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
Forced imbibition,the invasion of a wetting fluid into porous rocks,plays an important role in the effective exploitation of hydrocarbon resources and the geological sequestration of carbon dioxide.However,the interfa...Forced imbibition,the invasion of a wetting fluid into porous rocks,plays an important role in the effective exploitation of hydrocarbon resources and the geological sequestration of carbon dioxide.However,the interface dynamics influenced by complex topology commonly leads to non-wetting fluid trapping.Particularly,the underlying mechanisms under viscously unfavorable conditions remain unclear.This study employs a direct numerical simulation method to simulate forced imbibition through the reconstructed digital rocks of sandstone.The interface dynamics and fluid–fluid interactions are investigated through transient simulations,while the pore topology metrics are introduced to analyze the impact on steady-state residual fluid distribution obtained by a pseudo-transient scheme.The results show that the cooperative pore-filling process promoted by corner flow is dominant at low capillary numbers.This leads to unstable inlet pressure,mass flow,and interface curvature,which correspond to complicated interface dynamics and higher residual fluid saturation.During forced imbibition,the interface curvature gradually increases,with the pore-filling mechanisms involving the cooperation of main terminal meniscus movement and arc menisci filling.Complex topology with small diameter pores may result in the destabilization of interface curvature.The residual fluid saturation is negatively correlated with porosity and pore throat size,and positively correlated with tortuosity and aspect ratio.A large mean coordination number characterizing global connectivity promotes imbibition.However,high connectivity characterized by the standardized Euler number corresponding to small pores is associated with a high probability of non-wetting fluid trapping.展开更多
Biomass-derived hard carbons,usually prepared by pyrolysis,are widely considered the most promising anode materials for sodium-ion bat-teries(SIBs)due to their high capacity,low poten-tial,sustainability,cost-effectiv...Biomass-derived hard carbons,usually prepared by pyrolysis,are widely considered the most promising anode materials for sodium-ion bat-teries(SIBs)due to their high capacity,low poten-tial,sustainability,cost-effectiveness,and environ-mental friendliness.The pyrolysis method affects the microstructure of the material,and ultimately its so-dium storage performance.Our previous work has shown that pyrolysis in a sealed graphite vessel im-proved the sodium storage performance of the car-bon,however the changes in its microstructure and the way this influences the sodium storage are still unclear.A series of hard carbon materials derived from corncobs(CCG-T,where T is the pyrolysis temperature)were pyrolyzed in a sealed graphite vessel at different temperatures.As the pyrolysis temperature increased from 1000 to 1400℃ small carbon domains gradually transformed into long and curved domains.At the same time,a greater number of large open pores with uniform apertures,as well as more closed pores,were formed.With the further increase of pyrolysis temperature to 1600℃,the long and curved domains became longer and straighter,and some closed pores gradually became open.CCG-1400,with abundant closed pores,had a superior SIB performance,with an initial reversible ca-pacity of 320.73 mAh g^(-1) at a current density of 30 mA g^(-1),an initial Coulomb efficiency(ICE)of 84.34%,and a capacity re-tention of 96.70%after 100 cycles.This study provides a method for the precise regulation of the microcrystalline and pore structures of hard carbon materials.展开更多
Based on the experimental results of casting thin section,low temperature nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance T2 spectrum,contact angle and oil-water interfacial tension,the ...Based on the experimental results of casting thin section,low temperature nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance T2 spectrum,contact angle and oil-water interfacial tension,the relationship between pore throat structure and crude oil mobility characteristics of full particle sequence reservoirs in the Lower Permian Fengcheng Formation of Mahu Sag,Junggar Basin,are revealed.(1)With the decrease of reservoir particle size,the volume of pores connected by large throats and the volume of large pores show a decreasing trend,and the distribution and peak ranges of throat and pore radius shift to smaller size in an orderly manner.The upper limits of throat radius,porosity and permeability of unconventional reservoirs in Fengcheng Formation are approximately 0.7μm,8%and 0.1×10^(−3)μm^(2),respectively.(2)As the reservoir particle size decreases,the distribution and peak ranges of pores hosting retained oil and movable oil are shifted to a smaller size in an orderly manner.With the increase of driving pressure,the amount of retained and movable oil of the larger particle reservoir samples shows a more obvious trend of decreasing and increasing,respectively.(3)With the increase of throat radius,the driving pressure of reservoir with different particle levels presents three stages,namely rapid decrease,slow decrease and stabilization.The oil driving pressures of various reservoirs and the differences of them decrease with the increase of temperature and obviously decrease with the increase of throat radius.According to the above experimental analysis,it is concluded that the deep shale oil of Fengcheng Formation in Mahu Sag has great potential for production under geological conditions.展开更多
The development of sustainable electrode materials for energy storage systems has become very important and porous carbons derived from biomass have become an important candidate because of their tunable pore structur...The development of sustainable electrode materials for energy storage systems has become very important and porous carbons derived from biomass have become an important candidate because of their tunable pore structure,environmental friendliness,and cost-effectiveness.Recent advances in controlling the pore structure of these carbons and its relationship between to is energy storage performance are discussed,emphasizing the critical role of a balanced distribution of micropores,mesopores and macropores in determining electrochemical behavior.Particular attention is given to how the intrinsic components of biomass precursors(lignin,cellulose,and hemicellulose)influence pore formation during carbonization.Carbonization and activation strategies to precisely control the pore structure are introduced.Finally,key challenges in the industrial production of these carbons are outlined,and future research directions are proposed.These include the establishment of a database of biomass intrinsic structures and machine learning-assisted pore structure engineering,aimed at providing guidance for the design of high-performance carbon materials for next-generation energy storage devices.展开更多
Changes to the microstructure of a hard carbon(HC)and its solid electrolyte interface(SEI)can be effective in improving the electrode kinetics.However,achieving fast charging using a simple and inexpensive strategy wi...Changes to the microstructure of a hard carbon(HC)and its solid electrolyte interface(SEI)can be effective in improving the electrode kinetics.However,achieving fast charging using a simple and inexpensive strategy without sacrificing its initial Coulombic efficiency remains a challenge in sodium ion batteries.A simple liquid-phase coating approach has been used to generate a pitch-derived soft carbon layer on the HC surface,and its effect on the porosity of HC and SEI chemistry has been studied.A variety of structural characterizations show a soft carbon coating can increase the defect and ultra-micropore contents.The increase in ultra-micropore comes from both the soft carbon coatings and the larger pores within the HC that are partially filled by pitch,which provides more Na+storage sites.In-situ FTIR/EIS and ex-situ XPS showed that the soft carbon coating induced the formation of thinner SEI that is richer in NaF from the electrolyte,which stabilized the interface and promoted the charge transfer process.As a result,the anode produced fastcharging(329.8 mAh g^(−1)at 30 mA g^(−1)and 198.6 mAh g^(−1)at 300 mA g^(−1))and had a better cycling performance(a high capacity retention of 81.4%after 100 cycles at 150 mA g^(−1)).This work reveals the critical role of coating layer in changing the pore structure,SEI chemistry and diffusion kinetics of hard carbon,which enables rational design of sodium-ion battery anode with enhanced fast charging capability.展开更多
Four types of Mg-5Zn porous scaffolds with different pore geometries,including body-centered cubic(bcc),the rhombic dodecahedron(RD),gyroid(G),and primitive(P)types,were designed and fabricated using selective laser m...Four types of Mg-5Zn porous scaffolds with different pore geometries,including body-centered cubic(bcc),the rhombic dodecahedron(RD),gyroid(G),and primitive(P)types,were designed and fabricated using selective laser melting.Their forming quality,compression mechanical properties,and degradation behavior were investigated.Results indicate that the fabricated scaffolds exhibit good dimensional accuracy,and the surface chemical polishing treatment significantly improves the forming quality and reduces porosity error in porous scaffolds.Compared to the ones with rod structures(bcc,RD),the scaffolds with surface structures(G,P)have less powder particle adhesion.The G porous scaffold exhibits the best forming quality for the same design porosity.The predominant failure mode of scaffolds during compression is a 45°shear fracture.At a porosity of 75%,the compression property of all scaffolds meets the compressive property requirements of cancellous bone,while bcc and G structures show relatively better compression property.After immersion in Hank's solution for 168 h,the B-2-75% pore structure scaffold exhibits severe localized corrosion,with fractures in partial pillar connections.In contrast,the G-3-75% pore structure scaffold mainly undergoes uniform corrosion,maintaining structural integrity,and its corrosion rate and loss of compressive properties are less than those of the B-2-75%structure.After comparison,the G-pore structure scaffold is preferred.展开更多
Subsurface rocks,as complex porous media,exhibit multiscale pore structures and intricate physical properties.Digital rock physics technology has become increasingly influential in the study of subsurface rock propert...Subsurface rocks,as complex porous media,exhibit multiscale pore structures and intricate physical properties.Digital rock physics technology has become increasingly influential in the study of subsurface rock properties.Given the multiscale characteristics of rock pore structures,direct three-dimensional imaging at sub-micrometer and nanometer scales is typically infeasible.This study introduces a method for reconstructing porous media using multidimensional data,which combines one-dimensional pore structure parameters with two-dimensional images to reconstruct three-dimensional models.The pore network model(PNM)is stochastically reconstructed using one-dimensional parameters,and a generative adversarial network(GAN)is utilized to equip the PNM with pore morphologies derived from two-dimensional images.The digital rocks generated by this method possess excellent controllability.Using Berea sandstone and Grosmont carbonate samples,we performed digital rock reconstructions based on PNM extracted by the maximum ball algorithm and compared them with stochastically reconstructed PNM.Pore structure parameters,permeability,and formation factors were calculated.The results show that the generated samples exhibit good consistency with real samples in terms of pore morphology,pore structure,and physical properties.Furthermore,our method effectively supplements the micropores not captured in CT images,demonstrating its potential in multiscale carbonate samples.Thus,the proposed reconstruction method is promising for advancing porous media property research.展开更多
As a typical sedimentary soft rock,mudstone has the characteristics of being easily softened and disintegrated under the effect of wetting and drying(WD).The first cycle of WD plays an important role in the entire WD ...As a typical sedimentary soft rock,mudstone has the characteristics of being easily softened and disintegrated under the effect of wetting and drying(WD).The first cycle of WD plays an important role in the entire WD cycles.X-ray micro-computed tomography(micro-CT)was used as a non-destructive tool to quantitatively analyze microstructural changes of the mudstone due to the first cycle of WD.The test results show that WD leads to an increase of pore volume and pore connectivity in the mudstone.The porosity and fractal dimension of each slice of mudstone not only increase in value,but also in fluctuation amplitude.The pattern of variation in the frequency distribution of the equivalent radii of connected,isolated pores and pore throats in mudstone under WD effect satisfies the Gaussian distribution.Under the effect of WD,pores and pore throats with relatively small sizes increase the most.The sphericity of the pores in mudstones is positively correlated with the pore radius.The WD effect transforms the originally angular and flat pores into round and regular pores.This paper can provide a reference for the study of the deterioration and catastrophic mechanisms of mudstone under wetting and drying cycles.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
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
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
To obtain materials capable of efficiently separating acetylene(C_(2)H_(2))from carbon dioxide(CO_(2))and eth-ylene(C_(2)H_(4)),In this work,based on the pore space partition strategy,a pacs-metal-organic framework(MO...To obtain materials capable of efficiently separating acetylene(C_(2)H_(2))from carbon dioxide(CO_(2))and eth-ylene(C_(2)H_(4)),In this work,based on the pore space partition strategy,a pacs-metal-organic framework(MOF):(NH_(2)Me_(2))_(2)[Fe_(3)(μ_(3)-O)(bdc)_(3)][In(FA)_(3)Cl_(3)](Fe‑FAIn‑bdc)was synthesized successfully by using the metal-formate com-plex[In(FA)_(3)Cl_(3)]^(3-)as the pore partition units,where bdc^(2-)=terephthalate,FA-=formate.Owing to the pore partition effect of this metal-organic building block,fruitful confined spaces are formed in the network of Fe‑FAIn‑bdc,endowing this MOF with superior separation performance of acetylene and carbon dioxide.According to the adsorp-tion test,this MOF exhibited a high adsorption capacity for C_(2)H_(2)(50.79 cm^(3)·g^(-1))at 298 K and 100 kPa,which was much higher than that for CO_(2)(29.99 cm^(3)·g^(-1))and C_(2)H_(4)(30.94 cm^(3)·g^(-1))under the same conditions.Ideal adsorbed solution theory(IAST)calculations demonstrate that the adsorption selectivity of Fe‑FAIn‑bdc for the mixture of C_(2)H_(2)/CO_(2)and C_(2)H_(2)/C_(2)H_(4)in a volume ratio of 50∶50 was 3.08 and 3.65,respectively,which was higher than some reported MOFs such as NUM-11 and SNNU-18.CCDC:_(2)453954.展开更多
THE mechanical response and deformation mechanisms of pure nickel under nanoindentation were systematically investigated using molecular dynamics(MD)simulations,with a particular focus on the novel interplay between c...THE mechanical response and deformation mechanisms of pure nickel under nanoindentation were systematically investigated using molecular dynamics(MD)simulations,with a particular focus on the novel interplay between crystallographic orientation,grain boundary(GB)proximity,and pore characteristics(size/location).This study compares single-crystal nickel models along[100],[110],and[111]orientations with equiaxed polycrystalline models containing 0,1,and 2.5 nm pores in surface and subsurface configurations.Our results reveal that crystallographic anisotropy manifests as a 24.4%higher elastic modulus and 22.2%greater hardness in[111]-oriented single crystals compared to[100].Pore-GB synergistic effects are found to dominate the deformation behavior:2.5 nm subsurface pores reduce hardness by 25.2%through stress concentration and dislocation annihilation at GBs,whereas surface pores enable mechanical recovery via accelerated dislocation generation post-collapse.Additionally,size-dependent deformation regimes were identified,with 1 nm pores inducing negligible perturbation due to rapid atomic rearrangement,in contrast with persistent softening in 2.5 nm pores.These findings establish atomic-scale design principles for defect engineering in nickel-based aerospace components,demonstrating how crystallographic orientation,pore configuration,and GB interactions collectively govern nanoindentation behavior.展开更多
Pore structure directly affects the occurrence and migration of shale hydrocarbon,and the lack of research on the mechanism of the pore structure is an important reason for the hindrance of shale hydrocarbon explorati...Pore structure directly affects the occurrence and migration of shale hydrocarbon,and the lack of research on the mechanism of the pore structure is an important reason for the hindrance of shale hydrocarbon exploration.By analysing the geochemistry and reservoir characteristics of Jurassic lacustrine shales in Sichuan Basin,this study recovers their paleoenvironments and further discusses paleoenvironmental constraints on pore structure.The results show that the Lower Jurassic lacustrine shales in the Sichuan Basin are in a warm and humid semi-anoxic to anoxic lake environment with high productivity,a strong stagnant environment,and a rapid sedimentation rate,with water depths ranging from about 11.54-55.22 m,and a mixture of type Ⅱ/Ⅲ kerogen is developed.In terms of reservoir characteristics,they are dominated by open-slit pores,and the pores are relatively complex.The percentage of mesopores is the highest,while the percentage of macropores is the lowest.Further analysis shows that paleoclimate controls the overall pore complexity and surface relaxation of shales by influencing the weathering rate of mother rocks.Paleoredox conditions control the proportion and complexity of shale pores by influencing TOC content.The research results will provide theoretical basis for improving the exploration efficiency of lacustrine shale resources and expanding exploration target areas.展开更多
Clarifying the pore structure characteristics of shale reservoirs,which are low porosity,low permeability and high heterogeneity,is an essential prerequisite for the efficient development of shale oil and gas.Fractal ...Clarifying the pore structure characteristics of shale reservoirs,which are low porosity,low permeability and high heterogeneity,is an essential prerequisite for the efficient development of shale oil and gas.Fractal theory is especially suited for characterizing the complex pore structures of shales.This work compares the pore structure characteristics between marine shales from the Longmaxi Formation and continental shales from the Shahejie Formation through low-temperature nitrogen adsorption,nuclear magnetic resonance,and scanning electron microscopy.Different fractal scaling models are adopted to determine the fractal dimensions and lacunarities of shales by low-temperature nitrogen adsorption data and scanning electron microscopy images.In addition,the mineral compositions from X-ray diffraction are analyzed to elucidate the mechanisms by which mineral content influences fractal dimensions.Finally,the correlations between total organic carbon content and microscopic structure are discussed.These results indicate that the pore size of marine shale is smaller than that of continental shale.Additionally,the fractal dimensions of marine shales are greater than that of continental shales,suggesting a more complex pore structure.The more quartz and clay content lead to greater complexity in pore space,resulting in higher fractal dimensions.The illite/smectite mixed layer shows a strong positive correlation with fractal dimensions for marine shales,whereas this correlation is less pronounced for continental shales.The presence of microfractures in organic matter leads to a reduction for the pore surface fractal dimension in continental shales.展开更多
Tight oil is the most viable target for unconventional oil and gas exploration, but the complexity of micro-/nanopore throat systems significantly affects the oil content of reservoirs. To investigate the causes of he...Tight oil is the most viable target for unconventional oil and gas exploration, but the complexity of micro-/nanopore throat systems significantly affects the oil content of reservoirs. To investigate the causes of heterogeneity in oil-bearing reservoirs, a high-pressure mercury injection experiment combined with fractal theory was conducted to analyze the micro pore throat structure characteristics of the tight sandstone of Chang 7 Member reservoirs in the Ordos Basin. The factors controlling the variations in oil content among tight sandstone samples were identified based on mineral composition characteristics. The results indicate that the pore throat radius distribution is mainly unimodal an bimodal. In oil-bearing samples, the pore throat distributions align well with the corresponding permeability contribution curves, while in oil-free samples, there is a clear deviation from these curves. Mesopore throats exert the greatest influence on seepage capacity. Differences in fractal characteristics are primarily reflected in D1 values, with oil-free samples exhibiting D1 values close to 3, indicating an extremely nonuniform pore throat structure at this scale. The content of quartz, plagioclase, and chlorite is significantly higher in oil-bearing samples than in oil-free samples, whereas calcite content is lower in oil-bearing samples. There is a positive correlation between the contents of quartz, plagioclase, and chlorite with D1;their increased presence contributes to a more favorable pore throat structure.Conversely, the calcite contents show an inverse relationship with D1. Cementation increases the complexity of pore throat structures, while multiple diagenetic processes simultaneously control these characteristics, leading to variations in oil content.展开更多
By adding zeolite aggregate with good adsorption properties,different mix ratios of added zeolite pervious concrete(ZPC)were designed to compare the water purification effect of ordinary pervious concrete and water pu...By adding zeolite aggregate with good adsorption properties,different mix ratios of added zeolite pervious concrete(ZPC)were designed to compare the water purification effect of ordinary pervious concrete and water purification tests that were conducted.The pore characteristics of the pervious concrete were identified using three-dimensional reconstruction software and the relationship between pore structure and water purification performance was quantified by gray entropy correlation analysis.The results showed that the purification efficiency of zeolite-doped pervious concrete was 17.6%-22.3%higher than that of ordinary pervious concrete.The characteristic parameters of the pore structure of permeable concrete,i.e.planar porosity and tortuosity,were determined using three-dimensional reconstruction software.The correlation between the degree of tortuosity and the removal rate reached more than 0.90,indicating that the internal pore structure of pervious concrete has a good correlation with the water purification performance.展开更多
The flow characteristics of coalbed methane(CBM)are influenced by the coal rock fracture network,which serves as the primary gas transport channel.This has a significant effect on the permeability performance of coal ...The flow characteristics of coalbed methane(CBM)are influenced by the coal rock fracture network,which serves as the primary gas transport channel.This has a significant effect on the permeability performance of coal reservoirs.In any case,the traditional techniques of coal rock fracture observation are unable to precisely define the flow of CBM.In this study,coal samples were subjected to an in situ loading scanning test in order to create a pore network model(PNM)and determine the pore and fracture dynamic evolution law of the samples in the loading path.On this basis,the structural characteristic parameters of the samples were extracted from the PNM and the impact on the permeability performance of CBM was assessed.The findings demonstrate that the coal samples'internal porosity increases by 2.039%under uniaxial loading,the average throat pore radius increases by 205.5 to 36.1μm,and the loading has an impact on the distribution and morphology of the pores in the coal rock.The PNM was loaded into the finite element program COMSOL for seepage modeling,and the M3 stage showed isolated pore connectivity to produce microscopic fissures,which could serve as seepage channels.In order to confirm the viability of the PNM and COMSOL docking technology,the streamline distribution law of pressure and velocity fields during the coal sample loading process was examined.The absolute permeability of the coal samples was also obtained in order for comparison with the measured results.The macroscopic CBM flow mechanism in complex lowpermeability coal rocks can be revealed through three-dimensional reconstruction of the microscopic fracture structure and seepage simulation.This study lays the groundwork for the fine description and evaluation of coal reservoirs as well as the precise prediction of gas production in CBM wells.展开更多
In the production of castings,intrusive gas pore represents a kind of common defects which can lead to leakage in high gas-tightness requirement castings,such as cylinder blocks and cylinder heads for engines.It occur...In the production of castings,intrusive gas pore represents a kind of common defects which can lead to leakage in high gas-tightness requirement castings,such as cylinder blocks and cylinder heads for engines.It occurs due to the intrusion of gases generated during the resin burning of the sand core into castings during the casting process.Therefore,a gas generation and flow constitution model was established,in which the gas generation rate is a function of temperature and time,and the flow of gas is controlled by the gas release,conservation,and Darcy's law.The heat transfer and gas flow during casting process was numerically simulated.The dangerous point of cores is firstly identified by a virtual heat transfer method based on the similarity between heat transfer and gas flow in the sand core.The gas pores in castings are predicted by the gas pressure,the viscosity and state of the melt for these dangerous points.Three distinct sand core structures were designed and used for the production of iron castings,and the simulated gas pore results were validated by the obtained castings.展开更多
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 National Natural Science Foundation of China(Grant Nos.42172159 and 42302143)the Postdoctora Fellowship Program of the China Postdoctoral Science Foundation(CPSF)(Grant No.GZB20230864).
文摘Forced imbibition,the invasion of a wetting fluid into porous rocks,plays an important role in the effective exploitation of hydrocarbon resources and the geological sequestration of carbon dioxide.However,the interface dynamics influenced by complex topology commonly leads to non-wetting fluid trapping.Particularly,the underlying mechanisms under viscously unfavorable conditions remain unclear.This study employs a direct numerical simulation method to simulate forced imbibition through the reconstructed digital rocks of sandstone.The interface dynamics and fluid–fluid interactions are investigated through transient simulations,while the pore topology metrics are introduced to analyze the impact on steady-state residual fluid distribution obtained by a pseudo-transient scheme.The results show that the cooperative pore-filling process promoted by corner flow is dominant at low capillary numbers.This leads to unstable inlet pressure,mass flow,and interface curvature,which correspond to complicated interface dynamics and higher residual fluid saturation.During forced imbibition,the interface curvature gradually increases,with the pore-filling mechanisms involving the cooperation of main terminal meniscus movement and arc menisci filling.Complex topology with small diameter pores may result in the destabilization of interface curvature.The residual fluid saturation is negatively correlated with porosity and pore throat size,and positively correlated with tortuosity and aspect ratio.A large mean coordination number characterizing global connectivity promotes imbibition.However,high connectivity characterized by the standardized Euler number corresponding to small pores is associated with a high probability of non-wetting fluid trapping.
文摘Biomass-derived hard carbons,usually prepared by pyrolysis,are widely considered the most promising anode materials for sodium-ion bat-teries(SIBs)due to their high capacity,low poten-tial,sustainability,cost-effectiveness,and environ-mental friendliness.The pyrolysis method affects the microstructure of the material,and ultimately its so-dium storage performance.Our previous work has shown that pyrolysis in a sealed graphite vessel im-proved the sodium storage performance of the car-bon,however the changes in its microstructure and the way this influences the sodium storage are still unclear.A series of hard carbon materials derived from corncobs(CCG-T,where T is the pyrolysis temperature)were pyrolyzed in a sealed graphite vessel at different temperatures.As the pyrolysis temperature increased from 1000 to 1400℃ small carbon domains gradually transformed into long and curved domains.At the same time,a greater number of large open pores with uniform apertures,as well as more closed pores,were formed.With the further increase of pyrolysis temperature to 1600℃,the long and curved domains became longer and straighter,and some closed pores gradually became open.CCG-1400,with abundant closed pores,had a superior SIB performance,with an initial reversible ca-pacity of 320.73 mAh g^(-1) at a current density of 30 mA g^(-1),an initial Coulomb efficiency(ICE)of 84.34%,and a capacity re-tention of 96.70%after 100 cycles.This study provides a method for the precise regulation of the microcrystalline and pore structures of hard carbon materials.
基金Supported by Leading Talent Program of Autonomous Region(2022TSYCLJ0070)PetroChina Prospective and Basic Technological Project(2021DJ0108)Natural Science Foundation for Outstanding Young People in Shandong Province(ZR2022YQ30).
文摘Based on the experimental results of casting thin section,low temperature nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance T2 spectrum,contact angle and oil-water interfacial tension,the relationship between pore throat structure and crude oil mobility characteristics of full particle sequence reservoirs in the Lower Permian Fengcheng Formation of Mahu Sag,Junggar Basin,are revealed.(1)With the decrease of reservoir particle size,the volume of pores connected by large throats and the volume of large pores show a decreasing trend,and the distribution and peak ranges of throat and pore radius shift to smaller size in an orderly manner.The upper limits of throat radius,porosity and permeability of unconventional reservoirs in Fengcheng Formation are approximately 0.7μm,8%and 0.1×10^(−3)μm^(2),respectively.(2)As the reservoir particle size decreases,the distribution and peak ranges of pores hosting retained oil and movable oil are shifted to a smaller size in an orderly manner.With the increase of driving pressure,the amount of retained and movable oil of the larger particle reservoir samples shows a more obvious trend of decreasing and increasing,respectively.(3)With the increase of throat radius,the driving pressure of reservoir with different particle levels presents three stages,namely rapid decrease,slow decrease and stabilization.The oil driving pressures of various reservoirs and the differences of them decrease with the increase of temperature and obviously decrease with the increase of throat radius.According to the above experimental analysis,it is concluded that the deep shale oil of Fengcheng Formation in Mahu Sag has great potential for production under geological conditions.
文摘The development of sustainable electrode materials for energy storage systems has become very important and porous carbons derived from biomass have become an important candidate because of their tunable pore structure,environmental friendliness,and cost-effectiveness.Recent advances in controlling the pore structure of these carbons and its relationship between to is energy storage performance are discussed,emphasizing the critical role of a balanced distribution of micropores,mesopores and macropores in determining electrochemical behavior.Particular attention is given to how the intrinsic components of biomass precursors(lignin,cellulose,and hemicellulose)influence pore formation during carbonization.Carbonization and activation strategies to precisely control the pore structure are introduced.Finally,key challenges in the industrial production of these carbons are outlined,and future research directions are proposed.These include the establishment of a database of biomass intrinsic structures and machine learning-assisted pore structure engineering,aimed at providing guidance for the design of high-performance carbon materials for next-generation energy storage devices.
基金National Key Research and Development Program of China(2022YFE0206300)National Natural Science Foundation of China(U21A2081,22075074,22209047)+2 种基金Guangdong Basic and Applied Basic Research Foundation(2024A1515011620)Hunan Provincial Natural Science Foundation of China(2024JJ5068)Foundation of Yuelushan Center for Industrial Innovation(2023YCII0119)。
文摘Changes to the microstructure of a hard carbon(HC)and its solid electrolyte interface(SEI)can be effective in improving the electrode kinetics.However,achieving fast charging using a simple and inexpensive strategy without sacrificing its initial Coulombic efficiency remains a challenge in sodium ion batteries.A simple liquid-phase coating approach has been used to generate a pitch-derived soft carbon layer on the HC surface,and its effect on the porosity of HC and SEI chemistry has been studied.A variety of structural characterizations show a soft carbon coating can increase the defect and ultra-micropore contents.The increase in ultra-micropore comes from both the soft carbon coatings and the larger pores within the HC that are partially filled by pitch,which provides more Na+storage sites.In-situ FTIR/EIS and ex-situ XPS showed that the soft carbon coating induced the formation of thinner SEI that is richer in NaF from the electrolyte,which stabilized the interface and promoted the charge transfer process.As a result,the anode produced fastcharging(329.8 mAh g^(−1)at 30 mA g^(−1)and 198.6 mAh g^(−1)at 300 mA g^(−1))and had a better cycling performance(a high capacity retention of 81.4%after 100 cycles at 150 mA g^(−1)).This work reveals the critical role of coating layer in changing the pore structure,SEI chemistry and diffusion kinetics of hard carbon,which enables rational design of sodium-ion battery anode with enhanced fast charging capability.
基金Science and Technology Planning Project of Inner Mongolia Science and Technology Department(2022YFSH0021)Key Research and Development Program of Shaanxi Province(2024SF2-GJHX-14,2021SF-296)。
文摘Four types of Mg-5Zn porous scaffolds with different pore geometries,including body-centered cubic(bcc),the rhombic dodecahedron(RD),gyroid(G),and primitive(P)types,were designed and fabricated using selective laser melting.Their forming quality,compression mechanical properties,and degradation behavior were investigated.Results indicate that the fabricated scaffolds exhibit good dimensional accuracy,and the surface chemical polishing treatment significantly improves the forming quality and reduces porosity error in porous scaffolds.Compared to the ones with rod structures(bcc,RD),the scaffolds with surface structures(G,P)have less powder particle adhesion.The G porous scaffold exhibits the best forming quality for the same design porosity.The predominant failure mode of scaffolds during compression is a 45°shear fracture.At a porosity of 75%,the compression property of all scaffolds meets the compressive property requirements of cancellous bone,while bcc and G structures show relatively better compression property.After immersion in Hank's solution for 168 h,the B-2-75% pore structure scaffold exhibits severe localized corrosion,with fractures in partial pillar connections.In contrast,the G-3-75% pore structure scaffold mainly undergoes uniform corrosion,maintaining structural integrity,and its corrosion rate and loss of compressive properties are less than those of the B-2-75%structure.After comparison,the G-pore structure scaffold is preferred.
基金supported by the Shandong Provincial Natural Science Foundation(ZR2024MD116)National Natural Science Foundation of China(Grant Nos.42174143,42004098)Technology Innovation Leading Program of Shaanxi(No.2024 ZC-YYDP-27).
文摘Subsurface rocks,as complex porous media,exhibit multiscale pore structures and intricate physical properties.Digital rock physics technology has become increasingly influential in the study of subsurface rock properties.Given the multiscale characteristics of rock pore structures,direct three-dimensional imaging at sub-micrometer and nanometer scales is typically infeasible.This study introduces a method for reconstructing porous media using multidimensional data,which combines one-dimensional pore structure parameters with two-dimensional images to reconstruct three-dimensional models.The pore network model(PNM)is stochastically reconstructed using one-dimensional parameters,and a generative adversarial network(GAN)is utilized to equip the PNM with pore morphologies derived from two-dimensional images.The digital rocks generated by this method possess excellent controllability.Using Berea sandstone and Grosmont carbonate samples,we performed digital rock reconstructions based on PNM extracted by the maximum ball algorithm and compared them with stochastically reconstructed PNM.Pore structure parameters,permeability,and formation factors were calculated.The results show that the generated samples exhibit good consistency with real samples in terms of pore morphology,pore structure,and physical properties.Furthermore,our method effectively supplements the micropores not captured in CT images,demonstrating its potential in multiscale carbonate samples.Thus,the proposed reconstruction method is promising for advancing porous media property research.
基金Project(41877240)supported by the National Natural Science Foundation of China。
文摘As a typical sedimentary soft rock,mudstone has the characteristics of being easily softened and disintegrated under the effect of wetting and drying(WD).The first cycle of WD plays an important role in the entire WD cycles.X-ray micro-computed tomography(micro-CT)was used as a non-destructive tool to quantitatively analyze microstructural changes of the mudstone due to the first cycle of WD.The test results show that WD leads to an increase of pore volume and pore connectivity in the mudstone.The porosity and fractal dimension of each slice of mudstone not only increase in value,but also in fluctuation amplitude.The pattern of variation in the frequency distribution of the equivalent radii of connected,isolated pores and pore throats in mudstone under WD effect satisfies the Gaussian distribution.Under the effect of WD,pores and pore throats with relatively small sizes increase the most.The sphericity of the pores in mudstones is positively correlated with the pore radius.The WD effect transforms the originally angular and flat pores into round and regular pores.This paper can provide a reference for the study of the deterioration and catastrophic mechanisms of mudstone under wetting and drying cycles.
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 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.
文摘To obtain materials capable of efficiently separating acetylene(C_(2)H_(2))from carbon dioxide(CO_(2))and eth-ylene(C_(2)H_(4)),In this work,based on the pore space partition strategy,a pacs-metal-organic framework(MOF):(NH_(2)Me_(2))_(2)[Fe_(3)(μ_(3)-O)(bdc)_(3)][In(FA)_(3)Cl_(3)](Fe‑FAIn‑bdc)was synthesized successfully by using the metal-formate com-plex[In(FA)_(3)Cl_(3)]^(3-)as the pore partition units,where bdc^(2-)=terephthalate,FA-=formate.Owing to the pore partition effect of this metal-organic building block,fruitful confined spaces are formed in the network of Fe‑FAIn‑bdc,endowing this MOF with superior separation performance of acetylene and carbon dioxide.According to the adsorp-tion test,this MOF exhibited a high adsorption capacity for C_(2)H_(2)(50.79 cm^(3)·g^(-1))at 298 K and 100 kPa,which was much higher than that for CO_(2)(29.99 cm^(3)·g^(-1))and C_(2)H_(4)(30.94 cm^(3)·g^(-1))under the same conditions.Ideal adsorbed solution theory(IAST)calculations demonstrate that the adsorption selectivity of Fe‑FAIn‑bdc for the mixture of C_(2)H_(2)/CO_(2)and C_(2)H_(2)/C_(2)H_(4)in a volume ratio of 50∶50 was 3.08 and 3.65,respectively,which was higher than some reported MOFs such as NUM-11 and SNNU-18.CCDC:_(2)453954.
基金The National Natural Science Foundation of China(Grant No.12462006)Beijing Institute of Structure and Environment Engineering Joint Innovation Fund(No.BQJJ202414).
文摘THE mechanical response and deformation mechanisms of pure nickel under nanoindentation were systematically investigated using molecular dynamics(MD)simulations,with a particular focus on the novel interplay between crystallographic orientation,grain boundary(GB)proximity,and pore characteristics(size/location).This study compares single-crystal nickel models along[100],[110],and[111]orientations with equiaxed polycrystalline models containing 0,1,and 2.5 nm pores in surface and subsurface configurations.Our results reveal that crystallographic anisotropy manifests as a 24.4%higher elastic modulus and 22.2%greater hardness in[111]-oriented single crystals compared to[100].Pore-GB synergistic effects are found to dominate the deformation behavior:2.5 nm subsurface pores reduce hardness by 25.2%through stress concentration and dislocation annihilation at GBs,whereas surface pores enable mechanical recovery via accelerated dislocation generation post-collapse.Additionally,size-dependent deformation regimes were identified,with 1 nm pores inducing negligible perturbation due to rapid atomic rearrangement,in contrast with persistent softening in 2.5 nm pores.These findings establish atomic-scale design principles for defect engineering in nickel-based aerospace components,demonstrating how crystallographic orientation,pore configuration,and GB interactions collectively govern nanoindentation behavior.
基金supported from the Opening fund of State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development(33550000-22-ZC0613-0297)National Natural Science Foundation of China(42102196)the Natural Science Basis Research Plan in Shaanxi Province of China(2022JM-147).
文摘Pore structure directly affects the occurrence and migration of shale hydrocarbon,and the lack of research on the mechanism of the pore structure is an important reason for the hindrance of shale hydrocarbon exploration.By analysing the geochemistry and reservoir characteristics of Jurassic lacustrine shales in Sichuan Basin,this study recovers their paleoenvironments and further discusses paleoenvironmental constraints on pore structure.The results show that the Lower Jurassic lacustrine shales in the Sichuan Basin are in a warm and humid semi-anoxic to anoxic lake environment with high productivity,a strong stagnant environment,and a rapid sedimentation rate,with water depths ranging from about 11.54-55.22 m,and a mixture of type Ⅱ/Ⅲ kerogen is developed.In terms of reservoir characteristics,they are dominated by open-slit pores,and the pores are relatively complex.The percentage of mesopores is the highest,while the percentage of macropores is the lowest.Further analysis shows that paleoclimate controls the overall pore complexity and surface relaxation of shales by influencing the weathering rate of mother rocks.Paleoredox conditions control the proportion and complexity of shale pores by influencing TOC content.The research results will provide theoretical basis for improving the exploration efficiency of lacustrine shale resources and expanding exploration target areas.
基金supported by the National Natural Science Foundation of China(Grant Nos.42172159,42302143,and 52404048).
文摘Clarifying the pore structure characteristics of shale reservoirs,which are low porosity,low permeability and high heterogeneity,is an essential prerequisite for the efficient development of shale oil and gas.Fractal theory is especially suited for characterizing the complex pore structures of shales.This work compares the pore structure characteristics between marine shales from the Longmaxi Formation and continental shales from the Shahejie Formation through low-temperature nitrogen adsorption,nuclear magnetic resonance,and scanning electron microscopy.Different fractal scaling models are adopted to determine the fractal dimensions and lacunarities of shales by low-temperature nitrogen adsorption data and scanning electron microscopy images.In addition,the mineral compositions from X-ray diffraction are analyzed to elucidate the mechanisms by which mineral content influences fractal dimensions.Finally,the correlations between total organic carbon content and microscopic structure are discussed.These results indicate that the pore size of marine shale is smaller than that of continental shale.Additionally,the fractal dimensions of marine shales are greater than that of continental shales,suggesting a more complex pore structure.The more quartz and clay content lead to greater complexity in pore space,resulting in higher fractal dimensions.The illite/smectite mixed layer shows a strong positive correlation with fractal dimensions for marine shales,whereas this correlation is less pronounced for continental shales.The presence of microfractures in organic matter leads to a reduction for the pore surface fractal dimension in continental shales.
基金supported by the National Natural Science Foundation of China (Grant No. 42002139)the Basic Prospective Project of SINOPEC (Grant No. P23240-3)。
文摘Tight oil is the most viable target for unconventional oil and gas exploration, but the complexity of micro-/nanopore throat systems significantly affects the oil content of reservoirs. To investigate the causes of heterogeneity in oil-bearing reservoirs, a high-pressure mercury injection experiment combined with fractal theory was conducted to analyze the micro pore throat structure characteristics of the tight sandstone of Chang 7 Member reservoirs in the Ordos Basin. The factors controlling the variations in oil content among tight sandstone samples were identified based on mineral composition characteristics. The results indicate that the pore throat radius distribution is mainly unimodal an bimodal. In oil-bearing samples, the pore throat distributions align well with the corresponding permeability contribution curves, while in oil-free samples, there is a clear deviation from these curves. Mesopore throats exert the greatest influence on seepage capacity. Differences in fractal characteristics are primarily reflected in D1 values, with oil-free samples exhibiting D1 values close to 3, indicating an extremely nonuniform pore throat structure at this scale. The content of quartz, plagioclase, and chlorite is significantly higher in oil-bearing samples than in oil-free samples, whereas calcite content is lower in oil-bearing samples. There is a positive correlation between the contents of quartz, plagioclase, and chlorite with D1;their increased presence contributes to a more favorable pore throat structure.Conversely, the calcite contents show an inverse relationship with D1. Cementation increases the complexity of pore throat structures, while multiple diagenetic processes simultaneously control these characteristics, leading to variations in oil content.
基金Hunan Provincial Department of Water Resources:Research on Formula Optimization and Performance Evaluation System of Ecological Concrete for River Water Quality Purification Based on the Dual Carbon Goal(Project No.:XSKJ2024064-44)。
文摘By adding zeolite aggregate with good adsorption properties,different mix ratios of added zeolite pervious concrete(ZPC)were designed to compare the water purification effect of ordinary pervious concrete and water purification tests that were conducted.The pore characteristics of the pervious concrete were identified using three-dimensional reconstruction software and the relationship between pore structure and water purification performance was quantified by gray entropy correlation analysis.The results showed that the purification efficiency of zeolite-doped pervious concrete was 17.6%-22.3%higher than that of ordinary pervious concrete.The characteristic parameters of the pore structure of permeable concrete,i.e.planar porosity and tortuosity,were determined using three-dimensional reconstruction software.The correlation between the degree of tortuosity and the removal rate reached more than 0.90,indicating that the internal pore structure of pervious concrete has a good correlation with the water purification performance.
基金The National Key R&D Program,Grant/Award Number:2023YFC2907203National Natural Science Foundation of China,Grant/Award Numbers:52374121,52074121。
文摘The flow characteristics of coalbed methane(CBM)are influenced by the coal rock fracture network,which serves as the primary gas transport channel.This has a significant effect on the permeability performance of coal reservoirs.In any case,the traditional techniques of coal rock fracture observation are unable to precisely define the flow of CBM.In this study,coal samples were subjected to an in situ loading scanning test in order to create a pore network model(PNM)and determine the pore and fracture dynamic evolution law of the samples in the loading path.On this basis,the structural characteristic parameters of the samples were extracted from the PNM and the impact on the permeability performance of CBM was assessed.The findings demonstrate that the coal samples'internal porosity increases by 2.039%under uniaxial loading,the average throat pore radius increases by 205.5 to 36.1μm,and the loading has an impact on the distribution and morphology of the pores in the coal rock.The PNM was loaded into the finite element program COMSOL for seepage modeling,and the M3 stage showed isolated pore connectivity to produce microscopic fissures,which could serve as seepage channels.In order to confirm the viability of the PNM and COMSOL docking technology,the streamline distribution law of pressure and velocity fields during the coal sample loading process was examined.The absolute permeability of the coal samples was also obtained in order for comparison with the measured results.The macroscopic CBM flow mechanism in complex lowpermeability coal rocks can be revealed through three-dimensional reconstruction of the microscopic fracture structure and seepage simulation.This study lays the groundwork for the fine description and evaluation of coal reservoirs as well as the precise prediction of gas production in CBM wells.
基金funded by the Beijing Nature Sciences Fund Haidian Originality Cooperation Project (Grant No. L212002)。
文摘In the production of castings,intrusive gas pore represents a kind of common defects which can lead to leakage in high gas-tightness requirement castings,such as cylinder blocks and cylinder heads for engines.It occurs due to the intrusion of gases generated during the resin burning of the sand core into castings during the casting process.Therefore,a gas generation and flow constitution model was established,in which the gas generation rate is a function of temperature and time,and the flow of gas is controlled by the gas release,conservation,and Darcy's law.The heat transfer and gas flow during casting process was numerically simulated.The dangerous point of cores is firstly identified by a virtual heat transfer method based on the similarity between heat transfer and gas flow in the sand core.The gas pores in castings are predicted by the gas pressure,the viscosity and state of the melt for these dangerous points.Three distinct sand core structures were designed and used for the production of iron castings,and the simulated gas pore results were validated by the obtained castings.
