Engineering the pore structure of biomass-derived activated carbons is critical for optimizing their performance in adsorptionbased applications.This study demonstrates for the first time that washing hydrochars in so...Engineering the pore structure of biomass-derived activated carbons is critical for optimizing their performance in adsorptionbased applications.This study demonstrates for the first time that washing hydrochars in solvents of different polarity before activation is a simple yet powerful strategy to tailor pore size distribution.Hydrochar is produced from spent coffee grounds via hydrothermal carbonization,followed by washing in various solvents and activation in KOH.This results in carbons with a very large surface area(~2700 m^(2)/g),and washing is demonstrated to significantly increase product yield.Furthermore,washing in non-polar or mixed-polarity solvents removes long-chain carboxylic acids and esters from the hydrochar,promoting the development of narrow micropores while suppressing mesopore formation.To illustrate the impact of this structural control of porous carbons,post-combustion CO_(2)capture is investigated as a case study.Narrower pore size distribution enhances CO_(2)uptake,significantly improving capacity from 2.8 mmol/g for unwashed samples to 3.8 mmol/g for acetone-washed samples.Interestingly,moderate pore size(9-12Å)is shown to be optimal for CO_(2):N2 selectivity,while smaller pores result in lower selectivity due to stronger interactions between N2 and the pore walls.These findings highlight the potential role of solvent washing in directing pore architecture of hydrochars for adsorption-based carbon capture technologies and beyond.展开更多
Electrochemical liquid lithium extraction technology has attracted much attention because of its high selectivity,good efficiency,and eco-friendliness.However,the low energy density per unit area and poor stability of...Electrochemical liquid lithium extraction technology has attracted much attention because of its high selectivity,good efficiency,and eco-friendliness.However,the low energy density per unit area and poor stability of traditional thin film electrodes(F-LMO),as well as manganese dissolution loss induced by the Jahn-Teller distortion of LiMn_(2)O_(4),hinder their industrial scalability.Herein,a durable and high-efficiency multistage porous LiMn_(2)O_(4) thick electrode was prepared sustainably by 3D printing technology(3DPLMO)for enhancing lithium recovery from salt lake brine.The multistage porous structure reduced the mass transfer resistance and shortened the ion diffusion path,which was conducive to accelerating the diffusion rate of Li+.Simultaneously,the three-dimensional conductive networks composed of reduced graphene oxide(r GO)and carbon nanotubes(CNT)synergized with the multistage pores effectively weakened the polarization phenomenon of the electrode and improved the stability of 3DP-LMO.The3DP-LMO exhibited a 5.5-fold higher extraction capacity per unit area and the Mn dissolution loss rate was only 1/15 compared with the F-LMO.Notably,the capacity retention rate of 3DP-LMO was 87.6%,significantly better than that of F-LMO(66.3%).Based on the quasi-in situ X-ray Diffraction results,the mechanism of lithium intercalation and deintercalation in 3DP-LMO was elucidated.Furthermore,lithium extraction parameters were optimized using response surface method-center composite design(RSM-CCD),resulting in an increase in lithium extraction capacity to 15.66 mg g^(-1)and a reduction in energy consumption to only 12.33 Wh mol^(-1).The results show that 3DP-LMO has significantly improved lithium extraction performance and stability,and has considerable prospects in practical application.展开更多
Carbonaceous debris(CD) is widely disseminated within sandstones in the Shuanglong uranium deposit,southern Ordos Basin,and is the dominant enrichment agent for uranium precipitation.The occurrence and chemical compos...Carbonaceous debris(CD) is widely disseminated within sandstones in the Shuanglong uranium deposit,southern Ordos Basin,and is the dominant enrichment agent for uranium precipitation.The occurrence and chemical composition of uranium minerals within CD were investigated by using scanning electron microscope and electron microprobe analyses.The results show that uranium minerals mostly occur in cell pores in the forms of fructus aurantia and concentric band structure.Pitchblende and coffinite are the main uranium minerals,and the former is dominant.According to the crystal morphology and composition of trace elements of uranium minerals,uranium precipitation on the pores is grouped into two periods,orderly Ⅰ,Ⅱ.Moreover,the Ⅰ period is further divided into two sub-period,orderly Ⅰ_(1),Ⅰ_(2).Moreover,askew sphere uranium minerals could indicate fluid migration.Under certain geological environment condition,uranium is unevenly adsorbed on the surface of the pore by the Van der Waals(i.e.,Ⅰ_(1) period),and then is precipitated towards to the center of the pore until the whole pore is filled up with uranium minerals by complicated process such as microorganism activities(i.e.,Ⅰ_(2),Ⅱ period).It will provide some guidance for studying the metallogenic environment and genesis of sandstone-type uranium deposit.展开更多
A comprehensive analysis of the microstructure and defects of a thixomolded AZ91D alloy was conducted to elucidate their influences on mechanical properties.Samples were made at injection temperatures ranging from 580...A comprehensive analysis of the microstructure and defects of a thixomolded AZ91D alloy was conducted to elucidate their influences on mechanical properties.Samples were made at injection temperatures ranging from 580 to 640℃.X-ray computed tomography was used to visualize pores,and crystal plasticity finite element simulation was adopted for deformation analysis.The microstructure characterizations reveal a hierarchical cell feature composed of α-Mg and eutectic phases.With the increase of injection temperature,large cell content in the material decreases,while the strength of the alloy increases.The underlying mechanism about strength change is that coarse-grained solids experience smaller stress even in hard orientations.The sample fabricated at a moderate temperature of 620℃ exhibits the highest elongation,least quantity and lower local concentration of pores.The detachment and tearing cracks formed at lower injection temperature and defect bands formed at higher injection temperature add additional crack sources and deteriorate the ductility of the materials.展开更多
The basic geological characteristics of the Qiongzhusi Formation reservoirs and conditions for shale gas enrichment and high-yield were studied by using methods such as mineral scanning,organic and inorganic geochemis...The basic geological characteristics of the Qiongzhusi Formation reservoirs and conditions for shale gas enrichment and high-yield were studied by using methods such as mineral scanning,organic and inorganic geochemistry,breakthrough pressure,and triaxial mechanics testing based on the core,logging,seismic and production data.(1)Both types of silty shale,rich in organic matter in deep water and low in organic matter in shallow water,have good gas bearing properties.(2)The brittle mineral composition of shale is characterized by comparable feldspar and quartz content.(3)The pores are mainly inorganic pores with a small amount of organic pores.Pore development primarily hinges on a synergy between felsic minerals and total organic carbon content(TOC).(4)Dominated by Type I organic matters,the hydrocarbon generating organisms are algae and acritarch,with high maturity and high hydrocarbon generation potential.(5)Deep-and shallow-water shale gas exhibit in-situ and mixed gas generation characteristics,respectively.(6)The basic law of shale gas enrichment in the Qiongzhusi Formation was proposed as“TOC controlled accumulation and inorganic pore controlled enrichment”,which includes the in-situ enrichment model of“three highs and one over”(high TOC,high felsic mineral content,high inorganic pore content,overpressured formation)for organic rich shale represented by Well ZY2,and the in-situ+carrier-bed enrichment model of“two highs,one medium and one low”(high felsic content,high formation pressure,medium inorganic pore content,low TOC)for organic-poor shale gas represented by Well JS103.It is a new type of shale gas that is different from the Longmaxi Formation,enriching the formation mechanism of deep and ultra-deep shale gas.The deployment of multiple exploration wells has achieved significant breakthroughs in shale gas exploration.展开更多
The water adsorption performance of shale gas reservoirs is a very important factor affecting their gas in place(GIP)contents,but the water-holding capacity and mechanism of over-mature shale,especially organic pores,...The water adsorption performance of shale gas reservoirs is a very important factor affecting their gas in place(GIP)contents,but the water-holding capacity and mechanism of over-mature shale,especially organic pores,are still not fully understood.In this study,systematic water vapor adsorption(WVA)experiments were carried out on the Lower Cambrian over-mature shale and its kerogen from the Sichuan Basin,China to characterize their WVA behaviors,and combined with the low-pressure gas(N_(2) and CO_(2))adsorption experiments,the main influencing factors of WVA capacity of the shale and the absorbed-water distribution in its organic and inorganic nanopores were investigated.The results show that the WVA isotherms of shale and kerogen are all typeⅡ,with an obvious hysteresis loop in the multilayer adsorption range,and that the positive relationship of the shale TOC content with the WVA capacity(including total adsorption capacity,primary adsorption capacity and secondary adsorption capacity)and WVA hysteresis index(AHIW),and the greater adsorption capacity and AHIW of kerogen than the shale,all indicate that the hydrophilicity of organic matter(OM)in the over-mature shale was underestimated in previous research.Although both the shale OM and clay minerals have a significant positive effect on the WVA,the former has a stronger adsorption ability than the latter.The WVA capacity of the studied Lower Cambrian shale is significantly greater than that of the Longmaxi shale reported in literatures,which was believed to be mainly attributed to its higher maturity,with a significant graphitization of OM.The shale micropores and non-micropores play an important role in WVA,especially OM pores.There are primary and secondary adsorption for water vapor in both the micropores and non-micropores of OM,while these adsorptions of minerals mainly occur in their non-micropores.These results have important guides for understanding the gas storage mechanism and exploration and development potential of marine over-mature shale in southern China,especially the Lower Cambrian shale.展开更多
Peat soil is a loose,moisture-rich organic matter accumulation formed by the deposition of plants in swamps and lakes after their death.It is characterized by high moisture content,large void ratio,high compressibilit...Peat soil is a loose,moisture-rich organic matter accumulation formed by the deposition of plants in swamps and lakes after their death.It is characterized by high moisture content,large void ratio,high compressibility,and strong rheological properties.These characteristics result in a complex consolidation process.A systematic understanding of the consolidation mechanism of peat soil is essential for elucidating its consolidation behavior.Previous studies have failed to provide consistent information on the microscopic morphology of peat soil.Moreover,quantitative studies on pore structure changes during peat soil consolidation remain lacking.To resolve these research gaps,the microscopic morphology and pore types of peat,highly organic peaty soil,and medium organic peaty soil from certain regions of Yunnan province,China,were observed and analyzed using scanning electron microscopy.Additionally,quantitative research on pore structure changes during peat soil consolidation was conducted.The results show that the humic acid in peat soil of Yunnan province has no pores,and there is no pore between humic acid and clay minerals.There are three typical pore structures,and the three typical pores were quantitatively analyzed.During consolidation,the consolidation deformation of peat soil is primarily caused by the internal pore compression of plant residues and pores between plant residues.At the same time,the revelation of the differentiated influence mechanism of load levels on the compression of inter/intra-plant residue pores.The decrease in the proportion of pores between plant residues first increased and then decreased with an increase in load,reaching a peak between 100-200 kPa.The decrease in pores inside the plant residues increased with an increasing load.Additionally,pore compression between the plant residues under different load levels primarily caused the compression deformation of Dali peat during the primary consolidation stage.By contrast,the pore compression inside the plant residues primarily caused the compression deformation during the secondary consolidation stage.展开更多
Organic-rich shale is a significant potential source of oil and gas that requires development through in situ conversion technology.However,the evolution patterns of the internal three-dimensional(3D)pore structure an...Organic-rich shale is a significant potential source of oil and gas that requires development through in situ conversion technology.However,the evolution patterns of the internal three-dimensional(3D)pore structure and kerogen distribution at high temperatures are not well understood,making it difficult to microscopically explain the evolution of the flow conductivity in organic-rich shale at high temperatures.This study utilizes high-resolution X-ray computed tomography(micro-nano CT)to obtain the distribution of pores,kerogen,and inorganic matter at different temperatures.Combined with the pyrolysis results for the rock,the evolution of the pore structure at various temperatures is quantitatively analyzed.Based on three-phase segmentation technology,a model of kerogen distribution in organicrich shale is established by dividing the kerogen into clustered kerogen and dispersed kerogen stored in the inorganic matter and the pores into inorganic pores and organic pores within the kerogen skeleton.The results show that the inorganic pores in organic-rich shale evolve through three stages as the temperature increases:kerogen pyrolysis(200-400℃),clay mineral decomposition(400-600℃),and carbonate mineral decomposition(600-800℃).The inorganic pores porosity sequentially increases from 3%to 11.4%,13.1%,and 15.4%,and the roughness and connectivity of the inorganic pores gradually increase during this process.When the pyrolysis temperature reaches 400℃,the volume of clustered kerogen decreases from 25%to 12.5%.During this process,the relative density of kerogen decreases from9.5 g/cm^(3) in its original state to 5.4 g/cm^(3),while the kerogen skeleton density increases from 1.15 g/cm^(3) in its original state to 1.54 g/cm^(3).Correspondingly,7%-8%of organic pores develop within the clustered kerogen,accounting for approximately 50%of the volume of clustered kerogen.In addition,approximately 30%of the kerogen in organic-rich shale exists in the form of dispersed kerogen within inorganic matter,and its variation trend is similar to that of clustered kerogen,rapidly decreasing from 200 to 400℃ and stabilizing above 400℃.The results of this study provide an essential microscopic theoretical basis for the industrial development of organic-rich shale resources.展开更多
The low-voltage plateau capacity,which is highly related to the internal closed pores in hard carbon(HC),is the main contributor to the total capacity in sodium-ion batteries.However,the formation mechanism of closed ...The low-voltage plateau capacity,which is highly related to the internal closed pores in hard carbon(HC),is the main contributor to the total capacity in sodium-ion batteries.However,the formation mechanism of closed pores and modification strategies at the molecular level in HC polymer precursors remain poorly understood.Furthermore,the practical applications of HCs are significantly impeded by their low initial coulombic efficiency(ICE).In this study,the intramolecular heteroatom doping(IHP)effect was proposed to facilitate the formation of closed pores in polymer-derived HC for the first time by grafting sulfonyl,ether,and carbonyl groups between benzene rings.As a result,the optimized HC sample showed an increased closed pore volume and low Na^(+)adsorption energy,which delivered a reversible capacity of 307.9 mAh·g^(-1)and superior rate capability.Through further optimized presodiation,the formed presodiated HC featuring a thin,smooth,and dense solid electrolyte interface film exhibited a remarkably enhanced ICE of 94.4%and enhanced cycling stability(93.6%over 3000 cycles).This study provides an in-depth understanding of the formation mechanisms of closed pores via IHP engineering and develops a new synergistic strategy involving presodiation to prepare highly stable HC anodes.展开更多
The organic-inorganic transformation and interaction act as the critical role in the occurrence of nanopores within the organic-rich shales during thermal maturation.Hydrous pyrolysis experiments were conducted on the...The organic-inorganic transformation and interaction act as the critical role in the occurrence of nanopores within the organic-rich shales during thermal maturation.Hydrous pyrolysis experiments were conducted on the organic-rich mudrock collected from the Upper Cretaceous Nenjiang Formation of the Songliao Basin,China in a closed system.The pore types and pore network,and organic and inorganic compositions of pyrolyzed shales were detected from the early to over mature stages(%Ro=0.61-4.01).The experimental results indicate that geochemical transformation of organic matters and minerals and the interaction control the formation and evolution of nanoporosity.In oil window mineral matrix pores are infilled by the generated oil,K-feldspar dissolution by organic acids promotes clay illitization to form illite,and the catalytic effects of clays(e.g.illite)in the complex of organic matter and clays may promote the in-situ retained oil cracking to generate natural gas,resulting in the early occurrence of organic-matter pores in the complex within oil window.Due to significant primary cracking of solid kerogen to generate extractable liquid oil,pore volume for storing fluids presents a persistent increase and approaches the maximum at the end of oil window.In gas window intensive oil cracking facilitates the hydrocarbon migrating out of the source home and pyrobitumen formation,resulting in the significant occurrence of modified mineral matrix pores and organic-matter pores.Pore volume for hosting hydrocarbons presents a slight decrease at%Ro=1.36-2.47 due to pyrobitumen formation by oil secondary cracking.The organic-inorganic interaction favors clay illitization,quartz dissolution,and pyrite and carbonate decomposition,which facilitate the occurrence of nanoporosity.Pyrobitumen within the complex with illite and organic matters are much more porous than that hosted in modified mineral matrix pores and microfractures.The catalytic effects of clays are supposed to be responsible for this.This study improves our understanding of the formation and evolution pathways of nanoporosity and the underlying controls in organic-rich shales during thermal maturation,and hence should be helpful in evaluating the sweet spots for shale-oil and shale-gas plays in a sedimentary basin.展开更多
The connectivity of shale pores and the occurrence of movable oil in shales have long been the focus of research.In this study,samples from wells BX7 and BYY2 in the Eq3^4-10 cyclothem of Qianjiang Formation in the Qi...The connectivity of shale pores and the occurrence of movable oil in shales have long been the focus of research.In this study,samples from wells BX7 and BYY2 in the Eq3^4-10 cyclothem of Qianjiang Formation in the Qianjiang depression,were analyzed.A double mercury injection method was used to distinguish between invalid and effective connected pores.The pore characteristics for occurrence of retained hydrocarbons and movable shale oil were identified by comparing pore changes in low temperature nitrogen adsorption and high pressure mercury injection experiments before and after extraction and the change in the mercury injection amounts in the pores between two separate mercury injections.The results show that less than 50%of the total connected pores in the Eq34-10 cyclothem samples are effective.The development of effective connected pores affects the mobility of shale oil but varies with different lithofacies.The main factor limiting shale oil mobility in Well BX7 is the presence of pores with throat sizes less than 15 nm.In Well BYY2,residual mercury in injection testing of lamellar dolomitic mudstone facies was mainly concentrated in pores with throats of 10-200 nm,and in bulk argillaceous dolomite facies,it was mainly concentrated at 60-300 nm.The throats of hydrocarbon-retaining pores can be 5 nm or even smaller,but pores with movable shale oil in the well were found to have throat sizes greater than 40 nm.Excluding the influence of differences in wettability,the movability of shale oil is mainly affected by differences in lithofacies,the degree of pore deformation caused by diagenesis,the complexity of pore structures,and the connectivity of pore throats.Dissolution and reprecipitation of halite also inhibit the mobility of shale oil.展开更多
Hard carbon(HC)is considered the most promising anode material for sodium-ion batteries(SIBs)due to its high costeffectiveness and outstanding overall performance.However,the amorphous and intricate microstructure of ...Hard carbon(HC)is considered the most promising anode material for sodium-ion batteries(SIBs)due to its high costeffectiveness and outstanding overall performance.However,the amorphous and intricate microstructure of HC poses significant challenges in elucidating the structure-performance relationship,which has led to persistent misinterpretations regarding the intrinsic characteristics of closed pores.An irrational construction methodology of closed pores inevitably results in diminished plateau capacity,which severely restricts the practical application of HC in high-energy-density scenarios.This review provides a systematic exposition of the conceptual framework and origination mechanisms of closed pores,offering critical insights into their structural characteristics and formation pathways.Subsequently,by correlating lattice parameters with defect configurations,the structure-performance relationships governing desolvation kinetics and sodium storage behavior are rigorously established.Furthermore,pioneering advancements in structural engineering are critically synthesized to establish fundamental design principles for the rational modulation of closed pores in HC.It is imperative to emphasize that adopting a molecular-level perspective,coupled with a synergistic kinetic/thermodynamic approach,is critical for understanding and controlling the transformation process from open pores to closed pores.These innovative perspectives are strategically designed to accelerate the commercialization of HC,thereby catalyzing the sustainable and high-efficiency development of SIBs.展开更多
Organic matter(OM)is the primary gas occurrence carrier in shale reservoirs due to their abundant nanopores.To reveal the OM pore structure,adsorption capacity and evolution during thermal maturation,this study collec...Organic matter(OM)is the primary gas occurrence carrier in shale reservoirs due to their abundant nanopores.To reveal the OM pore structure,adsorption capacity and evolution during thermal maturation,this study collected data from samples spanning the entire evolution stage,from immature to over-mature.Scanning Electron Microscope(SEM)observation and low temperature gases adsorption experiments were used to qualitatively-semi-quantitatively and quantitatively analyze OM pore structure evolution,and CH_(4) isothermal adsorption experiments were used to reveal the adsorption capacity evolution.Then,the influence and mechanism of matu rity and hydrocarbon generation on pore development and adsorption capacity were quantitatively reviewed based on the experimental data.The results show that OM pores are poorly developed in the immature stage due to weak hydrocarbon generation,although micro-fractures are occasionally found at the edges of OM particles.In the low maturity stage,OM pores are partially developed due to liquid hydrocarbon generation,with liquid hydrocarbons also filling some OM pores.The contribution of total organic carbon content(TOC)to adsorption extent is not significant in these two stages.From high to high-over maturity stages,massive gaseous hydrocarbons are generated,significantly improving the surface porosity of OM.Clear positive linear correlations are observed between TOC and adsorption amount.However,the development of OM pores significantly declines when thermal maturity(R_(o))exceeds 3.5%due to excessive aromatization.The accuracy of research on the evolution of pore structure and adsorption capacity is limited by several factors:(ⅰ)errors caused by sample specification,calculation processes,parameter settings,and kerogen models in isothermal adsorption experiments and molecular simulations;(ⅱ)difficulty in achieving control variables due to the strong heterogeneity of natural maturation shale samples;and(ⅲ)the need to enhance compatibility between thermal simulation experiments and natural thermal evolution.Therefore,isothermal adsorption experiments on bulk shale and molecular simulations of intact shale model are necessary,taking into account the dynamic temperature and pressure of in-situ reservoirs.Moreover,shale samples with varying maturity,influenced by their distance from the paleo-thermal source,may provide significant verification for thermal simulation experiments.展开更多
Biomineralization of natural composites are usually highly finely adjusted to achieve extremely precise control over the shape,size and distribution of inorganic crystals,giving them unique structures and properties o...Biomineralization of natural composites are usually highly finely adjusted to achieve extremely precise control over the shape,size and distribution of inorganic crystals,giving them unique structures and properties of biomaterials.These underlying mechanisms and pathways provide inspiration for the design and construction of materials for repairing hard tissues.Due to good biocompatibility of hydrogels,materials using gel-like systems as media are inextricably linked to biological macrocomponents and mineralization.Inspired by those bioprocesses,polyacrylamide hydrogel with enzymes was 3D printed to form controlled shapes and structures,then was used as templates for mineralization.Effect of polyacrylamide hydrogel pore size on the mineralization was studied via incorporating NaF and CaCl2 and controlling the mineralization degree.The mineralization processes of 3D printed hydrogels with different pore sizes were also explored to find out the confinement influence of pores.Mineralization in hydrogels with smaller pores is developed in a columnar stacked pattern,which is similar to the vesicular mineralization stage of bone mineralization.展开更多
Marine organic-rich marl is not only a high-quality hydrocarbon source of conventional oil and gas,but also a new type and field of unconventional oil and gas exploration.An understanding of its pore structure evoluti...Marine organic-rich marl is not only a high-quality hydrocarbon source of conventional oil and gas,but also a new type and field of unconventional oil and gas exploration.An understanding of its pore structure evolution characteristics during a hydrocarbon generation process is theoretically significant and has application prospects for the exploration and development of this special type of natural gas reservoirs.This study conducted thermal simulation of hydrocarbon generation under near-geological conditions during a whole process for cylinder samples of low mature marine organic-rich marl in the Middle Devonian of Luquan,Yunnan Province,China.During this process,hydrocarbon products at different evolution stages were quantified and corresponding geochemical properties were analyzed.Simultaneously,field emission scanning electron microscopy(FE-SEM)and low-pressure gas adsorption(CO_(2),N_(2))tests were applied to the corresponding cylinder residue samples to reveal the mechanisms of different types of pore formation and evolution,and clarify the dynamic evolution processes of their pore systems.The results show that with an increase in temperature and pressure,the total oil yield peaks at an equivalent vitrinite reflectance(VR_(o))of 1.03%and is at the maximum retention stage of liquid hydrocarbons,which are 367.51 mg/g TOC and 211.67 mg/g TOC,respectively.The hydrocarbon gas yield increases continuously with an increase in maturity.The high retained oil rate at the peak of oil generation provides an abundant material basis for gas formation at high maturity and over-maturity stage.The lower limit of VR_(o)for organic matter(OM)pore mass development is about 1.6%,and bitumen pores,organic-clay complex pores together with intergranular pores,grain edge seams and dissolution pores constitute a complicated pore-seam-network system,which is the main reservoir space for unconventional carbonate gas.Pore formation and evolution are controlled synergistically by hydrocarbon generation,diagenesis and organic-inorganic interactions,and the pattern of pore structure evolution can be divided into four stages.A pore volume(PV)and a specific surface area(SSA)are at their highest values within the maturity range of 1.9%to 2.5%,which is conducive to exploring unconventional natural gas.展开更多
Lower Paleozoic black shales are important source rocks worldwide.The Upper Ordovician-Lower Silurian Renheqiao Formation of the Baoshan Block is a low-maturity equivalent of the Wufeng-Longmaxi(WF-LMX)Shale of the Si...Lower Paleozoic black shales are important source rocks worldwide.The Upper Ordovician-Lower Silurian Renheqiao Formation of the Baoshan Block is a low-maturity equivalent of the Wufeng-Longmaxi(WF-LMX)Shale of the Sichuan Basin.However,organic matter(OM)characteristics in these low-maturity Lower Paleozoic shales are not well understood.In this study,50 Renheqiao Formation shale samples collected from seven outcrop sections and one drill core were investigated with organic petrology,organic geochemistry,R_(o)ck-Eval pyrolysis,N_(2) and CO_(2) adsorption,and scanning electron microscope(SEM)analyses to study the OM content,type,thermal maturity,and the development of OM-hosted pores in these Lower Paleozoic shales.The total organic carbon(TOC)content of the Renheqiao Formation shales varies,with the maximum content of 10.07 wt%.R_(o)ck-Eval pyrolysis results show that present OM in the Renheqiao Formation shales is Type IV kerogen,a result of advanced thermal maturation.Graptolite reflectance(GR_(o))ranges from 1.26%to 1.85%,and equivalent vitrinite reflectance(EqR_(o))converted from GR_(o) ranges from 1.08%to 1.51%,indicating that the studied Renheqiao Formation shales are dominantly within the late-mature stage.EqR_(o) based on R_(o)ck-Eval T_(max) shows large variations,which indicates that R_(o)ck-Eval T_(max) is not a reliable thermal maturity indicator for the Lower Paleozoic Renheqiao Formation shales.Caution should be applied when assessing the thermal maturity of high-maturity black shales based on T_(max) when the S2 values are too low.Organic petrographic observations show that OM in these shales is dominated by solid bitumen(>70 vol%of total OM),with minor contributions by graptolites and chitinozoans.The specific surface area and pore volume of shales are controlled by TOC content.Organic pores are hosted by solid bitumen and were not observed in graptolites when examined under the SEM.Although the Renheqiao Formation has a lower thermal maturity than the over-mature WF-LMX Shale,it is mature enough that primary oil-prone macerals have been thermally transformed and could not be identified under the microscope.展开更多
Carbon isotope fractionation served as a key geochemical indicator for understanding shale gas storage and migration.However,the detailed mechanism of the fractionation behaviors of methane isotopes(^(12)CH_(4)/^(13)C...Carbon isotope fractionation served as a key geochemical indicator for understanding shale gas storage and migration.However,the detailed mechanism of the fractionation behaviors of methane isotopes(^(12)CH_(4)/^(13)CH_(4))was still limited,especially under two-phase flow.This study employed molecular dynamics(MD)simulations to investigate water-mediated nonlinear isotope transport in 3 nm hydrophilic silica nanopores,highlighting gas-liquid-solid interfacial effects on fractionation mechanisms.Simulations of different water saturation(0%-44.66%)showed a critical hydration threshold of 30.44%at a pressure gradient of 20 MPa.Below this threshold,continuous water film formed on pore walls,which transformed the gas transport from surface diffusion to viscous flow through gas-liquid interactions,while hydrogen bonds in the water film weakened gas-solid slip effects.However,when water saturation exceeded 30.44%,the formation of water bridges blocked the mobility of isotopic gases.The water film reduced the depth of solid-gas potential wells,leading to diminished adsorption capacity for isotopic gases,and lowered the surface roughness of pore walls(as characterized by potential energy surface,PES).Additionally,the water film enhanced the Knudsen diffusion effect of isotope gases due to the decrease in effective pore size.As a result,the formation of water film intensified methane isotopic fractionation,which was manifested as a decrease in the^(13)CH_(4)/^(12)CH_(4)diffusion coefficient ratio(D∗/D)from 0.975 to 0.942 and an increase in isotopic enthalpy differences(Δh_(^(12)C)_^(13)C) from 0.105 to 1.139 J/m^(3).Furthermore,in the gas-liquid-solid interfacial system,an elevated pressure differential modified the relative motion velocities among the methane-water-pore surface,resulting a non-monotonic isotopic fractionation trend(initial increase followed by decrease).These findings provided molecular-level insights into the complex isotopic fractionation in shale gas systems.展开更多
In recent years,drilling data from wells Pengshen 10,Heshen 9,Tongshen 17 and Zhengyang 1 in the Sichuan Basin have confirmed the presence of a set of porous reef-beach limestone reservoirs in the Upper Permian Changx...In recent years,drilling data from wells Pengshen 10,Heshen 9,Tongshen 17 and Zhengyang 1 in the Sichuan Basin have confirmed the presence of a set of porous reef-beach limestone reservoirs in the Upper Permian Changxing Formation,which breaks the traditional view that deep carbonate oil and gas are only distributed in porous dolomite reservoirs and karst fracture-cavity limestone reservoirs.Through core and thin section observations,geochemical analysis,and well-seismic based reservoir identification and tracking,the study on formation mechanism of pores in deep reef-beach limestone reservoirs is carried out,this study provides insights in four aspects.(1)Porous reef-beach limestone reservoirs are developed in the Changxing Formation in deep-buried layers.The reservoir space is composed of intergranular pores,framework pores,intra-fossil pores,moldic pores and dissolution pores,which are formed in depositional and epigenetic environments.(2)The intermittently distributed porous reef-beach complexes are surrounded by relatively dense micrite limestone,which leads to the formation of local abnormal high-pressure inside the reef-beach complexes with the temperature increased.(3)The floor of the Changxing Formation reservoir is composed with interbedded tight mudstone and limestone of the Upper Permian Wujiaping Formation,and the roof is the tight micrite limestone interbedded with mudstone of the first member of Lower Triassic Feixianguan Formation.Under the clamping of dense roof and floor,the abnormal high-pressure in the Changxing Formation is formed.Abnormal high-pressure(overpressured compartment)is the key to maintain the pores formed in the depositional and epigenetic environments in deep-buried layers.(4)Based on the identification of roof,floor and reef-beach complexes,the favorable reef-beach limestone reservoir distribution area of 10.3×10^(4) km^(2) is predicted by well-seismic integration.These insights lay the theoretical foundation for the development of deep porous limestone reservoirs,expand the new field of exploration of deep-buried limestone reservoirs in the Sichuan Basin.展开更多
Materials with high surface area,tailored pore size and good electrical conductivity are needed for improved supercapacitors(SCs).Metal-organic frameworks(MOFs)have high surface areas and tailored pore sizes.Here,the ...Materials with high surface area,tailored pore size and good electrical conductivity are needed for improved supercapacitors(SCs).Metal-organic frameworks(MOFs)have high surface areas and tailored pore sizes.Here,the MOF(1)of[Ni3(μ3 OH)(pba)3(bpdc)1.5]·11.5 DMA·0.5 CH3 OH·7 H2O is good enough to result in electrode materials with nearly ideal supercapacitive behavior at the rate up to 50 mV·s^-1 in a KOH electrolyte.The super capacitive performance of MOF(1)was measured using cyclic voltammogram,galvanostatic discharge and electrochemical impedance spectroscopy measurements.This MOF(1)as electrode exhibits the highest super capacitive properties with 417 F·g^-1,the maximum storage energy and power density are 9.27 and 2.38 kW·kg^-1.The long term stability of MOF(1)as SCs is checked that the capacitance is decreased by 17%after 1000 cycles.展开更多
Through the octree data structure analysis,a volumetric dataset of closed-cell porous materials is converted into a dataset of hierarchical octree nodes,and then the specific traversal search algorithm on the octree n...Through the octree data structure analysis,a volumetric dataset of closed-cell porous materials is converted into a dataset of hierarchical octree nodes,and then the specific traversal search algorithm on the octree nodes is depicted in details,which is involved in six steps of the volume growth model and one step of the volume decomposition model.Moreover,the conditions of both the proceeding traversal and three possibilities of terminating are given,and the traversal algorithm of completeness is proved from a theoretical perspective.Finally,using a simulated volumetric dataset of columnar pores,the extracting effectiveness of the octree traversal algorithm is verified.The results show that the volume and the distribution information of pores can be successfully extracted by the proposed algorithm,which builds a solid foundation for a more effective performance analysis of porous materials.展开更多
基金supported by JST,grant number JPMJFS2132JST SPRING,grant number JPMJSP2136by an external research grant from Mitsubishi Fuso Truck&Bus Corporation。
文摘Engineering the pore structure of biomass-derived activated carbons is critical for optimizing their performance in adsorptionbased applications.This study demonstrates for the first time that washing hydrochars in solvents of different polarity before activation is a simple yet powerful strategy to tailor pore size distribution.Hydrochar is produced from spent coffee grounds via hydrothermal carbonization,followed by washing in various solvents and activation in KOH.This results in carbons with a very large surface area(~2700 m^(2)/g),and washing is demonstrated to significantly increase product yield.Furthermore,washing in non-polar or mixed-polarity solvents removes long-chain carboxylic acids and esters from the hydrochar,promoting the development of narrow micropores while suppressing mesopore formation.To illustrate the impact of this structural control of porous carbons,post-combustion CO_(2)capture is investigated as a case study.Narrower pore size distribution enhances CO_(2)uptake,significantly improving capacity from 2.8 mmol/g for unwashed samples to 3.8 mmol/g for acetone-washed samples.Interestingly,moderate pore size(9-12Å)is shown to be optimal for CO_(2):N2 selectivity,while smaller pores result in lower selectivity due to stronger interactions between N2 and the pore walls.These findings highlight the potential role of solvent washing in directing pore architecture of hydrochars for adsorption-based carbon capture technologies and beyond.
基金supported by the National Key R&D Program of China(No.2022YFE0208300)the National Natural Science Foundation of China(No.22278426)+2 种基金the China National Funds for Distinguished Young Scientists(No.22425808)the China Postdoctoral Science Foundation(No.2025M771155)the Science Foundation of China University of Petroleum,Beijing(Nos.2462024XKBH001,2462022YJRC003,2462022YJRC002,2462025BJRC002)。
文摘Electrochemical liquid lithium extraction technology has attracted much attention because of its high selectivity,good efficiency,and eco-friendliness.However,the low energy density per unit area and poor stability of traditional thin film electrodes(F-LMO),as well as manganese dissolution loss induced by the Jahn-Teller distortion of LiMn_(2)O_(4),hinder their industrial scalability.Herein,a durable and high-efficiency multistage porous LiMn_(2)O_(4) thick electrode was prepared sustainably by 3D printing technology(3DPLMO)for enhancing lithium recovery from salt lake brine.The multistage porous structure reduced the mass transfer resistance and shortened the ion diffusion path,which was conducive to accelerating the diffusion rate of Li+.Simultaneously,the three-dimensional conductive networks composed of reduced graphene oxide(r GO)and carbon nanotubes(CNT)synergized with the multistage pores effectively weakened the polarization phenomenon of the electrode and improved the stability of 3DP-LMO.The3DP-LMO exhibited a 5.5-fold higher extraction capacity per unit area and the Mn dissolution loss rate was only 1/15 compared with the F-LMO.Notably,the capacity retention rate of 3DP-LMO was 87.6%,significantly better than that of F-LMO(66.3%).Based on the quasi-in situ X-ray Diffraction results,the mechanism of lithium intercalation and deintercalation in 3DP-LMO was elucidated.Furthermore,lithium extraction parameters were optimized using response surface method-center composite design(RSM-CCD),resulting in an increase in lithium extraction capacity to 15.66 mg g^(-1)and a reduction in energy consumption to only 12.33 Wh mol^(-1).The results show that 3DP-LMO has significantly improved lithium extraction performance and stability,and has considerable prospects in practical application.
基金supported by the China Postdoctoral Science Foundation (No.2021M703001)Fundamental Research Funds for the Central Universities,China University of Geosciences (Wuhan) (No.G1323521101)+3 种基金open fund of State Key Laboratory of Nuclear Resources and Environment (East China University of Technology) (No.2022NRE02)open fund of Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences (Wuhan)),Ministry of Education (No.TPR2019-08)Fund of Outstanding Talents in Discipline of China University of Geosciences (Wuhan) (No.102162301192664)support from SINO Shaanxi Industry Group in this study。
文摘Carbonaceous debris(CD) is widely disseminated within sandstones in the Shuanglong uranium deposit,southern Ordos Basin,and is the dominant enrichment agent for uranium precipitation.The occurrence and chemical composition of uranium minerals within CD were investigated by using scanning electron microscope and electron microprobe analyses.The results show that uranium minerals mostly occur in cell pores in the forms of fructus aurantia and concentric band structure.Pitchblende and coffinite are the main uranium minerals,and the former is dominant.According to the crystal morphology and composition of trace elements of uranium minerals,uranium precipitation on the pores is grouped into two periods,orderly Ⅰ,Ⅱ.Moreover,the Ⅰ period is further divided into two sub-period,orderly Ⅰ_(1),Ⅰ_(2).Moreover,askew sphere uranium minerals could indicate fluid migration.Under certain geological environment condition,uranium is unevenly adsorbed on the surface of the pore by the Van der Waals(i.e.,Ⅰ_(1) period),and then is precipitated towards to the center of the pore until the whole pore is filled up with uranium minerals by complicated process such as microorganism activities(i.e.,Ⅰ_(2),Ⅱ period).It will provide some guidance for studying the metallogenic environment and genesis of sandstone-type uranium deposit.
基金supported by the National Natural Science Foundation of China(Nos.51825101,52001202)the National Key Research and Development Program of China(No.2021YFA1600900)。
文摘A comprehensive analysis of the microstructure and defects of a thixomolded AZ91D alloy was conducted to elucidate their influences on mechanical properties.Samples were made at injection temperatures ranging from 580 to 640℃.X-ray computed tomography was used to visualize pores,and crystal plasticity finite element simulation was adopted for deformation analysis.The microstructure characterizations reveal a hierarchical cell feature composed of α-Mg and eutectic phases.With the increase of injection temperature,large cell content in the material decreases,while the strength of the alloy increases.The underlying mechanism about strength change is that coarse-grained solids experience smaller stress even in hard orientations.The sample fabricated at a moderate temperature of 620℃ exhibits the highest elongation,least quantity and lower local concentration of pores.The detachment and tearing cracks formed at lower injection temperature and defect bands formed at higher injection temperature add additional crack sources and deteriorate the ductility of the materials.
基金Supported by the Sinopec Major Science and Technology Project(P22081)National Natural Science Foundation of China(U24B60001).
文摘The basic geological characteristics of the Qiongzhusi Formation reservoirs and conditions for shale gas enrichment and high-yield were studied by using methods such as mineral scanning,organic and inorganic geochemistry,breakthrough pressure,and triaxial mechanics testing based on the core,logging,seismic and production data.(1)Both types of silty shale,rich in organic matter in deep water and low in organic matter in shallow water,have good gas bearing properties.(2)The brittle mineral composition of shale is characterized by comparable feldspar and quartz content.(3)The pores are mainly inorganic pores with a small amount of organic pores.Pore development primarily hinges on a synergy between felsic minerals and total organic carbon content(TOC).(4)Dominated by Type I organic matters,the hydrocarbon generating organisms are algae and acritarch,with high maturity and high hydrocarbon generation potential.(5)Deep-and shallow-water shale gas exhibit in-situ and mixed gas generation characteristics,respectively.(6)The basic law of shale gas enrichment in the Qiongzhusi Formation was proposed as“TOC controlled accumulation and inorganic pore controlled enrichment”,which includes the in-situ enrichment model of“three highs and one over”(high TOC,high felsic mineral content,high inorganic pore content,overpressured formation)for organic rich shale represented by Well ZY2,and the in-situ+carrier-bed enrichment model of“two highs,one medium and one low”(high felsic content,high formation pressure,medium inorganic pore content,low TOC)for organic-poor shale gas represented by Well JS103.It is a new type of shale gas that is different from the Longmaxi Formation,enriching the formation mechanism of deep and ultra-deep shale gas.The deployment of multiple exploration wells has achieved significant breakthroughs in shale gas exploration.
基金supported by the National Natural Science Foundation of China(42030804,42330811)the“Deep-time Digital Earth”Science and Technology Leading Talents Team Funds for the Central Universities for the Frontiers Science Center for Deep-time Digital Earth,China University of Geosciences(Fundamental Research Funds for the Central Universities,grant number:2652023001).
文摘The water adsorption performance of shale gas reservoirs is a very important factor affecting their gas in place(GIP)contents,but the water-holding capacity and mechanism of over-mature shale,especially organic pores,are still not fully understood.In this study,systematic water vapor adsorption(WVA)experiments were carried out on the Lower Cambrian over-mature shale and its kerogen from the Sichuan Basin,China to characterize their WVA behaviors,and combined with the low-pressure gas(N_(2) and CO_(2))adsorption experiments,the main influencing factors of WVA capacity of the shale and the absorbed-water distribution in its organic and inorganic nanopores were investigated.The results show that the WVA isotherms of shale and kerogen are all typeⅡ,with an obvious hysteresis loop in the multilayer adsorption range,and that the positive relationship of the shale TOC content with the WVA capacity(including total adsorption capacity,primary adsorption capacity and secondary adsorption capacity)and WVA hysteresis index(AHIW),and the greater adsorption capacity and AHIW of kerogen than the shale,all indicate that the hydrophilicity of organic matter(OM)in the over-mature shale was underestimated in previous research.Although both the shale OM and clay minerals have a significant positive effect on the WVA,the former has a stronger adsorption ability than the latter.The WVA capacity of the studied Lower Cambrian shale is significantly greater than that of the Longmaxi shale reported in literatures,which was believed to be mainly attributed to its higher maturity,with a significant graphitization of OM.The shale micropores and non-micropores play an important role in WVA,especially OM pores.There are primary and secondary adsorption for water vapor in both the micropores and non-micropores of OM,while these adsorptions of minerals mainly occur in their non-micropores.These results have important guides for understanding the gas storage mechanism and exploration and development potential of marine over-mature shale in southern China,especially the Lower Cambrian shale.
基金supported by the Fundamental Research Funds for the Central Universities(2025JBZY019)the Funding of Key Research and Development Project of CCCC(2021-ZJKJ-18).
文摘Peat soil is a loose,moisture-rich organic matter accumulation formed by the deposition of plants in swamps and lakes after their death.It is characterized by high moisture content,large void ratio,high compressibility,and strong rheological properties.These characteristics result in a complex consolidation process.A systematic understanding of the consolidation mechanism of peat soil is essential for elucidating its consolidation behavior.Previous studies have failed to provide consistent information on the microscopic morphology of peat soil.Moreover,quantitative studies on pore structure changes during peat soil consolidation remain lacking.To resolve these research gaps,the microscopic morphology and pore types of peat,highly organic peaty soil,and medium organic peaty soil from certain regions of Yunnan province,China,were observed and analyzed using scanning electron microscopy.Additionally,quantitative research on pore structure changes during peat soil consolidation was conducted.The results show that the humic acid in peat soil of Yunnan province has no pores,and there is no pore between humic acid and clay minerals.There are three typical pore structures,and the three typical pores were quantitatively analyzed.During consolidation,the consolidation deformation of peat soil is primarily caused by the internal pore compression of plant residues and pores between plant residues.At the same time,the revelation of the differentiated influence mechanism of load levels on the compression of inter/intra-plant residue pores.The decrease in the proportion of pores between plant residues first increased and then decreased with an increase in load,reaching a peak between 100-200 kPa.The decrease in pores inside the plant residues increased with an increasing load.Additionally,pore compression between the plant residues under different load levels primarily caused the compression deformation of Dali peat during the primary consolidation stage.By contrast,the pore compression inside the plant residues primarily caused the compression deformation during the secondary consolidation stage.
基金the financial support offered by the National Oil Shale Exploitation R&D Center Open Fund Project(Grant No.33550000-24-ZC0613-0055)National Key R&D Program of China(Grant No.2019YFA0705502,Grant No.2019YFA0705501)+1 种基金Science and technology research project of Education Department of Jilin Province(Grant No.JJKH20231185K)the National Natural Science Fund project of China(Grant No.4210020395,51974334)。
文摘Organic-rich shale is a significant potential source of oil and gas that requires development through in situ conversion technology.However,the evolution patterns of the internal three-dimensional(3D)pore structure and kerogen distribution at high temperatures are not well understood,making it difficult to microscopically explain the evolution of the flow conductivity in organic-rich shale at high temperatures.This study utilizes high-resolution X-ray computed tomography(micro-nano CT)to obtain the distribution of pores,kerogen,and inorganic matter at different temperatures.Combined with the pyrolysis results for the rock,the evolution of the pore structure at various temperatures is quantitatively analyzed.Based on three-phase segmentation technology,a model of kerogen distribution in organicrich shale is established by dividing the kerogen into clustered kerogen and dispersed kerogen stored in the inorganic matter and the pores into inorganic pores and organic pores within the kerogen skeleton.The results show that the inorganic pores in organic-rich shale evolve through three stages as the temperature increases:kerogen pyrolysis(200-400℃),clay mineral decomposition(400-600℃),and carbonate mineral decomposition(600-800℃).The inorganic pores porosity sequentially increases from 3%to 11.4%,13.1%,and 15.4%,and the roughness and connectivity of the inorganic pores gradually increase during this process.When the pyrolysis temperature reaches 400℃,the volume of clustered kerogen decreases from 25%to 12.5%.During this process,the relative density of kerogen decreases from9.5 g/cm^(3) in its original state to 5.4 g/cm^(3),while the kerogen skeleton density increases from 1.15 g/cm^(3) in its original state to 1.54 g/cm^(3).Correspondingly,7%-8%of organic pores develop within the clustered kerogen,accounting for approximately 50%of the volume of clustered kerogen.In addition,approximately 30%of the kerogen in organic-rich shale exists in the form of dispersed kerogen within inorganic matter,and its variation trend is similar to that of clustered kerogen,rapidly decreasing from 200 to 400℃ and stabilizing above 400℃.The results of this study provide an essential microscopic theoretical basis for the industrial development of organic-rich shale resources.
基金financially supported by the Ministry of Industry and Information Technology of Chinathe National Natural Science Foundation of China(No.52403263)+1 种基金Technology Research Project of Jiangxi Provincial Department of Education(No.GJJ2200385)Jiangxi Provincial Natural Science Foundation(Nos.20244BCE52213,20242BAB23031 and 20232BAB204006)。
文摘The low-voltage plateau capacity,which is highly related to the internal closed pores in hard carbon(HC),is the main contributor to the total capacity in sodium-ion batteries.However,the formation mechanism of closed pores and modification strategies at the molecular level in HC polymer precursors remain poorly understood.Furthermore,the practical applications of HCs are significantly impeded by their low initial coulombic efficiency(ICE).In this study,the intramolecular heteroatom doping(IHP)effect was proposed to facilitate the formation of closed pores in polymer-derived HC for the first time by grafting sulfonyl,ether,and carbonyl groups between benzene rings.As a result,the optimized HC sample showed an increased closed pore volume and low Na^(+)adsorption energy,which delivered a reversible capacity of 307.9 mAh·g^(-1)and superior rate capability.Through further optimized presodiation,the formed presodiated HC featuring a thin,smooth,and dense solid electrolyte interface film exhibited a remarkably enhanced ICE of 94.4%and enhanced cycling stability(93.6%over 3000 cycles).This study provides an in-depth understanding of the formation mechanisms of closed pores via IHP engineering and develops a new synergistic strategy involving presodiation to prepare highly stable HC anodes.
基金National Nature Science Foundation of China(No.42030803,42073066),and the valuable comments and suggestions by three anonymous referees that greatly improved this paper.
文摘The organic-inorganic transformation and interaction act as the critical role in the occurrence of nanopores within the organic-rich shales during thermal maturation.Hydrous pyrolysis experiments were conducted on the organic-rich mudrock collected from the Upper Cretaceous Nenjiang Formation of the Songliao Basin,China in a closed system.The pore types and pore network,and organic and inorganic compositions of pyrolyzed shales were detected from the early to over mature stages(%Ro=0.61-4.01).The experimental results indicate that geochemical transformation of organic matters and minerals and the interaction control the formation and evolution of nanoporosity.In oil window mineral matrix pores are infilled by the generated oil,K-feldspar dissolution by organic acids promotes clay illitization to form illite,and the catalytic effects of clays(e.g.illite)in the complex of organic matter and clays may promote the in-situ retained oil cracking to generate natural gas,resulting in the early occurrence of organic-matter pores in the complex within oil window.Due to significant primary cracking of solid kerogen to generate extractable liquid oil,pore volume for storing fluids presents a persistent increase and approaches the maximum at the end of oil window.In gas window intensive oil cracking facilitates the hydrocarbon migrating out of the source home and pyrobitumen formation,resulting in the significant occurrence of modified mineral matrix pores and organic-matter pores.Pore volume for hosting hydrocarbons presents a slight decrease at%Ro=1.36-2.47 due to pyrobitumen formation by oil secondary cracking.The organic-inorganic interaction favors clay illitization,quartz dissolution,and pyrite and carbonate decomposition,which facilitate the occurrence of nanoporosity.Pyrobitumen within the complex with illite and organic matters are much more porous than that hosted in modified mineral matrix pores and microfractures.The catalytic effects of clays are supposed to be responsible for this.This study improves our understanding of the formation and evolution pathways of nanoporosity and the underlying controls in organic-rich shales during thermal maturation,and hence should be helpful in evaluating the sweet spots for shale-oil and shale-gas plays in a sedimentary basin.
基金supported by the National Natural Science Foundation of China(No.U19B6003)。
文摘The connectivity of shale pores and the occurrence of movable oil in shales have long been the focus of research.In this study,samples from wells BX7 and BYY2 in the Eq3^4-10 cyclothem of Qianjiang Formation in the Qianjiang depression,were analyzed.A double mercury injection method was used to distinguish between invalid and effective connected pores.The pore characteristics for occurrence of retained hydrocarbons and movable shale oil were identified by comparing pore changes in low temperature nitrogen adsorption and high pressure mercury injection experiments before and after extraction and the change in the mercury injection amounts in the pores between two separate mercury injections.The results show that less than 50%of the total connected pores in the Eq34-10 cyclothem samples are effective.The development of effective connected pores affects the mobility of shale oil but varies with different lithofacies.The main factor limiting shale oil mobility in Well BX7 is the presence of pores with throat sizes less than 15 nm.In Well BYY2,residual mercury in injection testing of lamellar dolomitic mudstone facies was mainly concentrated in pores with throats of 10-200 nm,and in bulk argillaceous dolomite facies,it was mainly concentrated at 60-300 nm.The throats of hydrocarbon-retaining pores can be 5 nm or even smaller,but pores with movable shale oil in the well were found to have throat sizes greater than 40 nm.Excluding the influence of differences in wettability,the movability of shale oil is mainly affected by differences in lithofacies,the degree of pore deformation caused by diagenesis,the complexity of pore structures,and the connectivity of pore throats.Dissolution and reprecipitation of halite also inhibit the mobility of shale oil.
基金supported by the National Natural Science Foundation of China(22379165,U21A20284)Natural Science Foundation of Hunan Province(2023JJ40704).
文摘Hard carbon(HC)is considered the most promising anode material for sodium-ion batteries(SIBs)due to its high costeffectiveness and outstanding overall performance.However,the amorphous and intricate microstructure of HC poses significant challenges in elucidating the structure-performance relationship,which has led to persistent misinterpretations regarding the intrinsic characteristics of closed pores.An irrational construction methodology of closed pores inevitably results in diminished plateau capacity,which severely restricts the practical application of HC in high-energy-density scenarios.This review provides a systematic exposition of the conceptual framework and origination mechanisms of closed pores,offering critical insights into their structural characteristics and formation pathways.Subsequently,by correlating lattice parameters with defect configurations,the structure-performance relationships governing desolvation kinetics and sodium storage behavior are rigorously established.Furthermore,pioneering advancements in structural engineering are critically synthesized to establish fundamental design principles for the rational modulation of closed pores in HC.It is imperative to emphasize that adopting a molecular-level perspective,coupled with a synergistic kinetic/thermodynamic approach,is critical for understanding and controlling the transformation process from open pores to closed pores.These innovative perspectives are strategically designed to accelerate the commercialization of HC,thereby catalyzing the sustainable and high-efficiency development of SIBs.
基金the supports of the Na-tional Natural Science Foundation of China(No.U19B2007,42072202)the China Postdoctoral Science Foundation(No.2025MD774057)。
文摘Organic matter(OM)is the primary gas occurrence carrier in shale reservoirs due to their abundant nanopores.To reveal the OM pore structure,adsorption capacity and evolution during thermal maturation,this study collected data from samples spanning the entire evolution stage,from immature to over-mature.Scanning Electron Microscope(SEM)observation and low temperature gases adsorption experiments were used to qualitatively-semi-quantitatively and quantitatively analyze OM pore structure evolution,and CH_(4) isothermal adsorption experiments were used to reveal the adsorption capacity evolution.Then,the influence and mechanism of matu rity and hydrocarbon generation on pore development and adsorption capacity were quantitatively reviewed based on the experimental data.The results show that OM pores are poorly developed in the immature stage due to weak hydrocarbon generation,although micro-fractures are occasionally found at the edges of OM particles.In the low maturity stage,OM pores are partially developed due to liquid hydrocarbon generation,with liquid hydrocarbons also filling some OM pores.The contribution of total organic carbon content(TOC)to adsorption extent is not significant in these two stages.From high to high-over maturity stages,massive gaseous hydrocarbons are generated,significantly improving the surface porosity of OM.Clear positive linear correlations are observed between TOC and adsorption amount.However,the development of OM pores significantly declines when thermal maturity(R_(o))exceeds 3.5%due to excessive aromatization.The accuracy of research on the evolution of pore structure and adsorption capacity is limited by several factors:(ⅰ)errors caused by sample specification,calculation processes,parameter settings,and kerogen models in isothermal adsorption experiments and molecular simulations;(ⅱ)difficulty in achieving control variables due to the strong heterogeneity of natural maturation shale samples;and(ⅲ)the need to enhance compatibility between thermal simulation experiments and natural thermal evolution.Therefore,isothermal adsorption experiments on bulk shale and molecular simulations of intact shale model are necessary,taking into account the dynamic temperature and pressure of in-situ reservoirs.Moreover,shale samples with varying maturity,influenced by their distance from the paleo-thermal source,may provide significant verification for thermal simulation experiments.
基金Funded by the Joint Fund of Natural Science Foundation of Hubei Province(No.2024AFD033)the Open Fund of Hubei Longzhong Laboratory。
文摘Biomineralization of natural composites are usually highly finely adjusted to achieve extremely precise control over the shape,size and distribution of inorganic crystals,giving them unique structures and properties of biomaterials.These underlying mechanisms and pathways provide inspiration for the design and construction of materials for repairing hard tissues.Due to good biocompatibility of hydrogels,materials using gel-like systems as media are inextricably linked to biological macrocomponents and mineralization.Inspired by those bioprocesses,polyacrylamide hydrogel with enzymes was 3D printed to form controlled shapes and structures,then was used as templates for mineralization.Effect of polyacrylamide hydrogel pore size on the mineralization was studied via incorporating NaF and CaCl2 and controlling the mineralization degree.The mineralization processes of 3D printed hydrogels with different pore sizes were also explored to find out the confinement influence of pores.Mineralization in hydrogels with smaller pores is developed in a columnar stacked pattern,which is similar to the vesicular mineralization stage of bone mineralization.
基金supported by the National Natural Science Foundation of China(Grant No.41930426)。
文摘Marine organic-rich marl is not only a high-quality hydrocarbon source of conventional oil and gas,but also a new type and field of unconventional oil and gas exploration.An understanding of its pore structure evolution characteristics during a hydrocarbon generation process is theoretically significant and has application prospects for the exploration and development of this special type of natural gas reservoirs.This study conducted thermal simulation of hydrocarbon generation under near-geological conditions during a whole process for cylinder samples of low mature marine organic-rich marl in the Middle Devonian of Luquan,Yunnan Province,China.During this process,hydrocarbon products at different evolution stages were quantified and corresponding geochemical properties were analyzed.Simultaneously,field emission scanning electron microscopy(FE-SEM)and low-pressure gas adsorption(CO_(2),N_(2))tests were applied to the corresponding cylinder residue samples to reveal the mechanisms of different types of pore formation and evolution,and clarify the dynamic evolution processes of their pore systems.The results show that with an increase in temperature and pressure,the total oil yield peaks at an equivalent vitrinite reflectance(VR_(o))of 1.03%and is at the maximum retention stage of liquid hydrocarbons,which are 367.51 mg/g TOC and 211.67 mg/g TOC,respectively.The hydrocarbon gas yield increases continuously with an increase in maturity.The high retained oil rate at the peak of oil generation provides an abundant material basis for gas formation at high maturity and over-maturity stage.The lower limit of VR_(o)for organic matter(OM)pore mass development is about 1.6%,and bitumen pores,organic-clay complex pores together with intergranular pores,grain edge seams and dissolution pores constitute a complicated pore-seam-network system,which is the main reservoir space for unconventional carbonate gas.Pore formation and evolution are controlled synergistically by hydrocarbon generation,diagenesis and organic-inorganic interactions,and the pattern of pore structure evolution can be divided into four stages.A pore volume(PV)and a specific surface area(SSA)are at their highest values within the maturity range of 1.9%to 2.5%,which is conducive to exploring unconventional natural gas.
基金supported by the project of“Shale Gas Resources Investigation and Evaluation in the Baoshan Block”from Sinopec Exploration Company and the National Natural Science Foundation of China(41925014 and 42172192)。
文摘Lower Paleozoic black shales are important source rocks worldwide.The Upper Ordovician-Lower Silurian Renheqiao Formation of the Baoshan Block is a low-maturity equivalent of the Wufeng-Longmaxi(WF-LMX)Shale of the Sichuan Basin.However,organic matter(OM)characteristics in these low-maturity Lower Paleozoic shales are not well understood.In this study,50 Renheqiao Formation shale samples collected from seven outcrop sections and one drill core were investigated with organic petrology,organic geochemistry,R_(o)ck-Eval pyrolysis,N_(2) and CO_(2) adsorption,and scanning electron microscope(SEM)analyses to study the OM content,type,thermal maturity,and the development of OM-hosted pores in these Lower Paleozoic shales.The total organic carbon(TOC)content of the Renheqiao Formation shales varies,with the maximum content of 10.07 wt%.R_(o)ck-Eval pyrolysis results show that present OM in the Renheqiao Formation shales is Type IV kerogen,a result of advanced thermal maturation.Graptolite reflectance(GR_(o))ranges from 1.26%to 1.85%,and equivalent vitrinite reflectance(EqR_(o))converted from GR_(o) ranges from 1.08%to 1.51%,indicating that the studied Renheqiao Formation shales are dominantly within the late-mature stage.EqR_(o) based on R_(o)ck-Eval T_(max) shows large variations,which indicates that R_(o)ck-Eval T_(max) is not a reliable thermal maturity indicator for the Lower Paleozoic Renheqiao Formation shales.Caution should be applied when assessing the thermal maturity of high-maturity black shales based on T_(max) when the S2 values are too low.Organic petrographic observations show that OM in these shales is dominated by solid bitumen(>70 vol%of total OM),with minor contributions by graptolites and chitinozoans.The specific surface area and pore volume of shales are controlled by TOC content.Organic pores are hosted by solid bitumen and were not observed in graptolites when examined under the SEM.Although the Renheqiao Formation has a lower thermal maturity than the over-mature WF-LMX Shale,it is mature enough that primary oil-prone macerals have been thermally transformed and could not be identified under the microscope.
基金support from the National Natural Science Foundation of China,China(Grant 51776132)the Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process of the Ministry of Education(China University of Mining and Technology)(No.2024-007).
文摘Carbon isotope fractionation served as a key geochemical indicator for understanding shale gas storage and migration.However,the detailed mechanism of the fractionation behaviors of methane isotopes(^(12)CH_(4)/^(13)CH_(4))was still limited,especially under two-phase flow.This study employed molecular dynamics(MD)simulations to investigate water-mediated nonlinear isotope transport in 3 nm hydrophilic silica nanopores,highlighting gas-liquid-solid interfacial effects on fractionation mechanisms.Simulations of different water saturation(0%-44.66%)showed a critical hydration threshold of 30.44%at a pressure gradient of 20 MPa.Below this threshold,continuous water film formed on pore walls,which transformed the gas transport from surface diffusion to viscous flow through gas-liquid interactions,while hydrogen bonds in the water film weakened gas-solid slip effects.However,when water saturation exceeded 30.44%,the formation of water bridges blocked the mobility of isotopic gases.The water film reduced the depth of solid-gas potential wells,leading to diminished adsorption capacity for isotopic gases,and lowered the surface roughness of pore walls(as characterized by potential energy surface,PES).Additionally,the water film enhanced the Knudsen diffusion effect of isotope gases due to the decrease in effective pore size.As a result,the formation of water film intensified methane isotopic fractionation,which was manifested as a decrease in the^(13)CH_(4)/^(12)CH_(4)diffusion coefficient ratio(D∗/D)from 0.975 to 0.942 and an increase in isotopic enthalpy differences(Δh_(^(12)C)_^(13)C) from 0.105 to 1.139 J/m^(3).Furthermore,in the gas-liquid-solid interfacial system,an elevated pressure differential modified the relative motion velocities among the methane-water-pore surface,resulting a non-monotonic isotopic fractionation trend(initial increase followed by decrease).These findings provided molecular-level insights into the complex isotopic fractionation in shale gas systems.
基金Supported by the National Natural Science Foundation of China(U23B20154)General Program of the National Natural Science Foundation of China(42372169)。
文摘In recent years,drilling data from wells Pengshen 10,Heshen 9,Tongshen 17 and Zhengyang 1 in the Sichuan Basin have confirmed the presence of a set of porous reef-beach limestone reservoirs in the Upper Permian Changxing Formation,which breaks the traditional view that deep carbonate oil and gas are only distributed in porous dolomite reservoirs and karst fracture-cavity limestone reservoirs.Through core and thin section observations,geochemical analysis,and well-seismic based reservoir identification and tracking,the study on formation mechanism of pores in deep reef-beach limestone reservoirs is carried out,this study provides insights in four aspects.(1)Porous reef-beach limestone reservoirs are developed in the Changxing Formation in deep-buried layers.The reservoir space is composed of intergranular pores,framework pores,intra-fossil pores,moldic pores and dissolution pores,which are formed in depositional and epigenetic environments.(2)The intermittently distributed porous reef-beach complexes are surrounded by relatively dense micrite limestone,which leads to the formation of local abnormal high-pressure inside the reef-beach complexes with the temperature increased.(3)The floor of the Changxing Formation reservoir is composed with interbedded tight mudstone and limestone of the Upper Permian Wujiaping Formation,and the roof is the tight micrite limestone interbedded with mudstone of the first member of Lower Triassic Feixianguan Formation.Under the clamping of dense roof and floor,the abnormal high-pressure in the Changxing Formation is formed.Abnormal high-pressure(overpressured compartment)is the key to maintain the pores formed in the depositional and epigenetic environments in deep-buried layers.(4)Based on the identification of roof,floor and reef-beach complexes,the favorable reef-beach limestone reservoir distribution area of 10.3×10^(4) km^(2) is predicted by well-seismic integration.These insights lay the theoretical foundation for the development of deep porous limestone reservoirs,expand the new field of exploration of deep-buried limestone reservoirs in the Sichuan Basin.
基金supported by the National Natural Science Foundation of China(21663031,21503183)
文摘Materials with high surface area,tailored pore size and good electrical conductivity are needed for improved supercapacitors(SCs).Metal-organic frameworks(MOFs)have high surface areas and tailored pore sizes.Here,the MOF(1)of[Ni3(μ3 OH)(pba)3(bpdc)1.5]·11.5 DMA·0.5 CH3 OH·7 H2O is good enough to result in electrode materials with nearly ideal supercapacitive behavior at the rate up to 50 mV·s^-1 in a KOH electrolyte.The super capacitive performance of MOF(1)was measured using cyclic voltammogram,galvanostatic discharge and electrochemical impedance spectroscopy measurements.This MOF(1)as electrode exhibits the highest super capacitive properties with 417 F·g^-1,the maximum storage energy and power density are 9.27 and 2.38 kW·kg^-1.The long term stability of MOF(1)as SCs is checked that the capacitance is decreased by 17%after 1000 cycles.
基金The National Basic Research Program of China(973Program)(No.2006CB601202)
文摘Through the octree data structure analysis,a volumetric dataset of closed-cell porous materials is converted into a dataset of hierarchical octree nodes,and then the specific traversal search algorithm on the octree nodes is depicted in details,which is involved in six steps of the volume growth model and one step of the volume decomposition model.Moreover,the conditions of both the proceeding traversal and three possibilities of terminating are given,and the traversal algorithm of completeness is proved from a theoretical perspective.Finally,using a simulated volumetric dataset of columnar pores,the extracting effectiveness of the octree traversal algorithm is verified.The results show that the volume and the distribution information of pores can be successfully extracted by the proposed algorithm,which builds a solid foundation for a more effective performance analysis of porous materials.
