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About the Journal

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Journal:
Coal Geology & Exploration
Establishment year:
1973
 
Periodicity:
Biomonthly
Supervised by:
Xi’an Research Institute Co. Ltd., China Coal Technology and Engineering Group Corp.
Sponsored by：
Xi’an Research Institute Co. Ltd., China Coal Technology and Engineering Group Corp.
Editor-in-chief:
 DONG Shuning
 
Associate E ditor-in-chief:

 LIU Cheng, James W. LaMoreaux 

 

Executive Editor-in-chief:
JIN Xianglan 

 

ISSN:
1001-1986
CN:
61-1155/P
Web:
www.mdkt.cbpt.cnki.net

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Article list

  • Enrichment factors and play fairway mapping of helium in typical zones of the Ordos Basin

    GAO Jianrong;TAO Shizhen;LIU Xiangbai;YANG Wei;ZHAO Zhenyu;CHEN Xiuyan;XU Wanglin;ZHANG Chunlin;SONG Wei;CHEN Yue;HUANG Junping;MA Zhanrong;Research Institute of Petroleum Exploration and Development,PetroChina;Research Institute of Petroleum Exploration and Development-Northwest,PetroChina;Exploration Division,PetroChina Changqing Oilfield Company;

    [Background] The Ordos Basin enjoys abundant natural gas resources, which generally bear helium, making this basin hold great helium resource potential. In this case, detailed exploration is essential for the future transition from natural gas-helium joint exploration to special helium exploration in the basin. [Objective and Method] To systematically investigate the distribution and potential of helium resources in the Ordos Basin, natural gas samples were taken from different areas of the basin for analysis and tests. To examine the primary factors controlling helium accumulation and enrichment, this study conducted a systematic analysis of the basement, sedimentary rock layers, fault systems, and tectonic evolutionary process of the basin. [Results and conclusions] Two helium enrichment patterns are identified in the basin and can be further subdivided into three types. Specifically, two helium enrichment patterns are determined according to their carrier types: alkane and geothermal water as carriers. The alkane-carried gas can be further subdivided into two types based on the distance between gas reservoirs and the basement. The first type is represented by the Dongsheng gas field, characterized by the direct contact between gas reservoirs and the basement(vertical distance: less than50 m) and an average helium volume fraction of 0.118%. The second type is exemplified by the Qingyang gas field,characterized by the near-distance contact between gas reservoirs and the basement(vertical distance: less than 1 500 m)and an average helium volume fraction of 0.105%. The geothermal water-carried gas refers to helium-rich water-soluble gas migrating via deep-seated faults. Such gas is represented by the Weihe graben, characterized by vertical distances of1 500-5 000 m from water-soluble gas above geothermal water to the basement and an average helium volume fraction of 2.5%. By analyzing the geological characteristics and helium enrichment factors of helium-rich areas, this study determined the primary factors controlling helium enrichment. Specifically, ancient U-and Th-rich granites in the shallowly buried basement are identified as important helium source rocks while also providing a material basis for helium enrichment. The deep-seated faults play a key role in connecting helium to shallow reservoirs. For instance, the basal strike-slip fault zone within the Qinyang gas field produces controlling effects on the Qingyang and Zhengning gas fields, also serving as a play fairway for helium enrichment. In the Qingyang gas field, areas with large-scale faults in the gas layers of the Taiyuan Formation exhibit high helium volume fractions(average: 0.105%). The formation of largescale helium is inseparable from natural gas and water, with helium always emerging as an associated product. Therefore, effective reservoir-cap rock assemblages favor helium enrichment. Based on research on the magnetic anomalies and the distribution characteristics of deep-seated faults in the Ordos Basin, this study identified two optimal helium enrichment areas: shallow-buried areas of basal granites and areas with deep-seated faults. In combination with the current reservoir-cap rock configurations of gas fields, it determined nine play fairways with a total area of 40 000 km~2 in the basin: the Hetao Basin, the Yimeng paleocontinent, the northern Tianhuan sag, the Dingbian fault zone, the Zhidan-Jiaxian fault zone with a strong magnetic field, the Zijinshan volcanic rock invasion zone, the Qingyang paleo-uplift, the Yichuan-Huanglong fault zone, and the Weihe graben.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 3424K]

  • Molecular simulation of adsorption and diffusion behaviors of high-concentration helium in salt cavern storage reservoirs

    CHEN Zeya;WANYAN Qiqi;LIU Mancang;LIU Xiaoqiang;CHEN Jianfa;LI Kang;WU Jianan;YOU Bing;National Energy Underground Gas Storage Research and Development Center;PetroChina Research Institute of Petroleum Exploration & Development;Faculty of Petroleum,China University of Petroleum(Beijing) at Karamay;State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum (Beijing);College of Geosciences,China University of Petroleum (Beijing);

    [Background] Artificial salt cavern underground helium storage is the optimal approach for achieving long-term, large-scale strategic helium storage and represents an essential solution for establishing an autonomous, controllable helium supply system. The core challenge currently constraining China's development of salt cavern underground helium storage facilities lies in the sealing capacity of salt rock against high-concentration helium(helium volume fraction ≥70%). [Methods] Molecular dynamics simulation was used in this study, a composite model of salt rock slit pore and channel pore was constructed to reveal the influences of temperature-pressure conditions, helium concentration, and pore fluid properties on the occurrence state and diffusion patterns of helium in mixed gas systems.And the variations in helium self-diffusion coefficient and Fick diffusion coefficient under multi-factor coupling conditions were investigated.[Results and Conclusions] The simulation results indicate that helium primarily occurs in the free state in nanopores of salt rocks, with a minority distributed on mineral surfaces in an adsorbed state(heat adsorbed: 2.56-3.05 kJ/mol). This suggests an extremely weak competitive adsorption capacity of helium. When the helium volume fraction reaches 90%in narrow slit-like pores, helium occurs as larger helium clusters, facilitating the underground helium storage. Compared to pure helium, the helium in helium-methane mixed gas systems shows a significant decrease in the self-diffusion coefficient. Moreover, the self-diffusion coefficient of helium gradually decreases with increasing methane proportion, indicating that carrier gas can effectively inhibit the helium diffusion and migration. Besides, fluid properties in micropores in salt rocks serve as an important factor influencing the sealing performance of salt rocks. When pores in salt rocks are saturated with high-salinity formation water, the amount of helium escaping can be almost negligible on the timescale of helium storage facility operation compared to environments with a single gas phase.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 3213K]

  • Characteristics and formation processes of helium-bearing gas reservoirs in deep strata in the Xujiaweizi Fault Depression, Songliao Basin

    REN Jiahao;HE Yanxin;TIAN Wei;WANG Lei;School of Earth and Space Sciences,Peking University;College of Resources and Environmental Engineering,Jiangxi University of Science and Technology;

    [Objective and Method]The Xujiaweizi Fault Depression in the Songliao Basin contains multiple heliumbearing gas fields.However, the assessment methods for helium resources and helium accumulation patterns in the fault depression are yet to be determined.Using 3D seismic data and logs from 24 wells, this study optimized the helium resource assessment method based on natural gamma-ray spectral logging.Using the optimized method, this study quantitatively assessed the helium-generating potential and theoretical helium production of crust-derived helium in deep strata in the Xujiaweizi Fault Depression.By combining the geochemical characteristics of the helium-bearing gas reservoirs and the simulation results of crust-derived helium, this study explored the charging histories and accumulation patterns of gas reservoirs derived from the crust and from a mixed crust-mantle source in the study area.[Results and Conclusions]The results indicate that the Lower Cretaceous Yingcheng and Shahezi formations and the Jurassic Huoshiling Formation in the study area have helium-generating potential of 1.22×10~(-4)cm~3/g, 1.08×10~(-4)cm~3/g, and 0.90×10~(-4)cm~3/g,respectively.The deep strata in the study area exhibit average helium-generating potential of 0.96×?10~(-4)cm~3/g and total helium production of 7.4km~3, suggesting a moderate to slightly low helium-generating capacity.Crust-derived helium,generated by the radioactive decay of uranium and thorium in deep strata of the study area, migrated with hydrocarbon gases as carriers.From 95 Ma, such gas migrated on a large scale and then rapidly charged the volcanic and clastic reservoirs in the overlying Yingcheng Formation via fracture systems, contributing to the formation of in situ or proximal helium reservoirs.In contrast, mantle-derived helium migrated with mantle-sourced inorganic gases such as carbon dioxide as carriers.Such gas migrated upward via deep-seated faults, volcanic conduits, and unconformities.These two types of helium finally accumulated in traps, leading to the formation of helium-bearing gas reservoirs.The crust-derived helium reservoirs are governed by the quality of helium source rocks and the hydrocarbon-helium coupling, while helium reservoirs with a mixed crust-mantle source are controlled by mantle-derived fluid activity and deep-seated faults.It is recommended that exploration in basins in eastern China should highlight the charging of mantle-derived helium.Additionally, the future helium exploration in the Xujiaweizi Fault Depression should focus on the supplementation of helium reservoirs with mantle-derived helium.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 3645K]

  • Source and primary factors controlling differential enrichment for helium in the Dongping gas field, Qaidam Basin

    XU Zhusong;LI Jian;WANG Xiaobo;CUI Huiying;XIA Yutian;TIAN Jixian;LI Wanting;CHEN Dawei;Research Institute of Science and Technology,CNPC;Research Institute of Petroleum Exploration and Development,CNPC;Key Laboratory of Gas Reservoir Formation and Development,CNPC;

    [Background] In recent years, promising helium-rich natural gas shows have been discovered in the Dongping gas field. However, the helium resources in the gas field exhibit lateral heterogeneity and vertical differential accumulation in multiple sequences, which restrict the further exploration of these resources. [Methods] By analyzing the lateral and vertical distribution characteristics of helium in the Dongping gas field, this study explored its origin and sources, analyzed the differences in geological backgrounds between helium-rich and helium-deficient gas reservoirs,and systematically summarized the differential enrichment pattern across different blocks within the Dongping gas field.[Results and Conclusions] In the Dongping gas field, helium-rich gas reservoirs are predominantly distributed in the shallowly buried Dongping-3 well block, where there is a significant positive correlation between helium and nitrogen concentrations. In contrast, the Dongping-1 and Dongping-17 well blocks exhibit gas reservoirs with a low helium concentration. Helium in the Dongping gas field is typically of the crustal origin, derived primarily from ancient basement rocks including granites and granitic gneiss. The differential helium enrichment is jointly controlled by multiple factors,including source rock availability, groundwater dynamics, natural gas charging intensity, and tectonic framework. The Dongping-3 well block is characterized by U-and Th-rich ancient granites, active groundwater circulation, relatively weak natural gas charging, and traps located in structurally high parts, and the basement exhibits the highest helium generation intensity of 1.02×10~(-12) cm~3/(a·g). In this well block, small traps located in the structurally high parts were formed by the large-amplitude tectonic uplift during the Himalayan period. These traps are conducive to the upward migration of ancient formation water containing He and N_2 at depth while also determining the small intensity of natural gas charging.Conversely, the Dongping-1 well block, despite its higher helium reserves, features weak groundwater hydrodynamics,intense natural gas charging, and traps in structurally low parts, which restrict helium migration and enrichment. The Dongping-17 well block shows the lowest helium concentration due to helium source rocks comprising schists, slates,and limestones with low U and Th concentrations and deeply buried traps. Based on research on differential helium enrichment in gas reservoirs with different basal lithologies and tectonic morphologies in the Dongping gas field, it is predicted that the structurally high parts in the piedmont paleo-uplift and paleo-slope area of the Altun Mountain are potentially play fairways for helium enrichment. This prediction is expected to provide guidance for the subsequent helium exploration and development work in the Qaidam Basin.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 2078K]

  • A new genesis method-based methodology for helium resource evaluation: Application to the Jinzhong Basin and its geological implications

    ZHANG Qiao;ZHOU Junlin;MA Shangwei;GUO Wang;LI Yuhong;ZHANG Yunpeng;ZHANG Yuxuan;XU Haihong;WANG Jiawei;Xi'an Center, China Geology Survey, Geosciences Innovation Center of Northwest China;Research Center for Helium, China Geology Survey;Sinopec Green Energy Geothermal Development Co., Ltd.;

    [Background] Helium, a strategic resource in short supply, primarily occurs in natural gas. In China, helium resource assessment remains in its nascent stage, and limited helium exploration and exploitation have been conducted in general. Most especially, for regions experiencing no natural gas exploration and basins where helium reserves remain unproven, it is essential to develop reliable methods for helium resource evaluation. Among various approaches, genesis methods, based on models of helium generation, migration, and enrichment processes, offer advantages including simple models, accessible parameters, and rapid assessment. However, existing genesis methods focus primarily on the estimation of the total amount of generated helium from a single helium source rock, generally neglecting the characteristic of multi-source helium generation, the helium release efficiency of source rocks(i.e., helium expulsion coefficient), and helium migration and enrichment efficiency(i.e., migration–accumulation coefficient). These omissions tend to induce overestimated resources and reduced accuracy. [Methods] This study developed a genesis method-based, systematic methodology for helium resource evaluation. The helium expulsion coefficient and migration–accumulation coefficient were innovatively introduced into the new methodology based on helium genesis theories. Furthermore, methods for determining the values of various parameters were proposed through field observations and laboratory analyses. Finally,the new methodology was applied to the Jinzhong Basin for verification. [Results and Conclusions] A formula for calculating helium resources based on the genesis method was established, and methods for determining the parameters in the formula were also proposed. Experiments and calculations of representative helium-rich basins and gas fields in China and abroad reveal that various helium source rocks exhibit helium expulsion coefficients exceeding 80% and that stable helium accumulation systems show a maximum migration-accumulation coefficient of 3.7%. The new methodology was applied to the Jinzhong Basin, revealing that the total amount of generated helium from helium source rocks in the basin is 55.6 billion m~3 and that the helium resources produced by the helium accumulation systems since their formation are 0.34 billion m~3. The proposed methodology enriches the helium resource evaluation system of China, providing a methodological basis for helium resource evaluation in areas undergoing limited helium exploration. Medium-small basins in China, exemplified by the Jinzhong Basin, generally contain helium and thus hold great helium resource potential. These basins are expected to become significant potential regions for achieving helium exploration breakthroughs in the future.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 3421K]

  • Diagnosis, prevention, and control of liquid accumulation in horizontal wellbores for deep coalbed methane: A case study of the Daning-Jixian block along the eastern margin of the Ordos Basin

    ZENG Wenting;WANG Zhiming;ZHANG Lei;TIAN Zhida;ZHEN Huaibin;DAI Anna;ZENG Quanshu;SUI Tianyang;College of Petroleum Engineering, China University of Petroleum (Beijing);National Engineering Research Center of China United Coalbed Methane Co., Ltd.;

    [Objective] The Daning-Jixian block on the eastern margin of the Ordos Basin has achieved large-scale production of deep coalbed methane(CBM), with nearly 150 horizontal wells having been put into production. However,with a gradual decrease in formation energy during CBM production, gas wells exhibit declining liquid-carrying capacity. Consequently, liquid accumulation in wellbores has become a major factor affecting deep CBM production. Recovery of deep CBM shows the coexistence of free and desorbed gases, accompanied by significantly varying gas/liquid ratios. Moreover, gas production channels and techniques vary in different production stages. Hence, there is an urgent need to develop a method for liquid accumulation diagnosis and prediction that is suitable for the production characteristics of horizontal wells for deep CBM, aiming to provide a basis for the prevention and control of liquid accumulation and to avoid damage to reservoirs and their productivity caused by liquid accumulation. [Methods and Results] Using the Reynolds-averaged Navier-Stokes(RANS) κ-ε equation for incompressible viscous fluids and the volume of fluid(VOF) method, as well as the physical simulation experimental results of gas-liquid two-phase flow in a circular tube and an annulus, this study developed a numerical model of gas-liquid two-phase flow in horizontal wells for deep CBM utilizing the Fluent computational fluid dynamics tool and its secondary development. Based on the numerical simulation results, this study plotted the gas-liquid two-phase flow patterns in horizontal wells under different wellbore pressures, different inclinations, along with the circular tube and annulus conditions. Furthermore, this study established the corresponding relationship between the flow pattern and liquid accumulation based on the regularity and pattern evolution of gas-liquid two-phase flow in the production process. The results indicate that bubble and slug flows correspond to the liquid accumulation state. In contrast, churn flow corresponds to the transition state where liquid accumulation will occur, while annular flow corresponds to the state with no or low risk of liquid accumulation. Additionally, the well inclination is directly proportional to the liquid accumulation risk, whereas the pressure is inversely proportional to the risk. [Conclusions] The flow pattern chart board-based method for diagnosing liquid accumulation proposed in this study was applied to the horizontal wells for deep CBM in the Daning-Jixian block, providing guidance for proposing the intervention timing, taking control measures in time, with the efficiency of measures having been improved. In subsequent studies, this method will be optimized for intelligent analysis and prediction using artificial intelligence(AI)techniques. This will provide robust technical support for the prediction, prevention, and control of liquid accumulation in CBM wellbores.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 2370K]

  • Injection-production process parameters of well group configurations for autothermic pyrolysis in situ conversion of oil shale

    ZENG Yijian;ZHU Chaofan;LI Yanwei;SHUI Haoche;GUO Wei;State Key Laboratory of Deep Earth Exploration and Imaging, College of Construction Engineering, Jilin University;National-Local Joint Engineering Laboratory of In-situ Conversion, Drilling and Exploitation Technology for Oil Shale;Provincial and Ministerial Co-construction of Collaborative Innovation Center for Shale Oil &Gas Exploration and Development;Key Lab of Ministry of Natural Resources for Drilling and Exploitation Technology in Comp

    [Background] A well group acts as a multi-well synergistic unit, and its configuration directly determines both the selection of optimal injection–production process and the utilization efficiency of stratigraphic conditions, ultimately affecting the overall performance of resource recovery. [Methods] Using numerical simulations, this study assessed the performance of autothermic pyrolysis in situ conversion(ATS) under three vertical well group configurations:one injection well and one production well(1I1P), one injection well surrounded by four production wells(1I4P), and one injection well surrounded by six production wells(1I6P). Furthermore, it revealed the synergistic mechanisms between well group configuration and energy efficiency. [Results and Conclusions] Considering drilling costs, ATS under the 1I4P configuration showed the highest comprehensive efficiency. During the thermal excitation phase of ATS, a gas injection rate of 400 m~3/h for preheating exhibited optimal energy efficiency under consistent temperature of preheating gas and duration. During the autothermic reaction control stage, a gas injection rate of less than 200 m~3/h failed to initiate the autothermic pyrolysis reaction, while an excessive rate exceeding 1 000 m~3/h interrupted the reaction process.Within the effective injection rate range, a gas injection rate of 400 m~3/h yielded the optimal energy return ratio. The comparison of the performance of the 1I4P well pattern under varying well spacing values reveals that 25-meter spacing between the injection and production wells yielded high comprehensive energy efficiency. In this case, strata with a low oil content of 4% can be effectively developed using ATS, yielding an ideal energy ratio. Through joint optimization of well spacing and gas injection parameters, the development of field-scale oil shale through ATS yielded a peak energy return ratio of 8.85 after 3.7 years and a cumulative oil production of 10 519.5 t over four years. Moreover, ATS exhibited high economic viability in terms of average operating cost per barrel while contributing to the preservation of a considerable amount of available residual heat. The findings of this study provide support for the industrial application of the in situ conversion of oil shale by offering both a theoretical basis for well group configuration design and an economic assessment framework.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 3717K]

  • Molecular simulations of selective adsorption of lithium in the No.6 coal seam, Junggar Coalfield

    ZHANG Junshuang;SUN Beilei;ZHANG Bin;LIU Chao;College of Geological and Surveying Engineering,Taiyuan University of Technology;Key Laboratory of Coal Science and Technology,Ministry of Education,Taiyuan University of Technology;College of Mining Engineering,Taiyuan University of Technology;Key Laboratory of In-situ Property-improving Mining of Ministry of Education,Taiyuan University of Technology;

    [Objective] With the discovery of metal deposits in coal-bearing strata, the distribution and occurrence patterns of lithium in coals have attracted much attention. However, its partitioning mode between organic structures and minerals in coals remains poorly understood. [Methods] This study investigated typical coals with a high lithium content in the Junggar Coalfield in Inner Mongolia. By integrating multiple simulation methods, including quantum mechanics, Monte Carlo simulation, and molecular dynamics, this study established the structural models of organic matter and inorganic minerals, as well as a visualized lithium-coal molecular structure model. Accordingly, it investigated the preferential adsorption sites on both organic matter and minerals for lithium and explored the impacts of mineral types and the metamorphic grade of organic matter on lithium adsorption during coalification and heating. [Results] In organic matter of coals, carboxyl groups were identified as the preferential adsorption sites for lithium ions, with the adsorption capacities of different functional groups for lithium ions decreasing in the order of carboxyl groups, hydroxyl groups,pyrrole, carbonyl groups, pyridine, and benzene rings. In the kaolinite structure, the center of the six-membered ring containing oxygen atoms within silicon-oxygen tetrahedra emerged as the preferential adsorption sites for lithium. In the case where organic matter, kaolinites, and illites coexisted, kaolinites exhibited a stronger adsorption capacity for lithium than illites under the same temperature. Meanwhile, illites showed a higher capacity to bind organic matter than kaolinites. With increasing metamorphic grade of coals, the adsorption capacity of organic matter for lithium gradually decreased. [Conclusions] During coalification and heating, lithium experiences repartitioning between organic matter and minerals. The evolution of its occurrence state is difficult to be directly revealed using experiments. In contrast, molecular simulations can provide abundant molecular-scale information that is difficult to obtain through experiments, thereby providing important theoretical support for the exploration, exploitation, and utilization of lithium resources in coal-bearing strata.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 3110K]

  • Analysis of the connotation of hidden disaster-causing factors in coal mines and the key points of their reconnaissance

    LIAN Huiqing;WANG Xu;YIN Shangxian;XIA Xiangxue;CAO Min;LI Qixing;WU Xiaoming;ZHANG Bin;WANG Yangyu;ZHANG Qing;WANG Guo'an;Hebei Key Laboratory of Mine Disaster Prevention and Control,North China Institute of Science and Technology;Hebei Technology Innovation Center for Intelligent Emergency Response to Multi-Scenario Water Disaster Chain Accidents,North China Institute of Science and Technology;College of Geology and Environment,Xi'an University of Science and Technology;Huangyuchuan Coal Mine,

    [Background] To systematically normalize the reconnaissance of hidden disaster-causing factors in coal mines, the National Mine Safety Administration issued the Specification for General Survey of Hidden Disaster-causing Factors in Mine in 2024. Nevertheless, coal mining enterprises still face a range of notable issues in reconnaissance of hidden disaster-causing factors, including ambiguous connotations of the factors, broad scopes of reconnaissance, unclear implementation stages, a disjunction between explorations and reconnaissance, and improper conclusion descriptions. These problems severely restrict scientific and operational reconnaissance. [Methods] This study reviews the history of research on the reconnaissance of hidden disaster-causing factors, presents a summary of significant technical achievements across various development stages, and analyzes existing issues, especially critical technical and scientific issues. Furthermore, this study proposes future c in the industry, as well as primary technical and theoretical orientations to address the challenges. [Advances] This study holds that hidden disaster-causing factors consist merely of geologic and mining factors, which can be further categorized into five major types: coal seam storage conditions, geobodies, geological structures, mining, and others. Regarding general-survey implementation stages, this study proposes that the traditional survey mode with three years as a cycle should be replaced by a progressive approach, which comprises regional exploration before shaft construction, supplementary exploration before coal mining, detailed survey prior to panel design, integrated exploration and treatment before mining, and dynamic supplementary survey during mining. This approach emphasizes the dynamic evolution of the reconnaissance and treatment of hidden disaster-causing factors, enabling the dynamic coordination between mining engineering and disaster prevention and control. This study recommends that it is necessary to establish a data assessment mechanism for hidden disaster-causing factors, i.e., directly citing verified factors, partially verifying questionable factors, and comprehensively exploring unknown factors. This helps achieve efficient coordination between explorations and reconnaissance while avoiding redundant efforts. Moreover, this study proposes a standardized reconnaissance process comprising general provisions, data analysis, field exploration,risk assessment, and conclusions and suggestions. [Prospects] In China, complex geological structures underscore the critical role of exploring hidden disaster-causing factors in coal mining. With scientific advancements and the demand for transparency and intelligent mining of coal mines, it is necessary to develop a region-mine-coal seam assessment system for hidden disaster-causing factors and to promote the dynamic coordination between mining operations and disaster prevention and control. This helps provide a geological guarantee for safe coal mining and a scientific guide for reconnaissance of hidden disaster-causing factors in coal mines, holding great significance for enhancing the disaster prevention and control capability of coal mines.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 1709K]

  • Process and mechanism of defluorination using magnesium chloride-modified coal gangue

    ZHAO Li;ZHOU Wangxu;ZHANG Qing;XING Mingfei;XU Feng;KONG Weifang;LIU Yifei;QIN Guangyu;Henan Key Laboratory of Coal Measure Unconventional Resources Accumulation and Exploitation, School of Resources and Environment, Henan Polytechnic University;Shaanxi Key Laboratory of Prevention and Control Technology for Coal Mine Water Hazard;

    [Background] The rapid development of industry has resulted in a yearly increase in wastewater discharge,which induces a gradually rising fluorine concentration in water. In this context, removing fluoride using natural materials and industrial waste has emerged as a popular research topic. Coal gangue, one of the largest contributors to industrial waste in China, contains substantial clay minerals, and its pore structure can be effectively improved through modification. This helps significantly enhance its adsorption performance and thus achieve efficient fluoride removal from water. [Methods] This study investigated coal gangue from a typical mining area of the Henan Energy and Chemical Industry Group Co., Ltd., accompanied by wastewater with a high fluoride concentration of 200 mg/L. The modification conditions of coal gangue were initially determined through single factor experiments. In combination with the characterization and analysis using scanning electron microscopy(SEM) and organic element analysis, this study comprehensively investigated the adsorption patterns of fluorides by modified coal gangue and underlying defluorination mechanisms. [Results and Conclusions] Original coal gangue and magnesium chloride(MgCl_2) were evenly mixed at a mass ratio of 1∶0.25 and were then roasted at 450 ℃ for 1.5 h, yielding coal gangue-based defluorination materials. Subsequently, oscillatory adsorption experi-ments were carried out under a fluoride solution-to-coal gangue ratio of 20∶1, a temperature of 25 ℃, and a rotation speed of 120 r/min, yielding a defluorination rate of up to 94.451%. These experiments, as well as characterization and analysis, reveal that primary adsorption processes of modified coal gangue for fluoride ions include electrostatic adsorption, hy-drogen bonding, ion exchange, and precipitation combined with complexation. Brucite peaks were observed within the modified coal gangue. Meanwhile, mica-bearing materials and partial kaolinites transitioned into amorphous sili-con-aluminum compounds, while some kaolinites transformed into illites. All these enhanced the electrostatic adsorption and ion exchange within the coal gangue. Beryllium fluoride was observed in the coal gangue post-adsorption, corrobo-rating the adsorption of the modified coal gangue for fluoride ions. Furthermore, the post-adsorption coal gangue exhib-ited a looser overall morphology, elevated specific surface areas, and a slight increase in the relative content of metal ox-ides. These create favorable conditions for metal oxides to remove fluoride ions from water through hydrogen bonding and precipitation combined with complexation. The results of this study provide an important theoretical basis for pre-paring coal-gangue-based agents to treat wastewater.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 2110K]

  • Sedimentary environments and microscopic water control patterns in the Luohe Formation,Gaojiapu Coal Mine, Binchang mining area

    LI Xiaolong;CCTEG Xi'an Research Institute (Group) Co.Ltd.;Shaanxi Provincial Geological Survey Institute;College of Geology and Environment, Xi'an University of Science and Technology;Water Disaster Control Branch Laboratory, National Key Laboratory of Coal Mine Disaster Prevention and Control;

    [Objective and Method] The exploration of the Luohe Formation, located on the roof of the Huanglong Jurassic coalfield, faces challenges such as a lack of consensus on the sedimentary environments of sandstone aquifers and unclear lithologies with water yield properties in the aquifers. To address these challenges, this study investigated sandstones in the Luohe Formation in the Gaojiapu Coal Mine, Shaanxi Province. Specifically, a comprehensive analysis of core samples with different lithologies was conducted, including colors, lithologies, lithologic assemblages, the surface morphology of quartz grains, mineral components, and sedimentary structures and textures. Based on analytical results, as well as the grain size parameters, this study comprehensively analyzed the sedimentary environments of the samples.Through gas measurements and weighing under water saturation, this study measured the permeability, porosity, and saturated water content of sandstones with different lithologies and sedimentary environments throughout the Luohe Formation. Using nuclear magnetic resonance(NMR) and computed tomography(CT) scanning, this study investigated the microscopic pore structures of six types of sandstones, including gravelly and coarse-grained sandstones, in the Luohe Formation. By combining the characterization results of sedimentary environments, porosity, and permeability, this study comprehensively explored the microscopic water control patterns of various intervals of the Luohe Formation. [Results and Conclusions] The upper part of the Luohe Formation is purplish-red or brownish-red, interbedded with grayish-white gravelly sandstones. In contrast, its middle part is purplish-red or brownish-red, interbedded with white gravelly sandstones, while its lower part is brownish-red, interbedded with thin layers of grayish-white gravelly sandstones at the bottom. The detrital grains of the sandstones exhibit saucer-shaped impact pits, and large planar cross-bedding is observed in the sandstones, indicating an aeolian sedimentary environment. Primary minerals in the sandstones include quartz, feldspar, calcite, and clay minerals. Besides, at the bottom of the Luohe Formation in the study area, brownish-red mudstones are found to contain substantial analcimes. Therefore, the lower part of the Luohe Formation exhibits typical lacustrine sedimentary facies, and a sedimentary system consisting of alternating aeolian and aquatic deposits occurs throughout this formation. The sandstones in the formation exhibit saturated water content ranging from 2.87% to 11.84%, porosity from6.87% to 23.91%, and effective porosity from 2.32% to 12.79%. They primarily show large pores, followed by mesopores, with micro-fractures observed in fine-grained and coarser sandstones. Overall, the sandstones have pore sizes primarily ranging from 34.57 μm to 180.00 μm. Primary lithologies with water yield properties include coarse-to finegrained sandstones. In contrast, silty sandstones exhibit weak water yield properties, while the aqueous gravelly sandstones show the weakest water yield properties. The upper part of the formation exhibits a lower proportion of gravelly sandstones than the middle part. This part consists primarily of coarse-to fine-grained sandstones, with silty sandstones and mudstone roughly lacking. Therefore, the upper part features strong water yield properties. The upper and middle parts contain thick layers of the alluvial facies as markers, exhibiting the lowest porosity, effective porosity, and saturated water content. Furthermore, the middle part is dominated by medium-and fine-grained sandstones. In this part, the aqueous medium-grained mudstones show low porosity and effective porosity, and the proportions of mudstones and silty sandstones increase significantly. Consequently, the middle part shows weaker water-yield properties than the upper part.The lower part is dominated by thick layers of mudstones, interbedded with silty sandstones, also featuring weak wateryield properties. The results of this study provide a theoretical basis for identifying the water yield properties of the Luohe Formation while also serving as a guide for water hazard prevention and control in mines.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 3659K]

  • Water filling intensity assessment of a coal seam roof in the Dahaize Coal Mine,northern Ordos Basin

    LIU Xi;DING Xiang;HUANG Haiyu;LI Zhaoyang;LI Zhe;ZHENG Sheng;China Coal Energy Research Institute Co., Ltd.;Shanxi Yulin Energy Chemical Co., Ltd.of China Coal;

    [Background] Assessing water filling intensity in coal seam floors lays a foundation for the prevention and control of water hazards in mines. However, in the Jurassic coalfield in the northern Ordos Basin, complex hydrogeological structures and sedimentary heterogeneity pose severe challenges to traditional evaluation methods. [Methods] This study investigated the water hazard characteristics in the superimposed aquifers of the Jurassic Yan'an and Zhiluo formations in the Dahaize Coal Mine in northern Shaanxi. The purpose is to establish a zoning and assessment system of water filling intensity that is suitable for continental sedimentary settings and to provide a scientific basis for the prevention and control of water hazards in mines. Based on the law of sedimentary water control, this study determined five primary control indices(i.e., aquifer thickness, index of sedimentary environment quantitation, core recovery, permeability coefficient, and index of mining-induced aquifer damage) from the perspective of lithological, hydraulic, and mining characteristics. Subsequently, the weights of the five indices were determined at 0.270, 0.155, 0.059, 0.349, and 0.168, respectively using the analytic hierarchy process(AHP) method. In combination with GIS technology, this study performed normalization and spatial overlay analysis of the multi-source data, establishing a zoning-integrated dual assessment model. [Results and Conclusions] The third member of the Yan'an Formation exhibits high water filling intensity in the south and low in the north, and the reverse is true for the first member of the Zhiluo Formation. Using the Jenks natural breaks classification method, the superimposed water filling intensity was divided into five grades: very weak, weak,moderate, strong, and very strong, with the strong grade and above primarily distributed in the west-central and northeastern parts of the mining area. Verification using the water inflow data of mining faces 20101 and 20201 reveals a high degree of spatial match between the measured water inflow and the predicted zoning results, corroborating the reliability of the proposed model. The proposed zoning and evaluation method for water filling intensity of coal seam roofs in the Dahaize Coal Mine effectively overcomes the limitations of traditional homogenous models in terms of their limited suitability for discontinuous sand bodies and layered seepage mechanisms. This method provides a quantitative basis for decision-making in the prevention and control of water hazards in deep Jurassic coalfields, holding great value in widespread applications.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 11005K]

  • Geothermal resource assessment of the eastern Da'an area based on 3D geothermal geological modeling

    CHEN Wenwen;RAO Song;MENG Boyan;GUO Menghao;LUO Yang;CAI Jiahao;LI Wenjing;ZHANG Qiaoran;TANG Yucong;School of Geosciences, Yangtze University;Hubei Key Laboratory of Complex Shale Oil and Gas Geology and Development in Southern China, Yangtze University;Geothermal Comprehensive Utilization Engineering Research Center of Changjiang Design Group Co., Ltd;Oil Production Technology Research Institute,PetroChina Xinjiang Oilfield Company;Research Institute of Exploration and Development,Jilin Oilfie

    [Objective] The Da'an area in Jilin Province, located in the southwestern Central Depression of the Songliao Basin, exhibits significant geothermal anomalies, which suggest substantial potential for geothermal exploitation.However, there remains a lack of detailed geothermal resource assessment of this area. Among conventional assessment methodologies, the volumetric method fails to accurately characterize irregular stratigraphic geometries and the spatial heterogeneity of parameters, while the Monte Carlo method suffers from limitations such as heavy dependence on the probability distribution models of geothermal reservoir parameters. [Methods] To overcome the limitations of the conventional methods, this study established a 3D geothermal geological model by integrating regional geology, drilling data, and the thermophysical properties of reservoir rocks. Through 3D simulations of steady-state geothermal fields, this study characterized the temperature field distributions at depths of less than 2 600 m in the eastern Da'an area. Then, using the finite volume method, it assessed geothermal resources in three major Upper Cretaceous geothermal reservoirs:the fourth member of the Nenjiang Formation(K_2n~4), the second-third members of the Yaojia Formation(K_2y~(2+3)), and the second-third members of the Qingshankou Formation(K_2qn~(2+3)). [Results and Conclusions] The results indicate that the formation temperatures at depths of 500 m, 1 000 m, 1 500 m, 2 000 m, and 2 500 m in the study area measure25.8–36.4 ℃, 48.6–61.3 ℃, 63.1–84.6 ℃, 79.3–107.1 ℃, and 94.4–125.6 ℃, respectively. The geothermal contour lines are dense in the southwest and sparse in the northeast, with temperature distribution patterns roughly consistent across varying depths. In other words, the formation temperature is high in the northeast and low in the southwest. The geothermal reservoirs in K_2n~4, K_2y~(2+3), and K_2qn~(2+3) exhibit temperatures of 27.0–67.3 ℃, 38.2–96.7 ℃, and 43.2–103.58 ℃,respectively. Using the finite volume method, the geothermal resources in K_2n~4, K_2y~(2+3), and K_2qn~(2+3) were calculated via integration by units, yielding 19.2×10~(18) J, 30.4×10~(18) J, and 47.3×10~(18) J, respectively, which are equivalent to 6.55×10~8tonnes of coal equivalent(tce), 10.37×10~8 tce, and 16.14×10~8 tce, respectively. Using 25% as the recovery factor, recoverable resources of K_2n~4, K_2y~(2+3), and K_2qn~(2+3) are estimated at 1.64×10~8 tce, 2.59×10~8 tce, and 4.04×10~8 tce, respectively.Compared to the traditional volume method and Monte Carlo method, the combination of the finite volume method and numerical simulation technique enjoys unique advantages in geothermal resource assessment.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 7463K]

  • High-precision reconstruction of seismic data based on improved U-Net++

    WANG Minling;ZHOU Fei;WANG Honghua;HE Xiang;HOU Zhiyang;School of Geosciences, Guilin University of Technology;

    [Objective] Conventional reconstruction methods are insufficient for the reconstruction of seismic data with missing consecutive traces, producing a negative impact on subsequent processing accuracy. Hence, this study proposed CU-Net++, a deep learning network based on the U-Net++ architecture combined with the convolutional block attention module(CBAM). [Methods] During the reconstruction of missing data, the independent decoder for each sub-U-Net in the nested U-Net++ architecture enables the utilization of information from different depths. The long and short skip connections can effectively enhance the network's capability to extract multi-scale features from data. The core innovation of CU-Net++ is the introduction of CBAM, which can enhance the capacity to learn about seismic wave details and edge information, into the U-Net++. This helps improve the network's ability to identify and capture complex seismic wave characteristics. Through the reconstruction tests of simulated and measured data, this study presented a comparative analysis of the reconstruction effects for missing seismic data of the CU-Net++, U-Net++, CU-Net, U-Net, and curvelet-domain projection onto convex sets(POCS) methods from the perspective of F-K spectrum, residual profile,single-trace waveform, mean absolute error(MAE), signal-to-noise ratio(SNR), and peak signal-to-noise ratio(PSNR).[Results and Conclusions] CU-Net++ delivered the optimum overall performance across various assessment metrics,yielding the lowest reconstruction error. Compared to U-Net++, it reduced the MAE by approximately 51% and improved the SNR and PSNR by 5.87 dB each. Notably, CU-Net++ enables high-precision construction of seismic data with a proportion of consecutively missing traces not exceeding 12%.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 5512K]

  • Attenuation characteristics and wave impedance inversion of depth-domain nonstationary seismic data

    MA Ming;MA Feng;Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences;Technology Innovation Center for Geothermal & Hot Dry Rock Exploration and Development,Ministry of Natural Resources;

    [Background] The efficient application of depth migration methods has enabled the extensive implementation of depth-domain seismic data interpretation. Previous studies on the impacts of time-to-depth conversion and velocity models merely determine that an increase in depth corresponds to reduced dominant wavenumber of seismic waves and waveform stretching, without considering the changes in amplitude and phase. [Objective] This study aims to accurately characterize the waveforms of nonstationary seismic signals in the depth domain and enhance the impedance inversion accuracy. [Methods] First, based on energy dissipation and frequency dispersion effects during the propagation of seismic waves, this study investigated the complex mapping relationship between nonstationary seismic reflected waves and formation impedance and introduced the Q model that reflected the absorption attenuation of strata for seismic waves. Nonstationary convolution formula for seismic reflection data were proposed to simultaneously describe the amplitude attenuation, phase distortion, and decrease in the primary wavenumber of seismic waves. Accordingly, the impedance inversion equation was established under spatial constraints. Second, this study estimated the Q model for strata using deep learning technology. The multi-head self-attention mechanism was introduced into the network structure, allowing for the extraction of accurate attenuation characteristics of depth-domain seismic signals. The assumption of a known Q model in the conventional inversion process was abandoned. Instead, some synthetic data were employed for network training and validation, ensuring the convenient implementation of the estimation method. Third, the depth-varying seismic wavelets were calculated using Q values yielded from the network, and the multi-trace impedance inversion method based on the sparsity constraint from the l_p norm was employed. Ultimately, the high-resolution absolute impedance data volume in the depth domain was determined. [Results and Conclusions] Validation using the Pluto model demonstrated that the Q model and nonstationary inversion achieved using deep learning technology yielded a relative error in impedance of 13.7%, suggesting significantly improved inversion accuracy compared to the results of conventional stationary inversion(48.2%). Tests using field seismic data from an exploration area of the Jinzhong coalfield indicate that deep-domain nonstationary seismic inversion technology can capture the physical property parameters of subsurface media more intuitively and accurately. The impedance determined using the inversion technology showed a high similarity of 0.948 8 to the impedance curve determined based on log data, thus avoiding instability caused by multiple processing steps such as inverse Q filtering and recursive inversion. The results of this study provide depth-domain stratigraphic information for reference in subsequent seismic interpretation.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 2669K]

  • A collocation point sampling method for solving the Helmholtz equation using physics-informed neural networks

    SHAN Lianpu;YU Caixia;WANG Yanfei;Key Laboratory of Deep Petroleum Intelligent Exploration and Development, Institute of Geology and Geophysics, Chinese Academy of Sciences;College of Earth and Planetary Sciences, University of Chinese Academy of Sciences;

    [Background] In the field of seismic wavefield simulation, physics-informed neural networks(PINNs) have emerged as a new method for efficiently solving the Helmholtz equation due to their characteristic of grid-free computation. However, for the forward modeling of complex medium models using the Helmholtz equation, traditional uniform grid-based methods for collocation point sampling are insufficient to efficiently provide gradient information, leading to prolonged training time and high resource consumption. [Objective and Method] To improve the forward modeling efficiency and accuracy based on PINNs and overcome the anomalous concentration of collocation points in the seismic source during dynamic sampling, this study proposed a hybrid residual-based adaptive distribution(RAD-H) method and then compared this method with six fixed and four dynamic sampling methods. In the RAD-H method, fixed sampling is employed for the seismic source area to ensure the capture of the source features, and residual-based adaptive distribution(RAD) is used for other areas to ensure the consistency between the resampled collocation points and the spatial sampling of the high-residual target area. [Results] Numerical experiments indicate that for a homogeneous medium model, the RAD-H method reduced the L2 error of the wavefield by 3.050% using only 18.57% of collocation points compared to the classical baseline method. Moreover, the RAD-H method exhibited a model training time of approximately 4 192.5 s, suggesting an improvement of 231.74% in computational efficiency compared to the classical baseline method. For the Marmousi2 model, the RAD-H strategy remained the error within the same order of magnitude as the classical baseline method while reducing the number of collocation points by 57.75%. [Conclusions] The RAD-H method overcomes oversampling for seismic source areas and undersampling for other areas of other dynamic sampling methods, significantly enhancing the sampling efficiency of collocation points of PINNs during the forward modeling involving seismic sources. This study holds significant implications for efficient, high-precision wavefield simulation of complex geological models.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 2029K]

  • Application of geophysical logging to selection of optimum target horizons for salt cavern storage: A case study of borehole ZK01 in Qingjiang Salt Mine, Jiangxi Province, China

    LIU Dongming;LIN Zhenzhou;LIU Dongyan;QIU Changyi;LIANG Mingxing;ZHAI Jinghong;ZHANG Jie;JIANG Zhengzhong;State Key Laboratory of Deep Earth Exploration and Imaging, Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences;Laboratory of Geophysical EM Probing Technologies, Ministry of Natural Resources;State Research Center of Modern Geological Exploration Engineering Technology;Beijing Urban and Rural Construction Survey and Design Institute Co., Ltd.;The Fir

    [Background] Under the guidance of the strategies to achieve the goals of peak carbon dioxide emissions and carbon neutrality, salt cavern storage facilities, serving as key infrastructure for clean energy strategic reserves, have emerged as a core approach to promoting the transformation and upgrade of the salt industry and to building a low-carbon energy system in China. Jiangxi Province, located in the middle part of the Yangtze River Economic Belt, is endowed with abundant salt rock resources, making it a national priority zone for developing resources for salt cavern storage. However, traditional methods for the siting of the facilities rely on drilling and coring, facing bottlenecks such as high costs and inadequate vertical continuity assessment. Therefore, there is an urgent need to develop efficient and precise geological evaluation techniques to provide support for the scientific siting of salt cavern storage. [Objective and Method] This study investigated the borehole ZK01 used for the preliminary feasibility study of the salt cavern storage project of the Qingjiang Salt Mine. By integrating multiparameter geophysical logging and the geological records of cores, this study systematically analyzed the structural characteristics of salt-bearing strata and selected the optimum target horizons for salt cavern storage. By highlighting the identification of the log response characteristics of varying lithologies, this study established a mineral composition inversion model and extracted key parameters including ore-bearing coefficient, ore grade, interlayer distribution, and the properties of roof, floor, and cap rocks. [Results] The salt rocks showed typical log responses characterized by low gamma-ray(GR) values, low sonic interval transit time, low compensated neutron log(CNL) values, and high three lateral resistivity. In contrast, the mudstones showed log responses featuring high GR values, high CNL values, high sonic interval transit time, and low three lateral resistivity. Additionally, the transition rocks exhibited a continuously gradational trend in their petrophysical property parameters. Compared to curve overlapping and reconstruction methods, the GR-CNL cross plots significantly enhanced the lithological identification efficiency, achieving semi-quantitative identification of four lithologies. The interval at depths ranging from 906 m to 1 095 m exhibited an ore-bearing coefficient of 51.1%, an average NaCl grade of 69.46%, a predominance of 2-4-m-thick mudstone interlayers, thick mudstone roof and floor, and tight salt rocks as cap rocks. Therefore,this interval was identified as the optimum target horizon for salt cavern storage. [Conclusions] Geophysical logging technique enables the quantitative characterization of the structural characteristics and mineral assemblages of salt-bearing strata, providing key geological parameters and a basis for scientific decision-making for the siting of salt cavern storage. This methodology proves universally applicable to salt-bearing basins with high tectonic stability and simple mineral assemblages. For areas with complex geological settings, it is necessary to conduct adaptive optimization using high-resolution logging techniques.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 4266K]

  • Anomalous responses of coal seam mining face floor derived based on stress-induced failure modeling and 3D direct current electric method

    GAO Weifu;ZOU Xu;NIU Chao;XIAO Lele;ZI Jianxiao;College of Energy and Mining Engineering,Shandong University of Science and Technology;College of Geology and Environment,Xi'an University of Science and Technology;Liangbaosi Energy Co.,Ltd.,Luxi Mining Group;

    [Objective] In recent years, floor water inrushes have frequently occurred in North China-type coalfields. To address this challenge, determining the anomalous responses of water inrushes from stope floors has emerged as a focus of research on water disaster prevention and control. [Methods] This study established a stress model of the stope floor based on the mine pressure theory. Using this model, it analyzed the stress distribution and failure characteristics of the stope floor. The floor failure characteristics revealed that the coal seam floor can be divided into three zones: the compression, expansion, and recovery zones. Through stress-resistivity tests, this study investigated the resistivity variation patterns of rock samples under the loading, failure, and recovery states and simulated the resistivity variations in the compression, expansion, and recovery zones in the mining face floor, thus determining the resistivity in the three zones.In combination with the resistivity variations of field strata, this study established a dynamic 3D geoelectric model to examine the spatiotemporal evolution of the floor resistivity during different mining stages. Using procedures of the 3D direct current electric method, this study conducted forward modeling and inversion using the geoelectric model and prepared 3D resistivity plots of the anomalous responses from the mining face floor. Accordingly, this study investigated the anomalous responses from the mining face floor and summarized the anomalous response characteristics during the mining face advancement. [Results] As the mining face advanced for 20 m, a stress anomaly zone and a low-resistivity anomaly zone appeared in the geoelectric model. The stress anomaly zone appeared in front of the mining position of the working face. It primarily influenced shallow strata, disappearing with increasing depth. In contrast, the low-resistivity anomaly zone primarily affected deep strata while producing no impact on shallow strata. When the mining face advanced for 30 m, the stress anomaly zone moved forward as well. Consequently, the stress anomaly zone was connected to the low-resistivity anomaly zone, accompanied by the continuous expansion of the low-resistivity anomaly zone and a constant decrease in the apparent resistivity. As a result, significantly low resistivity anomalous responses occurred, indicating an increased possibility of water inrushes from the mining face floor. When the mining face advanced for 50 m,two low-resistivity anomaly zones were observed along the mining face. Among these, one was identified as a stress-induced low-resistivity anomaly zone, moving forward as the mining face advanced. Another low-resistivity zone was found in the goaf. This area was characterized by a large range and extremely low apparent resistivity, which differed significantly from that of the surrounding rocks. This suggests an extremely high possibility of water inrushes from the mining face floor. [Conclusions] During the advancement of the mining face, the characteristics of stress and low-resistivity anomalous responses can be observed. Among them, the stress anomalous responses show a limited influence range, keeping moving forward as the mining face advances. In contrast, low-resistivity anomalous responses exhibit a wide influence range and a significantly different apparent resistivity from the surrounding rocks. These responses keep expanding as the mining face advances. Prevention and control measures should be taken in time to prevent water inrushes from the mining face floor.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 2621K]

  • Technologies and equipment for efficient drilling rescue

    YAO Ningping;ZOU Zujie;ZHANG Zhonghai;ZHAO Jiyun;HAO Shijun;FAN Dong;DOU Bin;CCTEG Xi'an Research Institute (Group) Co.,Ltd.;Xuzhou Xugong Foundation Construction Co.,Ltd.;School of Mechanical and Electrical Engineering,China University of Mining and Technology;School of Engineering,China University of Geosciences;

    [Objective] In China, mining operations are progressively extending to greater depths, with annual tunneling of mine roadways and tunnels nationwide reaching nearly 20000 km. In this context, mine(tunnel) accidents occur frequently, threatening the safety of state property and people's lives. To meet the great demand for emergency rescue in mine(tunnel) accidents, drilling rescue, emerging as a hot topic, has been employed as an effective approach. [Methods]Techniques and equipment for efficient and safe drilling of surface and underground(tunnel) rescue boreholes were investigated by centering on two main roadmaps:(1) surface rescue equipment – forming techniques for search and rescue boreholes-engineering trials, and(2) underground rescue equipment-forming techniques for horizontal rescue boreholesengineering trials. Consequently, the technical challenges in the efficient drilling and forming of deep rescue boreholes have been addressed by developing(1) a high-power truck-mounted surface rescue drilling rig, which allows for self-adaptive drilling, and a rapid rod changing device,(2) efficient drilling techniques of three-stage one-trip drilling for surface search boreholes and the gas-liquid dual-circulation drilling for rescue boreholes, as well as associated drilling tools,and(3) casing welding robots. These techniques and devices can meet the need for efficient forming of search and rescue boreholes. Furthermore, the technical difficulties in efficiently breaking rocks under complex collapse conditions and in borehole protection while drilling were resolved by developing underground modular casing while drilling(CwD) rigs for large-diameter boreholes, multi-functional operation vehicles, belt conveyors, rescue capsules, and a drilling site protection system. These devices enable the rapid construction of horizontal rescue passages. [Results and Conclusions]Two sets of integrated drilling rescue equipment have been developed: a surface truck-mounted drilling rig and an underground CwD rig. Furthermore, two rescue borehole drilling techniques have been devised, i.e., efficient forming techniques for surface vertical rescue boreholes and underground horizontal large-diameter rescue boreholes. These sets of equipment and techniques constitute a technology and equipment system for surface and underground joint drilling rescue. They have been subjected to joint commissioning, engineering tests, and integration trials at sites in Wuxiang of Shanxi Province, Xuzhou of Jiangsu Province, Shangluo of Shaanxi Province, and Yuxi of Yunnan Province, verifying their reliability, applicability, and safety. These techniques and equipment will support mine rescue in China.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 4745K]

  • A modular casing while drilling rig for large-diameter horizontal boreholes for underground rescue

    FAN Dong;NI Xiaoyang;MU Shuyuan;ZOU Zujie;WEN Guojun;LI Yingping;LU Feifei;College for Elite Engineers,China University of Geosciences;CCTEG Xi'an Research Institute (Group)Co.,Ltd.;School of Engineering,China University of Geosciences;China Railway No.2 Bureau Kunming Team,National Tunnel Emergency Rescue;China Railway No.2 Engineering Group Co.,Ltd.,Rescue Subsidiary Company;School of Mechanical Engineering and Electronic Information,China University of Geosciences;

    [Objective] Operations in a narrow space pose a challenge to rescue in the case of the collapse of mine roadways or tunnels. To address this challenge, this study developed a modular rescue casing while drilling(CwD) rig system for horizontal boreholes. With the capacity for quick responses, this CwD rig was designed to enhance the rescue efficiency and safety under complex geological conditions. [Methods] Following the modular design concept and compact layout principle, this study optimized core components such as the power heads, feed devices, and power system.The auxiliary operation vehicle was checked against overturning through multibody dynamics(MBD) simulations to ensure its stability under complex conditions. The structure of the ultra-thin foldable belt conveyor for drilling slag was optimized using the discrete element method(DEM)-MBD coupled simulation, thus significantly improving the conveying efficiency and spatial adaptability of the conveyor. A safety and risk assessment model for drilling sites was established by combining the analytic hierarchy process(AHP) method and the technique for order preference by similarity to ideal solution(TOPSIS). Furthermore, an intelligent early warning software was developed by integrating the autoregressive moving average(ARMA) and exponential smoothing algorithms. These contributed to the dynamic safety assessment and risk prediction of drilling sites. Finally, the performance of the developed CwD rig was verified through static loading tests, engineering trials in Shangluo, Shaanxi Province, and integrated tests in Yuxi, Yunnan Province. [Results and Conclusions] The modular, remote-controlled rescue CwD rig for large-diameter boreholes, with a maximum module size of 4 000 mm × 1 700 mm × 1 450 mm, can be quickly assembled within three hours in a restricted space. The key components developed include dual rotary power heads, a feed system with independently driven inner and outer pipes, a top-opening variable-diameter clamping and centralizing system, and a remote-controlled monorail hoisting system. In combination with the electro-hydraulic dual-controlled, load-sensitive hydraulic control, remote-controlled explosionproof techniques, and matched multi-stage casings, the drilling rig represents a set of rescue equipment integrating drilling, discharge, conveying, and protection. Static loading tests indicate that the maximum torque of casing reached up to 255 kN·m and the maximum propulsion force of the outer pipe measured up to 1 600 kN. During the engineering trials and integrated tests conducted in Shangluo, Shaanxi Province and Yuxi, Yunnan Province, respectively, three horizontal boreholes were drilled, with a maximum borehole length of 61.5 m and an evacuation passage diameter of570 mm, verifying the performance of the drilling rig and the suitability of the multi-stage CwD process. The developed drilling equipment for underground rescue significantly improves the adaptability and rescue efficiency under narrow roadway environments, providing devices for emergency rescue in mines and tunnels.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 2336K]

  • A simulation and experimental study of bottomhole flow field in a large-diameter rescue borehole

    ZHAO Yan;LIU Songhe;HAO Shijun;ZHAO Jiangpeng;LI Peishu;WANG Xuebo;YU Yongping;GAO Ke;DONG Bo;ZHANG Bo;State Key Laboratory of Deep Earth Exploration and Imaging,Jilin University;College of Construction Engineering,Jilin University;CCTEG Xi'an Research Institute (Group) Co.,Ltd.;Geological Team of Shandong Provincial Bureau of Geology and Mineral Resources;

    [Objective] In mine rescue, reaming using a large-diameter down-the-hole(DTH) hammer faces is challenged by complex bottomhole flow fields and difficult slag discharge. This study aims to address these challenges.[Methods] To reveal the influence patterns of drilling parameters on the bottomhole flow field and slag discharge efficiency, this study determined the optimal drilling parameter combination. Then, using the computational fluid dynamics(CFD)-discrete phase model(DPM) method, this study established a numerical model for the slag discharge and bottomhole flow field during the reverse circulation drilling using a DTH hammer. Relying on this model, this study analyzed the variation patterns of the flow velocity distribution, cutting transport, and slag removal rate of the bottomhole flow field under a rate of penetration(ROP) of 3 m/h. Furthermore, this study developed a simulation device of bottomhole multi-phase flow for reverse circulation drilling of a large-diameter rescue borehole. This device allows for the adjustment of various drilling parameters and the maintenance of records of the transport trajectory of cuttings at the bottomhole. Using this device and simulated cuttings, this study conducted experiments on bottomhole two-phase flow during reverse circulation drilling and, accordingly, investigated the influence patterns of the drilling fluid flow rate and drill bit's rotational speed on the flow field. Additionally, orthogonal experiments involving three values of the drilling fluid flow rate and drill bit's rotational speed were designed based on the experimentally validated numerical model. [Results] The results indicate that with an increase in the drilling fluid flow rate, the slag removal rate increased, while the increasing magnitude diminished. With an increase in the drill bit's rotational speed, the slag removal rate increased initially and then decreased, peaking at 15 r/min. The orthogonal experiments indicate that the highest slag discharge performance was achieved under a relatively high drilling fluid flow rate and a moderate rotational speed of the drill bit. Under ROPs ranging from 3 m/h to 6.2 m/h, the drilling parameter combination that contributed to the highest slag discharge efficiency comprised a drilling fluid flow rate of 216 m~3/h and a rotational speed of the drill bit of 20 r/min. [Conclusions]The results of this study provide a theoretical reference for selecting rational drilling parameters for large-diameter rescue wells, assisting in enhancing the borehole-forming efficiency of drilling rescue engineering.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 3982K]

  • Structural optimization for transfer chutes based on energy dissipation mechanisms of coal particles

    SHI Yaocheng;ZOU Zujie;WEN Guojun;CHENG Siyi;WU Laijie;WANG Yudan;LIU Pu;CHEN Mengxi;School of Mechanical Engineering and Electronic Information,China University of Geosciences;CCTEG Xi'an Research Institute (Group) Co.,Ltd.;Hubei Provincial Engineering Technology Research Center for Intelligent Geological Equipment,China University of Geosciences (Wuhan);

    [Objective] Bulk material transport in emergency rescue scenarios and coal transportation poses stringent demands for the structural performance of transfer chutes. Given this, from the perspective of the energy dissipation mechanisms of particles, this study proposed structural optimization methods for transfer chutes based on the regulation of particle energy dissipation. [Methods] An experiment–simulation integrated analysis framework was established. Using this framework, this study systematically simulated the impact process of particles between two-stage walls Ⅰ and Ⅱ using the discrete element method(DEM), highlighting the coupling mechanisms among velocity fluctuations, stress distribution, and energy transformation pathways. Based on the results, this study defined an energy loss ratio coefficient(α)related to particle-particle interactions and constructed mathematical expressions for the relationships of the total energy dissipation of particles with the installation heights and angles of the walls. Additionally, it developed a control model of energy dissipation equilibrium and quantitatively analyzed the relationships of particle energy dissipation with wall geometry. [Results and Conclusions] The results indicate that the wall installation angle governed the relative proportions of the particle-particle and particle-wall energy dissipation pathways, with three representative energy dissipation mechanisms identified: local instability, stress continuity, and impact-dominated behavior. In combination with the particle velocity contour maps and stress distributions, this study further analyzed the synergistic evolution between the macroscopic flow behavior of particles and microscopic energy dissipation pathways. Accordingly, two structural optimization strategies were proposed:(1) A guiding structure was arranged to reduce the initial impact intensity, and(2) A stepped surface was introduced into the chute walls to enhance local shear and convert energy dissipation pathways.Both approaches significantly increased energy dissipation induced by particle-particle interactions while avoiding reverse flow and the local overloading of the walls. These methods proved effective through engineering applications. The results of this study provide theoretical and engineering bases for the energy management and structural design of chute systems under complex constraints.

    2025 09 v.53;No.333 [Abstract][OnlineView][Download 3157K]