Biogenic gas, the primary component of coalbed methane, is produced through complex interactions among coal, minerals, and microbial consortia. However, the underlying mechanisms remain poorly understood. This study examines coals with varying metamorphic degrees and elucidates the intrinsic relationships among biogenic gas production efficiency, structural evolution, mineralogical transformations, and microbial community dynamics. The results indicate that coals with medium metamorphic degrees achieve the highest methane yield (3.93 mL/g) and production rate (12.54 mL/day), driven by the synergistic degradation of oxygen-containing functional groups and favorable pore structure evolution. Initial coal properties-including vitrinite reflectance (Ro), ash yield, volatile matter content, and clay mineral content-are identified as key factors influencing microbial beta-diversity and methanogenic activity. Infrared spectroscopy and X-ray diffraction (XRD) analyses reveal the formation of secondary clay minerals and characteristic shifts in silicate structures, particularly in coals with medium and high metamorphic degrees. Microbial degradation increases nanopore density and interlayer spacing, decreases the surface fractal dimension (D1), and increases matrix complexity (D2). Dominant microbial taxa include Aminivibrio and Methanothrix, with acetoclastic methanogenesis identified as the primary methane production pathway. This study provides a multi-scale understanding of coal-mineral-microbe interactions and offers a theoretical framework for assessing the biogenic gas potential of coal seams.

To address the challenge of poor compatibility between fracturing fluid thickeners and microbial metabolism in biogenic coalbed methane(CBM)reservoir stimulation,this study developed a multidimensional evaluation system en-compassing gel-breaking efficiency,pore structure modification,and metabolic activation.Using this framework,the syn-ergistic mechanisms of methane enhancement by three thickeners—guar gum,xanthan gum,and modified cellulose—were systematically compared.Gel-breaking agents comprising microbial consortia and ammonium persulfate were used to as-sess the viscosity degradation kinetics of the thickeners at 0.4%concentration.Xanthan gum and guar gum exhibited su-perior viscosity reduction,with final viscosities of 3.5 mPa·s and 2.3 mPa·s after 60 hours,significantly outperforming modified cellulose(4.8 mPa·s).Polyacrylamide was excluded due to its resistance to biodegradation,with a residual vis-cosity of 8.6 mPa·s.Anaerobic co-fermentation experiments with lignite and thickeners revealed that the xanthan gum system achieved a cumulative gas production of 321 mL,representing increases of 40.8%and 205.7%over guar gum and modified cellulose,respectively.Improved Gompertz model fitting indicated a maximum gas production potential 4.7 times that of the control lignite group.Pore structure characterization showed that xanthan gum reduced the specific sur-face area of lignite by 28.4%and expanded the mesopore volume to 0.047 cm3/g.Fourier transform infrared spectroscopy(FTIR)analysis confirmed its role in promoting the cleavage of aliphatic chains and aromatic structures,thereby releasing soluble organic matter.Three-dimensional fluorescence spectroscopy further revealed that xanthan gum increased the con-tent of soluble organic matter in the fermentation broth,providing sufficient substrates for microbial metabolism.Metage-nomic analysis demonstrated that xanthan gum specifically enriched the aceticlastic methanogen Methanothrix and signi-ficantly upregulated the acetate decarboxylation pathway.The expression level of the key gene K00925 reached 356.8,notably higher than that in the guar gum system(259.9).Moreover,the total abundance of related functional genes in-creased by more than 20%.This study established a multidimensional evaluation framework integrating gel-breaking per-formance,pore structure modification,and metabolic activation,elucidating the structure-function relationship of thicken-er-microbe synergy.The results demonstrate that xanthan gum enables simultaneous optimization of reservoir physical properties and reconstruction of microbial metabolic networks,offering theoretical and technical support for the develop-ment of bio-compatible fracturing fluids.

Although the exploitation of coal resources has driven regional economic growth, it has also inflicted considerable ecological damage. The sustainable development of ecological security in coal resource-exhausted villages is challenged by multiple pressures, states, and response requirements. Identifying potential risks and assessing the coupling coordination in these areas is a critical research topic for promoting their transformation and development. This study uses Jiawang District, a representative coal resource-exhausted village in China, as a case study to examine the evolution of ecological security at the rural scale from 2000 to 2021. It innovatively constructs a comprehensive evaluation model based on “resilience support—state characteristics—response mechanism” and integrates coupling coordination degree analysis with grey relational analysis to quantitatively reveal the spatio-temporal differentiation features and driving mechanisms of ecological security coupling coordination in coal resource-depleted rural areas. The findings indicate the following: (1) Between 2000 and 2021, the comprehensive ecological security index of coal resource-exhausted villages in Jiawang District exhibited a sustained upward trend; (2) The coupling coordination degree of six sampled villages across the district displayed a gradient distribution pattern characterized by “higher in the west and lower in the east, higher in the north and lower in the south”, with each unit achieving phased improvements in coordination levels; (3) Through grey relational analysis, key factors influencing the coupling coordination of coal resource-exhausted villages were identified across three dimensions—coupling coordination degree, the overall Jiawang region, and the rural scale. This study offers targeted policy recommendations for coal resource-exhausted villages at varying levels of coupling coordination.

Coal mining activities, while promoting urban development, also lead to significant ecological and environmental issues that directly impact regional habitat quality and perception levels. The effective assessment of habitat services and zoning optimization can facilitate ecological restoration in coal mining subsidence areas and enhance public awareness of the ecological service value of habitats. Taking the Longdai River Basin in Huaibei City as a case study, this research constructs a “habitat quality–habitat perception” assessment framework from a social–ecological coupling perspective, integrating the InVEST and SolVES models for a comprehensive evaluation. The coupling coordination degree model is used to analyze the relationship between habitat quality and perception, allowing for the zoning of habitat services. The results indicate that the average habitat quality in the study area is 0.373, reflecting an overall low level. Its spatial distribution exhibits a trend of “higher in the central–southern and northwestern regions and lower in the southwestern and northeastern regions”. Habitat perception mainly presents a “multi-patch” spatial pattern. The coupling degree C between habitat quality and habitat perception is 0.676, while the coupling coordination degree D is only 0.377, indicating a state of mild imbalance in the coupling coordination development. Moreover, disordered units account for as much as 69.22%. Based on the matching and coupling coordination between habitat quality and perception, the study area can be classified into four main categories and eight smaller habitat service zones. Considering the differences in urban–rural gradient spaces, optimization strategies for habitat services based on social–ecological coupling are proposed.

The Eastern Huang–Huai region of China is a representative mining area with a high groundwater level. High-intensity underground mining activities have not only induced land cover and land use changes (LUCC) but also significantly changed the watershed hydrological behavior. This study integrated the land use prediction model PLUS and the hydrological simulation model MIKE 21. Taking the Bahe River Watershed in Huaibei City, China, as an example, it simulated the hydrological response trends of the watershed in 2037 under different land use scenarios. The results demonstrate the following: (1) The land use predictions for each scenario exhibit significant variation. In the maximum subsidence scenario, the expansion of water areas is most pronounced. In the planning scenario, the increase in construction land is notable. Across all scenarios, the area of cultivated land decreases. (2) In the maximum subsidence scenario, the area of high-intensity waterlogging is the greatest, accounting for 31.35% of the total area of the watershed; in the planning scenario, the proportion of high-intensity waterlogged is the least, at 19.10%. (3) In the maximum subsidence scenario, owing to the water storage effect of the subsidence depression, the flood peak is conspicuously delayed and attains the maximum value of 192.3 m3/s. In the planning scenario, the land reclamation rate and ecological restoration rate of subsidence area are the highest, while the regional water storage capacity is the lowest. As a result, the total cumulative runoff is the greatest, and the peak flood value is reduced. The influence of different degrees of subsidence on the watershed hydrological behavior varies, and the coal mining subsidence area has the potential to regulate and store runoff and perform hydrological regulation. The results reveal the mechanism through which different land use scenarios influence hydrological processes, which provides a scientific basis for the territorial space planning and sustainable development of coal mining subsidence areas.

The influence of clay mineral content on biogenic gas production in coal seams remains insufficiently understood. This study systematically investigated the mechanisms by which clay minerals affect biogas production in low- and medium-rank coals by integrating simulated biogas production experiments with multidimensional analytical techniques, including infrared spectroscopy, X-ray diffraction, scanning electron microscopy, gas chromatography–mass spectrometry, fluorescence spectroscopy, and metagenomic analysis. The results demonstrated that in low-rank coal, increasing the clay content from 2.78 to 4.75 g per 20 g of coal reduced the biogas yield from 6.30 to 3.47 mL/g. Conversely, in medium-rank coal, increasing the clay content from 1.66 to 2.65 g per 20 g of coal enhanced the biogas yield from 3.45 to 5.28 mL/g. These contrasting outcomes are primarily attributed to the distinct mechanistic roles of clay minerals across coal ranks. In low-rank coal, the hydration-induced swelling of clay minerals intensified pore blockage, impeded gas diffusion, decreased the abundance of genes involved in propionate degradation, and suppressed microbial metabolic activity, ultimately limiting methane production. In contrast, in medium-rank coal, clay minerals facilitated the enrichment of key functional microbial taxa, such as Acetobacteroides and Methanoculleus, promoted the degradation of fatty acids, hydroxyls, and amines, and enhanced the activity of acidogenic and methanogenic pathways, thereby increasing methane yield. This study elucidates the microbial mechanisms underlying the regulatory role of clay minerals in biogas production, offering new theoretical insights into the origin of coalbed methane (CBM) and providing a scientific foundation for optimizing biogenic CBM recovery.

This study explores the microbial degradation mechanisms and molecular structural transitions of coal during the bioconversion process. We built macromolecular structure models of coal samples at various stages of anaerobic fermentation by analyzing its elemental makeup, carbon framework, surface groups, and pore changes, and using molecular simulation. Experimental results indicate that: the pore size of the coal sample increased from 3.04 nm to 5.0 nm, accompanied by a slight increase in the interlayer spacing d002 of the aromatic layers, with a decrease in both the microcrystalline extension La and the stacking height Lc, suggesting the disruption of the coal sample's microcrystalline structure. During the biogas production process, the molecular structural transformations are primarily focused on the side chains, specifically characterized by a reduction in - CH2 - groups within the aliphatic chains, consumption of - OH groups, and the formation of - COOH groups. Notably, the cleavage of benzene rings occurs at the initial stage of biogas production, while the degradation of naphthalene rings takes place during the biogas production peak, indicating that the aromatic structures significantly influence the biogas production process in lignite. GC-MS analysis of the fermentation liquid revealed that benzene compounds are the main constituents, suggesting that the degradation of naphthalene rings occurs through an open-ring mechanism rather than a direct degradation pathway. During microbial fermentation, the model's total potential energy drops significantly, making it more stable. This change increases non-six-membered rings and lattice defects, affecting the coal's pore structure and reducing its surface fractal dimension.

The brittleness index is a significant indicator for forecasting the characteristics of coalbed methane reservoirs. However, the brittleness index of coalbed methane reservoirs is susceptible to a number of influencing factors, including the pore structure, coalbed methane content and pore fluid. Moreover, coalbed methane reservoirs are characterized by vertical transverse isotropy anisotropy, which presents a significant challenge to the accurate prediction of brittleness. Accordingly, this paper presents a new rock physics model for coalbed methane reservoirs, based on experimental test data obtained from coal samples. This model considers the vertical transverse isotropy anisotropy characteristics of coalbed methane reservoirs and the influence of pore structure, adsorbed gas and pore fluid in coal. The accuracy of the model is corroborated by the results of the experimental tests. The model predictions indicate that organic matter and clay content exert a greater influence than the stratification indicator factor. The impact of content is smaller than that of pore structure, and the influence of coalbed methane increases following water saturation. The model may be employed to forecast the elastic anisotropy and brittleness index of vertical transverse isotropy-type coalbed methane reservoirs. The inversion results of the logging data indicate that the brittleness index of coalbed methane reservoirs exhibits some variation in different directions and the brittleness index is greater along the bedding direction. The study assists in elucidating the interrelationship between the rock physical parameters of coalbed methane reservoirs and the brittleness index of coal seams, thereby furnishing a basis for anticipating the anisotropic sweet spot in coalbed methane reservoirs.

Numerous studies have focused on factors influencing biogenic enhancement of coalbed methane (CBM). However, less attention has been given to the surrounding rock formations associated with coal, which may also impact coalbed methane enhancement. Simulated experiments with coal were conducted under conditions with various surrounding rock types to investigate their effects on biogenic gas production. Results indicate that the addition of mudstone or sandy mudstone increased biogenic gas production by 8.7%–34.7% and raised methane concentration by 2.56%–3.37%. This enhancement is mainly attributed to the addition of sandy mudstone, which increased trace element Fe in the fermentation system, thereby optimizing the microbial community structure. Specifically, the abundance of Synergistota (electrochemical bacteria) and Euryarchaeota (archaea) significantly increased, along with genes related to methane metabolic pathways. Furthermore, the gene abundance of Fe receptor fepA increased, and there was enhanced enrichment of transport gene for Co and Ni (cbiO, cbiM, cbiQ, and cbiN). These findings reveal the influence of mudstone and sandy mudstone on coalbed biogenic gas formation, providing experimental insights for enhancing biogenic gas production in coal-related systems.

Coal measure gas is a hot spot for gas exploration at present, which mainly includes coalbed methane, shale gas and tight sandstone gas. A good understanding of the effect of water on the shear moduli of coal measure gas reservoir rocks, despite being essential for seismic exploration, has not yet been well studied and understood. Therefore, three major groups of coal measure rock types, including sandstone, mudstone and coal from the Qinshui Basin, are selected to investigate the effects of confining pressure and fluid on the elastic properties of the rocks. The P-wave velocities of dry coal measure rocks are more sensitive to confining pressure than the Swave velocities, while the contrary situation occurs under saturated condition. The differential Kuster-Toksoz model can simulate the change in shear moduli caused by saturated water and can assume specific pore geometry, suggesting that the pore structure of coal measure rocks is affected by the combined effect of pressure and pore fluid. The change in shear modulus of coal measure rocks is sensitive to the confining pressure, the ratio of saturated to dry shear moduli decreases exponentially with the confining pressure. Further, the change in shear modulus after saturation is a very complex process. As confining pressure increases, coals and mudstone always display shear softening after saturation, while the shear moduli of sandstone could transit from stiffening to softening. Due to their importance in prediction of shear wave velocity, this complex variation pattern should be considered during the fracturing process.

Restoring biodiversity is a key component of ecological rehabilitation in mining areas. The coal resource-based cities in the eastern Huang-Huai Region are typical mining areas with a high underground water level, where coal mining and urbanization have profoundly impacted regional wetland ecological functions. To reveal the processes and trends of wetland habitat quality changes in coal resource-based cities in the eastern Huang-Huai Region, this study takes Huaibei City as a case and develops a land use scenario simulation model and dataset tailored to the characteristics of mining areas with high underground water levels. Based on land use results of 2012 and 2022, four wetland landscape evolution scenarios are simulated for 2032. Subsequently, a comparative analysis of wetland habitat quality trends across different scenarios was conducted using the In-VEST model. ①The results indicate that from 2002 to 2022, the habitat quality of wetlands in the study area showed an initial increase followed by a decrease, a trend inversely correlated with changes in wetland area. ② Under the land reclamation priority scenario, wetland habitat quality showed improvement by 2032, while all other scenarios exhibited declining trends. Among the scenarios, the wetland conservation priority scenario outperformed the natural development scenario, while the urbanization priority scenario exhibited the lowest performance. ③Spatial autocorrelation analysis showed that changes in habitat quality exhibited overall positive correlation. The area of H-H clusters was the largest in the land reclamation priority scenario, while the L-L clusters was the largest in the urbanization priority scenario. Therefore, rational regulation through territorial spatial planning can achieve balanced development between wetland habitat functionality restoration and agricultural land restoration. The results of this study are highly significant for optimizing spatial planning in resource-based cities, improving habitat quality in mining areas, and enhancing regional biodiversity.

Underground coal gasification (UCG) is a clean technology for in-situ coal conversion with development potential, and numerical simulation is an effective means to study the complex gasification process. After nearly 50 years of development, UCG numerical simulation technology has achieved fruitful research results, but the technical development is still immature, which has become one of the main technical shortcomings restricting the industrialization of UCG. In order to accelerate the development of domestic UCG numerical simulation technology and better serve the field test, the framework of UCG numerical simulation technology are presented, the physicochemical behavior of gasification process is elaborated, and the main research progress and the latest achievements at home and abroad are summarized, and the existing problems and the directions for breakthroughs are pointed out. The study shows that: ① The gasification process involves many physicochemical reactions, large time and space span, complex heat and mass transfer processes, which lead to the challenging UCG numerical simulation technology, and the development of the world’s UCG numerical simulation technology can be divided into three phases, and numerical simulation technology has a certain lag compared with the field test, but the gasification process is not an unpredictable “black box”. ② The scientific essence of UCG is mass, momentum, heat transfer and chemical reactions in variable space, the prediction of gasification products and gasification cavity is one of the main tasks of numerical simulation, the expansion mechanism of gasification cavity includes chemical reaction consumption, coal spalling and roof collapse, the fluid flow in the gasification cavity is mainly controlled by double-diffusive natural convection driven by temperature and concentration gradients, radiation heat transfer dominates the heat transfer, and the permeability ratio of rubble to ash has an impact on the morphology development of the gasification cavity. ③ Packed bed model, channel model and coal slab model have advantages in product prediction, cavity prediction and drying front and combustion front tracking, respectively. The process model portrays the main physicochemical phenomena involved in gasification through different functional modules, which is a feasible strategy to realize the simulation of complex gasification processes, and the computational fluid dynamics model has developed rapidly in recent years and is the main simulation means at present. ④ In the future, the UCG numerical simulation technology needs to develop in the direction of more accurate, more systematic, more efficient and more intelligent, and urgently needs to solve the problems of large-size lump coal chemical reaction kinetics, multifunctional integration, the coupling of discrete element method and continuous medium method, the three-dimensional geological modeling of mine scale, and the integration of numerical simulation technology and artificial intelligence as soon as possible. With the continuous development and improvement of numerical simulation technology, it will certainly play a more important technical support role in the process of UCG industrialization.

Tar-rich coal (with a tar yield ≥ 7%), as a special coal-based oil and gas resource, is of great significance for ensuring national energy security and promoting the clean conversion of coal. The selection of suitable geological sites represents a core challenge for the safe and efficient application of its in situ pyrolysis technology. Focusing on the tar-rich coal seams in the Santanghu Basin, this study constructed a comprehensive geological evaluation system for site selection by integrating numerical simulation, data mining, and laboratory experiments. The Analytic Hierarchy Process (AHP) and a fuzzy comprehensive evaluation method were employed to achieve a quantitative assessment and identify favorable areas within the study region. The results indicate that resource scale, coal seam conditions, and the properties of the roof and floor strata are the key controlling factors. One optimally comprehensive Class I favorable area (Tiao IV block) was successfully identified. This block exhibits a large resource scale, favorable coal seam conditions, a high tar yield, excellent geological sealing, and superior engineering compatibility, making it the recommended priority target for pilot testing. The evaluation system developed in this study can provide a theoretical basis and technical reference for the geological site selection of in situ pyrolysis of tar-rich coal in similar mining areas and advance its industrialization.

The introduction of water vapor as a gasification agent in the study of Underground Coal Gasification (UCG) is conducive to the improvement of combustible gas generation, which is of greatsignificance in promoting the advancement of coal clean utilization technology. The effect of the change of vapor-oxygen ratio on the generated gas components during underground coal gasification was investigated, and the effect of the change of vapor-oxygen ratio on the calorific value of coal gas and gasification efficiency (the ratio of calorific value of coal gas to the heat of combustion of carbon) was analyzed through the evaluation of energy recovery. On this basis, the gasification process was divided into an ideal gasification stage and a secondary conversion stage, and the effects of oxygen excess and deviation (the deviation between the actual reaction occurring in the gasification process and the ideal gasification reaction) on the generated gases and calorific values were investigated. The results indicate that changes in the air-to-oxygen ratio significantly affect the volume fraction content of the main combustible components (CO+H2) in the generated gas. When the steam-to-oxygen ratio increases from 1.5∶1.0 to 2.0∶1.0, the volume fraction of (CO+H2) in the generated gas increases with the increase in the steam-to-oxygen ratio, reaching a maximum of 62.39% at a steam-to-oxygen ratio of 2.0∶1.0, with the H2 volume fraction stabilizing at approximately 30%. The gasification efficiency and gas calorific value both reach their maximum values. However, when the steam-to-oxygen ratio exceeds 2.0∶1.0, the volume fraction of the main combustible gases begins to decrease. Through staged analysis, it was found that when the oxygen supply exceeds the amount required for the ideal gasification reaction, the combustible gases produced by the reaction undergo a secondary reaction with excess oxygen, generating low-calorific CO2, thereby reducing the calorific value of the gas. As the deviation increases, the water gas reaction and water gas shift reaction become more intense, leading to an increase in the volume fraction of (CO+H2), thereby increasing the calorific value. However, when the supply of steam is excessive, the excess steam lowers the reaction temperature, inhibits the water gas reaction, reduces the deviation, and consequently decreases the volume fraction of CO and H2 in the generated gas, leading to a decrease in calorific value. Therefore, in the experiment, the oxygen excess should be moderately reduced to minimize CO2 production, while the steam supply should be appropriately increased to enhance the deviation, promote the water gas reaction, and improve gasification efficiency and gas calorific value.

Under the goal of"dual carbon","taking hydrogen and retaining carbon"has become an inevitable choice for the clean utilization of coal,and underground coal pyrolysis provides a new idea for increasing domestic tar and gas pro-duction.Scientific prediction of underground tar-rich coal pyrolysis capacity is critical for project economics and energy return assessment,but fewer studies have been conducted on the underground coal pyrolysis in mid to deep layers,and pyrolysis experiments on block coal considering real confining pressure conditions have not yet been reported.To predict underground tar-rich coal pyrolysis capacity and identify the laws of oil and gas production,this paper proposed a hori-zontal well development method suitable for underground coal pyrolysis in mid to deep layers based on the characteristics of underground coal pyrolysis.Block coal overburden pyrolysis experiments were conducted on two sets of main coal seams in the Santanghu Basin.The overlying pyrolysis yield evaluation model of tar-rich coal in Badaowan Formation based on Boltsmann function and the productivity prediction method of U-shaped horizontal well were established.The variation law of tar and coal gas production capacity and energy return rate were discussed.The results show that:① Un-derground coal pyrolysis has the advantages of high resource abundance,clean and low-carbon gas products,and low geo-logical risk.U-shaped,L-shaped and multi-branch horizontal Wells can be produced intermittently or continuously.② The coal of Badaowan Formation has a higher tar and coal gas yield than that of Xishanyao Formation.Tar production reaches its peak at 400-500 ℃,confining pressure also has a negative effect on reducing the mass transfer capacity of pyrolysis products and a positive effect on improving heat transfer efficiency.When the temperature is lower than 400 ℃,the negat-ive effect dominates,and the positive effect gradually dominates as the temperature rises.The coal gas production in-creases rapidly at 300-400 ℃,slows down at 400-600 ℃,and rapidly decreases after 600 ℃.H2 and CO in coal gas in-crease monotonously with increasing temperature.CH4 and CO2 increase first and then decrease with temperature,the ef-fect of confining pressure on the two sets of coal is different,and the application of confining pressure is more beneficial to coal gas production of Badaowan Formation coal.③ Tar-rich coal pyrolysis product yield shows an S-shaped variation pattern of"slow increase-rapid increase-tends to stabilize"with increasing temperature,the Boltsmann function can bet-ter fit the law of tar-rich coal pyrolysis product yield.The linear and triangular well patterns form rectangular and circular temperature fields,respectively.To reach the effective pyrolysis temperature(350 ℃)required for the coal seam between wells,the well spacing of horizontal wells is 4.5 and 5.5 meters respectively,which shows that the heating effect of trian-gular well pattern is better than that of linear well pattern.④ Tar and coal gas productivity is divided into three stages:low production in the early stage,rapid production in the middle stage,and stable production in the late stage.According to 1 W/(m·℃)coal thermal conductivity,the production capacity of tar,methane and hydrogen in a single U-type well for 5 years is expected to reach 1.56×104 t/a、260.21×104 m3/a and 201.83×104 m3/a,and the energy return rate can reach 2.09.The mass ratio of pyrolysis water and tar in pyrolysis products is the largest,and the production capacity is the first to sta-bilize.The mass proportion of CH4 and CO2 in coal gas is the highest,CO2 increases first and then decreases with produc-tion years,while CO and H2 increase monotonically with production years.The production capacity contribution in the later stage of heating is mainly from CO and H2 in the coal gas.⑤ In the case of equal calorific value,underground coal pyrolysis reduces carbon emissions by 97％compared with surface coal combustion,ideally,and the CO2 produced can be absorbed and buried through the semi-coke layer to achieve carbon neutrality.Overall,underground coal pyrolysis has the resource base,technical feasibility and good economic prospect for scale development,which is a new technology for clean and low-carbon development of fossil energy with great development potential.

The coal-series kaolin in China possesses abundant resources, and its efficient utilization can be promoted by separation. In this paper, a cascade electrostatic field was designed for the triboelectric separation of coal-series kaolin. The motion behavior of charged particles with different size fraction in cascade electrostatic field was investigated by high-speed dynamic camera system, and the distribution characteristic of charge-to-mass ratio of products was analyzed by the coulometer. The influence of key operating parameters (e.g., feed speed, rotation speed and plate voltage) on product distribution were studied by electric separation test. The results indicated that the charge-to-mass ratio of the product after separation has the characteristics of cascade distribution. In addition, compared with 0.05-0.25 mm and 0.25-0.125 mm, the dispersion performance of 0.125-0.074 mm coal-series kaolin in the cascade electrostatic field was poor. For 0.5-0.25 mm, 0.125-0.25 mm and 0.074-0.125 mm coal-series kaolin, the decarburization efficiency after separation in cascade electric field was 47.09 %, 53.48 % and 44.63 %, respectively. Our study indicates that the setting of cascade electrostatic field achieved efficient purification and enrichment of coal-series kaolin.

Using carbon dioxide as a gasification agent for underground coal gasification (UCG) can not only reduce carbon dioxide emissions but is also expected to lead to a new natural gas technology revolution and ensure national energy security. To explore the effect of the oxygen content in oxygen-enriched carbon dioxide gasification agents on the results of gasification experiments, underground gasification experiments under different oxygen-enrichment conditions were designed, and quantitative parameters were used to analyze and evaluate the gas produced in the gasification experiments. The results showed that as the oxygen content in the oxygen-enriched carbon dioxide gasification agent increased, the CO and H2 in the combustible gas gradually increased, and the calorific value of the combustible gas also slowly increased, reaching a peak value under the gasification condition of 60% oxygen concentration, and then decreased slightly; the product formation rate and the gas production per unit mass of coal fluctuated. The coal consumption rate increased with time and was relatively stable. According to theoretical calculations for the gasification energy recovery evaluation system, the overall energy recovery rate was 56.34%, and the energy utilization rate was relatively high. Research on quantitative indicators based on gas production data has good practical significance for evaluating the gasification efficiency of UCG, which can be used to better evaluate and control the reaction process of UCG.

水平井投球暂堵压裂封堵炮眼技术是油气增产的重要技术之一,可有效地提高非常规油气资源开发效率.水平井中暂堵球运动和封堵炮眼过程较为复杂,存在井下暂堵位置不确定、暂堵球易脱落等问题.文章采用DEM—CFD耦合方法建立水平井投球暂堵数值模型,分析了水平井筒流场特性及暂堵球封堵炮眼的过程,以及不同工况参数对暂堵球封堵炮眼有效性的影响.结果表明:水平井压裂中射孔分流能力具有差异性,改变压裂液排量、黏度对改善簇内射孔分流均匀性不明显;当暂堵球在炮眼处满足封堵临界力学条件,可有效封堵炮眼,反之则脱离炮眼;只增加注入排量对封堵炮眼效率提高不明显,进入射孔簇前减小暂堵球与炮眼垂直距离,有利于暂堵球封堵炮眼;通过增大直径比、投放浮力球或悬浮球可以有效提高暂堵球封堵炮眼效率.该研究对认识水平井投球暂堵压裂工艺过程具有指导意义,为优化水平井炮眼封堵工艺提供理论和技术支撑.

Objective:To analyze the internal conditions and external environment of high-quality development of high-level public hospitals and establish a high-quality development strategy model, for reference of public hospitals to formulate and implement high-quality development strategies.Methods:The case hospital was a pilot in high-quality development of high-level public hospitals. SWOT method was used to analyze the influencing factors, AHP analytic hierarchy process was used to compare the importance of each influencing factor, and then the four-quadrant coordinate system method was used to establish a high-quality development strategy model.Results:The total strength(S), the total weaknesses(W), the total opportunity(O), and the total threat(T)were 0.095, 0.063, 0.065 and 0.024 respectively, reflecting that the strength of internal conditions was greater than the weaknesses, and the opportunities of external environment were greater than the threats. In the four-quadrants, the growth strategy model had the largest triangle area(0.003), and the strategic quadrilateral center of gravity was located in the opportunity area of the growth strategy.Conclusions:High-level public hospitals as represented by the case hospital had entered a period of important strategic opportunities, which the external opportunities were greater than its own strength. These hospitals were recommended to fully leverage the external opportunities, adopt a positive growth oriented(SO)strategy, formulate a development strategy with their own characteristics, promote the interaction of internal conditions and external environment to form new momentum, hence achieving high-quality development.

以3-巯丙基-1,1,1,3,5,5,5-七甲基三硅氧烷与1-烯烃基-3-甲基咪唑溴盐为原料,通过巯基-烯烃点击反应高效合成含有不同联接基团(—CH 2—)的咪唑盐阳离子三硅氧烷表面活性剂([Si 3-C n-Min]Br).通过表面张力探索—CH 2—链节数量对其表面活性的影响.发现其最低表面张力为27～29 mN/m,最低表面张力和饱和吸附量随着—CH 2—数量的增加而增大,而临界胶束浓度和单分子在界面上所占面积则随之减小.