This study developed a modeling methodology for statistical optimization-based geologic hazard susceptibility assessment,aiming to enhance the comprehensive performance and classification accuracy of the assessment mo...This study developed a modeling methodology for statistical optimization-based geologic hazard susceptibility assessment,aiming to enhance the comprehensive performance and classification accuracy of the assessment models.First,the cumulative probability method revealed that a low probability(15%)of geologic hazards between any two geologic hazard points occurred outside a buffer zone with a radius of 2297 m(i.e.,the distance threshold).The training dataset was established,consisting of negative samples(non-hazard points)randomly generated based on the distance threshold,positive samples(i.e.,historical hazards),and 13 conditioning factors.Then,models were built using five machine learning algorithms,namely random forest(RF),gradient boosting decision tree(GBDT),naive Bayes(NB),logistic regression(LR),and support vector machine(SVM).The comprehensive performance of the models was assessed using the area under the receiver operating characteristic curve(AUC)and overall accuracy(OA)as indicators,revealing that RF exhibited the best performance,with OA and AUC values of 2.7127 and 0.981,respectively.Furthermore,the machine learning models constructed by considering the distance threshold outperformed those built using the unoptimized dataset.The characteristic factors were ranked using the mutual information method,with their scores decreasing in the order of rainfall(0.1616),altitude(0.06),normalized difference vegetation index(NDVI;0.04),and distance from roads(0.03).Finally,the geologic hazard susceptibility classification was assessed using the natural breaks method combined with a clustering algorithm.The results indicate that the clustering algorithm exhibited higher classification accuracy than the natural breaks method.The findings of this study demonstrate that the proposed model optimization scheme can provide a scientific basis for the prevention and control of geologic hazards.展开更多
In recent years, in order to meet the basic needs of social and economic development for mineral resources, China has gradually increased the utilization of mineral resources. However, the mineral resources in China a...In recent years, in order to meet the basic needs of social and economic development for mineral resources, China has gradually increased the utilization of mineral resources. However, the mineral resources in China are very scattered, and most of the non-rare mineral resources are in the hands of enterprises. Therefore, the exploitation of mineral resources has not been effectively controlled, and there is an unreasonable phenomenon of mining. Unreasonable mining of coal mines does great harm to the whole mine, which not only damages the geological environment of the mining area, but also increases the occurrence rate of mine accidents. Combined with the actual situation of mining development in China, this paper makes a simple analysis of common geological disasters in coal mines and the basic principles of mine geological protection, and discusses how to prevent and protect the geological environment of mines.展开更多
This study investigated the impacts of random negative training datasets(NTDs)on the uncertainty of machine learning models for geologic hazard susceptibility assessment of the Loess Plateau,northern Shaanxi Province,...This study investigated the impacts of random negative training datasets(NTDs)on the uncertainty of machine learning models for geologic hazard susceptibility assessment of the Loess Plateau,northern Shaanxi Province,China.Based on randomly generated 40 NTDs,the study developed models for the geologic hazard susceptibility assessment using the random forest algorithm and evaluated their performances using the area under the receiver operating characteristic curve(AUC).Specifically,the means and standard deviations of the AUC values from all models were then utilized to assess the overall spatial correlation between the conditioning factors and the susceptibility assessment,as well as the uncertainty introduced by the NTDs.A risk and return methodology was thus employed to quantify and mitigate the uncertainty,with log odds ratios used to characterize the susceptibility assessment levels.The risk and return values were calculated based on the standard deviations and means of the log odds ratios of various locations.After the mean log odds ratios were converted into probability values,the final susceptibility map was plotted,which accounts for the uncertainty induced by random NTDs.The results indicate that the AUC values of the models ranged from 0.810 to 0.963,with an average of 0.852 and a standard deviation of 0.035,indicating encouraging prediction effects and certain uncertainty.The risk and return analysis reveals that low-risk and high-return areas suggest lower standard deviations and higher means across multiple model-derived assessments.Overall,this study introduces a new framework for quantifying the uncertainty of multiple training and evaluation models,aimed at improving their robustness and reliability.Additionally,by identifying low-risk and high-return areas,resource allocation for geologic hazard prevention and control can be optimized,thus ensuring that limited resources are directed toward the most effective prevention and control measures.展开更多
Climate change and anthropogenic activities have profoundly affected coastal systems,making geomorphological research a critical focus for coastal protection and sustainable development.In this study,a comprehensive c...Climate change and anthropogenic activities have profoundly affected coastal systems,making geomorphological research a critical focus for coastal protection and sustainable development.In this study,a comprehensive classification of beach states around Hainan Island is conducted for the first time by utilizing theΩ-RTR model and geological control modes.Six distinct classic beach states ranging from dissipative to reflective are identified:barred dissipative beaches or no-barred dissipative beaches(BD or NBD),barred beaches(B),low-tide terrace or low-tide bar with rip(LTTR or LTBR),and reflective state(R).Among these,the BD and B types are predominant on Hainan Island.Notably,the beach states are subject to multiple factors,such as hydrodynamic forcings,geomorphic features and underlying substrates,and exhibit remarkable spatiotemporal variability.During extreme events,hydrodynamic forcings impact beach states more substantially than geological and geomorphic features do,leading to a more homogeneous distribution of beach states.Under normal circumstance,beach states are predominantly controlled by geological and geomorphic features.Coastal geological and geomorphic features have a pronounced influence on beach morphology and stability.For example,hard substrates underpin wide and stable dissipative beaches,whereas softer substrates lead to narrower,erosion-prone beaches.Three geological control modes are identified,namely,gently sloping hard substrates with dissipative beaches,moderately sloping hard substrates with seasonally variable reflective beaches,and steeply sloping soft substrates with dynamic sandbar-dominated beaches.These findings highlight the necessity of integrating geological settings in tandem with hydrodynamic forcings into coastal management practices.A dual-mode strategy is proposed:maintaining geomorphic self-organization on hard-substrate coasts under normal conditions and implementing hybrid engineering–ecological measures(e.g.,artificial sand replenishment and vegetation restoration)on erosion-prone soft substrates.展开更多
The geological characteristics of coalbed methane from the research carried out in Liupanshui is based on analysis of faults, folds, roof and floor lithology, and depth of coal seam gas content, combined with the asse...The geological characteristics of coalbed methane from the research carried out in Liupanshui is based on analysis of faults, folds, roof and floor lithology, and depth of coal seam gas content, combined with the assessment of CBM resources calculated through buried depth scope, average coal seam thickness, and gas content, organized by the Ministry of Land and Resources in 2006, which launched the ＂national new round of coalbed methane re-sources evaluation＂ project to evaluate the coalbcd methane resources in the standard category and divided coal-bed methane resources into Ⅰ, Ⅱand Ⅲ Category of three resources categories. With this method on the other syncline to resources assessment, the area below 1 000 m is named as ] Category resources. And with the depth increasing, resources level decreases.展开更多
1 Introduction The Weibei Uplift is located in the southwest of the North China Plate,where is the stable block(the Ordos Block)in the north and the active belt(the QinlingOrogenic Belt)in the south(Ren et al,2014,201...1 Introduction The Weibei Uplift is located in the southwest of the North China Plate,where is the stable block(the Ordos Block)in the north and the active belt(the QinlingOrogenic Belt)in the south(Ren et al,2014,2015).And the belt is separated from the Weihe basin.The Weibei uplift has a uniform crystalline basement with the North展开更多
Impulsion discharge technique is a new technology to prevent geological disasters, such an approach is in a liquid medium into the borehole electrode to gain access ,o high-voltage, forme discharge, and mechanical wav...Impulsion discharge technique is a new technology to prevent geological disasters, such an approach is in a liquid medium into the borehole electrode to gain access ,o high-voltage, forme discharge, and mechanical wave energy into electrical energy, produce a shockwave and in the same time compact the surrounding soil. Building on the existing foundation of the Act has been applied to engineering and water conservancy projects, the results were very good.展开更多
The new Austrian tunneling method （NATM） is widely applied in design and construction of underground engineering projects. When the type and distribution of unfavorable geological bodies （UGBs） associated with the...The new Austrian tunneling method （NATM） is widely applied in design and construction of underground engineering projects. When the type and distribution of unfavorable geological bodies （UGBs） associated with their influences on geoengineering are complicated or unfortunately are overlooked, we should pay more attentions to internal features of rocks grades IV and V （even in local but mostly controlling zones）. With increasing attentions to the characteristics, mechanism and influences of engineering construction-triggered geohazards, it is crucial to fully understand the disturbance of these geohazards on project construction. A reasonable determination method in construction procedure, i.e. the shape of working face, the type of engineering support and the choice of feasible procedure, should be considered in order to mitigate the construction-triggered geohazards. Due to their high sensitivity to groundwater and in-situ stress, various UGBs exhibit hysteretic nature and failure modes. To give a complete understanding on the internal causes, the emphasis on advanced comprehensive geological forecasting and overall reinforcement treatment is therefore of more practical significance. Compre- hensive evaluation of influential factors, identification of UGB, and measures of discontinuity dynamic controlling comprises the geoengineering condition evaluation and dynamic controlling method. In a case of a cut slope, the variations of UGBs and the impacts of key environmental factors are presented, where more severe construction-triggered geohazards emerged in construction stage than those predicted in design and field investigation stages. As a result, the weight ratios of different influential factors with respect to field investigation, design and construction are obtained.展开更多
This article aims to enhance seismic hazard assessment methods for Kazakhstan’s seismotectonic conditions.It combines probabilistic seismic hazard analysis(PSHA),ground motion simulation,sitespecific geological and g...This article aims to enhance seismic hazard assessment methods for Kazakhstan’s seismotectonic conditions.It combines probabilistic seismic hazard analysis(PSHA),ground motion simulation,sitespecific geological and geotechnical data analysis,and seismic scenario analysis to develop Probabilistic General Seismic Zoning(GSZ)maps for Kazakhstan and Probabilistic Seismic Microzoning maps for Almaty.These maps align with Eurocode 8 principles,incorporating seismic intensity and engineering parameters like peak ground acceleration(PGA).The new procedure,applied in national projects,has resulted in GSZ maps for the country,seismic microzoning maps for Almaty,and detailed seismic zoning maps for East Kazakhstan.These maps,part of a regulatory document,guide earthquake-resistant design and construction.They offer a comprehensive assessment of seismic hazards,integrating traditional Medvedev-Sponheuer-Karnik(MSK-64)intensity scale points with quantitative parameters like peak ground acceleration.This innovative approach promises to advance methods for quantifying seismic hazards in specific regions.展开更多
Sandy debris flow deposits are present in Unit I during Miocene of Gas Field A in the Baiyun Depression of the South China Sea. The paucity of well data and the great variability of the sedimentary microfacies make it...Sandy debris flow deposits are present in Unit I during Miocene of Gas Field A in the Baiyun Depression of the South China Sea. The paucity of well data and the great variability of the sedimentary microfacies make it difficult to identify and predict the distribution patterns of the main gas reservoir, and have seriously hindered further exploration and development of the gas field. Therefore, making full use of the available seismic data is extremely important for predicting the spatial distribution of sedimentary microfacies when constructing three-dimensional reservoir models. A suitable reservoir modeling strategy or workflow controlled by sedimentary microfacies and seismic data has been developed. Five types of seismic attributes were selected to correlate with the sand percentage, and the root mean square （RMS） amplitude performed the best. The relation between the RMS amplitude and the sand percentage was used to construct a reservoir sand distribution map. Three types of main sedimentary microfacies were identified： debris channels, fan lobes, and natural levees. Using constraints from the sedimentary microfacies boundaries, a sedimentary microfacies model was constructed using the sequential indicator and assigned value simulation methods. Finally, reservoir models of physical properties for sandy debris flow deposits controlled by sedimentary microfacies and seismic inversion data were established. Property cutoff values were adopted because the sedimentary microfacies and the reservoir properties from well-logging interpretation are intrinsically different. Selection of appropriate reservoir property cutoffs is a key step in reservoir modeling when using simulation methods based on sedimentary microfacies control. When the abnormal data are truncated and the reservoir properties probability distribution fits a normal distribution, microfacies-controlled reservoir property models are more reliable than those obtained from the sequence Gauss simulation method. The cutoffs for effective porosity of the debris channel, fan lobe, and natural levee facies were 0.2, 0.09, and 0.12, respectively; the corresponding average effective porosities were 0.24, 0.13, and 0.15. The proposed modeling method makes full use of seismic attributes and seismic inversion data, and also makes the property data of single-well depositional microfacies more conformable to a normal distribution with geological significance. Thus, the method allows use of more reliable input data when we construct a model of a sandy debris flow.展开更多
To understand the natural gas characteristics of multi-thin coal seam,this study selected the desorbed gas of coal seams in different layers of Well A in the Wujiu depression,Hailar Basin in northeast Inner Mongolia.T...To understand the natural gas characteristics of multi-thin coal seam,this study selected the desorbed gas of coal seams in different layers of Well A in the Wujiu depression,Hailar Basin in northeast Inner Mongolia.The results show that the heavy hydrocarbon content of desorbed gas increases significantly with the increasing depth.Methane carbon(δ13C_(1))and ethane carbon(δ13C_(2))isotope values are vertically become heavier downwards,while the δ13 values did not change significantly.The kerogen is close to the III–II mixed type with the source rocks mainly deposited in a shore/shallow lake or braided-river delta front,and the gas produced has certain characteristics of oil associated gas.However,the characteristics of oil associated gas produced by the organic formed in the shallow-water environment(braided-river delta plain)are not obvious.The sandstone pore and fracture systems interbedded with multi-thin coal seam are well developed.And it is conducive to the migration of methanogenic micro-organisms to coal seams via groundwater,making it easier to produce biogenic gas under this geological condition.During the burial evolution of coal-bearing strata in the study area,when the burial depth reaches the maximum,there are significant differences in the paleotemperature experienced by different vertical coal seams,caused by a high-paleogeothermal gradient,increasing the δ13C_(2) of desorbed gas with increasing depth.The above research indicates that there is less biogenic gas in the multi-thin coal seams with relatively developed mudstone,and the multi-thin coal seams with relatively developed sandstones have obvious biogenic gas characteristics.Therefore,for the exploration and development of biogenic gas in low-rank multi-thin coal seams,it is necessary to give priority to the layer with high sandstone content.展开更多
An improved evaluation method for estimating gas content during the inversion process of deep-burial coal was established based on the on-site natural desorption curves.The accuracy of the US Bureau of Mines(USBM),Pol...An improved evaluation method for estimating gas content during the inversion process of deep-burial coal was established based on the on-site natural desorption curves.The accuracy of the US Bureau of Mines(USBM),Polynomial fitting,Amoco,and the improved evaluation methods in the predicting of lost gas volume in deep seams in the Mabidong Block of the Qinshui Basin were then compared.Furthermore,the calculation errors of these different methods in simulating lost gas content based on coring time were compared.A newly established nonlinear equation was developed to estimate the minimum error value,by controlling the lost time within 16 min,the related errors can be reduced.The improved evaluation was shown to accurately and rapidly predict the gas content in deep seams.The results show that the deep coal bed methane accumulation is influenced by various factors,including geological structure,hydrodynamic conditions,roof lithology,and coalification.Reverse faults and weak groundwater runoff can hinder the escape of methane,and these factors should be considered in the future exploration and development of coalbed methane.展开更多
Tectonically deformed coal(TDC)develops because of the superimposed deformation and metamorphism of a coal seam by tectonic movements.The migration and accumulation of trace elements in TDC is largely in response to s...Tectonically deformed coal(TDC)develops because of the superimposed deformation and metamorphism of a coal seam by tectonic movements.The migration and accumulation of trace elements in TDC is largely in response to stress-strain conditions.To develop a law governing the migration and aggregation of sensitive elements and investigate the geological controls on TDC,coal samples from different deformation sequences were collected from the Haizi mine,in the Huaibei coalfield in Anhui Province,China,and the concentrations of 49 elements were determined by XRF and ICP-MS,and then microscopically analyzed.The results show that the distribution and morphology of minerals in coal is related to the deformation degree of TDC.The evolutionary process runs from orderly distribution of minerals in a weak brittle deformed coal to disordered distributions in ductile deformed coal.According to the elemental distribution characteristics in TDC,four types of element migration can be identified:stable,aggregate,declining,and undulate types,which are closely related to the deformation degree of TDC.Present data indicate that the overall distribution of rare earth elements(REE)does not change with metamorphism and deformation,but it shows obvious dynamic differentiation phenomena along with the deformation of TDC.Tectonic action after coal-formation,brittle or ductile deformation,and the metamorphic mechanism and its accompanying dynamic thermal effects are the main factors that influence the redistribution of elements in TDC.We conclude that tectonic movements provide the motivation and basis for the redistribution of elements and the paths and modes of element migration are controlled by brittle and ductile deformation metamorphic processes.The dynamic thermal effect has the most significant effect on coal metamorphism and tectonic-stress-accelerated element migration and accumulation.These factors then induce the tectonic-dynamic differentiation phenomenon of element migration.展开更多
The efficiency of gas hydrate production depends on the success of gas exploration and occurrence evaluation.The existing evaluation models are generally univariate and only applicable to certain geological settings.T...The efficiency of gas hydrate production depends on the success of gas exploration and occurrence evaluation.The existing evaluation models are generally univariate and only applicable to certain geological settings.This study presents a holistic approach to evaluate the likelihood of gas hydrate occurrence by supplying an index for mapping gas hydrate levels with depth.The approach integrates a generalised TOPSIS method with the fuzzy set theory.An expedition of gas hydrate conducted in the Shenhu area of the South China Sea was adopted as a case study to assess the reliability of the proposed index.As a multivariate model,the proposed approach enables the capture of non-linearity associated with gas hydrates in its entirety.The magnitude of the strength of the influential factor varies substantially from one site to another across the Shenhu area.The results also show that no site achieves the highest likelihood‘Level V’.These results are consistent with the gas saturation values obtained using Archie’s relationship.For example,at SH4 and SH7,the values of the likelihood index are the highest between 170–185 m and 150–165 m,respectively,and the observed saturation at these locations varies from 20%(SH4)to 43%(SH7).The proposed likelihood index yields a prominent ability to quantify the level of occurrence of gas hydrates with depth at different sites.It appears to be an efficient multicriteria system bound to improve the management of the gas production trial stage.展开更多
基金supported by a project entitled Loess Plateau Region-Watershed-Slope Geological Hazard Multi-Scale Collaborative Intelligent Early Warning System of the National Key R&D Program of China(2022YFC3003404)a project of the Shaanxi Youth Science and Technology Star(2021KJXX-87)public welfare geological survey projects of Shaanxi Institute of Geologic Survey(20180301,201918,202103,and 202413)。
文摘This study developed a modeling methodology for statistical optimization-based geologic hazard susceptibility assessment,aiming to enhance the comprehensive performance and classification accuracy of the assessment models.First,the cumulative probability method revealed that a low probability(15%)of geologic hazards between any two geologic hazard points occurred outside a buffer zone with a radius of 2297 m(i.e.,the distance threshold).The training dataset was established,consisting of negative samples(non-hazard points)randomly generated based on the distance threshold,positive samples(i.e.,historical hazards),and 13 conditioning factors.Then,models were built using five machine learning algorithms,namely random forest(RF),gradient boosting decision tree(GBDT),naive Bayes(NB),logistic regression(LR),and support vector machine(SVM).The comprehensive performance of the models was assessed using the area under the receiver operating characteristic curve(AUC)and overall accuracy(OA)as indicators,revealing that RF exhibited the best performance,with OA and AUC values of 2.7127 and 0.981,respectively.Furthermore,the machine learning models constructed by considering the distance threshold outperformed those built using the unoptimized dataset.The characteristic factors were ranked using the mutual information method,with their scores decreasing in the order of rainfall(0.1616),altitude(0.06),normalized difference vegetation index(NDVI;0.04),and distance from roads(0.03).Finally,the geologic hazard susceptibility classification was assessed using the natural breaks method combined with a clustering algorithm.The results indicate that the clustering algorithm exhibited higher classification accuracy than the natural breaks method.The findings of this study demonstrate that the proposed model optimization scheme can provide a scientific basis for the prevention and control of geologic hazards.
文摘In recent years, in order to meet the basic needs of social and economic development for mineral resources, China has gradually increased the utilization of mineral resources. However, the mineral resources in China are very scattered, and most of the non-rare mineral resources are in the hands of enterprises. Therefore, the exploitation of mineral resources has not been effectively controlled, and there is an unreasonable phenomenon of mining. Unreasonable mining of coal mines does great harm to the whole mine, which not only damages the geological environment of the mining area, but also increases the occurrence rate of mine accidents. Combined with the actual situation of mining development in China, this paper makes a simple analysis of common geological disasters in coal mines and the basic principles of mine geological protection, and discusses how to prevent and protect the geological environment of mines.
基金supported by a project entitled Loess Plateau Region-Watershed-Slope Geological Hazard Multi-Scale Collaborative Intelligent Early Warning System of the National Key R&D Program of China(2022YFC3003404)a project of the Shaanxi Youth Science and Technology Star(2021KJXX-87)public welfare geological survey projects of Shaanxi Institute of Geologic Survey(20180301,201918,202103,and 202413).
文摘This study investigated the impacts of random negative training datasets(NTDs)on the uncertainty of machine learning models for geologic hazard susceptibility assessment of the Loess Plateau,northern Shaanxi Province,China.Based on randomly generated 40 NTDs,the study developed models for the geologic hazard susceptibility assessment using the random forest algorithm and evaluated their performances using the area under the receiver operating characteristic curve(AUC).Specifically,the means and standard deviations of the AUC values from all models were then utilized to assess the overall spatial correlation between the conditioning factors and the susceptibility assessment,as well as the uncertainty introduced by the NTDs.A risk and return methodology was thus employed to quantify and mitigate the uncertainty,with log odds ratios used to characterize the susceptibility assessment levels.The risk and return values were calculated based on the standard deviations and means of the log odds ratios of various locations.After the mean log odds ratios were converted into probability values,the final susceptibility map was plotted,which accounts for the uncertainty induced by random NTDs.The results indicate that the AUC values of the models ranged from 0.810 to 0.963,with an average of 0.852 and a standard deviation of 0.035,indicating encouraging prediction effects and certain uncertainty.The risk and return analysis reveals that low-risk and high-return areas suggest lower standard deviations and higher means across multiple model-derived assessments.Overall,this study introduces a new framework for quantifying the uncertainty of multiple training and evaluation models,aimed at improving their robustness and reliability.Additionally,by identifying low-risk and high-return areas,resource allocation for geologic hazard prevention and control can be optimized,thus ensuring that limited resources are directed toward the most effective prevention and control measures.
基金The Science and Technology Basic Investigation Program of China,No.2022FY202404。
文摘Climate change and anthropogenic activities have profoundly affected coastal systems,making geomorphological research a critical focus for coastal protection and sustainable development.In this study,a comprehensive classification of beach states around Hainan Island is conducted for the first time by utilizing theΩ-RTR model and geological control modes.Six distinct classic beach states ranging from dissipative to reflective are identified:barred dissipative beaches or no-barred dissipative beaches(BD or NBD),barred beaches(B),low-tide terrace or low-tide bar with rip(LTTR or LTBR),and reflective state(R).Among these,the BD and B types are predominant on Hainan Island.Notably,the beach states are subject to multiple factors,such as hydrodynamic forcings,geomorphic features and underlying substrates,and exhibit remarkable spatiotemporal variability.During extreme events,hydrodynamic forcings impact beach states more substantially than geological and geomorphic features do,leading to a more homogeneous distribution of beach states.Under normal circumstance,beach states are predominantly controlled by geological and geomorphic features.Coastal geological and geomorphic features have a pronounced influence on beach morphology and stability.For example,hard substrates underpin wide and stable dissipative beaches,whereas softer substrates lead to narrower,erosion-prone beaches.Three geological control modes are identified,namely,gently sloping hard substrates with dissipative beaches,moderately sloping hard substrates with seasonally variable reflective beaches,and steeply sloping soft substrates with dynamic sandbar-dominated beaches.These findings highlight the necessity of integrating geological settings in tandem with hydrodynamic forcings into coastal management practices.A dual-mode strategy is proposed:maintaining geomorphic self-organization on hard-substrate coasts under normal conditions and implementing hybrid engineering–ecological measures(e.g.,artificial sand replenishment and vegetation restoration)on erosion-prone soft substrates.
基金Supported by the National ＂973＂ CBM project （2009CB219605） the National Science and Technology of major special projects （201 IZX05034）： the National Natural Science Foundation of China （40730422）
文摘The geological characteristics of coalbed methane from the research carried out in Liupanshui is based on analysis of faults, folds, roof and floor lithology, and depth of coal seam gas content, combined with the assessment of CBM resources calculated through buried depth scope, average coal seam thickness, and gas content, organized by the Ministry of Land and Resources in 2006, which launched the ＂national new round of coalbed methane re-sources evaluation＂ project to evaluate the coalbcd methane resources in the standard category and divided coal-bed methane resources into Ⅰ, Ⅱand Ⅲ Category of three resources categories. With this method on the other syncline to resources assessment, the area below 1 000 m is named as ] Category resources. And with the depth increasing, resources level decreases.
基金supported by Natural Science Foundation of China (Project No. 41630312)The National Nature Science Foundation of China (Project No. 41372208 and 40534019)The Open Found of the State Key Laboratory of Ore Deposit Geochemistry, CAS(Project No. 201304)
文摘1 Introduction The Weibei Uplift is located in the southwest of the North China Plate,where is the stable block(the Ordos Block)in the north and the active belt(the QinlingOrogenic Belt)in the south(Ren et al,2014,2015).And the belt is separated from the Weihe basin.The Weibei uplift has a uniform crystalline basement with the North
文摘Impulsion discharge technique is a new technology to prevent geological disasters, such an approach is in a liquid medium into the borehole electrode to gain access ,o high-voltage, forme discharge, and mechanical wave energy into electrical energy, produce a shockwave and in the same time compact the surrounding soil. Building on the existing foundation of the Act has been applied to engineering and water conservancy projects, the results were very good.
基金support by the National Natural Science Foundation of China (No. 41372324)support from the Chinese Special Funds for Major State Basic Research Project under Grant No. 2010CB732001
文摘The new Austrian tunneling method （NATM） is widely applied in design and construction of underground engineering projects. When the type and distribution of unfavorable geological bodies （UGBs） associated with their influences on geoengineering are complicated or unfortunately are overlooked, we should pay more attentions to internal features of rocks grades IV and V （even in local but mostly controlling zones）. With increasing attentions to the characteristics, mechanism and influences of engineering construction-triggered geohazards, it is crucial to fully understand the disturbance of these geohazards on project construction. A reasonable determination method in construction procedure, i.e. the shape of working face, the type of engineering support and the choice of feasible procedure, should be considered in order to mitigate the construction-triggered geohazards. Due to their high sensitivity to groundwater and in-situ stress, various UGBs exhibit hysteretic nature and failure modes. To give a complete understanding on the internal causes, the emphasis on advanced comprehensive geological forecasting and overall reinforcement treatment is therefore of more practical significance. Compre- hensive evaluation of influential factors, identification of UGB, and measures of discontinuity dynamic controlling comprises the geoengineering condition evaluation and dynamic controlling method. In a case of a cut slope, the variations of UGBs and the impacts of key environmental factors are presented, where more severe construction-triggered geohazards emerged in construction stage than those predicted in design and field investigation stages. As a result, the weight ratios of different influential factors with respect to field investigation, design and construction are obtained.
基金The work was carried out in the framework of earmarked funding“Assessment of seismic hazard of territories of Kazakhstan on modern scientific and methodological basis”,programme code number F.0980.Source of funding-Ministry of Science and Higher Education of the Republic of Kazakhstan.
文摘This article aims to enhance seismic hazard assessment methods for Kazakhstan’s seismotectonic conditions.It combines probabilistic seismic hazard analysis(PSHA),ground motion simulation,sitespecific geological and geotechnical data analysis,and seismic scenario analysis to develop Probabilistic General Seismic Zoning(GSZ)maps for Kazakhstan and Probabilistic Seismic Microzoning maps for Almaty.These maps align with Eurocode 8 principles,incorporating seismic intensity and engineering parameters like peak ground acceleration(PGA).The new procedure,applied in national projects,has resulted in GSZ maps for the country,seismic microzoning maps for Almaty,and detailed seismic zoning maps for East Kazakhstan.These maps,part of a regulatory document,guide earthquake-resistant design and construction.They offer a comprehensive assessment of seismic hazards,integrating traditional Medvedev-Sponheuer-Karnik(MSK-64)intensity scale points with quantitative parameters like peak ground acceleration.This innovative approach promises to advance methods for quantifying seismic hazards in specific regions.
基金partly supported by the National Natural Science Foundation of China(grants no.41272132 and 41572080)the Fundamental Research Funds for central Universities(grant no.2-9-2013-97)the Major State Science and Technology Research Programs(grants no.2008ZX05056-002-02-01 and 2011ZX05010-001-009)
文摘Sandy debris flow deposits are present in Unit I during Miocene of Gas Field A in the Baiyun Depression of the South China Sea. The paucity of well data and the great variability of the sedimentary microfacies make it difficult to identify and predict the distribution patterns of the main gas reservoir, and have seriously hindered further exploration and development of the gas field. Therefore, making full use of the available seismic data is extremely important for predicting the spatial distribution of sedimentary microfacies when constructing three-dimensional reservoir models. A suitable reservoir modeling strategy or workflow controlled by sedimentary microfacies and seismic data has been developed. Five types of seismic attributes were selected to correlate with the sand percentage, and the root mean square （RMS） amplitude performed the best. The relation between the RMS amplitude and the sand percentage was used to construct a reservoir sand distribution map. Three types of main sedimentary microfacies were identified： debris channels, fan lobes, and natural levees. Using constraints from the sedimentary microfacies boundaries, a sedimentary microfacies model was constructed using the sequential indicator and assigned value simulation methods. Finally, reservoir models of physical properties for sandy debris flow deposits controlled by sedimentary microfacies and seismic inversion data were established. Property cutoff values were adopted because the sedimentary microfacies and the reservoir properties from well-logging interpretation are intrinsically different. Selection of appropriate reservoir property cutoffs is a key step in reservoir modeling when using simulation methods based on sedimentary microfacies control. When the abnormal data are truncated and the reservoir properties probability distribution fits a normal distribution, microfacies-controlled reservoir property models are more reliable than those obtained from the sequence Gauss simulation method. The cutoffs for effective porosity of the debris channel, fan lobe, and natural levee facies were 0.2, 0.09, and 0.12, respectively; the corresponding average effective porosities were 0.24, 0.13, and 0.15. The proposed modeling method makes full use of seismic attributes and seismic inversion data, and also makes the property data of single-well depositional microfacies more conformable to a normal distribution with geological significance. Thus, the method allows use of more reliable input data when we construct a model of a sandy debris flow.
基金We would like to thank the National Natural Science Foundation of China(Grant Nos.42130802,42002193,and 42002186)researchers Yanqiu Zhang,Wutao Hu,Haitao Lin,and Fengchun Li from Inner Mongolia Coal Geology Bureau for their help in sample acquisition.
文摘To understand the natural gas characteristics of multi-thin coal seam,this study selected the desorbed gas of coal seams in different layers of Well A in the Wujiu depression,Hailar Basin in northeast Inner Mongolia.The results show that the heavy hydrocarbon content of desorbed gas increases significantly with the increasing depth.Methane carbon(δ13C_(1))and ethane carbon(δ13C_(2))isotope values are vertically become heavier downwards,while the δ13 values did not change significantly.The kerogen is close to the III–II mixed type with the source rocks mainly deposited in a shore/shallow lake or braided-river delta front,and the gas produced has certain characteristics of oil associated gas.However,the characteristics of oil associated gas produced by the organic formed in the shallow-water environment(braided-river delta plain)are not obvious.The sandstone pore and fracture systems interbedded with multi-thin coal seam are well developed.And it is conducive to the migration of methanogenic micro-organisms to coal seams via groundwater,making it easier to produce biogenic gas under this geological condition.During the burial evolution of coal-bearing strata in the study area,when the burial depth reaches the maximum,there are significant differences in the paleotemperature experienced by different vertical coal seams,caused by a high-paleogeothermal gradient,increasing the δ13C_(2) of desorbed gas with increasing depth.The above research indicates that there is less biogenic gas in the multi-thin coal seams with relatively developed mudstone,and the multi-thin coal seams with relatively developed sandstones have obvious biogenic gas characteristics.Therefore,for the exploration and development of biogenic gas in low-rank multi-thin coal seams,it is necessary to give priority to the layer with high sandstone content.
基金supported by the National Natural Science Foundation of China(Grant No.42130802)PetroChina Company Limited“14th Five Year Plan”Science and Technology Major Project(No.2021DJ2301).
文摘An improved evaluation method for estimating gas content during the inversion process of deep-burial coal was established based on the on-site natural desorption curves.The accuracy of the US Bureau of Mines(USBM),Polynomial fitting,Amoco,and the improved evaluation methods in the predicting of lost gas volume in deep seams in the Mabidong Block of the Qinshui Basin were then compared.Furthermore,the calculation errors of these different methods in simulating lost gas content based on coring time were compared.A newly established nonlinear equation was developed to estimate the minimum error value,by controlling the lost time within 16 min,the related errors can be reduced.The improved evaluation was shown to accurately and rapidly predict the gas content in deep seams.The results show that the deep coal bed methane accumulation is influenced by various factors,including geological structure,hydrodynamic conditions,roof lithology,and coalification.Reverse faults and weak groundwater runoff can hinder the escape of methane,and these factors should be considered in the future exploration and development of coalbed methane.
基金supported by National Science and Technology Major Project(Grant No.2011ZX05034)the Research Fund of Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process,Ministry of Education(Grant No.2013-007)+1 种基金Innovation of Graduate Student Training Project in Jiangsu Province(Grant No.CXZZ13-0944)Fundamental Research Funds for the Central Universities(Grant No.2013XK06)
文摘Tectonically deformed coal(TDC)develops because of the superimposed deformation and metamorphism of a coal seam by tectonic movements.The migration and accumulation of trace elements in TDC is largely in response to stress-strain conditions.To develop a law governing the migration and aggregation of sensitive elements and investigate the geological controls on TDC,coal samples from different deformation sequences were collected from the Haizi mine,in the Huaibei coalfield in Anhui Province,China,and the concentrations of 49 elements were determined by XRF and ICP-MS,and then microscopically analyzed.The results show that the distribution and morphology of minerals in coal is related to the deformation degree of TDC.The evolutionary process runs from orderly distribution of minerals in a weak brittle deformed coal to disordered distributions in ductile deformed coal.According to the elemental distribution characteristics in TDC,four types of element migration can be identified:stable,aggregate,declining,and undulate types,which are closely related to the deformation degree of TDC.Present data indicate that the overall distribution of rare earth elements(REE)does not change with metamorphism and deformation,but it shows obvious dynamic differentiation phenomena along with the deformation of TDC.Tectonic action after coal-formation,brittle or ductile deformation,and the metamorphic mechanism and its accompanying dynamic thermal effects are the main factors that influence the redistribution of elements in TDC.We conclude that tectonic movements provide the motivation and basis for the redistribution of elements and the paths and modes of element migration are controlled by brittle and ductile deformation metamorphic processes.The dynamic thermal effect has the most significant effect on coal metamorphism and tectonic-stress-accelerated element migration and accumulation.These factors then induce the tectonic-dynamic differentiation phenomenon of element migration.
基金funded by“The Pearl River Talent Recruitment Program”in 2019(Grant No.2019CX01G338)Guangdong Province and the Scientific Research Initiation Grant of Shantou University for New Faculty Member(Grant No.NTF19024-2019).
文摘The efficiency of gas hydrate production depends on the success of gas exploration and occurrence evaluation.The existing evaluation models are generally univariate and only applicable to certain geological settings.This study presents a holistic approach to evaluate the likelihood of gas hydrate occurrence by supplying an index for mapping gas hydrate levels with depth.The approach integrates a generalised TOPSIS method with the fuzzy set theory.An expedition of gas hydrate conducted in the Shenhu area of the South China Sea was adopted as a case study to assess the reliability of the proposed index.As a multivariate model,the proposed approach enables the capture of non-linearity associated with gas hydrates in its entirety.The magnitude of the strength of the influential factor varies substantially from one site to another across the Shenhu area.The results also show that no site achieves the highest likelihood‘Level V’.These results are consistent with the gas saturation values obtained using Archie’s relationship.For example,at SH4 and SH7,the values of the likelihood index are the highest between 170–185 m and 150–165 m,respectively,and the observed saturation at these locations varies from 20%(SH4)to 43%(SH7).The proposed likelihood index yields a prominent ability to quantify the level of occurrence of gas hydrates with depth at different sites.It appears to be an efficient multicriteria system bound to improve the management of the gas production trial stage.
