Based on the coalbed methane(CBM)/coal-rock gas(CRG)geological,geophysical,and experimental testing data from the Daji block in the Ordos Basin,the coal-forming and hydrocarbon generation&accumulation characterist...Based on the coalbed methane(CBM)/coal-rock gas(CRG)geological,geophysical,and experimental testing data from the Daji block in the Ordos Basin,the coal-forming and hydrocarbon generation&accumulation characteristics across different zones were dissected,and the key factors controlling the differential CBM/CRG enrichment were identified.The No.8 coal seam of the Carboniferous Benxi Formation in the Daji block is 8-10 m thick,typically overlain by limestone.The primary hydrocarbon generation phase occurred during the Early Cretaceous.Based on the differences in tectonic evolution and CRG occurrence,and with the maximum vitrinite reflectance of 2.0%and burial depth of 1800 m as boundaries,the study area is divided into deeply buried and deeply preserved,deeply buried and shallowly preserved,and shallowly buried and shallowly preserved zones.The deeply buried and deeply preserved zone contains gas content of 22-35 m^(3)/t,adsorbed gas saturation of 95%-100%,and formation water with total dissolved solid(TDS)higher than 50000 mg/L.This zone features structural stability and strong sealing capacity,with high gas production rates.The deeply buried and shallowly preserved zone contains gas content of 16-20 m^(3)/t,adsorbed gas saturation of 80%-95%,and formation water with TDS of 5000-50000 mg/L.This zone exhibits localized structural modification and hydrodynamic sealing,with moderate gas production rate.The shallowly buried and shallowly preserved zone contains gas content of 8-16 m^(3)/t,adsorbed gas saturation of 50%-70%,and formation water with TDS lower than 5000 mg/L.This zone experienced intense uplift,resulting in poor sealing and secondary alteration of the primary gas reservoir,with partial adsorbed gas loss,and low gas production rate.A depositional unification and structural divergence model is proposed,that is,although coal seams across the basin experienced broadly similar depositional and tectonic histories,differences in tectonic intensity have led to spatial heterogeneity in the maximum burial depth(i.e.,thermal maturity of coal)and current burial depth and occurrence of CRG(i.e.,gas content and occurrence state).The research results provide valuable guidance for advancing the theoretical understanding of CBM/CRG enrichment and for improving exploration and development practices.展开更多
In the development of coalbed methane(CBM)reservoirs using multistage fractured horizontal wells,there often exist areas that are either repeatedly stimulated or completely unstimulated between fracturing stages,leadi...In the development of coalbed methane(CBM)reservoirs using multistage fractured horizontal wells,there often exist areas that are either repeatedly stimulated or completely unstimulated between fracturing stages,leading to suboptimal reservoir performance.Currently,there is no well-established method for accurately evaluating the effectiveness of such stimulation.This study introduces,for the first time,the concept of the Fracture Network Bridging Coefficient(FNBC)as a novel metric to assess stimulation performance.By quantitatively coupling the proportions of unstimulated and overstimulated volumes,the FNBC effectively characterizes the connectivity and efficiency of the fracture network.A background grid calibration method is developed to quantify the stage-controlled volume,effectively stimulated volume,unstimulated volume,and repeatedly stimulated volume among different stages of horizontal wells.Furthermore,an optimization model is constructed by taking the FNBC as the objective function and the fracturing injection rate and fluid volume as optimization variables.The Simultaneous Perturbation Stochastic Approximation(SPSA)algorithm is employed to iteratively perturb and optimize these variables,progressively improving the FNBC until the optimal displacement rate and fluid volume corresponding to the maximum FNBC are obtained.Field application in a typical CBM multistage fractured horizontal well in China demonstrates that the FNBC increased from 0.358 to 0.539(a 50.6% improvement),with the injection rate rising from 16 m^(3)/min to 24 m^(3)/min and the average fluid volume per stage increasing from 2490 m^(3) to 3192 m^(3),significantly enhancing the stimulation effectiveness.This research provides theoretical support for designing high-efficiency stimulation strategies in unconventional reservoirs under dynamic limits.展开更多
Significant differences exist between deep and medium-shallow coalbed methane(CBM)reservoirs.The unclear understanding of flowback and production behavior severely constrains the development of deep CBM resources.To a...Significant differences exist between deep and medium-shallow coalbed methane(CBM)reservoirs.The unclear understanding of flowback and production behavior severely constrains the development of deep CBM resources.To address this challenge,guided by the gas-liquid two-phase flow theory in ultra-low permeability reservoirs,and integrating theoretical analysis,numerical simulation,and insights from production practices,this study classifies the flowback and production stages of deep CBM well considering the Daning-Jixian Block,Eastern Ordos Basin as a representative case.We summarize the flowback characteristics for each stage and establish a standard flowback production type curve,aiming to guide field operations.The results indicate that:(a)The production process of deep CBM horizontal wells can be divided into five distinct stages:initial single-phase water dewatering stage,initial gas appearance to peak water production stage,gas breakthrough to peak gas production stage,stable production and decline stage,and low-rate production stage.(b)Based on reservoir energy,two standard type curves for horizontal well flowback production are established:the‘Sufficient Reservoir Energy’type and the‘Insufficient Reservoir Energy’type.The former achieves a higher initial gas rate(up to 12×10^(4)m^(3)/d)but exhibits poorer stability,while the latter achieves a lower stable rate(up to 8×10^(4)m^(3)/d)but demonstrates stronger stability.Numerical simulation confirms these behavioral patterns and reveals the underlying mechanisms related to the effectively drained area where pressure is significantly depleted.The findings from this study have guided the flowback production operations in 53 deep CBM wells with positive results,demonstrating high potential for broad application.展开更多
With the maturation of coalbed methane(CBM)exploitation and the transition into the late stages of dewatering and gas production,liquid loading in gathering pipelines has emerged as a major constraint on productivity ...With the maturation of coalbed methane(CBM)exploitation and the transition into the late stages of dewatering and gas production,liquid loading in gathering pipelines has emerged as a major constraint on productivity and operational stability.Based on real-time field data and gas-liquid physicochemical analyses,this study elucidates the mechanisms governing liquid loading formation under varying temperature,pressure,and water saturation conditions.An HYSYS model is employed to determine the water dew point,while the Turner model is used to evaluate the critical conditions for liquid holdup.The results indicate that gas water saturation exerts the dominant influence on liquid loading risk,followed by pressure,whereas temperature plays a comparatively minor role.When water saturation exceeds 2%and the operating temperature falls below the dew point,condensation-driven liquid loading increases sharply.To further characterize the spatial distribution of liquid accumulation,a steady-state OLGA model of a DN100 gathering pipeline network is developed to examine the effects of pipe diameter,water saturation,and soil temperature.The simulations show that larger pipe diameters and higher water saturation significantly aggravate liquid holdup,while elevated soil temperature mitigates liquid accumulation.Moreover,the liquid holdup ratio is found to correlate closely with flow regime transitions,confirming its suitability as a key indicator of liquid loading risk.Based on these findings,optimization strategies for pipeline design and operation are proposed.To mitigate liquid loading,the gathering pipeline velocity should be maintained above the critical value of 1.63 m/s,and the gas water content should be strictly controlled below 2%.Under operating conditions representative of the Hancheng block,it is recommended to reduce the pipeline diameter from DN130 to DN100 to enhance self-cleaning capacity.In addition,thermal insulation should be applied during winter operation to maintain the pipe wall temperature above 10◦C,thereby suppressing condensation-induced liquid accumulation.展开更多
The vertical heterogeneity of the pore structure in deep coal seams with varying ash yields is a key control for coalbed methane storage and producibility;however,its specific impact on gas adsorption is not clearly d...The vertical heterogeneity of the pore structure in deep coal seams with varying ash yields is a key control for coalbed methane storage and producibility;however,its specific impact on gas adsorption is not clearly defined.The focus of this study is the No.8 coal seam of the Carboniferous Benxi Formation in the Central-Eastern Ordos Basin.By integrating microscopic identification,proximate analysis,gas adsorption(CO_(2),N_(2),and CH_(4)),and the multifractal theory,we quantitatively characterized the nanopore structure(micropores<2 nm and mesopores 2 nm-100 nm)of coal reservoirs with varying ash yields.The results indicate that(1)ash yield is the primary factor that controls the vertical evolution of pore structures in coal seams.In low-ash yield coal seams,the extent of thermal evolution and ash yield jointly constrain the heterogeneity of pore size distribution.In mediumto high-ash yield coal seams,the heterogeneity of pore structure and pore size distribution are predominantly constrained by ash yield.(2)As the ash yield vertically increases,the mesoporous pore volume and specific surface area initially decrease and subsequently increase,while the contribution of micropores to both pore volume and specific surface area continuously diminishes.Consequently,the total pore volume and specific surface area of the coal samples exhibit a two-stage reduction close to an ash yield threshold of approximately 20%.(3)Further,the Langmuir volume for CH_(4)adsorption sharply declines below the 20%threshold,followed by a gradual decrease;in contrast,the Langmuir pressure initially decreases and subsequently increases.Hence,the vertical increase in ash yield constrains the development of pore systems and diminishes pore connectivity,thereby reducing methane adsorption capacity and adversely affecting coalbed methane productivity.(4)Low-ash yield coal reservoirs are characterized by a rapid gas breakthrough and high productivity,whereas medium-ash yield coal reservoirs generally require prolonged depressurization to achieve peak gas production.These findings reveal that in medium-high rank coal,ash yield―and not thermal evolution―is the main factor that controls vertical pore evolution and methane adsorption efficiency.The quantitative ash yield threshold(20%)established in this study provides a practical criterion for evaluating reservoir quality and predicting vertical variations in gas storage potential in the Ordos Basin.展开更多
Under the backdrop of“Carbon Peak and Carbon Neutrality”(dual carbon)goal in China,the methane-carbon dioxide reforming reaction has attracted considerable attention due to its environmental benefits of converting t...Under the backdrop of“Carbon Peak and Carbon Neutrality”(dual carbon)goal in China,the methane-carbon dioxide reforming reaction has attracted considerable attention due to its environmental benefits of converting two greenhouse gases(methane and carbon dioxide)into syngas and its promising industrial applications.Nickel(Ni)-based catalysts,with high catalytic activity,low cost,and abundant resources,are considered ideal candidates for industrial applications.In this article,three reaction kinetic models were briefly introduced,namely the Power-Law(PL)model,the Eley-Rideal(ER)model,and the Langmuir-Hinshelwood-Hougen-Watson(LHHW)model.Based on the LHHW model,the reaction kinetics and mechanisms of different catalytic systems were systematically discussed,including the properties of supports,the doping of noble metals and transition metals,the role of promoters,and the influence of the geometric and electronic structures of Ni on the reaction mechanism.Furthermore,the kinetics of carbon deposition and elimination on various catalysts were analyzed.Based on the reaction rate expressions for carbon elimination,the reasons for the high activity of transition metal iron(Fe)-doped catalysts and core-shell structured catalysts in carbon elimination were explained.Based on the detailed collation and comparative analysis of the reaction mechanisms and kinetic characteristics across diverse Ni-based catalytic systems,a theoretical guidance for the designing of high-performance catalysts was provided in this work.展开更多
Catalytic decomposition of methane,which produces high-purity hydrogen and high-value-added carbon nanomaterials,has shown considerable potential for development and is expected to yield significant economic benefits ...Catalytic decomposition of methane,which produces high-purity hydrogen and high-value-added carbon nanomaterials,has shown considerable potential for development and is expected to yield significant economic benefits in the future.However,designing catalysts that simultaneously exhibit high activity and long-term stability remains a significant challenge.Tuning the catalyst’s structure and electronic properties is an effective strategy for enhancing the reaction performance.In this work,a series of NixZr/ZSM-5 catalysts were prepared using the incipient wetness impregnation method,and the effect of Zr loadings on catalyst properties and performance was systematically investigated.The calcined and reduced catalysts were characterized by low-temperature N_(2)adsorption-desorption,XRD,SEM,H_(2)-TPR and XPS.The results showed that the addition of Zr significantly increased the specific surface area of the catalyst and reduced the metal particle size.Smaller NiO particles were found to enter the pores of the HZSM-5 support,and electronic interactions between NiO and ZrO_(2)markedly enhanced the metal-support interaction.The catalyst exhibited optimal catalytic performance at a Zr loading of 5%,achieving a maximum methane conversion of 68%at 625℃,maintaining activity for 900 min,and delivering a carbon yield of 1927%.Further increasing the Zr loading yielded only limited improvements in catalytic performance.Characterization of the spent catalysts and carbon products via TEM,Raman spectroscopy,and TGA revealed that the introduction of ZrO_(2)reduced metal sintering and promoted a shift in carbon nanofibers growth mode from tip-growth to base-growth.The mechanism of base-growth enabled the catalyst to maintain reaction activity for an extended period.展开更多
Low-concentration coal mine methane(LC-CMM),which is predominantly composed of methane,serves as a clean and low-carbon energy resource with significant potential for utilization.Utilizing LC-CMM as fuel for solid oxi...Low-concentration coal mine methane(LC-CMM),which is predominantly composed of methane,serves as a clean and low-carbon energy resource with significant potential for utilization.Utilizing LC-CMM as fuel for solid oxide fuel cells(SOFCs)represents an efficient and promising strategy for its effective utilization.However,direct application in Ni-based anodes induces carbon deposition,which severely degrades cell performance.Herein,a medium-entropy oxide Sr_(2)FeNi_(0.1)Cr_(0.3)Mn_(0.3)Mo_(0.3)O_(6−δ)(SFNCMM)was developed as an anode internal reforming catalyst.Following reduction treatment,FeNi_(3) nano-alloy particles precipitate on the surface of the material,thereby significantly enhancing its catalytic activity for LC-CMM reforming process.The catalyst achieved a methane conversion rate of 53.3%,demonstrating excellent catalytic performance.Electrochemical evaluations revealed that SFNCMM-Gd_(0.1)Ce_(0.9)O_(2−δ)(GDC)with a weight ratio of 7:3 exhibited superior electrochemical performance when employed as the anodic catalytic layer.With H_(2) and LC-CMM as fuels,the single cell achieved maximum power densities of 1467.32 and 1116.97 mW·cm^(−2) at 800℃,respectively,with corresponding polarization impedances of 0.17 and 1.35Ω·cm^(2).Furthermore,the single cell maintained stable operation for over 100 h under LC-CMM fueling without significant carbon deposition,confirming its robust resistance to carbon formation.These results underscore the potential of medium-entropy oxides as highly effective catalytic layers for mitigating carbon deposition in SOFCs.展开更多
Background The enteric methane inhibitor 3-nitrooxypropanol(3-NOP)inhibits the key enzyme in ruminal methanogenesis,but whether short-term(ST)and long-term(LT)dietary supplementation has similar effects on rumen micro...Background The enteric methane inhibitor 3-nitrooxypropanol(3-NOP)inhibits the key enzyme in ruminal methanogenesis,but whether short-term(ST)and long-term(LT)dietary supplementation has similar effects on rumen microbiota in beef cattle and how microbes change after 3-NOP withdrawal have not been studied.This study investigated changes in rumen bacteria,archaea,and protozoa after ST and LT dietary supplementation and removal of 3-NOP using metataxonomic analysis.Results A total of 143 rumen samples were collected from two beef cattle studies with 3-NOP supplementation.The ST study(95 samples)used eight ruminally cannulated beef cattle in a 4×4 Latin square design with four 28-d of 3-NOP treatments[mg/kg of dry matter(DM)]:control:0,low:53,med:161,and high:345.The LT study(48 samples)was a completely randomized design with two 3-NOP treatments[control:0,and high:280 mg/kg of DM)fed for 112-d followed by a 16-d withdrawal(without 3-NOP).Bacterial and archaeal communities were significantly affected by 3-NOP supplementation but limited effects on protozoal communities were observed.Under ST supplementation,the relative abundances of Prevotella,Methanobrevibacter(Mbb.)ruminantium,Methanosphaera sp.ISO3-F5,and Entodinium were increased(Q<0.05),whereas those of Mbb.gottschalkii and Epidinium were decreased(Q<0.05)with 3-NOP supplementation.In LT study,relative abundances of Mbb.ruminantium,and Methanosphaera sp.Group5 were increased(Q<0.05),while those of Saccharofermentans and Mbb.gottschalkii were decreased(Q<0.05)with 3-NOP supplementation.Comparison between 3-NOP supplementation and the withdrawal revealed increased relative abundances of Clostridia UCG-014 and Oscillospiraceae NK4A214 group and decreased those of Eubacterium nodatum group and Methanosphaera sp.Group5(P<0.05)after 3-NOP withdrawal.Further comparison of rumen microbiota between control and 3-NOP withdrawal showed significantly higher(P=0.029)relative abundances of Eggerthellaceae DNF00809,p-1088-a5 gut group,and Family XII UCG-001 in control group while no significant differences were detected for archaea and protozoa.Microbial network analysis revealed that microbial interactions differed by both 3-NOP dose and durations.Conclusions Both ST and LT supplementation affected overall rumen microbial profile,with individual microbial groups responded to 3-NOP supplementation differently.After 3-NOP withdrawal,not all microbes showed recovery,indicating that the 3-NOP driven shifts were only partially reversible.These findings provide an understanding of the effects of 3-NOP on rumen microbial communities and their adaptability to methane mitigation strategies.展开更多
Background Methane(CH_(4))emissions from ruminants significantly contribute to greenhouse gas effects and energy loss in livestock production.Methyl-coenzyme M reductase(MCR)is the key enzyme in methanogenesis,making ...Background Methane(CH_(4))emissions from ruminants significantly contribute to greenhouse gas effects and energy loss in livestock production.Methyl-coenzyme M reductase(MCR)is the key enzyme in methanogenesis,making it a promising target for CH_(4) mitigation.This study aimed to identify and validate plant-derived inhibitors by using molecular docking to screen compounds with strong binding affinity to the F430 active site of MCR and assessing their efficacy in reducing CH_(4) emissions.Results Molecular docking analysis identified salvianolic acid C(SAC)as a potent inhibitor of MCR,showing a strong binding affinity to the F430 active site(binding energy:-8.2 kcal/mol).Enzymatic inhibition assays confirmed its inhibitory effect,with a half-maximal inhibitory concentration(IC50)of 692.3μmol/L.In vitro rumen fermentation experiments demonstrated that SAC supplementation(1.5 mg/g DM)significantly reduced CH_(4)production(P<0.01)without negatively affecting major fermentation parameters.Microbial community analysis using 16S rRNA sequencing and metagenomics revealed that SAC selectively altered the rumen microbiota,increasing the relative abundance of Bacteroidota while significantly reducing Methanobrevibacter(P=0.04).Moreover,metagenomic analysis showed the downregulation of key methanogenesis-related genes(mcrA and rnfC),suggesting a dual mechanism involving direct enzymatic inhibition and microbial community modulation.Conclusions These findings indicate that SAC effectively reduces CH_(4)production by inhibiting MCR activity and reshaping the rumen microbial community.As a plant-derived compound with strong inhibitory effects on methanogenesis,SAC presents a promising and sustainable alternative to synthetic CH_(4) inhibitors,offering potential applications for mitigating CH_(4)emissions in livestock production.展开更多
The photocatalytic oxidation of methane(CH_(4)) to valuable chemicals like low alcohols(CH_(3)OH and C_(2)H_(5)OH) represents a significant technological advancement with implications for energy conversion and environ...The photocatalytic oxidation of methane(CH_(4)) to valuable chemicals like low alcohols(CH_(3)OH and C_(2)H_(5)OH) represents a significant technological advancement with implications for energy conversion and environmental purification.A major challenge in this field is the chemical inertness of methane and the strong oxidizing nature of photogenerated holes,which can lead to over-oxidation and reduced selectivity and efficiency.To address these issues,we have developed a sodium-doped zinc oxide(Na-ZnO) modified with cobalt oxide(CoO) catalyst.This catalyst has demonstrated excellent performance in converting methane to low alcohols,achieving a yield of 130 μmol g^(-1)h^(-1) and a selectivity of up to 96 %.The doping of Na in ZnO significantly enhances methane adsorption,while the surface-modified CoO effectively captures photogenerated holes,activates water molecules,and uses hydroxyl radicals to activate methane,thus controlling the dehydrogenation degree of methane and preventing the formation of over-oxidized products.This strategy has successfully improved the efficiency and selectivity of photocatalytic methane oxidation to low alcohols,offering a new perspective for the application of photocatalytic technology in energy and environmental fields.展开更多
Hydrate-based gas separation offers a promising approach for coalbed methane recovery,reaching energy conservation and emissions reduction.This study innovatively applied high-gravity technology to enhance hydrate for...Hydrate-based gas separation offers a promising approach for coalbed methane recovery,reaching energy conservation and emissions reduction.This study innovatively applied high-gravity technology to enhance hydrate formation in separating 25%CH_(4)/67%N_(2)/8%O_(2) for achieving rapid and efficient methane recovery.Systematic investigations were conducted at 283.2 K and 3.0 MPa with tetrahydrofuran at a molar concentration of 5.56%and L-tryptophan at a mass concentration of 0.5%additives,first evaluating liquid flow rate effects(0–20 mL/min)on mixed hydrate kinetic performance and separation efficiency,followed by rotating speed optimization(0–1200 r·min^(-1))under the optimal liquid flow rate.The high-gravity system amplified the gas–liquid contact area by~1155 times through cascaded liquid supply and secondary shear effects,methane molecules entered the hydrate phase rapidly under the highest driving force with the significantly intensified mass transfer.Optimal conditions(20 mL/min,600 r·min^(-1))yielded an exceptional initial hydrate growth rate of 58.59 mmol/(mol·h)and methane recovery of 50.76%,about 71.33 and 0.58 times higher than the static system,respectively.Gas chromatography and Raman spectrometer analyses revealed superior methane enrichment in hydrate phase at 90%gas uptake completion,with a concurrent 41.17%reduction in process duration.These findings demonstrate the efficacy of high-gravity-enhanced hydrate technology for coalbed methane separation,offering valuable insights for optimizing clean energy utilization.展开更多
Chinese coal reservoirs are characterized by low pressure and low permeability,which need to be enhanced so as to increase production.However,conventional methods for permeability enhancement can only increase the per...Chinese coal reservoirs are characterized by low pressure and low permeability,which need to be enhanced so as to increase production.However,conventional methods for permeability enhancement can only increase the permeability in fractures,but not the ultra-low permeability in coal matrices.Attempts to enhance such impermeable structures lead to rapid attenuation of gas production,especially in the late stage of gas extraction.Thermal stimulation by injecting high-temperature steam is a promising method to increase gas production.The critical scientific challenges that still hinder its widespread application are related to the evolution law of permeability of high-temperature steam in coal and the thermal deformation of coal.In this study,an experimental approach is developed to explore the high-temperature steam seepage coupled with the thermal deformation in coal under triaxial stress.The tests were conducted using cylindrical coal specimens of?50 mm×100 mm.The permeability and thermal strain in coal were investigated when high-temperature steam was injected at151.11,183.20,213.65,and 239.76°C.The experimental results reveal for the first time that as the amount of injected fluid increases,the steam permeability shows periodic pulsation changes.This paper introduces and explains the main traits of this discovery that may shed more light on the seepage phenomenon.When the injected steam temperature increases,the amplitude of pulsating permeability decreases,whereas the frequency increases;meanwhile,the period becomes shorter,the pulsation peak appears earlier,and the stabilization time becomes longer.The average peak permeability shows a“U-shaped”trend,decreasing first and then increasing as the steam temperature increases.Meanwhile,with the extension of steam injection time,the axial,radial,and volumetric strains of coal show a stage-wise expansion characteristic at different temperatures of steam injection,except for the radial strains at 151.11°C.A two-phase flow theory of gas–liquid is adopted to elucidate the mechanism of pulsating seepage of steam.Moreover,the influencing mechanism of inward and outward thermal expansion on the permeability of coal is interpreted.The results presented in this paper provide new insight into the feasibility of thermal gas recovery by steam injection.展开更多
The methane adsorption capacity,gas content,and carbon isotope characteristics of coal are crucial parameters that determine the productivity of coalbed methane(CBM)wells and their development potential.In this paper,...The methane adsorption capacity,gas content,and carbon isotope characteristics of coal are crucial parameters that determine the productivity of coalbed methane(CBM)wells and their development potential.In this paper,test analyses of methane adsorption,gas content and carbon isotope of methane were carried out using 89 samples from the No.3 coal seam in the southwestern part of the Qinshui Basin.Their characteristics and correlations were analyzed.A relationship model between methane adsorption,gas content,carbon isotopes,coal metamorphism and material composition were established,and its controlling mechanism was investigated.The results indicate that the distribution patterns of Langmuir volume and Langmuir pressure in No.3 coal seam are mainly determined by the material composition and the thermal evolution level.The methane gas content in coal is mainly affected by the burial depth,microcosmic co mposition,mineral conte nt,moisture content and ash yield,adsorption capacity and metamorphism of the coal.The methane carbon isotope(δ^(13)C_(1))values in the natural desorbed gas from No.3 coal seam range from-26.95%to-57.80‰,with a mean value of-34.53‰.δ^(13)C_(1)in coal shows a two-stage variation pattern with increasing in vitrinite reflectance(R_(max)^(o)).When R_(max)^(o)is blow 3.0%,δ^(13)C_(1)values of methane in coal become progressively heavier with increasing R_(max)^(o).When R_(max)^(o)reaches or exceeds 3.0%,δ^(13)C_(1)values exhibit a lightning trend with furth er increases in R_(max)^(o),which is primarily controlled by the carbon isotope fractionation effects during thermal evolution.展开更多
Selective dinitrogen(N_(2))capture from coalbed methane(CBM)is significant in chemical industries,but it remains a challenge because of similar physicochemical properties of N_(2) and CH_(4).Herein,the adsorption of t...Selective dinitrogen(N_(2))capture from coalbed methane(CBM)is significant in chemical industries,but it remains a challenge because of similar physicochemical properties of N_(2) and CH_(4).Herein,the adsorption of them on the 2D porphyrin sheets doped with various 3d transition metal ions(marked as MPor,M=Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn)were comparatively investigated by using density functional theory to screen a suitable adsorbent for CBM separation.Though systematical comparison of adsorption energies of gas molecules and Gibbs free energy change the N_(2) desorption process on all MPor surfaces,FePor is confirmed to be a promising adsorbent because of its undemanding regeneration conditions and modest chemical bonding state with N_(2) molecule.Further mechanism analysis reveals that the charge transferred from lone pair of N_(2) molecule to d_(z2)orbital of Fe ion and back-donated from d_(xz)and d_(yz)orbitals of Fe ion to the unoccupiedπ*orbital of N_(2) molecule.Such hybridization of orbitals improves the selective adsorption of N_(2) from CBM.展开更多
During gas extraction from deep coal,the rock endures high effective stress,with both the time-dependent deformation and anisotropic structure of the rock controlling the permeability evolution.To reveal this phenomen...During gas extraction from deep coal,the rock endures high effective stress,with both the time-dependent deformation and anisotropic structure of the rock controlling the permeability evolution.To reveal this phenomenon,a numerical simulation framework of the finite volume method and transient embedded discrete fracture model is proposed to establish a new constitutive model that links poroelastoplastic deformation,adsorption-induced swelling,and aperture compression.From this model,anisotropic permeability tensors were derived to further achieve the simulation of coevolution.Meanwhile,our permeability model was verified against the measured permeability data,and the history match of the numerical model showed better results where the mismatch was less than 5%.The results indicate that(1)the long-term permeability evolution clearly showed the competitive effects of multiple deformation mechanisms,which involves three stages:compaction-dominated decline,adsorption-dominated rebound,and creep-controlled loss.(2)The increased number of compressible cleats/fractures accelerated the initial permeability decline,while the increased desorption-induced strain promoted faster rebound and enhancement and higher viscosity coefficients enhanced the creep effect,which led to significant long-term permeability loss.(3)Massive hydraulic fracturing created a larger drainage area,accelerating methane desorption and causing sharp permeability rebound with reduced residual gas,which shows that the permeability remained higher than the initial values even after the extensive extraction via the fractured horizontal wells.The permeability evolution mechanisms displayed varying properties,such as coal rank and burial depth,and distinct characteristics.A precise understanding of multiple competitive stress effects is crucial for optimizing coalbed methane extraction techniques and improving recovery efficiency.展开更多
China’s deep coalbed methane(CBM)resources demonstrate immense potential with extensive developmental prospects.However,the coupling relationship between the negative adsorption effect and the positive desorption-pro...China’s deep coalbed methane(CBM)resources demonstrate immense potential with extensive developmental prospects.However,the coupling relationship between the negative adsorption effect and the positive desorption-promotion effect under high-temperature conditions remains unclear.In this study,a self-built high-temperature adsorption-desorption system was used to investigate the coupled effects of temperature and coal rank on methane adsorption-desorption behavior in deep CBM.The results show that elevated temperatures significantly reduce methane adsorption capacity,with high-rank coals exhibiting greater sensitivity.Conversely,high-temperature conditions significantly enhance methane desorption and diffusion behavior,accelerating initial desorption rates,enabling rapid gas release in a short period,and thus improving desorption efficiency.The desorption volume and desorption-diffusion rate exhibited an asymmetric U-shaped variation with coal rank.By coupling the positive and negative effects of temperature and defining the desorption ratio,it was found that a 10 K increase in temperature raised the desorption ratio by 3.78%-8.05%.Finally,an effective gas content prediction model is proposed,and the key regulatory role of temperature in the resource potential and gas production characteristics of deep CBM is clarified.These findings can provide theoretical guidance for the subsequent optimization of deep CBM exploration and development strategies.展开更多
Coalbed methane(CBM)is a vital unconventional energy resource,and predicting its spatiotemporal pressure dynamics is crucial for efficient development strategies.This paper proposes a novel deep learningebased data-dr...Coalbed methane(CBM)is a vital unconventional energy resource,and predicting its spatiotemporal pressure dynamics is crucial for efficient development strategies.This paper proposes a novel deep learningebased data-driven surrogate model,AxialViT-ConvLSTM,which integrates AxialAttention Vision Transformer,ConvLSTM,and an enhanced loss function to predict pressure dynamics in CBM reservoirs.The results showed that the model achieves a mean square error of 0.003,a learned perceptual image patch similarity of 0.037,a structural similarity of 0.979,and an R^(2) of 0.982 between predictions and actual pressures,indicating excellent performance.The model also demonstrates strong robustness and accuracy in capturing spatialetemporal pressure features.展开更多
Coal dust explosion accidents often cause substantial property damage and casualties and frequently involve nano-sized coal dust.In order to study the impact of nano-sized coal on coal dust and methane–coal dust expl...Coal dust explosion accidents often cause substantial property damage and casualties and frequently involve nano-sized coal dust.In order to study the impact of nano-sized coal on coal dust and methane–coal dust explosions,a pipe test apparatus was used to analyze the explosion pressure characteristics of five types of micro-nano particle dusts(800 nm,1200 nm,45μm,60μm,and 75μm)at five concentrations(100 g/m3,250 g/m3,500 g/m3,750 g/m3,and 1000 g/m3).The explosion pressure characteristics were closely related to the coal dust particle size and concentration.The maximum explosion pressure,maximum rate of pressure rise,and deflagration index for nano-sized coal dust were larger than for its micro-sized counterpart,indicating that a nano-sized coal dust explosion is more dangerous.The highest deflagration index Kst for coal dust was 13.97 MPa/(m·s),indicating weak explosibility.When 7%methane was added to the air,the maximum deflagration index Kst for methane–coal dust was 42.62 MPa/(m·s),indicating very strong explosibility.This indicates that adding methane to the coal dust mixture substantially increased the hazard grade.展开更多
Sequestration of CO2 in deep and unmineable coal seams is one of the attractive alternatives to reduce its atmospheric concentration. Injection of CO2 in coal seams may help in enhancing the recovery of coalbed methan...Sequestration of CO2 in deep and unmineable coal seams is one of the attractive alternatives to reduce its atmospheric concentration. Injection of CO2 in coal seams may help in enhancing the recovery of coalbed methane. An experimental study has been carried out using coal samples from three different coal seams, to evaluate the enhanced gas recovery and sequestration potential of these coals. The coals were first saturated with methane and then by depressurization some of the adsorbed methane was desorbed. After partial desorption, CO2 was injected into the coals and subsequently they were depressurized again. Desorption of methane after the injections was studied, to investigate the ability of CO2 to displace and enhance the recovery of methane from the coals. The coals exhibited varying behavior of adsorption of CO2 and release of methane. For one coal, the release of methane was enhanced by injection of CO2, suggesting preferential adsorption of CO2 and desorption of methane. For the other two coals, CO2 injection did not produce incremental methane initially, as there was initial resistance to methane release. However with continued CO2 injection, most of the remaining methane was produced. The study suggested that preferential sorption behavior of coal and enhanced gas recovery pattern could not be generalized for all coals.展开更多
基金Supported by the China National Science and Technology Major Project(2025ZD1405700)CNPC Science and Technology Project(2023YQX20117).
文摘Based on the coalbed methane(CBM)/coal-rock gas(CRG)geological,geophysical,and experimental testing data from the Daji block in the Ordos Basin,the coal-forming and hydrocarbon generation&accumulation characteristics across different zones were dissected,and the key factors controlling the differential CBM/CRG enrichment were identified.The No.8 coal seam of the Carboniferous Benxi Formation in the Daji block is 8-10 m thick,typically overlain by limestone.The primary hydrocarbon generation phase occurred during the Early Cretaceous.Based on the differences in tectonic evolution and CRG occurrence,and with the maximum vitrinite reflectance of 2.0%and burial depth of 1800 m as boundaries,the study area is divided into deeply buried and deeply preserved,deeply buried and shallowly preserved,and shallowly buried and shallowly preserved zones.The deeply buried and deeply preserved zone contains gas content of 22-35 m^(3)/t,adsorbed gas saturation of 95%-100%,and formation water with total dissolved solid(TDS)higher than 50000 mg/L.This zone features structural stability and strong sealing capacity,with high gas production rates.The deeply buried and shallowly preserved zone contains gas content of 16-20 m^(3)/t,adsorbed gas saturation of 80%-95%,and formation water with TDS of 5000-50000 mg/L.This zone exhibits localized structural modification and hydrodynamic sealing,with moderate gas production rate.The shallowly buried and shallowly preserved zone contains gas content of 8-16 m^(3)/t,adsorbed gas saturation of 50%-70%,and formation water with TDS lower than 5000 mg/L.This zone experienced intense uplift,resulting in poor sealing and secondary alteration of the primary gas reservoir,with partial adsorbed gas loss,and low gas production rate.A depositional unification and structural divergence model is proposed,that is,although coal seams across the basin experienced broadly similar depositional and tectonic histories,differences in tectonic intensity have led to spatial heterogeneity in the maximum burial depth(i.e.,thermal maturity of coal)and current burial depth and occurrence of CRG(i.e.,gas content and occurrence state).The research results provide valuable guidance for advancing the theoretical understanding of CBM/CRG enrichment and for improving exploration and development practices.
基金the financial support from National Natural Science Foundation of China(No.52474029)Strategic and Applied Scientific Research Project of PetroChina Company Limited(2023ZZ18,2023ZZ18YJ04).
文摘In the development of coalbed methane(CBM)reservoirs using multistage fractured horizontal wells,there often exist areas that are either repeatedly stimulated or completely unstimulated between fracturing stages,leading to suboptimal reservoir performance.Currently,there is no well-established method for accurately evaluating the effectiveness of such stimulation.This study introduces,for the first time,the concept of the Fracture Network Bridging Coefficient(FNBC)as a novel metric to assess stimulation performance.By quantitatively coupling the proportions of unstimulated and overstimulated volumes,the FNBC effectively characterizes the connectivity and efficiency of the fracture network.A background grid calibration method is developed to quantify the stage-controlled volume,effectively stimulated volume,unstimulated volume,and repeatedly stimulated volume among different stages of horizontal wells.Furthermore,an optimization model is constructed by taking the FNBC as the objective function and the fracturing injection rate and fluid volume as optimization variables.The Simultaneous Perturbation Stochastic Approximation(SPSA)algorithm is employed to iteratively perturb and optimize these variables,progressively improving the FNBC until the optimal displacement rate and fluid volume corresponding to the maximum FNBC are obtained.Field application in a typical CBM multistage fractured horizontal well in China demonstrates that the FNBC increased from 0.358 to 0.539(a 50.6% improvement),with the injection rate rising from 16 m^(3)/min to 24 m^(3)/min and the average fluid volume per stage increasing from 2490 m^(3) to 3192 m^(3),significantly enhancing the stimulation effectiveness.This research provides theoretical support for designing high-efficiency stimulation strategies in unconventional reservoirs under dynamic limits.
基金supported by the National Science and Technology Major Project of China(No.2025ZD1405702)the Scientific Research and Technology Development Project of PetroChina Coalbed Methane Co.,Ltd.(Project No.25MQCTSG010)Applied Science and Technology Project of PetroChina Company Limited(2023ZZ18YJ04).
文摘Significant differences exist between deep and medium-shallow coalbed methane(CBM)reservoirs.The unclear understanding of flowback and production behavior severely constrains the development of deep CBM resources.To address this challenge,guided by the gas-liquid two-phase flow theory in ultra-low permeability reservoirs,and integrating theoretical analysis,numerical simulation,and insights from production practices,this study classifies the flowback and production stages of deep CBM well considering the Daning-Jixian Block,Eastern Ordos Basin as a representative case.We summarize the flowback characteristics for each stage and establish a standard flowback production type curve,aiming to guide field operations.The results indicate that:(a)The production process of deep CBM horizontal wells can be divided into five distinct stages:initial single-phase water dewatering stage,initial gas appearance to peak water production stage,gas breakthrough to peak gas production stage,stable production and decline stage,and low-rate production stage.(b)Based on reservoir energy,two standard type curves for horizontal well flowback production are established:the‘Sufficient Reservoir Energy’type and the‘Insufficient Reservoir Energy’type.The former achieves a higher initial gas rate(up to 12×10^(4)m^(3)/d)but exhibits poorer stability,while the latter achieves a lower stable rate(up to 8×10^(4)m^(3)/d)but demonstrates stronger stability.Numerical simulation confirms these behavioral patterns and reveals the underlying mechanisms related to the effectively drained area where pressure is significantly depleted.The findings from this study have guided the flowback production operations in 53 deep CBM wells with positive results,demonstrating high potential for broad application.
基金supported by PetroChina Coalbed Methane Co.,Ltd.
文摘With the maturation of coalbed methane(CBM)exploitation and the transition into the late stages of dewatering and gas production,liquid loading in gathering pipelines has emerged as a major constraint on productivity and operational stability.Based on real-time field data and gas-liquid physicochemical analyses,this study elucidates the mechanisms governing liquid loading formation under varying temperature,pressure,and water saturation conditions.An HYSYS model is employed to determine the water dew point,while the Turner model is used to evaluate the critical conditions for liquid holdup.The results indicate that gas water saturation exerts the dominant influence on liquid loading risk,followed by pressure,whereas temperature plays a comparatively minor role.When water saturation exceeds 2%and the operating temperature falls below the dew point,condensation-driven liquid loading increases sharply.To further characterize the spatial distribution of liquid accumulation,a steady-state OLGA model of a DN100 gathering pipeline network is developed to examine the effects of pipe diameter,water saturation,and soil temperature.The simulations show that larger pipe diameters and higher water saturation significantly aggravate liquid holdup,while elevated soil temperature mitigates liquid accumulation.Moreover,the liquid holdup ratio is found to correlate closely with flow regime transitions,confirming its suitability as a key indicator of liquid loading risk.Based on these findings,optimization strategies for pipeline design and operation are proposed.To mitigate liquid loading,the gathering pipeline velocity should be maintained above the critical value of 1.63 m/s,and the gas water content should be strictly controlled below 2%.Under operating conditions representative of the Hancheng block,it is recommended to reduce the pipeline diameter from DN130 to DN100 to enhance self-cleaning capacity.In addition,thermal insulation should be applied during winter operation to maintain the pipe wall temperature above 10◦C,thereby suppressing condensation-induced liquid accumulation.
基金sponsored by the National Natural Science Foundation of China(Grant No.42202205)Natural Science Foundation of Shandong Province,China(Grant No.ZR2021QD072).-。
文摘The vertical heterogeneity of the pore structure in deep coal seams with varying ash yields is a key control for coalbed methane storage and producibility;however,its specific impact on gas adsorption is not clearly defined.The focus of this study is the No.8 coal seam of the Carboniferous Benxi Formation in the Central-Eastern Ordos Basin.By integrating microscopic identification,proximate analysis,gas adsorption(CO_(2),N_(2),and CH_(4)),and the multifractal theory,we quantitatively characterized the nanopore structure(micropores<2 nm and mesopores 2 nm-100 nm)of coal reservoirs with varying ash yields.The results indicate that(1)ash yield is the primary factor that controls the vertical evolution of pore structures in coal seams.In low-ash yield coal seams,the extent of thermal evolution and ash yield jointly constrain the heterogeneity of pore size distribution.In mediumto high-ash yield coal seams,the heterogeneity of pore structure and pore size distribution are predominantly constrained by ash yield.(2)As the ash yield vertically increases,the mesoporous pore volume and specific surface area initially decrease and subsequently increase,while the contribution of micropores to both pore volume and specific surface area continuously diminishes.Consequently,the total pore volume and specific surface area of the coal samples exhibit a two-stage reduction close to an ash yield threshold of approximately 20%.(3)Further,the Langmuir volume for CH_(4)adsorption sharply declines below the 20%threshold,followed by a gradual decrease;in contrast,the Langmuir pressure initially decreases and subsequently increases.Hence,the vertical increase in ash yield constrains the development of pore systems and diminishes pore connectivity,thereby reducing methane adsorption capacity and adversely affecting coalbed methane productivity.(4)Low-ash yield coal reservoirs are characterized by a rapid gas breakthrough and high productivity,whereas medium-ash yield coal reservoirs generally require prolonged depressurization to achieve peak gas production.These findings reveal that in medium-high rank coal,ash yield―and not thermal evolution―is the main factor that controls vertical pore evolution and methane adsorption efficiency.The quantitative ash yield threshold(20%)established in this study provides a practical criterion for evaluating reservoir quality and predicting vertical variations in gas storage potential in the Ordos Basin.
基金Supported by Innovation Capability Support Program of Shaanxi(2024RS-CXTD-53,2024ZC-KJXX-096)the Key R&D Program of Shaanxi Province(2022QCY-LL-69)Xi’an Science and Technology Project(24GXFW0089)。
文摘Under the backdrop of“Carbon Peak and Carbon Neutrality”(dual carbon)goal in China,the methane-carbon dioxide reforming reaction has attracted considerable attention due to its environmental benefits of converting two greenhouse gases(methane and carbon dioxide)into syngas and its promising industrial applications.Nickel(Ni)-based catalysts,with high catalytic activity,low cost,and abundant resources,are considered ideal candidates for industrial applications.In this article,three reaction kinetic models were briefly introduced,namely the Power-Law(PL)model,the Eley-Rideal(ER)model,and the Langmuir-Hinshelwood-Hougen-Watson(LHHW)model.Based on the LHHW model,the reaction kinetics and mechanisms of different catalytic systems were systematically discussed,including the properties of supports,the doping of noble metals and transition metals,the role of promoters,and the influence of the geometric and electronic structures of Ni on the reaction mechanism.Furthermore,the kinetics of carbon deposition and elimination on various catalysts were analyzed.Based on the reaction rate expressions for carbon elimination,the reasons for the high activity of transition metal iron(Fe)-doped catalysts and core-shell structured catalysts in carbon elimination were explained.Based on the detailed collation and comparative analysis of the reaction mechanisms and kinetic characteristics across diverse Ni-based catalytic systems,a theoretical guidance for the designing of high-performance catalysts was provided in this work.
基金Supported by Innovative Research Groups of the National Natural Science Foundation of China(22021004)。
文摘Catalytic decomposition of methane,which produces high-purity hydrogen and high-value-added carbon nanomaterials,has shown considerable potential for development and is expected to yield significant economic benefits in the future.However,designing catalysts that simultaneously exhibit high activity and long-term stability remains a significant challenge.Tuning the catalyst’s structure and electronic properties is an effective strategy for enhancing the reaction performance.In this work,a series of NixZr/ZSM-5 catalysts were prepared using the incipient wetness impregnation method,and the effect of Zr loadings on catalyst properties and performance was systematically investigated.The calcined and reduced catalysts were characterized by low-temperature N_(2)adsorption-desorption,XRD,SEM,H_(2)-TPR and XPS.The results showed that the addition of Zr significantly increased the specific surface area of the catalyst and reduced the metal particle size.Smaller NiO particles were found to enter the pores of the HZSM-5 support,and electronic interactions between NiO and ZrO_(2)markedly enhanced the metal-support interaction.The catalyst exhibited optimal catalytic performance at a Zr loading of 5%,achieving a maximum methane conversion of 68%at 625℃,maintaining activity for 900 min,and delivering a carbon yield of 1927%.Further increasing the Zr loading yielded only limited improvements in catalytic performance.Characterization of the spent catalysts and carbon products via TEM,Raman spectroscopy,and TGA revealed that the introduction of ZrO_(2)reduced metal sintering and promoted a shift in carbon nanofibers growth mode from tip-growth to base-growth.The mechanism of base-growth enabled the catalyst to maintain reaction activity for an extended period.
基金supported by the National Key R&D Program of China(No.2024YFB4007501)the Natural Science Foundation of Jiangsu Province(No.BK20240109)the project of Jiangsu Key Laboratory for Clean Utilization of Carbon Resources(No.BM2024007).
文摘Low-concentration coal mine methane(LC-CMM),which is predominantly composed of methane,serves as a clean and low-carbon energy resource with significant potential for utilization.Utilizing LC-CMM as fuel for solid oxide fuel cells(SOFCs)represents an efficient and promising strategy for its effective utilization.However,direct application in Ni-based anodes induces carbon deposition,which severely degrades cell performance.Herein,a medium-entropy oxide Sr_(2)FeNi_(0.1)Cr_(0.3)Mn_(0.3)Mo_(0.3)O_(6−δ)(SFNCMM)was developed as an anode internal reforming catalyst.Following reduction treatment,FeNi_(3) nano-alloy particles precipitate on the surface of the material,thereby significantly enhancing its catalytic activity for LC-CMM reforming process.The catalyst achieved a methane conversion rate of 53.3%,demonstrating excellent catalytic performance.Electrochemical evaluations revealed that SFNCMM-Gd_(0.1)Ce_(0.9)O_(2−δ)(GDC)with a weight ratio of 7:3 exhibited superior electrochemical performance when employed as the anodic catalytic layer.With H_(2) and LC-CMM as fuels,the single cell achieved maximum power densities of 1467.32 and 1116.97 mW·cm^(−2) at 800℃,respectively,with corresponding polarization impedances of 0.17 and 1.35Ω·cm^(2).Furthermore,the single cell maintained stable operation for over 100 h under LC-CMM fueling without significant carbon deposition,confirming its robust resistance to carbon formation.These results underscore the potential of medium-entropy oxides as highly effective catalytic layers for mitigating carbon deposition in SOFCs.
基金funded by the Beef Cattle Research Council Cluster(FDE.18.21C)Natural Sciences and Engineering Research Council of Canada(NSERC)Discovery,NSERC Canadian Research Chair(Tier 1)program+2 种基金NSERC Alliance program(ALLRP 588541‐23)Foundation for Food&Agriculture Research Greener Cattle Initiative(Award ID 22‐000373)DSM Nutritional Products,Kaiseraugst,Switzerland。
文摘Background The enteric methane inhibitor 3-nitrooxypropanol(3-NOP)inhibits the key enzyme in ruminal methanogenesis,but whether short-term(ST)and long-term(LT)dietary supplementation has similar effects on rumen microbiota in beef cattle and how microbes change after 3-NOP withdrawal have not been studied.This study investigated changes in rumen bacteria,archaea,and protozoa after ST and LT dietary supplementation and removal of 3-NOP using metataxonomic analysis.Results A total of 143 rumen samples were collected from two beef cattle studies with 3-NOP supplementation.The ST study(95 samples)used eight ruminally cannulated beef cattle in a 4×4 Latin square design with four 28-d of 3-NOP treatments[mg/kg of dry matter(DM)]:control:0,low:53,med:161,and high:345.The LT study(48 samples)was a completely randomized design with two 3-NOP treatments[control:0,and high:280 mg/kg of DM)fed for 112-d followed by a 16-d withdrawal(without 3-NOP).Bacterial and archaeal communities were significantly affected by 3-NOP supplementation but limited effects on protozoal communities were observed.Under ST supplementation,the relative abundances of Prevotella,Methanobrevibacter(Mbb.)ruminantium,Methanosphaera sp.ISO3-F5,and Entodinium were increased(Q<0.05),whereas those of Mbb.gottschalkii and Epidinium were decreased(Q<0.05)with 3-NOP supplementation.In LT study,relative abundances of Mbb.ruminantium,and Methanosphaera sp.Group5 were increased(Q<0.05),while those of Saccharofermentans and Mbb.gottschalkii were decreased(Q<0.05)with 3-NOP supplementation.Comparison between 3-NOP supplementation and the withdrawal revealed increased relative abundances of Clostridia UCG-014 and Oscillospiraceae NK4A214 group and decreased those of Eubacterium nodatum group and Methanosphaera sp.Group5(P<0.05)after 3-NOP withdrawal.Further comparison of rumen microbiota between control and 3-NOP withdrawal showed significantly higher(P=0.029)relative abundances of Eggerthellaceae DNF00809,p-1088-a5 gut group,and Family XII UCG-001 in control group while no significant differences were detected for archaea and protozoa.Microbial network analysis revealed that microbial interactions differed by both 3-NOP dose and durations.Conclusions Both ST and LT supplementation affected overall rumen microbial profile,with individual microbial groups responded to 3-NOP supplementation differently.After 3-NOP withdrawal,not all microbes showed recovery,indicating that the 3-NOP driven shifts were only partially reversible.These findings provide an understanding of the effects of 3-NOP on rumen microbial communities and their adaptability to methane mitigation strategies.
基金funded by the Integrated Demonstration of Scalable and Efficient Healthy Breeding for Cattle and Sheep(Grant No.2022YFD1301100)Instant Intelligent Diagnosis and Risk Warning Methods for Nutritional and Metabolic-Type Periparturient Cow Paralysis(Grant No.2024-YWF-ZYSQ-10)。
文摘Background Methane(CH_(4))emissions from ruminants significantly contribute to greenhouse gas effects and energy loss in livestock production.Methyl-coenzyme M reductase(MCR)is the key enzyme in methanogenesis,making it a promising target for CH_(4) mitigation.This study aimed to identify and validate plant-derived inhibitors by using molecular docking to screen compounds with strong binding affinity to the F430 active site of MCR and assessing their efficacy in reducing CH_(4) emissions.Results Molecular docking analysis identified salvianolic acid C(SAC)as a potent inhibitor of MCR,showing a strong binding affinity to the F430 active site(binding energy:-8.2 kcal/mol).Enzymatic inhibition assays confirmed its inhibitory effect,with a half-maximal inhibitory concentration(IC50)of 692.3μmol/L.In vitro rumen fermentation experiments demonstrated that SAC supplementation(1.5 mg/g DM)significantly reduced CH_(4)production(P<0.01)without negatively affecting major fermentation parameters.Microbial community analysis using 16S rRNA sequencing and metagenomics revealed that SAC selectively altered the rumen microbiota,increasing the relative abundance of Bacteroidota while significantly reducing Methanobrevibacter(P=0.04).Moreover,metagenomic analysis showed the downregulation of key methanogenesis-related genes(mcrA and rnfC),suggesting a dual mechanism involving direct enzymatic inhibition and microbial community modulation.Conclusions These findings indicate that SAC effectively reduces CH_(4)production by inhibiting MCR activity and reshaping the rumen microbial community.As a plant-derived compound with strong inhibitory effects on methanogenesis,SAC presents a promising and sustainable alternative to synthetic CH_(4) inhibitors,offering potential applications for mitigating CH_(4)emissions in livestock production.
基金support from the Zhejiang Provincial Natural Science Foundation of China (No.LQ24B030011)the Ningbo Natural Science Foundation (No.2023J181)+4 种基金the Open Research Fund of Key Laboratory of Functional Inorganic Materials Chemistry of the Ministry of Education (Heilongjiang University)the Start-up Funding offered by Ningbo University of Technology to J.D.LiNational Natural Science Foundation of China (No.U24A2071)Postdoctoral Research Start-up Fund (No.2111224002)Harbin Normal University Talent Plan (No.1305124213) to Y.D.Liu。
文摘The photocatalytic oxidation of methane(CH_(4)) to valuable chemicals like low alcohols(CH_(3)OH and C_(2)H_(5)OH) represents a significant technological advancement with implications for energy conversion and environmental purification.A major challenge in this field is the chemical inertness of methane and the strong oxidizing nature of photogenerated holes,which can lead to over-oxidation and reduced selectivity and efficiency.To address these issues,we have developed a sodium-doped zinc oxide(Na-ZnO) modified with cobalt oxide(CoO) catalyst.This catalyst has demonstrated excellent performance in converting methane to low alcohols,achieving a yield of 130 μmol g^(-1)h^(-1) and a selectivity of up to 96 %.The doping of Na in ZnO significantly enhances methane adsorption,while the surface-modified CoO effectively captures photogenerated holes,activates water molecules,and uses hydroxyl radicals to activate methane,thus controlling the dehydrogenation degree of methane and preventing the formation of over-oxidized products.This strategy has successfully improved the efficiency and selectivity of photocatalytic methane oxidation to low alcohols,offering a new perspective for the application of photocatalytic technology in energy and environmental fields.
基金The financial support from the Nature Scientific Foundation of Heilongjiang Province(No.YQ2022E041)the Postdoctoral Research Start-up Funds in Heilongjiang Province(No.2023BSH14)the Basic scientific research project of Heilongjiang Provincial University(No.2024-KYYWF-1090)。
文摘Hydrate-based gas separation offers a promising approach for coalbed methane recovery,reaching energy conservation and emissions reduction.This study innovatively applied high-gravity technology to enhance hydrate formation in separating 25%CH_(4)/67%N_(2)/8%O_(2) for achieving rapid and efficient methane recovery.Systematic investigations were conducted at 283.2 K and 3.0 MPa with tetrahydrofuran at a molar concentration of 5.56%and L-tryptophan at a mass concentration of 0.5%additives,first evaluating liquid flow rate effects(0–20 mL/min)on mixed hydrate kinetic performance and separation efficiency,followed by rotating speed optimization(0–1200 r·min^(-1))under the optimal liquid flow rate.The high-gravity system amplified the gas–liquid contact area by~1155 times through cascaded liquid supply and secondary shear effects,methane molecules entered the hydrate phase rapidly under the highest driving force with the significantly intensified mass transfer.Optimal conditions(20 mL/min,600 r·min^(-1))yielded an exceptional initial hydrate growth rate of 58.59 mmol/(mol·h)and methane recovery of 50.76%,about 71.33 and 0.58 times higher than the static system,respectively.Gas chromatography and Raman spectrometer analyses revealed superior methane enrichment in hydrate phase at 90%gas uptake completion,with a concurrent 41.17%reduction in process duration.These findings demonstrate the efficacy of high-gravity-enhanced hydrate technology for coalbed methane separation,offering valuable insights for optimizing clean energy utilization.
基金Fundamental Research Funds for the Universities of Henan Province,Grant/Award Number:NSFRF180305。
文摘Chinese coal reservoirs are characterized by low pressure and low permeability,which need to be enhanced so as to increase production.However,conventional methods for permeability enhancement can only increase the permeability in fractures,but not the ultra-low permeability in coal matrices.Attempts to enhance such impermeable structures lead to rapid attenuation of gas production,especially in the late stage of gas extraction.Thermal stimulation by injecting high-temperature steam is a promising method to increase gas production.The critical scientific challenges that still hinder its widespread application are related to the evolution law of permeability of high-temperature steam in coal and the thermal deformation of coal.In this study,an experimental approach is developed to explore the high-temperature steam seepage coupled with the thermal deformation in coal under triaxial stress.The tests were conducted using cylindrical coal specimens of?50 mm×100 mm.The permeability and thermal strain in coal were investigated when high-temperature steam was injected at151.11,183.20,213.65,and 239.76°C.The experimental results reveal for the first time that as the amount of injected fluid increases,the steam permeability shows periodic pulsation changes.This paper introduces and explains the main traits of this discovery that may shed more light on the seepage phenomenon.When the injected steam temperature increases,the amplitude of pulsating permeability decreases,whereas the frequency increases;meanwhile,the period becomes shorter,the pulsation peak appears earlier,and the stabilization time becomes longer.The average peak permeability shows a“U-shaped”trend,decreasing first and then increasing as the steam temperature increases.Meanwhile,with the extension of steam injection time,the axial,radial,and volumetric strains of coal show a stage-wise expansion characteristic at different temperatures of steam injection,except for the radial strains at 151.11°C.A two-phase flow theory of gas–liquid is adopted to elucidate the mechanism of pulsating seepage of steam.Moreover,the influencing mechanism of inward and outward thermal expansion on the permeability of coal is interpreted.The results presented in this paper provide new insight into the feasibility of thermal gas recovery by steam injection.
基金supported by the National Natural Science Foundation of China(No.42372192)Shanxi Province science and technology plan joint unveiling project(No.20201101002)。
文摘The methane adsorption capacity,gas content,and carbon isotope characteristics of coal are crucial parameters that determine the productivity of coalbed methane(CBM)wells and their development potential.In this paper,test analyses of methane adsorption,gas content and carbon isotope of methane were carried out using 89 samples from the No.3 coal seam in the southwestern part of the Qinshui Basin.Their characteristics and correlations were analyzed.A relationship model between methane adsorption,gas content,carbon isotopes,coal metamorphism and material composition were established,and its controlling mechanism was investigated.The results indicate that the distribution patterns of Langmuir volume and Langmuir pressure in No.3 coal seam are mainly determined by the material composition and the thermal evolution level.The methane gas content in coal is mainly affected by the burial depth,microcosmic co mposition,mineral conte nt,moisture content and ash yield,adsorption capacity and metamorphism of the coal.The methane carbon isotope(δ^(13)C_(1))values in the natural desorbed gas from No.3 coal seam range from-26.95%to-57.80‰,with a mean value of-34.53‰.δ^(13)C_(1)in coal shows a two-stage variation pattern with increasing in vitrinite reflectance(R_(max)^(o)).When R_(max)^(o)is blow 3.0%,δ^(13)C_(1)values of methane in coal become progressively heavier with increasing R_(max)^(o).When R_(max)^(o)reaches or exceeds 3.0%,δ^(13)C_(1)values exhibit a lightning trend with furth er increases in R_(max)^(o),which is primarily controlled by the carbon isotope fractionation effects during thermal evolution.
基金Supported by the National Natural Science Foundation of China(Nos.52476170 and 51906232)the Natural Science Foundation of Shanxi Province of China(Nos.202303021211156,202203021212140)Project of Science and Technology Innovation Team of Shanxi Province(No.202204051002023)。
文摘Selective dinitrogen(N_(2))capture from coalbed methane(CBM)is significant in chemical industries,but it remains a challenge because of similar physicochemical properties of N_(2) and CH_(4).Herein,the adsorption of them on the 2D porphyrin sheets doped with various 3d transition metal ions(marked as MPor,M=Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn)were comparatively investigated by using density functional theory to screen a suitable adsorbent for CBM separation.Though systematical comparison of adsorption energies of gas molecules and Gibbs free energy change the N_(2) desorption process on all MPor surfaces,FePor is confirmed to be a promising adsorbent because of its undemanding regeneration conditions and modest chemical bonding state with N_(2) molecule.Further mechanism analysis reveals that the charge transferred from lone pair of N_(2) molecule to d_(z2)orbital of Fe ion and back-donated from d_(xz)and d_(yz)orbitals of Fe ion to the unoccupiedπ*orbital of N_(2) molecule.Such hybridization of orbitals improves the selective adsorption of N_(2) from CBM.
基金support of the National Natural Science Foundation of China(U23B6004 and 52404045)the CAST Young Talent Support Program,Doctoral Student Special Project.
文摘During gas extraction from deep coal,the rock endures high effective stress,with both the time-dependent deformation and anisotropic structure of the rock controlling the permeability evolution.To reveal this phenomenon,a numerical simulation framework of the finite volume method and transient embedded discrete fracture model is proposed to establish a new constitutive model that links poroelastoplastic deformation,adsorption-induced swelling,and aperture compression.From this model,anisotropic permeability tensors were derived to further achieve the simulation of coevolution.Meanwhile,our permeability model was verified against the measured permeability data,and the history match of the numerical model showed better results where the mismatch was less than 5%.The results indicate that(1)the long-term permeability evolution clearly showed the competitive effects of multiple deformation mechanisms,which involves three stages:compaction-dominated decline,adsorption-dominated rebound,and creep-controlled loss.(2)The increased number of compressible cleats/fractures accelerated the initial permeability decline,while the increased desorption-induced strain promoted faster rebound and enhancement and higher viscosity coefficients enhanced the creep effect,which led to significant long-term permeability loss.(3)Massive hydraulic fracturing created a larger drainage area,accelerating methane desorption and causing sharp permeability rebound with reduced residual gas,which shows that the permeability remained higher than the initial values even after the extensive extraction via the fractured horizontal wells.The permeability evolution mechanisms displayed varying properties,such as coal rank and burial depth,and distinct characteristics.A precise understanding of multiple competitive stress effects is crucial for optimizing coalbed methane extraction techniques and improving recovery efficiency.
基金supported by the National Natural Science Fund of China(No.42272195)the National Natural Science Fund of China(No.42130802)+2 种基金the Fundamental Research Funds for the Central Universities(No.2025ZDPY10)the China National Petroleum Co.,Ltd..Research applied science and technology special(No.2023ZZ18)the PetroChina Changqing oilfield science and technology major project(No.2023DZZ01).
文摘China’s deep coalbed methane(CBM)resources demonstrate immense potential with extensive developmental prospects.However,the coupling relationship between the negative adsorption effect and the positive desorption-promotion effect under high-temperature conditions remains unclear.In this study,a self-built high-temperature adsorption-desorption system was used to investigate the coupled effects of temperature and coal rank on methane adsorption-desorption behavior in deep CBM.The results show that elevated temperatures significantly reduce methane adsorption capacity,with high-rank coals exhibiting greater sensitivity.Conversely,high-temperature conditions significantly enhance methane desorption and diffusion behavior,accelerating initial desorption rates,enabling rapid gas release in a short period,and thus improving desorption efficiency.The desorption volume and desorption-diffusion rate exhibited an asymmetric U-shaped variation with coal rank.By coupling the positive and negative effects of temperature and defining the desorption ratio,it was found that a 10 K increase in temperature raised the desorption ratio by 3.78%-8.05%.Finally,an effective gas content prediction model is proposed,and the key regulatory role of temperature in the resource potential and gas production characteristics of deep CBM is clarified.These findings can provide theoretical guidance for the subsequent optimization of deep CBM exploration and development strategies.
基金the National Natural Science Foundation of China(No.52474068)the Major Collab-orative Innovation Project of Prospecting Breakthrough Stra-tegic Action in Guizhou Province(No.[2022]ZD001-003).
文摘Coalbed methane(CBM)is a vital unconventional energy resource,and predicting its spatiotemporal pressure dynamics is crucial for efficient development strategies.This paper proposes a novel deep learningebased data-driven surrogate model,AxialViT-ConvLSTM,which integrates AxialAttention Vision Transformer,ConvLSTM,and an enhanced loss function to predict pressure dynamics in CBM reservoirs.The results showed that the model achieves a mean square error of 0.003,a learned perceptual image patch similarity of 0.037,a structural similarity of 0.979,and an R^(2) of 0.982 between predictions and actual pressures,indicating excellent performance.The model also demonstrates strong robustness and accuracy in capturing spatialetemporal pressure features.
基金This research was supported by the National Key Research and Development Program of China(2016YFC0801800)the National Nature Science Foundation of China(51774291,51864045).
文摘Coal dust explosion accidents often cause substantial property damage and casualties and frequently involve nano-sized coal dust.In order to study the impact of nano-sized coal on coal dust and methane–coal dust explosions,a pipe test apparatus was used to analyze the explosion pressure characteristics of five types of micro-nano particle dusts(800 nm,1200 nm,45μm,60μm,and 75μm)at five concentrations(100 g/m3,250 g/m3,500 g/m3,750 g/m3,and 1000 g/m3).The explosion pressure characteristics were closely related to the coal dust particle size and concentration.The maximum explosion pressure,maximum rate of pressure rise,and deflagration index for nano-sized coal dust were larger than for its micro-sized counterpart,indicating that a nano-sized coal dust explosion is more dangerous.The highest deflagration index Kst for coal dust was 13.97 MPa/(m·s),indicating weak explosibility.When 7%methane was added to the air,the maximum deflagration index Kst for methane–coal dust was 42.62 MPa/(m·s),indicating very strong explosibility.This indicates that adding methane to the coal dust mixture substantially increased the hazard grade.
文摘Sequestration of CO2 in deep and unmineable coal seams is one of the attractive alternatives to reduce its atmospheric concentration. Injection of CO2 in coal seams may help in enhancing the recovery of coalbed methane. An experimental study has been carried out using coal samples from three different coal seams, to evaluate the enhanced gas recovery and sequestration potential of these coals. The coals were first saturated with methane and then by depressurization some of the adsorbed methane was desorbed. After partial desorption, CO2 was injected into the coals and subsequently they were depressurized again. Desorption of methane after the injections was studied, to investigate the ability of CO2 to displace and enhance the recovery of methane from the coals. The coals exhibited varying behavior of adsorption of CO2 and release of methane. For one coal, the release of methane was enhanced by injection of CO2, suggesting preferential adsorption of CO2 and desorption of methane. For the other two coals, CO2 injection did not produce incremental methane initially, as there was initial resistance to methane release. However with continued CO2 injection, most of the remaining methane was produced. The study suggested that preferential sorption behavior of coal and enhanced gas recovery pattern could not be generalized for all coals.
