayan period,the source rocks reached overmaturity,and the residual oil cracking gas was efficiently transported along the late-stage faults/fractures.Wells with high production capacity were mainly located in Type I and II fault/fracture zones comprising the late-stage north-south trending fourth-order faults and the late-stage fractures.The productivity of the wells was controlled by the transformation of the late-stage faults/fractures.(4)The Xinchang structural belt underwent three stages of tectonic evolution,two stages of reservoir formation,and three stages of fault/fractures development.Hydrocarbons mainly accumulated in the paleo-structure highs.After reservoir densification and late fault/fracture adjustment,a complex gas-water distribution pattern was formed.Thus,it is summarized as the model of“near-source and low-abundance hydrocarbon charging in the early stage,and differential enrichment of natural gas under the joint control of fault-fold-fracture complex,high-quality reservoirs and structural highs in the late stage”.Faults/fractures with well-coupled fault-fold-fracture-pore are favorable exploration targets with high exploration effectiveness.展开更多
The conversion of forest land to other types of land cover is one of the major issues in the global fight against climate change. Understanding the direct and indirect factors of these conversions from local studies i...The conversion of forest land to other types of land cover is one of the major issues in the global fight against climate change. Understanding the direct and indirect factors of these conversions from local studies in the tropics is essential to project the future impact of human activities on the preservation of tropical forests in general and the forests of the Republic of Congo in particular. This study, conducted in five localities with different socioeconomic contexts in the Republic of Congo, aims to analyze the variability of drivers of deforestation and forest degradation linked to urbanization in the Congo Basin. Using a series of land cover maps from the years 1986, 2003 and 2019 for the cities of Ouesso, Pokola, Ngombe, Impfondo and Dongou, as well as field data and socio-economic information collected from local and central administrations, a unique model has been developed to understand the explanatory patterns of forest loss. Deforestation around urban centers is mainly due to urban agriculture due to population growth, as well as the spatial expansion of cities, which have a major impact on the stability and integrity of forests. Shifting agriculture is the main direct cause of deforestation and forest degradation, representing 48% of the total sample, followed by the collection of wood fuel (22%), the collection of construction wood (19%), illegal logging (6%) and urban expansion (5%). Forecasts indicate that forest loss around major cities will increase by 487, 20 ha to 5266, 73 ha by 2050 compared to the base year of 2019. This study highlights the need for a new system of land management and poverty alleviation of local populations to ensure the stability of the Congo Basin tropical forests around large and small African cities.展开更多
Research on the distribution and development of black shales in the Lianggaoshan Formation has been deficient,which has hindered exploration for lacustrine shale oil in the Sichuan Basin.Our study characterized the we...Research on the distribution and development of black shales in the Lianggaoshan Formation has been deficient,which has hindered exploration for lacustrine shale oil in the Sichuan Basin.Our study characterized the well logging data,core samples,outcrops,and geochemistry of black shales in the Lianggaoshan Formation in the Sichuan Basin.Our analysis focused on the lake basin evolution and the migration characteristics,paleoenvironmental features,formation mechanisms,and developmental model of the black shales.The results indicated that black shales in the Lianggaoshan Formation exhibited significant lateral migration,with an overall thickening trend from east to west.Within the 1st Member of the formation,black shale occurred as a single thick layer in the eastern region that gradually thinned toward the central region.Multiple sets of shale developed within the 2nd and 3rd members,and these had lower thicknesses than the 1st Member and migrated toward central Sichuan.Paleoproductivity and terrigenous input were the main factors controlling the deposition of black shales.A semi-humid climate influenced the deposition of black shales,bringing abundant freshwater,terrigenous debris,and nutrients into the basin.Decomposition of organic matter consumed oxygen in sediment and bottom water,causing localized oxygen deficiency in the strata.展开更多
The occurrence types and controlling factors of organic matter in the sepiolite-containing successions of the first member of Mid-Permian Maokou Formation(Mao-1 Member for short)in the Eastern Sichuan Basin,SW China,h...The occurrence types and controlling factors of organic matter in the sepiolite-containing successions of the first member of Mid-Permian Maokou Formation(Mao-1 Member for short)in the Eastern Sichuan Basin,SW China,have been investigated through outcrop section measurement,core observation,thin section identification,argon ion polishing-field scanning electron microscopy,energy spectrum analysis,X-ray diffraction,total organic carbon content(TOC),major and trace element analysis.Finally,the symbiotic adsorption model of sepiolite for organic matter enrichment has been established.The results show that the sepiolite-containing successions of the Mao-1 Member are composed of the rhythmite of mudstone,argillaceous limestone and limestone,with five depositional intervals vertically and the organic matter mostly developed in the mudstone and argillaceous limestone layers within the lower three intervals.The organic matter occurrence types are mostly layered or nodular in macro to meso-scale,blocky-vein-like under a microscope,but scattered,interstitial or adsorbed at a mesoscopic scale.It underwent transition processes from lower to higher salinity,from oxygen-poor and anoxic reduction to oxygen-poor and localized oxygen enrichment on the palaeo-environment of the Mao-1 Member.The first two intervals of the early depositional phase of Mao-1 Member constitute the cyclothems of mudstone,argillaceous limestone and limestone and quantities of fibrous-feathered sepiolite settle down within the Tongjiang-Changshou sag with continuous patchy organic matter from adsorption of alginate by sepiolite in intercrystalline,bedding surfaces and interlayer pores.The third and fourth intervals in the mid-depositional phase are mostly composed of the mudstone and argillaceous limestone alternations with the continuous patchy or banded organic matter in the surface and inter-crystalline pores of fibrous,feathered and flaky sepiolite.And the fifth interval in the late depositional phase of the Mao-1 Member comprises the cyclothems of extremely thin layered argillaceous limestone and thick-layered limestone with the fibrous sepiolite depositing in the argillaceous limestone and irregular organic matter dispersing around the sepiolite.Therefore,the symbiotic adsorption between organic matter and sepiolite effectively enhances the preservation efficiency of organic matter and improves the source rock quality of the Mao-1 Member,which enhances our understanding on the enrichment model of the depositional organic matter.展开更多
This study employs the Long Short-Term Memory(LSTM)rainfall-runoff model to simulate and predict runoff in typical basins of the Jiziwan Region of the Yellow River,aiming to overcome the shortcomings of traditional hy...This study employs the Long Short-Term Memory(LSTM)rainfall-runoff model to simulate and predict runoff in typical basins of the Jiziwan Region of the Yellow River,aiming to overcome the shortcomings of traditional hydrological models in complex nonlinear environments.The Jiziwan Region of the Yellow River is affected by human activities such as urbanization,agricultural development,and water resource management,leading to increasingly complex hydrological processes.Traditional hydrological models struggle to effectively capture the relationship between rainfall and runoff.The LSTM rainfall-runoff model,using deep learning techniques,automatically extracts features from data,identifies complex patterns and long-term dependency in time series,and provides more accurate and reliable runoff predictions.The results demonstrate that the LSTM rainfall-runoff model adapts well to the complex hydrological characteristics of the Jiziwan Region,showing superior performance over traditional hydrological models,especially in addressing the changing trends under the influence of climate change and human activities.By analyzing the interannual and within-year variations of runoff under different climate change scenarios,the model can predict the evolution trends of runoff under future climate conditions,providing a scientific basis for water resource management and decision-making.The results indicate that under different climate change scenarios,the runoff in several typical basins of the Jiziwan Region exhibits different variation trends.Under SSP1-2.6 and SSP2-4.5,some basins,such as the Wuding River Basin,Tuwei River Basin,and Gushanchuan Basin,show a decreasing trend in annual runoff.For example,in the Wuding River Basin,the average runoff from 2025 to 2040 is 12.48 m^(3)/s(SSP1-2.6),with an annual decrease of 0.10 m^(3)/s;in the Tuwei River Basin,the runoff from 2025 to 2040 is 12.96 m^(3)/s(SSP1-2.6),with an annual decrease of 0.10 m^(3)/s.In contrast,under SSP3-7.0 and SSP5-8.5,with climate warming and changes in precipitation patterns,runoff in some basins shows an increasing trend,particularly during the snowmelt period and with increased summer precipitation,leading to a significant rise in runoff.展开更多
The area of the intermontane basins in the Xuefeng Mountain region is 4,000 km2. These basins are the most favourable area for agriculture in the mountainous region. Unfortunately, in each basin the eco-environment ha...The area of the intermontane basins in the Xuefeng Mountain region is 4,000 km2. These basins are the most favourable area for agriculture in the mountainous region. Unfortunately, in each basin the eco-environment has gradually worsened because of the irrational utilization of natural resources. A rational model of agro-ecologic- economic system of intermontane basin must be formed so as to exploit and utilize rationally the natural resources. The intermontane basins may be divided into 3 ecologic belts of agriculture. Here are some ecologic-economic problems in the development: The resources of the outer mountains lie waste, but the valley basins in centre are over-development; the low mountains and hillocks are cultivated for dry crops so that the water and soil losses are serious and the natural disasters are frequent. Therefore, the agro-economic, agro-biologic and eco-environmental subsystems form a complete agro-ecologic-economic system of intermontane basins. Developing rationally the展开更多
The BGHMS system described in this paper was designed to model the geohistory for cratonic basins and written in turbo BASIC language with a user-friendly interface for data inputs and outputs on IBM PC-compatible com...The BGHMS system described in this paper was designed to model the geohistory for cratonic basins and written in turbo BASIC language with a user-friendly interface for data inputs and outputs on IBM PC-compatible computers. The major mathematical models in this system include the models of compaction correction. unconformity restoration. sea-level change and paleo-water-depth correction. and tectonic subsidence modeling. Two geological events of sediment compaction and erosion are considered in this system. It consists of three modules for data input, geohistory modeling and graph conversion and output. containing more than twenty subroutine programs, is an easy-to-use. menu-driven program system with many obvious advantages, and is a useful tool for hydrocarbon geologists to make quantitative studies on geohistory and to make exploration decisions in regional evaluation.展开更多
基金supported by Special major projects for research and development of Henan Provincial(Science and Technology Research Project)(No.252102321104)Humanities and Social Sciences Youth Foundation,Ministry of Education(24YJCZH410)。
文摘Effective management of mining areas in the Luo River Basin,located in the eastern Qinling Mountains,is vital for the integrated protection and restoration needed to support the high-quality development of the Yellow River Basin.Using the‘cupball'model,this study analyzes the limiting factors and restoration characteristics across four mining areas and proposes a conceptual model for selecting appropriate restoration approaches.A second conceptual model is then introduced to address regional development needs,incorporating ecological conservation,safety protection,and people's wellbeing.The applicability of the integrated model selection framework is demonstrated through a case study on the south bank of the Qinglongjian River.The results indicate that:(1)The key limiting factors are similar across cases,but the degree of ecological degradation varies.(2)Mildly degraded areas are represented by a shallower and narrower‘cup',where natural recovery is the preferred approach,whereas moderately and severely degraded systems call for assisted regeneration and ecological reconstruction,respectively.(3)When the restoration models determined based on limiting factors and development needs are consistent,the model is directly applicable;if they differ,the option involving less artificial intervention is preferred;(4)Monitoring of the restored mining area on the Qinglongjian River's south bank confirms significant improvements in soil erosion control and vegetation coverage.This study provides a transferable methodology for balancing resource extraction with ecosystem conservation,offering practical insights for other ecologically vulnerable mining regions.
基金Supported by Open Project Fund of China Meteorological Administration Basin Heavy Rainfall Key Laboratory(2023BHR-Y26)Innovation Project Fund of Wuhan Metropolitan Area Meteorological Joint Science and Technology(WHCSQY202305)+1 种基金Innovation and Development Special Project of China Meteorological Administration(CXFZ2022J019)Project of Huanggang Meteorological Bureau's Scientific Research(2022Y02).
文摘It is an important standard to judge the flood disaster in the basin whether the rainfall at the flood-inducing interface is reached.In this paper,the Xin'anjiang model,Topmodel model and SCS model were selected to calculate and compare the rainfall at the flood-inducing interface in the Zhanghe Reservoir basin in Hubei Province.The results showed that average relative error and average absolute error of Xin'anjiang model were-3.36%and-21.46×10^(5)m^(3),which were the minimum,followed by Topmodel model with 5.72%and 26.22×10^(5)m^(3),SCS model with 11.33%and 58.13×10^(5)m^(3).The minimum absolute error of the three hydrological models in calculating the rainfall at the critical interface was 3.26 mm,while the maximum was 49.24 mm.When the initial water level exceeded 120 m,the difference among the three models in calculating the rainfall at the critical interface became more and more obvious.When the reservoir water level was lower than 120 m,it mainly referred to the calculation results of Xin'anjiang model.When the reservoir water level was higher than 120 m,it mainly referred to the calculation results of Topmodel model.The research conclusion can provide reference for small and medium-sized basins selecting hydrological model to calculate the rainfall at the flood-inducing interface.
文摘The stretching process of some Tertiary rift basins in eastern China is characterized by multiphase rifting. A multiple instantaneous uniform stretching model is proposed in this paper to simulate the formation of the basins as the rifting process cannot be accurately described by a simple (one episode) stretching model. The study shows that the multiphase stretching model, combined with the back-stripping technique, can be used to reconstruct the subsidence history and the stretching process of the lithosphere, and to evaluate the depth to the top of the asthenosphere and the deep thermal evolution of the basins. The calculated results obtained by applying the quantitative model to the episodic rifting process of the Tertiary Qiongdongnan and Yinggehai basins in the South China Sea are in agreement with geophysical data and geological observations. This provides a new method for quantitative evaluation of the geodynamic process of multiphase rifting occurring during the Tertiary in eastern China.
基金supported by the National Basic Research Program (2006CB202308)
文摘The geologic conditions of superimposed basins in China are very complicated. This is mainly shown by multi-phase structural evolution, multiple sets of source-reservoir-cap rock combinations, multiple stages of hydrocarbon generation and expulsion from source rocks, multi-cycle hydrocarbon enrichment and accumulation, and multi-phase reservoir adjustment and reconstruction. The enrichment, accumulation and distribution of hydrocarbon is mainly controlled by the source rock kitchen, paleo- anticline, regional cap rock and intensity of tectonic movement. In this paper, the T-BCMS model has been developed to predict favorable areas of hydrocarbon accumulation in complicated superimposed basins according to time and spatial relationships among five key factors. The five factors include unconformity surface representing tectonic balancing （B）, regional cap rock representing hydrocarbon protection （C）, paleo-anticline representing hydrocarbon migration and accumulation （M）, source rock kitchen representing hydrocarbon generation and expulsion （S） and geological time （T）. There are three necessary conditions to form favorable areas of hydrocarbon accumulation. First, four key factors BCMS should be strictly in the order of BCMS from top to bottom. Second, superimposition of four key factors BCMS in the same area is the most favorable for hydrocarbon accumulation. Third, vertically ordered combination and superimposition in the same area of BCMS should occur at the same geological time. The model has been used to predict the most favorable exploration areas in Ordovician in the Tarim Basin in the main hydrocarbon accumulation periods. The result shows that 95% of the discovered Ordovician hydrocarbon reservoirs are located in the predicted areas, which indicates the feasibility and reliability of the key factor matching T-BCMS model for hydrocarbon accumulation and enrichment.
文摘Three series of sandbox modeling experiments were performed to study the fault-increment pattern in extensional basins. Experimental results showed that the tectonic action mode of boundaries and the shape of major boundary faults control the formation and evolution of faults in extensional basins. In the process of extensional deformation, the increase in the number and length of faults was episodic, and every ＇episode＇ experienced three periods, strain-accumulation period, quick fault-increment period and strain-adjustment period. The more complex the shape of the boundary fault, the higher the strain increment each ＇episode＇ experienced. Different extensional modes resulted in different fault-increment patterns. The horizontal detachment extensional mode has the ＇linear＇ style of fault-increment pattern, while the extensional mode controlled by a listric fault has the ＇stepwise＇ style of fault-increment pattern, and the extensional mode controlled by a ramp-flat boundary fault has the ＇stepwise-linear＇ style of fault-increment pattern. These fault-increment patterns given above could provide a theoretical method of fault interpretation and fracture prediction in extensional basins.
文摘The Carboniferous prototype sedimentary basin in the Tazhong (Central Tarimbasin) area is recognized as a compressive intracratonic depressional one. Three type Ⅰ sequenceboundaries and three type Ⅱ sequence boundaries can be identified in the CarboniferousSystem, which can accordingly be divided into five sedimentary sequences. These sequencespossess stratigraphic characters of the standard sequence and correspond to the depositionalstratigraphic unit of a third-order eustatic cycle. They can be regionally or globally correlatedwith each other. The framework of sequence stratigraphy of the intracratonict basin in thestudy area distinctly differs from that of the passive continental-margin basin in the lack ofdepositional systems of early-middle lowstand, poor development of the deeply incised valleyand condensed section of the maximum sea-flood, good development of type Ⅱ sequenceboundaries and coastal plain depositional systems coexisting with shelf-type fan deltas underwet climatic conditions, Which consequently led to the formation of a paralic lithofacies frame-work.
基金supported by the Open Fund Project of State Key Laboratory of Lithospheric Evolution [SKL-K202103]support of the Exploration and Development Research Institute of Petro China Southwest Oil & Gas Field
文摘Hydrocarbon expulsion features and resource potential evaluation of source rocks are crucial for the petroleum exploration.High-maturity marine source rocks have not exhibited a hydrocarbon expulsion mode owing to the lack of low-maturity source rocks in deep petroliferous basins.We considered the Ediacaran microbial dolomite in the Sichuan Basin,the largest high-maturity marine gas layer in China,to exhibit a method that quantitatively characterizes the hydrocarbon expulsion of high-maturity marine source rocks.The experiment of fluid inclusion,rock pyrolysis,and vitrinite reflectance(Ro)of 119 microbial dolomite core samples obtained from the Dengying Formation were performed.A hydrocarbon expulsion model of high-maturity source rock was established,and its resource potential was evaluated.The results showed that the Ediacaran microbial dolomite in the Sichuan Basin is a good source rock showing vast resource potential.The hydrocarbon expulsion threshold is determined to be vitrinite reflectance at 0.92%.The hydrocarbon expulsion intensities in the geologic history is high with maximum of 1.6×10^(7)t/km^(2).The Ediacaran microbial dolomite expelled approximately 1.008×10^(12)t of hydrocarbons,and the recoverable resource was 1.5×10^(12)m^(3).The region can be categorized into areasⅠ,Ⅱ,Ⅲ,andⅣ,in decreasing order of hydrocarbon expulsion intensity.Areas with a higher hydrocarbon expulsion intensity have a lower drilling risk and should be prioritized for exploration in the orderⅠ>Ⅱ>Ⅲ>Ⅳ.Two areas,northern and central parts of Ediacaran in the Sichuan Basin,were selected as prospects which had the drilling priority in the future gas exploration.The production data of 55 drilled wells verified the high reliability of this method.This model in this study does not require low-maturity samples and can be used for evaluating high-maturity marine source rocks,which has broad applicability in deep basins worldwide.
基金jointly supported by the National Nature Science Foundation of China(No.41402095)the Chinese Postdoctoral Science Foundation(No.2014M550380)+1 种基金National Nature Science Foundation of China(No.U1262203)the Special Foundation of Postdoctoral Innovation Project of Shandong Province
文摘A large quantity of drilling core, paleontology, geochemistry and geophysics data revealed several features of the Jiyang subbasin during the deposition of the Ekl-ES4x members： （1） the paleotopography of the gentle slope belt had an extremely low gradient; （2） the paleoclimate frequently alternated between dry and wet periods in a generally arid setting; （3） there was strong weathering around the periphery of the basin; （4） the lake was very shallow; （5） the lake level frequently rose and fell; and （6） the sedimentary environment of the gentle slope belt was an over- flooding lake. All of these factors provided favorable geological conditions for the development of an over-flooding lake delta. The lithologies of the continental over-flooding lake delta deposits are complex and diverse. The compositional maturity is moderate to low, and the grain size distribution curves and sedimentary structures indicate the presence of both gravity and traction currents. The sedimentary microfacies associations consist of a combination of ordered superposition of flood channels, distributary channels and sheet sands. The delta exhibits a weak foreset seismic reflection. The over-flooding lake delta deposits are laterally extensive. The sandstone content is high, and the individual sandstone beds are thin. The flood channel and distributary channel deposits exhibit evidence of bifurcation and lateral migration. The distribution of the sandbodies and the oxidation color of the mudstones provide evidence of cyclic deposition. The paleoclimate was the dominant factor controlling the development of the over-flooding lake delta. Due to the frequently alternating wet and dry paleoclimates, the over-flooding lake delta is characterized by the development of a broad upper plain and a lower delta plain. The upper delta plain is characterized by flood channel deposits, whereas the lower delta plain is represented by distributary channel deposits. The transition zone is characterized by the interaction of flood channels and distributary channels. Due to fault activity, the sandbodies of the over-flooding lake delta were juxtaposed against hydrocarbon source rocks, which was favorable for the development of lithologic reservoirs or structural-lithologic reservoirs. The lower delta plain deposits comprise the most favorable reservoirs.
基金granted by the Xinjiang Geological Exploration Fund。
文摘The northwestern margin of Junggar Basin is the region with the richest oil sand resources in China.For better understanding the enrichment rules and deployment of exploration and development of regional oil sand,it is of great scientific significance to study the accumulation conditions of oil sand in different strata and mining areas of the Junggar Basin.Through a large number of field investigations,drilling verification and sampling tests,it is found that the oil sand in the region covers an area of 2000 km^(2),with shallow and thick reservoir,and predicted resource of 180 million tons.The oil sand resources are mainly distributed in four geological strata,namely the Middle Triassic Karamay Formation,Early Jurassic Badaowan Formation,Late Jurassic Qigu Formation,and Early Cretaceous Qingshuihe Formation.The reservoir is mainly composed of sandstone with high porosity and permeability,and the reservoir space is mainly intergranular pores with a medium average oil content.The oil sand deposit in the region is a typical destructive oil reservoir.The crude oil in the oil sand layer is degraded and thickened from the deep to the shallow,the content of saturated hydrocarbon decreased,and the content of aromatic hydrocarbon,non-hydrocarbon and asphaltene increased.The oil source comes from the deep Permian hydrocarbon-generating depression.Unconformities,faults and marginal fan delta-braided river depositional systems constitute effective migration and storage systems.Caprocks of the Upper Triassic Baijiantan Formation,Lower Jurassic Sangonghe Formation and Lower Cretaceous Hutubihe Formation were formed by three large scale lake transgressions.The Indosinian,Yanshan and Late Yanshan movements are the main driving forces for the migration of deep oil and gas to the shallow edge to form oil sand deposits.It is considered that the oil sand in the northwestern margin of Junggar Basin is of a slope complex migration type.
文摘This study systematically reviews the development history and key technological breakthroughs of large gas fields in the Ordos Basin,and summarizes the development models of three gas reservoir types,low-permeability carbonate,low-permeability sandstone and tight sandstone,as well as the progress in deep coal-rock gas development.The current challenges and future development directions are also discussed.Mature development models have been formed for the three representative types of gas reservoirs in the Ordos Basin:(1)Low-permeability carbonate reservoir development model featuring groove fine-scale characterization and three-dimensional vertical succession between Upper and Lower Paleozoic formations.(2)Low-permeability sandstone reservoir development model emphasizing horizontal well pressure-depletion production and vertical well pressure-controlled production.(3)Tight sandstone gas reservoir development model focusing on single-well productivity enhancement and well placement optimization.In deep coal-rock gas development,significant progress has been achieved in reservoir evaluation,sweet spot prediction,and geosteering of horizontal wells.The three types of reservoirs have entered the mid-to-late stages of the development,when the main challenge lies in accurately characterizing residual gas,evaluating secondary gas-bearing layers,and developing precise potential-tapping strategies.In contrast,for the early-stage development of deep coal-rock gas,continuous technological upgrades and cost reduction are essential to achieving economically viable large-scale development.Four key directions of future research and technological breakthroughs are proposed:(1)Utilizing dual-porosity(fracture-matrix)modeling techniques in low-permeability carbonate reservoirs to delineate the volume and distribution of remaining gas in secondary pay zones,supporting well pattern optimization and production enhancement of existing wells.(2)Integrating well-log and seismic data to characterize reservoir spatial distribution of successive strata,enhancing drilling success rates in low-permeability sandstone reservoirs.(3)Utilizing the advantages of horizontal wells to penetrate effective reservoirs laterally,achieving meter-scale quantification of small-scale single sand bodies in tight gas reservoirs,and applying high-resolution 3D geological models to clarify the distribution of remaining gas and guide well placement optimization.(4)Further strengthening the evaluation of deep coal-rock gas in terms of resource potential,well type and pattern,reservoir stimulation,single-well performance,and economic viability.
基金Supported by the Research Project of CNOOC(KJZH-2021-0003-00).
文摘Based on petroleum exploration and new progress of oil and gas geology study in the Qiongdongnan Basin,combined with seismic,logging,drilling,core,sidewall coring,geochemistry data,a systematic study is conducted on the source,reservoir-cap conditions,trap types,migration and accumulation characteristics,enrichment mechanisms,and reservoir formation models of ultra-deep water and ultra-shallow natural gas,taking the Lingshui 36-1 gas field as an example.(1)The genetic types of the ultra-deep water and ultra-shallow natural gas in the Qiongdongnan Basin include thermogenic gas and biogenic gas,and dominated by thermogenic gas.(2)The reservoirs are mainly composed of the Quaternary deep-water submarine fan sandstone.(3)The types of cap rocks include deep-sea mudstone,mass transport deposits mudstone,and hydrate-bearing formations.(4)The types of traps are mainly lithological,and also include structural-lithological traps.(5)The migration channels include vertical transport channels such as faults,gas chimneys,fracture zones,and lateral transport layers such as large sand bodies and unconformity surfaces,forming a single or composite transport framework.A new natural gas accumulation model is proposed for ultra-deep water and ultra-shallow layers,that is,dual source hydrocarbon supply,gas chimney and submarine fan composite migration,deep-sea mudstone-mass transport deposits mudstone-hydrate-bearing strata ternary sealing,late dynamic accumulation,and large-scale enrichment at ridges.The new understanding obtained from the research has reference and enlightening significance for the next step of deepwater and ultra-shallow layers,as well as oil and gas exploration in related fields or regions.
基金Supported by the Research Project of China National Offshore Oil Corporation(SCKY-2023-HN-3)。
文摘Based on the comprehensive analysis of data from petrology and mineralogy,well logging,seismic surveys,paleontology,and geochemistry,a detailed research was conducted on paleoenvironmental and paleoclimatic conditions,and modeling of the source rocks in the second member of the Eocene Wenchang Formation(Wen 2 Member)in the Northern Shunde Subsag at the southwestern margin of the Pearl River Mouth Basin.The Wen 2 Member hosts excellent,thick lacustrine source rocks with strong longitudinal heterogeneity and an average total organic carbon(TOC)content of over 4.9%.The Wen 2 Member can be divided into three units(I,II,III)from bottom to top.Unit I features excellent source rocks with Type I organic matters(average TOC of 5.9%)primarily sourced from lake organisms;Unit II hosts source rocks dominated by Type II2 organic matters(average TOC of 2.2%),which are originated from mixed sources dominated by terrestrial input.Unit III contains good to excellent source rocks dominated by Type II1 organic matters(average TOC of 4.9%),which are mainly contributed by lake organisms and partially by terrestrial input.Under the background of rapid subsidence and limited source supply during intense rifting period in the Eocene,excellent source rocks were developed in Wen 2 Member in the Northern Shunde Subsag under the coordinated control of warm and humid climate,volcanic activity,and deep-water reducing conditions.During the deposition of Unit I,the warm and humid climate and volcanic activity promoted the proliferation of lake algaes,primarily Granodiscus,resulting in high initial productivity,and deep-water reducing conditions enabled satisfactory preservation of organic matters.These factors jointly controlled the development and occurrence of excellent source rocks.During the deposition of Unit II,a transition from warm to cool and semi-arid paleoclimatic conditions led to a decrease in lake algaes and initial productivity.Additionally,enhanced terrestrial input and shallow-water,weakly oxidizing water conditions caused a significant dilution and decomposition of organic matters,degrading the quality of source rocks.During the deposition of Unit III,when the paleoclimatic conditions are cool and humid,Pediastrum and Botryococcus began to thrive,leading to an increase in productivity.Meanwhile,the reducing environment of semi-deep water facilitated the preservation of excellent source rocks,albeit slightly inferior to those in Unit I.The study results clarify the differential origins and development models of various source rocks in the Shunde Sag,offering valuable guidance for evaluating source rocks and selecting petroleum exploration targets in similar marginal sags.
基金Supported by the National Natural Science Foundation of China(42302141).
文摘Taking the second member of the Xujiahe Formation of the Upper Triassic in the Xinchang structural belt as an example,based on data such as logging,production,seismic interpretation and test,a systematic analysis was conducted on the structural characteristics and evolution,reservoir diagenesis and densification processes,and types and stages of faults/fractures,and revealing the multi-stage and multi-factor dynamic coupled enrichment mechanisms of tight gas reservoirs.(1)In the early Yanshan period,the paleo-structural traps were formed with low-medium maturity hydrocarbons accumulating in structural highs driven by buoyancy since reservoirs were not fully densified in this stage,demonstrating paleo-structure control on traps and early hydrocarbon accumulation.(2)In the middle-late Yanshan period,the source rocks became mature to generate and expel a large quantity of hydrocarbons.Grain size and type of sandstone controlled the time of reservoir densification,which restricted the scale of hydrocarbon charging,allowing for only a small-scale migration through sand bodies near the fault/fracture or less-densified matrix reservoirs.(3)During the Himalayan period,the source rocks reached overmaturity,and the residual oil cracking gas was efficiently transported along the late-stage faults/fractures.Wells with high production capacity were mainly located in Type I and II fault/fracture zones comprising the late-stage north-south trending fourth-order faults and the late-stage fractures.The productivity of the wells was controlled by the transformation of the late-stage faults/fractures.(4)The Xinchang structural belt underwent three stages of tectonic evolution,two stages of reservoir formation,and three stages of fault/fractures development.Hydrocarbons mainly accumulated in the paleo-structure highs.After reservoir densification and late fault/fracture adjustment,a complex gas-water distribution pattern was formed.Thus,it is summarized as the model of“near-source and low-abundance hydrocarbon charging in the early stage,and differential enrichment of natural gas under the joint control of fault-fold-fracture complex,high-quality reservoirs and structural highs in the late stage”.Faults/fractures with well-coupled fault-fold-fracture-pore are favorable exploration targets with high exploration effectiveness.
文摘The conversion of forest land to other types of land cover is one of the major issues in the global fight against climate change. Understanding the direct and indirect factors of these conversions from local studies in the tropics is essential to project the future impact of human activities on the preservation of tropical forests in general and the forests of the Republic of Congo in particular. This study, conducted in five localities with different socioeconomic contexts in the Republic of Congo, aims to analyze the variability of drivers of deforestation and forest degradation linked to urbanization in the Congo Basin. Using a series of land cover maps from the years 1986, 2003 and 2019 for the cities of Ouesso, Pokola, Ngombe, Impfondo and Dongou, as well as field data and socio-economic information collected from local and central administrations, a unique model has been developed to understand the explanatory patterns of forest loss. Deforestation around urban centers is mainly due to urban agriculture due to population growth, as well as the spatial expansion of cities, which have a major impact on the stability and integrity of forests. Shifting agriculture is the main direct cause of deforestation and forest degradation, representing 48% of the total sample, followed by the collection of wood fuel (22%), the collection of construction wood (19%), illegal logging (6%) and urban expansion (5%). Forecasts indicate that forest loss around major cities will increase by 487, 20 ha to 5266, 73 ha by 2050 compared to the base year of 2019. This study highlights the need for a new system of land management and poverty alleviation of local populations to ensure the stability of the Congo Basin tropical forests around large and small African cities.
基金funded by Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(2020CX050103).
文摘Research on the distribution and development of black shales in the Lianggaoshan Formation has been deficient,which has hindered exploration for lacustrine shale oil in the Sichuan Basin.Our study characterized the well logging data,core samples,outcrops,and geochemistry of black shales in the Lianggaoshan Formation in the Sichuan Basin.Our analysis focused on the lake basin evolution and the migration characteristics,paleoenvironmental features,formation mechanisms,and developmental model of the black shales.The results indicated that black shales in the Lianggaoshan Formation exhibited significant lateral migration,with an overall thickening trend from east to west.Within the 1st Member of the formation,black shale occurred as a single thick layer in the eastern region that gradually thinned toward the central region.Multiple sets of shale developed within the 2nd and 3rd members,and these had lower thicknesses than the 1st Member and migrated toward central Sichuan.Paleoproductivity and terrigenous input were the main factors controlling the deposition of black shales.A semi-humid climate influenced the deposition of black shales,bringing abundant freshwater,terrigenous debris,and nutrients into the basin.Decomposition of organic matter consumed oxygen in sediment and bottom water,causing localized oxygen deficiency in the strata.
基金Supported by National Natural Science Foundation of China(42572132,U24B6001,41872150,42230310,U2344209).
文摘The occurrence types and controlling factors of organic matter in the sepiolite-containing successions of the first member of Mid-Permian Maokou Formation(Mao-1 Member for short)in the Eastern Sichuan Basin,SW China,have been investigated through outcrop section measurement,core observation,thin section identification,argon ion polishing-field scanning electron microscopy,energy spectrum analysis,X-ray diffraction,total organic carbon content(TOC),major and trace element analysis.Finally,the symbiotic adsorption model of sepiolite for organic matter enrichment has been established.The results show that the sepiolite-containing successions of the Mao-1 Member are composed of the rhythmite of mudstone,argillaceous limestone and limestone,with five depositional intervals vertically and the organic matter mostly developed in the mudstone and argillaceous limestone layers within the lower three intervals.The organic matter occurrence types are mostly layered or nodular in macro to meso-scale,blocky-vein-like under a microscope,but scattered,interstitial or adsorbed at a mesoscopic scale.It underwent transition processes from lower to higher salinity,from oxygen-poor and anoxic reduction to oxygen-poor and localized oxygen enrichment on the palaeo-environment of the Mao-1 Member.The first two intervals of the early depositional phase of Mao-1 Member constitute the cyclothems of mudstone,argillaceous limestone and limestone and quantities of fibrous-feathered sepiolite settle down within the Tongjiang-Changshou sag with continuous patchy organic matter from adsorption of alginate by sepiolite in intercrystalline,bedding surfaces and interlayer pores.The third and fourth intervals in the mid-depositional phase are mostly composed of the mudstone and argillaceous limestone alternations with the continuous patchy or banded organic matter in the surface and inter-crystalline pores of fibrous,feathered and flaky sepiolite.And the fifth interval in the late depositional phase of the Mao-1 Member comprises the cyclothems of extremely thin layered argillaceous limestone and thick-layered limestone with the fibrous sepiolite depositing in the argillaceous limestone and irregular organic matter dispersing around the sepiolite.Therefore,the symbiotic adsorption between organic matter and sepiolite effectively enhances the preservation efficiency of organic matter and improves the source rock quality of the Mao-1 Member,which enhances our understanding on the enrichment model of the depositional organic matter.
基金the National Key R&D Program of China(No.2023YFC3206504)National Natural Science Foundation of China(Nos.52121006,41961124006,51911540477)+1 种基金Young Top-Notch Talent Support Program of National High-level Talents Special Support PlanResearch Project of Ministry of Natural Resources(No.20210103)for providing financial support for this research。
文摘This study employs the Long Short-Term Memory(LSTM)rainfall-runoff model to simulate and predict runoff in typical basins of the Jiziwan Region of the Yellow River,aiming to overcome the shortcomings of traditional hydrological models in complex nonlinear environments.The Jiziwan Region of the Yellow River is affected by human activities such as urbanization,agricultural development,and water resource management,leading to increasingly complex hydrological processes.Traditional hydrological models struggle to effectively capture the relationship between rainfall and runoff.The LSTM rainfall-runoff model,using deep learning techniques,automatically extracts features from data,identifies complex patterns and long-term dependency in time series,and provides more accurate and reliable runoff predictions.The results demonstrate that the LSTM rainfall-runoff model adapts well to the complex hydrological characteristics of the Jiziwan Region,showing superior performance over traditional hydrological models,especially in addressing the changing trends under the influence of climate change and human activities.By analyzing the interannual and within-year variations of runoff under different climate change scenarios,the model can predict the evolution trends of runoff under future climate conditions,providing a scientific basis for water resource management and decision-making.The results indicate that under different climate change scenarios,the runoff in several typical basins of the Jiziwan Region exhibits different variation trends.Under SSP1-2.6 and SSP2-4.5,some basins,such as the Wuding River Basin,Tuwei River Basin,and Gushanchuan Basin,show a decreasing trend in annual runoff.For example,in the Wuding River Basin,the average runoff from 2025 to 2040 is 12.48 m^(3)/s(SSP1-2.6),with an annual decrease of 0.10 m^(3)/s;in the Tuwei River Basin,the runoff from 2025 to 2040 is 12.96 m^(3)/s(SSP1-2.6),with an annual decrease of 0.10 m^(3)/s.In contrast,under SSP3-7.0 and SSP5-8.5,with climate warming and changes in precipitation patterns,runoff in some basins shows an increasing trend,particularly during the snowmelt period and with increased summer precipitation,leading to a significant rise in runoff.
文摘The area of the intermontane basins in the Xuefeng Mountain region is 4,000 km2. These basins are the most favourable area for agriculture in the mountainous region. Unfortunately, in each basin the eco-environment has gradually worsened because of the irrational utilization of natural resources. A rational model of agro-ecologic- economic system of intermontane basin must be formed so as to exploit and utilize rationally the natural resources. The intermontane basins may be divided into 3 ecologic belts of agriculture. Here are some ecologic-economic problems in the development: The resources of the outer mountains lie waste, but the valley basins in centre are over-development; the low mountains and hillocks are cultivated for dry crops so that the water and soil losses are serious and the natural disasters are frequent. Therefore, the agro-economic, agro-biologic and eco-environmental subsystems form a complete agro-ecologic-economic system of intermontane basins. Developing rationally the
文摘The BGHMS system described in this paper was designed to model the geohistory for cratonic basins and written in turbo BASIC language with a user-friendly interface for data inputs and outputs on IBM PC-compatible computers. The major mathematical models in this system include the models of compaction correction. unconformity restoration. sea-level change and paleo-water-depth correction. and tectonic subsidence modeling. Two geological events of sediment compaction and erosion are considered in this system. It consists of three modules for data input, geohistory modeling and graph conversion and output. containing more than twenty subroutine programs, is an easy-to-use. menu-driven program system with many obvious advantages, and is a useful tool for hydrocarbon geologists to make quantitative studies on geohistory and to make exploration decisions in regional evaluation.
