The Maichen Sag in the south-central part of the Beibuwan Basin is abundant in geothermal resources that have not been widely exploited and utilized due to inadequate research on it.This study evaluated the geothermal...The Maichen Sag in the south-central part of the Beibuwan Basin is abundant in geothermal resources that have not been widely exploited and utilized due to inadequate research on it.This study evaluated the geothermal resources in the Maichen Sag based on the regional geological setting and geothermal conditions.Grid units for assessment and a geological model for areas with geothermal resources were established using spatial analysis techniques.The spatial distribution models of the physical and thermophysical properties of the geothermal reservoirs were also built using the Kriging interpolation method.Based on the terrestrial heat flow distribution in the target areas,the spatial distribution of the geo-temperature field through the inversion under the constraints of the temperature data from boreholes were predicted.Factors such as deep geo-temperature,thermophysical properties of rocks,and terrestrial heat flow values,were integrated into this quantitative evaluation of geothermal resources through the geological modeling-based volume method and the geothermal reservoir engineering-based numerical simulation method.The results show that the Maichen Sag has favorable heat source conditions with intersected,deep-rooted faults and widely developed Upper Paleozoic fissured granite geothermal reservoirs.The northern outer slope zone at a burial depth of 3‒5 km on the tectonic plane of the basement in the sag is suggested to be a potential target area,where,as calculated using the volume method,is likely to be the home to the total geothermal resources of 80.4×10^(9)GJ(i.e.,2.75×10^(9)tonnes of coal equivalent(tce))in the bedrock geothermal reservoirs at a burial depth of 3‒6 km.The geotemperature of 172‒201℃at a formation depth of 5 km in the sag also indicates that the deep geothermal resources are of high value for exploitation.展开更多
America had been attempting to annex Canadian West and posed a threat to the security of the fledgling country. Therefore the antipathy towards America as well as independent-nation complex of Canadians drove Canadian...America had been attempting to annex Canadian West and posed a threat to the security of the fledgling country. Therefore the antipathy towards America as well as independent-nation complex of Canadians drove Canadian government to incorporate the west exploitation into the national strategy of creating an independent country. Canadian west exploitation thus took on some distinctiveness.展开更多
Groundwater over-exploitation is a major problem in groundwater development, utilization and protection. At present, the area of shallow groundwater over-exploitation in the High-tech Zone is 76 km^(2). In this study,...Groundwater over-exploitation is a major problem in groundwater development, utilization and protection. At present, the area of shallow groundwater over-exploitation in the High-tech Zone is 76 km^(2). In this study, the system and mechanism construction, engineering measure construction, and control effect of national comprehensive control project of groundwater over-exploitation areas in the High-tech Zone in 2020 were evaluated, and the comprehensive control of groundwater over-exploitation in the High-tech Zone in the year was summarized to provide effective basis for the continuous implementation of comprehensive control of groundwater over-exploitation. At the same time, the water-saving and exploitation reduction effect and generalizability of different measures were studied to provide useful reference for other over-exploitation areas.展开更多
Calculated in terms of surface runoff plus irrepeated groundwater, there is about 8. 67 ×1010m3 of total available water resources in the inland river basins of arid Northwest China. Water resources is the decisi...Calculated in terms of surface runoff plus irrepeated groundwater, there is about 8. 67 ×1010m3 of total available water resources in the inland river basins of arid Northwest China. Water resources is the decisive factor for survival of oases and human being. But there have arisen several aspects of Serious eco-environment problems resulted from irrational exploitation and utilization. From now on, the development and utilization of water not only requires to promote regional economy, but also needs to protect and improve the environment based on their potential. Sustainable utilization needs to broaden new sources and saving water at first. Then three measures are recommended.展开更多
Wave energy resources assessment is a very important process before the exploitation and utilization of the wave energy. At present, the existing wave energy assessment is focused on theoretical wave energy conditions...Wave energy resources assessment is a very important process before the exploitation and utilization of the wave energy. At present, the existing wave energy assessment is focused on theoretical wave energy conditions for interesting areas. While the evaluation for exploitable wave energy conditions is scarcely ever performed. Generally speaking, the wave energy are non-exploitable under a high sea state and a lower sea state which must be ignored when assessing wave energy. Aiming at this situation, a case study of the East China Sea and the South China Sea is performed. First, a division basis between the theoretical wave energy and the exploitable wave energy is studied. Next, based on recent 20 a ERA-Interim wave field data, some indexes including the spatial and temporal distribution of wave power density, a wave energy exploitable ratio, a wave energy level, a wave energy stability, a total wave energy density, the seasonal variation of the total wave energy and a high sea condition frequency are calculated. And then the theoretical wave energy and the exploitable wave energy are compared each other; the distributions of the exploitable wave energy are assessed and a regional division for exploitable wave energy resources is carried out; the influence of the high sea state is evaluated. The results show that considering collapsing force of the high sea state and the utilization efficiency for wave energy, it is determined that the energy by wave with a significant wave height being not less 1 m or not greater than 4 m is the exploitable wave energy. Compared with the theoretical wave energy, the average wave power density, energy level, total wave energy density and total wave energy of the exploitable wave energy decrease obviously and the stability enhances somewhat. Pronounced differences between the theoretical wave energy and the exploitable wave energy are present. In the East China Sea and the South China Sea, the areas of an abundant and stable exploitable wave energy are primarily located in the north-central part of the South China Sea, the Luzon Strait, east of Taiwan, China and north of Ryukyu Islands; annual average exploitable wave power density values in these areas are approximately 10-15 kW/m; the exploitable coefficient of variation (COV) and seasonal variation (SV) values in these areas are less than 1.2 and 1, respectively. Some coastal areas of the Beibu Gulf, the Changjiang Estuary, the Hangzhou Bay and the Zhujiang Estuary are the poor areas of the wave energy. The areas of the high wave energy exploitable ratio is primarily in nearshore waters. The influence of the high sea state for the wave energy in nearshore waters is less than that in offshore waters. In the areas of the abundant wave energy, the influence of the high sea state for the wave energy is prominent and the utilization of wave energy is relatively difficult. The developed evaluation method may give some references for an exploitable wave energy assessment and is valuable for practical applications.展开更多
Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer (salt deposit) in Qarhan Salt Lake was studied by using the Pitzer theory. Th...Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer (salt deposit) in Qarhan Salt Lake was studied by using the Pitzer theory. The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented, which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake. And secondly, with a model forming idea of transport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference, a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system (salt deposits) was developed by using the Pitzer theory. Meanwhile, the model was applied to model potassium/magnesium transport in Qarhan Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/ Magnesium in the mining of salt deposits in Qarhan Salt Lake.展开更多
In 2001, the International Seabed Authority (ISBA) initiated the consideration relating to the Regulations for Prospecting and Exploration for Hydrothermal Polymetallic Sulphides and Cobalt-rich Ferromanganese Crust...In 2001, the International Seabed Authority (ISBA) initiated the consideration relating to the Regulations for Prospecting and Exploration for Hydrothermal Polymetallic Sulphides and Cobalt-rich Ferromanganese Crusts in the Area at its 7th session. Since then, the consideration of the Regulations has been mainly focused on the size of areas to be allocated for exploration and exploitation of the crusts. This paper, based on the investigation data and the analysis of the distribution characteristics of the crusts, suggests a model for determining the size of areas for exploration and exploitation of the crusts, taking into account various factors such as production scale, crust thickness and grade, mineable area proportion, recovery efficiency, exploration venture, and so on. Through the modeling, the paper suggests that the exploration area (the area covered by each application for approval of a plan of work for exploration of cobalt-rich crusts) shall be 4 856 km2 and the exploitation area (the mine site area) shall be 1 214 km2, for 20 years of 1 million wet tonnes annual production.展开更多
China has nearly a hundred mining cities derived from mining development.While mining development has brought about immense achievements in a city’s economic construction,it has also resulted in different levels of d...China has nearly a hundred mining cities derived from mining development.While mining development has brought about immense achievements in a city’s economic construction,it has also resulted in different levels of damage to the eco-environment of the mining city,leaving behind a lot of subsided wasteland and heavily confining the sustainable development and transformation there.How to restore and exploit the land and eco-environment disrupted by mining development in an effective way,therefore,has become a pressing challenge that Chinese mining cities are facing.In this paper,the planning and construction of Nanhu Eco-city in the suburb of Tangshan City is analyzed as an example.After characterizing the coal-mining subsided lands in Kailuan Tangshan Mine originated in different periods and under different geological mining conditions and evaluating their safety level,the authors try to demonstrate how eco-restoration and comprehensive land exploitation should be implemented by making the best use of available local resources to achieve "economy-society-environment" sustainability and coexistence in a mining city.展开更多
Multifactorial correlation analysis is a new method used to predict the land subsidence caused by groundwater exploitation This article introduces and applies the method to establish the function of the surface settle...Multifactorial correlation analysis is a new method used to predict the land subsidence caused by groundwater exploitation This article introduces and applies the method to establish the function of the surface settlement rate (Vs) and the function of the time-dependent surface settlement (St) caused by groundwater exploitation, based on data acquired at three land subsidence monitoring stations in the Hanoi area of Vietnam. Comparison with actual monitoring data indicates that the prediction results are relatively close to the monitoring data. From this, we conclude that multifactorial correlation analysis is a reliable method and can be used to predict future land subsidence caused by groundwater exploitation in Hanoi.展开更多
CO_(2) can be used as an alternative injectant to exploit geothermal energy from depleted high-temperature gas reservoirs due to its high mobility and unique thermal properties.However,there has been a lack of systema...CO_(2) can be used as an alternative injectant to exploit geothermal energy from depleted high-temperature gas reservoirs due to its high mobility and unique thermal properties.However,there has been a lack of systematic analysis on the heat mining mechanism and performance of CO_(2),as well as the problems that may occur during geothermal energy exploitation at specific gas reservoir conditions.In this paper,a base numerical simulation model of a typical depleted high-temperature gas reservoir was established to simulate the geothermal energy exploitation processes via recycling CO_(2) and water,with a view to investigate whether and/or at which conditions CO_(2) is more suitable than water for geothermal energy exploitation.The problems that may occur during the CO_(2)-based geothermal energy exploitation were also analyzed along with proposed feasible solutions.The results indicate that,for a depleted low-permeability gas reservoir with dimensions of 1000 m×500 m×50 m and temperature of 150℃ using a single injection-production well group for 40 years of operation,the heat mining rate of CO_(2) can be up to 3.8 MW at a circulation flow rate of 18 kg s^(-1)due to its high mobility along with the flow path in the gas reservoir,while the heat mining rate of water is only about 2 MW due to limitations on the injectivity and mobility.The reservoir physical property and injection-production scheme have some effects on the heat mining rate,but CO_(2)always has better performance than water at most reservoir and operation conditions,even under a high water saturation.The main problems for CO_(2) circulation are wellbore corrosion and salt precipitation that can occur when the reservoir has high water saturation and high salinity,in which serious salt precipitation can reduce formation permeability and result in a decline of CO_(2) heat mining rate (e.g.up to 24%reduction).It is proposed to apply a low-salinity water slug before CO_(2)injection to reduce the damage caused by salt precipitation.For high-permeability gas reservoirs with high water saturation and high salinity,the superiority of CO_(2) as a heat transmission fluid becomes obscure and water injection is recommended.展开更多
This paper discusses the rational exploitation of main resources and prevention of geohazards in karst regions. There exist relationship chains between natural disasters in the earth, which include the chain between g...This paper discusses the rational exploitation of main resources and prevention of geohazards in karst regions. There exist relationship chains between natural disasters in the earth, which include the chain between geological hazards and climatic hazards, the chain between geological hazards and biogenic hazards as well as the one between geological hazards. Irrational exploitation of all resources will inevitably cause hazards. Therefore it is very important to discuss the problem related to prevention of geohazards by rational exploitation of resources.展开更多
The Tahe Oilfield is a complex petroleum reservoir of Ordovician carbonate formation and made up of spatially overlapping fracture-cavity units. The oilfield is controlled by a cave system resulting from structure-kar...The Tahe Oilfield is a complex petroleum reservoir of Ordovician carbonate formation and made up of spatially overlapping fracture-cavity units. The oilfield is controlled by a cave system resulting from structure-karst cyclic sedimentation. Due to significant heterogeneity of the reservoir, the distribution of oil and water is complicated. Horizontally, a fresh water zone due to meteoric water can be found in the north part of the Akekule uplift. A marginal freshening zone caused by water released from mudstone compaction is found at the bottom of the southern slope. Located in a crossformational flow discharge zone caused by centripetal and the centrifugal flows, the main part of the Tahe Oilfield, featuring high salinity and concentrations of CI^- and K^++Na^+, is favorable for accumulation of hydrocarbon. Three types of formation water in the Tahe Ordovician reservoir are identified: (1) residual water at the bottom of the cave after oil and gas displacement, (2) residual water in fractures/pores around the cave after oil and gas displacement, and (3) interlayer water below reservoirs. The cave system is the main reservoir space, which consists of the main cave, branch caves and depressions between caves. Taking Cave System S48 in the Ordovician reservoir as an example, the paper analyzes the fluid distribution and exploitation performance in the cave system. Owing to evaporation of groundwater during cross-formational flow, the central part of the main cave, where oil layers are thick and there is a high degree of displacement, is characterized by high salinity and Br^- concentration. With high potential and a long stable production period, most wells in the central part of the main cave have a long water-free oil production period. Even after water breakthrough, the water content has a slow or stepwise increase and the hydrochemistral characteristics of the produced water in the central part of the main cave are uniform. From the center to the edge of the main cave, displacement and enrichment of oil/gas become weaker, residual water increases, and the salinity and concentration of Br^- decrease. At the edge of the main cave, although the wells have a high deliverability at the beginning with a short stable production period and water-free production period. After water breakthrough, the pressure and deliverability drop quickly, and the water content rises quickly. The hydrochemistral characteristics of the produced water are relatively uniform. Wells in the branch caves have a relatively low deliverability at the beginning, with a short stable production period. Water breakthrough appears quickly and then the pressure and deliverability drop quickly. The salinity and concentrations of CI^-and K^++Na^+ are usually fluctuant or descend slowly in the produced water. Wells in low areas of ancient karst have a low deliverability and a short stable production period. The yield drops quickly and the water content is high, while the characteristics of the produced water may vary significantly well to well. The salinity and concentrations of CI^-and K^++Na^+ in the produced water are usually fluctuant with a precipitous decline.展开更多
Genetic search plays an important role in Evolutionary Computation (EC). There are two important issues in the evolution process of the genetic search: exploration and exploitation. Exploration is the creation of popu...Genetic search plays an important role in Evolutionary Computation (EC). There are two important issues in the evolution process of the genetic search: exploration and exploitation. Exploration is the creation of population diversity by exploring the search space; exploitation is the reduction of the diversity by focusing on the individuals of higher fitness, or exploiting the fitness information (or knowledge) represented within the population. We theoretically analyze the impact of the genetic operators on the balance. In order to further explain the impact, some results of our research on ESs are showed. Finally we conclude that to make the algorithm more efficient, it is important to strike a balance between these two factors.展开更多
In the current data-intensive era, the traditional hands-on method of conducting scientific research by exploring related publications to generate a testable hypothesis is well on its way of becoming obsolete within j...In the current data-intensive era, the traditional hands-on method of conducting scientific research by exploring related publications to generate a testable hypothesis is well on its way of becoming obsolete within just a year or two. Analyzing the literature and data to automatically generate a hypothesis might become the de facto approach to inform the core research efforts of those trying to master the exponentially rapid expansion of publications and datasets. Here, viewpoints are provided and discussed to help the understanding of challenges of data-driven discovery.展开更多
Coal and coalbed methane(CBM)coordinated exploitation is a key technology for the safe exploitation of both resources.However,existing studies lack the quantification and evaluation of the degree of coordination betwe...Coal and coalbed methane(CBM)coordinated exploitation is a key technology for the safe exploitation of both resources.However,existing studies lack the quantification and evaluation of the degree of coordination between coal mining and coalbed methane extraction.In this study,the concept of coal and coalbed methane coupling coordinated exploitation was proposed,and the corresponding evaluation model was established using the Bayesian principle.On this basis,the objective function of coal and coalbed methane coordinated exploitation deployment was established,and the optimal deployment was determined through a cuckoo search.The results show that clarifying the coupling coordinated level of coal and coalbed methane resource exploitation in coal mines is conducive to adjusting the deployment plan in advance.The case study results show that the evaluation and intelligent deployment method proposed in this paper can effectively evaluate the coupling coordinated level of coal and coalbed methane resource exploitation and intelligently optimize the deployment of coal mine operations.The optimization results demonstrate that the safe and efficient exploitation of coal and CBM resources is promoted,and coal mining and coalbed methane extraction processes show greater cooperation.The observations and findings of this study provide a critical reference for coal mine resource exploitation in the future.展开更多
We study a non-autonomous ratio-dependent predator-prey model with exploited terms. This model is of periodic coefficients, which incorporates the periodicity of the varying environment. By means of the coincidence de...We study a non-autonomous ratio-dependent predator-prey model with exploited terms. This model is of periodic coefficients, which incorporates the periodicity of the varying environment. By means of the coincidence degree theory, we establish sufficient conditions for the existence of at least four positive periodic solutions of this model.展开更多
基金This work was funded by multiple scientific research programs,including Evaluation and Optimal Target Selection of Deep Geothermal Resources in the Igneous Province in South China(No.:2019YFC0604903)Analysis and Geothermal Reservoir Stimulation Methods of Deep High-temperature Geothermal Systems in East China(No.:2021YFA0716004)of the National Key Research and Development Program of China+1 种基金a project entitled Deep Geological Processes and Resource Effects of Basins(No.:U20B6001)of the Joint Fund Program of the National Natural Science Foundation of China and Sinopeca project entitled Siting and Target Evaluation of Deep Geothermal Resources in Key Areas of Southeastern China(No.:P20041-1)of the Sinopec Science and Technology Research Program.
文摘The Maichen Sag in the south-central part of the Beibuwan Basin is abundant in geothermal resources that have not been widely exploited and utilized due to inadequate research on it.This study evaluated the geothermal resources in the Maichen Sag based on the regional geological setting and geothermal conditions.Grid units for assessment and a geological model for areas with geothermal resources were established using spatial analysis techniques.The spatial distribution models of the physical and thermophysical properties of the geothermal reservoirs were also built using the Kriging interpolation method.Based on the terrestrial heat flow distribution in the target areas,the spatial distribution of the geo-temperature field through the inversion under the constraints of the temperature data from boreholes were predicted.Factors such as deep geo-temperature,thermophysical properties of rocks,and terrestrial heat flow values,were integrated into this quantitative evaluation of geothermal resources through the geological modeling-based volume method and the geothermal reservoir engineering-based numerical simulation method.The results show that the Maichen Sag has favorable heat source conditions with intersected,deep-rooted faults and widely developed Upper Paleozoic fissured granite geothermal reservoirs.The northern outer slope zone at a burial depth of 3‒5 km on the tectonic plane of the basement in the sag is suggested to be a potential target area,where,as calculated using the volume method,is likely to be the home to the total geothermal resources of 80.4×10^(9)GJ(i.e.,2.75×10^(9)tonnes of coal equivalent(tce))in the bedrock geothermal reservoirs at a burial depth of 3‒6 km.The geotemperature of 172‒201℃at a formation depth of 5 km in the sag also indicates that the deep geothermal resources are of high value for exploitation.
文摘America had been attempting to annex Canadian West and posed a threat to the security of the fledgling country. Therefore the antipathy towards America as well as independent-nation complex of Canadians drove Canadian government to incorporate the west exploitation into the national strategy of creating an independent country. Canadian west exploitation thus took on some distinctiveness.
文摘Groundwater over-exploitation is a major problem in groundwater development, utilization and protection. At present, the area of shallow groundwater over-exploitation in the High-tech Zone is 76 km^(2). In this study, the system and mechanism construction, engineering measure construction, and control effect of national comprehensive control project of groundwater over-exploitation areas in the High-tech Zone in 2020 were evaluated, and the comprehensive control of groundwater over-exploitation in the High-tech Zone in the year was summarized to provide effective basis for the continuous implementation of comprehensive control of groundwater over-exploitation. At the same time, the water-saving and exploitation reduction effect and generalizability of different measures were studied to provide useful reference for other over-exploitation areas.
文摘Calculated in terms of surface runoff plus irrepeated groundwater, there is about 8. 67 ×1010m3 of total available water resources in the inland river basins of arid Northwest China. Water resources is the decisive factor for survival of oases and human being. But there have arisen several aspects of Serious eco-environment problems resulted from irrational exploitation and utilization. From now on, the development and utilization of water not only requires to promote regional economy, but also needs to protect and improve the environment based on their potential. Sustainable utilization needs to broaden new sources and saving water at first. Then three measures are recommended.
基金The Dragon III Project of the European Space Agency and Ministry of Science and Technology of China under contract No.10412the Ocean Renewable Energy Special Fund Project of State Oceanic Administration of China under contract No.GHME2011ZC07the National Natural Science Foundation of China(NSFC)under contract No.41176157
文摘Wave energy resources assessment is a very important process before the exploitation and utilization of the wave energy. At present, the existing wave energy assessment is focused on theoretical wave energy conditions for interesting areas. While the evaluation for exploitable wave energy conditions is scarcely ever performed. Generally speaking, the wave energy are non-exploitable under a high sea state and a lower sea state which must be ignored when assessing wave energy. Aiming at this situation, a case study of the East China Sea and the South China Sea is performed. First, a division basis between the theoretical wave energy and the exploitable wave energy is studied. Next, based on recent 20 a ERA-Interim wave field data, some indexes including the spatial and temporal distribution of wave power density, a wave energy exploitable ratio, a wave energy level, a wave energy stability, a total wave energy density, the seasonal variation of the total wave energy and a high sea condition frequency are calculated. And then the theoretical wave energy and the exploitable wave energy are compared each other; the distributions of the exploitable wave energy are assessed and a regional division for exploitable wave energy resources is carried out; the influence of the high sea state is evaluated. The results show that considering collapsing force of the high sea state and the utilization efficiency for wave energy, it is determined that the energy by wave with a significant wave height being not less 1 m or not greater than 4 m is the exploitable wave energy. Compared with the theoretical wave energy, the average wave power density, energy level, total wave energy density and total wave energy of the exploitable wave energy decrease obviously and the stability enhances somewhat. Pronounced differences between the theoretical wave energy and the exploitable wave energy are present. In the East China Sea and the South China Sea, the areas of an abundant and stable exploitable wave energy are primarily located in the north-central part of the South China Sea, the Luzon Strait, east of Taiwan, China and north of Ryukyu Islands; annual average exploitable wave power density values in these areas are approximately 10-15 kW/m; the exploitable coefficient of variation (COV) and seasonal variation (SV) values in these areas are less than 1.2 and 1, respectively. Some coastal areas of the Beibu Gulf, the Changjiang Estuary, the Hangzhou Bay and the Zhujiang Estuary are the poor areas of the wave energy. The areas of the high wave energy exploitable ratio is primarily in nearshore waters. The influence of the high sea state for the wave energy in nearshore waters is less than that in offshore waters. In the areas of the abundant wave energy, the influence of the high sea state for the wave energy is prominent and the utilization of wave energy is relatively difficult. The developed evaluation method may give some references for an exploitable wave energy assessment and is valuable for practical applications.
基金the National Natural Science Foundation of China
文摘Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer (salt deposit) in Qarhan Salt Lake was studied by using the Pitzer theory. The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented, which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake. And secondly, with a model forming idea of transport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference, a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system (salt deposits) was developed by using the Pitzer theory. Meanwhile, the model was applied to model potassium/magnesium transport in Qarhan Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/ Magnesium in the mining of salt deposits in Qarhan Salt Lake.
基金China International Seabed Area R & D Program under contract No.DYXM-115-01-1
文摘In 2001, the International Seabed Authority (ISBA) initiated the consideration relating to the Regulations for Prospecting and Exploration for Hydrothermal Polymetallic Sulphides and Cobalt-rich Ferromanganese Crusts in the Area at its 7th session. Since then, the consideration of the Regulations has been mainly focused on the size of areas to be allocated for exploration and exploitation of the crusts. This paper, based on the investigation data and the analysis of the distribution characteristics of the crusts, suggests a model for determining the size of areas for exploration and exploitation of the crusts, taking into account various factors such as production scale, crust thickness and grade, mineable area proportion, recovery efficiency, exploration venture, and so on. Through the modeling, the paper suggests that the exploration area (the area covered by each application for approval of a plan of work for exploration of cobalt-rich crusts) shall be 4 856 km2 and the exploitation area (the mine site area) shall be 1 214 km2, for 20 years of 1 million wet tonnes annual production.
文摘China has nearly a hundred mining cities derived from mining development.While mining development has brought about immense achievements in a city’s economic construction,it has also resulted in different levels of damage to the eco-environment of the mining city,leaving behind a lot of subsided wasteland and heavily confining the sustainable development and transformation there.How to restore and exploit the land and eco-environment disrupted by mining development in an effective way,therefore,has become a pressing challenge that Chinese mining cities are facing.In this paper,the planning and construction of Nanhu Eco-city in the suburb of Tangshan City is analyzed as an example.After characterizing the coal-mining subsided lands in Kailuan Tangshan Mine originated in different periods and under different geological mining conditions and evaluating their safety level,the authors try to demonstrate how eco-restoration and comprehensive land exploitation should be implemented by making the best use of available local resources to achieve "economy-society-environment" sustainability and coexistence in a mining city.
基金supported by Vietnam National Funds of Education and Training
文摘Multifactorial correlation analysis is a new method used to predict the land subsidence caused by groundwater exploitation This article introduces and applies the method to establish the function of the surface settlement rate (Vs) and the function of the time-dependent surface settlement (St) caused by groundwater exploitation, based on data acquired at three land subsidence monitoring stations in the Hanoi area of Vietnam. Comparison with actual monitoring data indicates that the prediction results are relatively close to the monitoring data. From this, we conclude that multifactorial correlation analysis is a reliable method and can be used to predict future land subsidence caused by groundwater exploitation in Hanoi.
基金This research was financially supported by the National Natural Science Foundation of China(Grant No.51674282)the National Key R&D Programs of China(Grant No.2019YFB1504201,2019YFB1504203,and 2019YFB1504204)+2 种基金the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(Grant No.CUGGC09 and CUG200637)the Open Project Program of Key Laboratory of Groundwater Resources and Environment(Jilin University),Ministry of Education(Grant No.202005001KF)Opening Fund of Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)),Ministry of Education(Grant No.19CX05005A-201)。
文摘CO_(2) can be used as an alternative injectant to exploit geothermal energy from depleted high-temperature gas reservoirs due to its high mobility and unique thermal properties.However,there has been a lack of systematic analysis on the heat mining mechanism and performance of CO_(2),as well as the problems that may occur during geothermal energy exploitation at specific gas reservoir conditions.In this paper,a base numerical simulation model of a typical depleted high-temperature gas reservoir was established to simulate the geothermal energy exploitation processes via recycling CO_(2) and water,with a view to investigate whether and/or at which conditions CO_(2) is more suitable than water for geothermal energy exploitation.The problems that may occur during the CO_(2)-based geothermal energy exploitation were also analyzed along with proposed feasible solutions.The results indicate that,for a depleted low-permeability gas reservoir with dimensions of 1000 m×500 m×50 m and temperature of 150℃ using a single injection-production well group for 40 years of operation,the heat mining rate of CO_(2) can be up to 3.8 MW at a circulation flow rate of 18 kg s^(-1)due to its high mobility along with the flow path in the gas reservoir,while the heat mining rate of water is only about 2 MW due to limitations on the injectivity and mobility.The reservoir physical property and injection-production scheme have some effects on the heat mining rate,but CO_(2)always has better performance than water at most reservoir and operation conditions,even under a high water saturation.The main problems for CO_(2) circulation are wellbore corrosion and salt precipitation that can occur when the reservoir has high water saturation and high salinity,in which serious salt precipitation can reduce formation permeability and result in a decline of CO_(2) heat mining rate (e.g.up to 24%reduction).It is proposed to apply a low-salinity water slug before CO_(2)injection to reduce the damage caused by salt precipitation.For high-permeability gas reservoirs with high water saturation and high salinity,the superiority of CO_(2) as a heat transmission fluid becomes obscure and water injection is recommended.
文摘This paper discusses the rational exploitation of main resources and prevention of geohazards in karst regions. There exist relationship chains between natural disasters in the earth, which include the chain between geological hazards and climatic hazards, the chain between geological hazards and biogenic hazards as well as the one between geological hazards. Irrational exploitation of all resources will inevitably cause hazards. Therefore it is very important to discuss the problem related to prevention of geohazards by rational exploitation of resources.
文摘The Tahe Oilfield is a complex petroleum reservoir of Ordovician carbonate formation and made up of spatially overlapping fracture-cavity units. The oilfield is controlled by a cave system resulting from structure-karst cyclic sedimentation. Due to significant heterogeneity of the reservoir, the distribution of oil and water is complicated. Horizontally, a fresh water zone due to meteoric water can be found in the north part of the Akekule uplift. A marginal freshening zone caused by water released from mudstone compaction is found at the bottom of the southern slope. Located in a crossformational flow discharge zone caused by centripetal and the centrifugal flows, the main part of the Tahe Oilfield, featuring high salinity and concentrations of CI^- and K^++Na^+, is favorable for accumulation of hydrocarbon. Three types of formation water in the Tahe Ordovician reservoir are identified: (1) residual water at the bottom of the cave after oil and gas displacement, (2) residual water in fractures/pores around the cave after oil and gas displacement, and (3) interlayer water below reservoirs. The cave system is the main reservoir space, which consists of the main cave, branch caves and depressions between caves. Taking Cave System S48 in the Ordovician reservoir as an example, the paper analyzes the fluid distribution and exploitation performance in the cave system. Owing to evaporation of groundwater during cross-formational flow, the central part of the main cave, where oil layers are thick and there is a high degree of displacement, is characterized by high salinity and Br^- concentration. With high potential and a long stable production period, most wells in the central part of the main cave have a long water-free oil production period. Even after water breakthrough, the water content has a slow or stepwise increase and the hydrochemistral characteristics of the produced water in the central part of the main cave are uniform. From the center to the edge of the main cave, displacement and enrichment of oil/gas become weaker, residual water increases, and the salinity and concentration of Br^- decrease. At the edge of the main cave, although the wells have a high deliverability at the beginning with a short stable production period and water-free production period. After water breakthrough, the pressure and deliverability drop quickly, and the water content rises quickly. The hydrochemistral characteristics of the produced water are relatively uniform. Wells in the branch caves have a relatively low deliverability at the beginning, with a short stable production period. Water breakthrough appears quickly and then the pressure and deliverability drop quickly. The salinity and concentrations of CI^-and K^++Na^+ are usually fluctuant or descend slowly in the produced water. Wells in low areas of ancient karst have a low deliverability and a short stable production period. The yield drops quickly and the water content is high, while the characteristics of the produced water may vary significantly well to well. The salinity and concentrations of CI^-and K^++Na^+ in the produced water are usually fluctuant with a precipitous decline.
文摘Genetic search plays an important role in Evolutionary Computation (EC). There are two important issues in the evolution process of the genetic search: exploration and exploitation. Exploration is the creation of population diversity by exploring the search space; exploitation is the reduction of the diversity by focusing on the individuals of higher fitness, or exploiting the fitness information (or knowledge) represented within the population. We theoretically analyze the impact of the genetic operators on the balance. In order to further explain the impact, some results of our research on ESs are showed. Finally we conclude that to make the algorithm more efficient, it is important to strike a balance between these two factors.
文摘In the current data-intensive era, the traditional hands-on method of conducting scientific research by exploring related publications to generate a testable hypothesis is well on its way of becoming obsolete within just a year or two. Analyzing the literature and data to automatically generate a hypothesis might become the de facto approach to inform the core research efforts of those trying to master the exponentially rapid expansion of publications and datasets. Here, viewpoints are provided and discussed to help the understanding of challenges of data-driven discovery.
基金supported by the Natural Science Foundation of Chongqing,China(No.cstc2020jcyj-msxmX0836)the Fundamental Research Funds for the Central Universities(No.2020CDJ-LHZZ-002)the National Natural Science Foundation of China(No.52074041).
文摘Coal and coalbed methane(CBM)coordinated exploitation is a key technology for the safe exploitation of both resources.However,existing studies lack the quantification and evaluation of the degree of coordination between coal mining and coalbed methane extraction.In this study,the concept of coal and coalbed methane coupling coordinated exploitation was proposed,and the corresponding evaluation model was established using the Bayesian principle.On this basis,the objective function of coal and coalbed methane coordinated exploitation deployment was established,and the optimal deployment was determined through a cuckoo search.The results show that clarifying the coupling coordinated level of coal and coalbed methane resource exploitation in coal mines is conducive to adjusting the deployment plan in advance.The case study results show that the evaluation and intelligent deployment method proposed in this paper can effectively evaluate the coupling coordinated level of coal and coalbed methane resource exploitation and intelligently optimize the deployment of coal mine operations.The optimization results demonstrate that the safe and efficient exploitation of coal and CBM resources is promoted,and coal mining and coalbed methane extraction processes show greater cooperation.The observations and findings of this study provide a critical reference for coal mine resource exploitation in the future.
基金Supported by the China Postdoctoral Science Foundation (20060400267)
文摘We study a non-autonomous ratio-dependent predator-prey model with exploited terms. This model is of periodic coefficients, which incorporates the periodicity of the varying environment. By means of the coincidence degree theory, we establish sufficient conditions for the existence of at least four positive periodic solutions of this model.