The physical properties of hydrocarbon reservoirs are important factors affecting the percolation ability of the reservoirs.Tight-sand reservoirs exhibit complex pore throat connectivity due to the extensive developme...The physical properties of hydrocarbon reservoirs are important factors affecting the percolation ability of the reservoirs.Tight-sand reservoirs exhibit complex pore throat connectivity due to the extensive development of micro-and nano-scale pore and throat systems.Characterizing the microscopic properties of these reservoirs using nondestructive,quantitative methods serves as an important means to determine the characteristics of microscopic pores and throats in tight-sand reservoirs and the mechanism behind the influence of these characteristics on reservoir porosity and permeability.In this study,a low-permeability sandstone sample and two tight sandstone samples collected from the Ordos Basin were nondestructively tested using high-resolution nano-CT technology to quantitively characterize their microscopic pore throat structures and model them three-dimensionally(in 3D)based on CT threshold differences and gray models.A thorough analysis and comparison reveal that the three samples exhibit a certain positive correlation between their porosity and permeability but the most important factor affecting both porosity and permeability is the microscopic pore throat structure.Although the number of pores in tight sandstones shows a minor impact on their porosity,large pores(more than 20μm)contribute predominantly to porosity,suggesting that the permeability of tight sandstones is controlled primarily by large pore throats.For these samples,higher permeability corresponds to larger average throat sizes.Therefore,throats with average radii greater than 2μm can significantly improve the permeability of tight sandstones.展开更多
Nano-computed tomography(Nano-CT)is an emerging,high-resolution imaging technique.However,due to their low-light properties,tabletop Nano-CT has to be scanned under long exposure conditions,which the scanning process ...Nano-computed tomography(Nano-CT)is an emerging,high-resolution imaging technique.However,due to their low-light properties,tabletop Nano-CT has to be scanned under long exposure conditions,which the scanning process is time-consuming.For 3D reconstruction data,this paper proposed a lightweight 3D noise reduction method for desktop-level Nano-CT called AAD-ResNet(Axial Attention DeNoise ResNet).The network is framed by theU-net structure.The encoder and decoder are incorporated with the proposed 3D axial attention mechanism and residual dense block.Each layer of the residual dense block can directly access the features of the previous layer,which reduces the redundancy of parameters and improves the efficiency of network training.The 3D axial attention mechanism enhances the correlation between 3D information in the training process and captures the long-distance dependence.It can improve the noise reduction effect and avoid the loss of image structure details.Experimental results show that the network can effectively improve the image quality of a 0.1-s exposure scan to a level close to a 3-s exposure,significantly shortening the sample scanning time.展开更多
Considering the complementarity of synchrotron radiation SAXS and nano-CT in the pore structure detection range,synchrotron radiation SAXS and nano-CT methods were combined to characterize the nano-to micropore struct...Considering the complementarity of synchrotron radiation SAXS and nano-CT in the pore structure detection range,synchrotron radiation SAXS and nano-CT methods were combined to characterize the nano-to micropore structure of two bituminous coal samples.In mesopores,the pore size distribution curves exhibit unimodal distribution and the average pore diameters are similar due to the affinity of metamorphic grades of the two samples.In macropores,the sample with higher mineral matter content,especially clay mineral content,has a much higher number of pores.The fractal dimensions representing the pore surface irregularity and the pore structure heterogeneity were also characterized by synchrotron radiation SAXS and nano-CT.The fractal dimensions estimated by both methods for different pore sizes show consistency and the sample with smaller average pore diameters has a more complex pore structure within the full tested range.展开更多
X-ray computed tomography at the nanometer scale （nano-CT） offers a wide range of applications in scientific and industrial areas. Here we describe a reliable, user-friendly, and fast software package based on LabVI...X-ray computed tomography at the nanometer scale （nano-CT） offers a wide range of applications in scientific and industrial areas. Here we describe a reliable, user-friendly, and fast software package based on LabVIEW that may allow us to perform all procedures after the acquisition of raw projection images in order to obtain the inner structure of the investigated sample. A suitable image alignment process to address misalignment problems among image series due to mechanical manufacturing errors, thermal expansion, and other external factors has been considered, together with a novel fast parallel beam 3D reconstruction procedure that was developed ad hoc to perform the tomographic reconstruction. We have obtained remarkably improved reconstruction results at the Beijing Synchrotron Radiation Facility after the image calibration, the fundamental role of this image alignment procedure was confirmed, which minimizes the unwanted blurs and additional streaking artifacts that are always present in reconstructed slices. Moreover, this nano-CT image alignment and its associated 3D reconstruction procedure are fully based on LabVIEW routines, significantly reducing the data post-processing cycle, thus making the activity of the users faster and easier during experimental runs.展开更多
Phenolic resin-based porous composites are the promising thermal protection materials for aerospace applications.The high-temperature evolution of microstructure due to the decomposition of the resin also presents gre...Phenolic resin-based porous composites are the promising thermal protection materials for aerospace applications.The high-temperature evolution of microstructure due to the decomposition of the resin also presents great challenges to predict the internal heat and mass transport behaviors.This work investigates the effects of microstructural characteristics such as the number of pores,size distribution,pore-throats size and volume fraction on the permeation behaviors of fluid in the needle-punched short-cut fiber reinforced silicon phenolic resin-based porous composites.The specimens are prepared by the sol-gel method and the atmospheric pressure drying process and the pyrolysis experiment are conducted at 400℃and 800℃.Then,a scanning electron microscope and a Nano-CT computer tomography are applied to obtain the surface morphologies and the interior slice images of the specimens.The AVIZO software is employed to accurately extract and analyze the pore structural model and simulated calculate the absolute permeability.It is found that the small pores develop gradually during pyrolysis due to the resin decomposition and the quartz fibers rearrangement,resulting in an increase in number of large pores.Nonetheless,the equivalent radii of most pores are less than 1μm.Very few pores possess a large radius over 5μm.However,the volume fraction of these large pores exceeds 99%.In addition,with the pore size growing,the connectivity between these pores is enhanced,immediately causing an increase in number and size of the pore-throats.Larger pore and more pore-throats would add the unblocked flow channels for the fluid passing,reducing flow resistance.The seepage simulation also confirms that the absolute permeability gains significant increase after pyrolysis in all directions.For example,the absolute permeability of the pyrolyzed sample is 9.0×10^(-13)m^(2) in X direction,which is an order of magnitude greater than that of the unpyrolyzed sample.This study provides important insights for understanding the high-temperature evolution at of microstructure and the permeation behavior of fluid in porous thermal protection materials.展开更多
We selected a cell with superior electrochemical performance to characterization microstructure characterization.Here,we employed high-resolution SEM and X-ray nano-CT to investigate a porous LSCrRu-GDC composite anod...We selected a cell with superior electrochemical performance to characterization microstructure characterization.Here,we employed high-resolution SEM and X-ray nano-CT to investigate a porous LSCrRu-GDC composite anode.These experimental results are utilized for characterize and quantify the key structural parameters,such as the volume ratio of the three phases(LSCrRu,GDC,and pore),connected porosity,tortuosity,surface area of each phase,interface of LSCrRu/GDC,and three-phase boundary length(TPB where the LSCrRu,GDC and fuel gas phases come together)of the anode.展开更多
文摘The physical properties of hydrocarbon reservoirs are important factors affecting the percolation ability of the reservoirs.Tight-sand reservoirs exhibit complex pore throat connectivity due to the extensive development of micro-and nano-scale pore and throat systems.Characterizing the microscopic properties of these reservoirs using nondestructive,quantitative methods serves as an important means to determine the characteristics of microscopic pores and throats in tight-sand reservoirs and the mechanism behind the influence of these characteristics on reservoir porosity and permeability.In this study,a low-permeability sandstone sample and two tight sandstone samples collected from the Ordos Basin were nondestructively tested using high-resolution nano-CT technology to quantitively characterize their microscopic pore throat structures and model them three-dimensionally(in 3D)based on CT threshold differences and gray models.A thorough analysis and comparison reveal that the three samples exhibit a certain positive correlation between their porosity and permeability but the most important factor affecting both porosity and permeability is the microscopic pore throat structure.Although the number of pores in tight sandstones shows a minor impact on their porosity,large pores(more than 20μm)contribute predominantly to porosity,suggesting that the permeability of tight sandstones is controlled primarily by large pore throats.For these samples,higher permeability corresponds to larger average throat sizes.Therefore,throats with average radii greater than 2μm can significantly improve the permeability of tight sandstones.
基金supported by the National Natural Science Foundation of China(62201618).
文摘Nano-computed tomography(Nano-CT)is an emerging,high-resolution imaging technique.However,due to their low-light properties,tabletop Nano-CT has to be scanned under long exposure conditions,which the scanning process is time-consuming.For 3D reconstruction data,this paper proposed a lightweight 3D noise reduction method for desktop-level Nano-CT called AAD-ResNet(Axial Attention DeNoise ResNet).The network is framed by theU-net structure.The encoder and decoder are incorporated with the proposed 3D axial attention mechanism and residual dense block.Each layer of the residual dense block can directly access the features of the previous layer,which reduces the redundancy of parameters and improves the efficiency of network training.The 3D axial attention mechanism enhances the correlation between 3D information in the training process and captures the long-distance dependence.It can improve the noise reduction effect and avoid the loss of image structure details.Experimental results show that the network can effectively improve the image quality of a 0.1-s exposure scan to a level close to a 3-s exposure,significantly shortening the sample scanning time.
基金financially sponsored by the National Natural Science Foundation of China(Grant Nos.U1910206,51861145403,51874312,52004293)China Postdoctoral Science Foundation(No.2018M641526)+2 种基金Yue Qi Distinguished Scholar Project of China University of Mining&Technology(Beijing)Fundamental Research Funds for the Central UniversitiesFund of China Scholarship Council and the Open Project Program of Key Laboratory of Deep Earth Science and Engineering(Sichuan University),Ministry of Education(No.DESE 202004)。
文摘Considering the complementarity of synchrotron radiation SAXS and nano-CT in the pore structure detection range,synchrotron radiation SAXS and nano-CT methods were combined to characterize the nano-to micropore structure of two bituminous coal samples.In mesopores,the pore size distribution curves exhibit unimodal distribution and the average pore diameters are similar due to the affinity of metamorphic grades of the two samples.In macropores,the sample with higher mineral matter content,especially clay mineral content,has a much higher number of pores.The fractal dimensions representing the pore surface irregularity and the pore structure heterogeneity were also characterized by synchrotron radiation SAXS and nano-CT.The fractal dimensions estimated by both methods for different pore sizes show consistency and the sample with smaller average pore diameters has a more complex pore structure within the full tested range.
基金Supported by Major State Basic Research Development Program(2012CB825800)Science Fund for Creative Research Groups(11321503)+2 种基金Knowledge Innovation Program of The Chinese Academy of Sciences(KJCX2-YW-N42)National Natural Science Foundation of China(11179004,10979055,11205189,11205157)Fundamental Research Funds for the Central Universities(WK2310000021)
文摘X-ray computed tomography at the nanometer scale （nano-CT） offers a wide range of applications in scientific and industrial areas. Here we describe a reliable, user-friendly, and fast software package based on LabVIEW that may allow us to perform all procedures after the acquisition of raw projection images in order to obtain the inner structure of the investigated sample. A suitable image alignment process to address misalignment problems among image series due to mechanical manufacturing errors, thermal expansion, and other external factors has been considered, together with a novel fast parallel beam 3D reconstruction procedure that was developed ad hoc to perform the tomographic reconstruction. We have obtained remarkably improved reconstruction results at the Beijing Synchrotron Radiation Facility after the image calibration, the fundamental role of this image alignment procedure was confirmed, which minimizes the unwanted blurs and additional streaking artifacts that are always present in reconstructed slices. Moreover, this nano-CT image alignment and its associated 3D reconstruction procedure are fully based on LabVIEW routines, significantly reducing the data post-processing cycle, thus making the activity of the users faster and easier during experimental runs.
基金supported by the Projection of State Key Laboratory of Environment-friendly Energy Materials,Southwest University of Science and Technology(20FKSY23)。
文摘Phenolic resin-based porous composites are the promising thermal protection materials for aerospace applications.The high-temperature evolution of microstructure due to the decomposition of the resin also presents great challenges to predict the internal heat and mass transport behaviors.This work investigates the effects of microstructural characteristics such as the number of pores,size distribution,pore-throats size and volume fraction on the permeation behaviors of fluid in the needle-punched short-cut fiber reinforced silicon phenolic resin-based porous composites.The specimens are prepared by the sol-gel method and the atmospheric pressure drying process and the pyrolysis experiment are conducted at 400℃and 800℃.Then,a scanning electron microscope and a Nano-CT computer tomography are applied to obtain the surface morphologies and the interior slice images of the specimens.The AVIZO software is employed to accurately extract and analyze the pore structural model and simulated calculate the absolute permeability.It is found that the small pores develop gradually during pyrolysis due to the resin decomposition and the quartz fibers rearrangement,resulting in an increase in number of large pores.Nonetheless,the equivalent radii of most pores are less than 1μm.Very few pores possess a large radius over 5μm.However,the volume fraction of these large pores exceeds 99%.In addition,with the pore size growing,the connectivity between these pores is enhanced,immediately causing an increase in number and size of the pore-throats.Larger pore and more pore-throats would add the unblocked flow channels for the fluid passing,reducing flow resistance.The seepage simulation also confirms that the absolute permeability gains significant increase after pyrolysis in all directions.For example,the absolute permeability of the pyrolyzed sample is 9.0×10^(-13)m^(2) in X direction,which is an order of magnitude greater than that of the unpyrolyzed sample.This study provides important insights for understanding the high-temperature evolution at of microstructure and the permeation behavior of fluid in porous thermal protection materials.
基金Funded by the Science and Technology Fund of Jiangxi Provincial Department of Education(No.GJJ2201105)the Innovation Fund Designated for Graduate Students of Jiangxi Province(No.YC2023-S733)。
文摘We selected a cell with superior electrochemical performance to characterization microstructure characterization.Here,we employed high-resolution SEM and X-ray nano-CT to investigate a porous LSCrRu-GDC composite anode.These experimental results are utilized for characterize and quantify the key structural parameters,such as the volume ratio of the three phases(LSCrRu,GDC,and pore),connected porosity,tortuosity,surface area of each phase,interface of LSCrRu/GDC,and three-phase boundary length(TPB where the LSCrRu,GDC and fuel gas phases come together)of the anode.
