The types and structures of inorganic pores are key factors in evaluations of the reservoir space and distribution characteristics of shale oil and gas.However,quantitative identification methods for pores of differen...The types and structures of inorganic pores are key factors in evaluations of the reservoir space and distribution characteristics of shale oil and gas.However,quantitative identification methods for pores of different inorganic components have not yet been fully developed.For this reason,a quantitative characterization method of inorganic pores using pixel information was proposed in this study.A machine learning algorithm was used to assist the field emission scanning electron microscopy(FE-SEM)image processing of shale to realize the accurate identification and quantitative characterization of inorganic pores on the surface of high-precision images of shale with a small view.Moreover,large-view image splicing technology,combined with quantitative evaluation of minerals by scanning electron microscopy(QEMSCAN)image joint characterization technology,was used to accurately analyze the distribution characteristics of inorganic pores under different mineral components.The quantitative methods of pore characteristics of different inorganic components under the pixel information of shale were studied.The results showed that(1)the Waikato Environment for Knowledge Analysis(WEKA)machine learning model can effectively identify and extract shale mineral components and inorganic pore distribution,and the large-view FE-SEM images are representative of samples at the 200μm×200μm view scale,meeting statistical requirements and eliminating the influence of heterogeneity;(2)the pores developed by different mineral components of shale had obvious differences,indicating that the development of inorganic pores is highly correlated with the properties of shale minerals themselves;and(3)the pore-forming ability of different mineral components is calculated by the quantitative method of single component pore-forming coefficient.Chlorite showed the highest pore-forming ability,followed by(in descending order)illite,pyrite,calcite,dolomite,albite,orthoclase,quartz,and apatite.This study contributes to advancing our understanding of inorganic pore characteristics in shale.展开更多
Organic matter pores are considered to be the most important type of pore for preserving hydrocarbon gases in shale gas reservoirs.The organic matter in each over-mature marine shale sample was separated into two orga...Organic matter pores are considered to be the most important type of pore for preserving hydrocarbon gases in shale gas reservoirs.The organic matter in each over-mature marine shale sample was separated into two organic fractions with densities of greater than and less than 1.25 g/cm^(3),and then their molecular compositions and pore characteristics were quantitatively evaluated using solid state 13C-nuclear magnetic resonance(NMR)and gas(N2 and CO_(2))adsorption analyses,respectively.The results revealed that aromatic carbon is the dominant molecular composition of the over-mature organic matter in the Lower Cambrian Niutitang shale.During the over-mature stage,the organic fractions with densities of greater than and less than 1.25 g/cm^(3) have no significant differences in molecular composition.The organic fractions with densities of greater than and less than 1.25 g/cm^(3) do have significant differences in their organic pore characteristics.In contrast to the high density organic fraction,the low density fraction contained abundant micropores and lacked mesopores and macropores.The organic pore structures of the different occurrence states of organic matter were significantly different.The C/O of organic matter in different occurrence states are obviously different,which proves that the organic pore structure is closely related to both the occurrence state and density of the organic matter.However,these relationships are still unclear and require further study.展开更多
基金supported by the National Natural Science Foundation of China(42372144)the Natural Science Foundation of Xinjiang Uygur Autonomous Region(2024D01E09)the Strategic Cooperation Technology Projects of CNPC and CUPB(ZLZX2020-01-05).
文摘The types and structures of inorganic pores are key factors in evaluations of the reservoir space and distribution characteristics of shale oil and gas.However,quantitative identification methods for pores of different inorganic components have not yet been fully developed.For this reason,a quantitative characterization method of inorganic pores using pixel information was proposed in this study.A machine learning algorithm was used to assist the field emission scanning electron microscopy(FE-SEM)image processing of shale to realize the accurate identification and quantitative characterization of inorganic pores on the surface of high-precision images of shale with a small view.Moreover,large-view image splicing technology,combined with quantitative evaluation of minerals by scanning electron microscopy(QEMSCAN)image joint characterization technology,was used to accurately analyze the distribution characteristics of inorganic pores under different mineral components.The quantitative methods of pore characteristics of different inorganic components under the pixel information of shale were studied.The results showed that(1)the Waikato Environment for Knowledge Analysis(WEKA)machine learning model can effectively identify and extract shale mineral components and inorganic pore distribution,and the large-view FE-SEM images are representative of samples at the 200μm×200μm view scale,meeting statistical requirements and eliminating the influence of heterogeneity;(2)the pores developed by different mineral components of shale had obvious differences,indicating that the development of inorganic pores is highly correlated with the properties of shale minerals themselves;and(3)the pore-forming ability of different mineral components is calculated by the quantitative method of single component pore-forming coefficient.Chlorite showed the highest pore-forming ability,followed by(in descending order)illite,pyrite,calcite,dolomite,albite,orthoclase,quartz,and apatite.This study contributes to advancing our understanding of inorganic pore characteristics in shale.
基金This work was financially supported by the National Natural Science Foundation of China (Grant Nos. 42002166 and 42162016)the Guizhou Provincial Fund Project (Nos. [2020]1Y161 and ZK[2022]106).
文摘Organic matter pores are considered to be the most important type of pore for preserving hydrocarbon gases in shale gas reservoirs.The organic matter in each over-mature marine shale sample was separated into two organic fractions with densities of greater than and less than 1.25 g/cm^(3),and then their molecular compositions and pore characteristics were quantitatively evaluated using solid state 13C-nuclear magnetic resonance(NMR)and gas(N2 and CO_(2))adsorption analyses,respectively.The results revealed that aromatic carbon is the dominant molecular composition of the over-mature organic matter in the Lower Cambrian Niutitang shale.During the over-mature stage,the organic fractions with densities of greater than and less than 1.25 g/cm^(3) have no significant differences in molecular composition.The organic fractions with densities of greater than and less than 1.25 g/cm^(3) do have significant differences in their organic pore characteristics.In contrast to the high density organic fraction,the low density fraction contained abundant micropores and lacked mesopores and macropores.The organic pore structures of the different occurrence states of organic matter were significantly different.The C/O of organic matter in different occurrence states are obviously different,which proves that the organic pore structure is closely related to both the occurrence state and density of the organic matter.However,these relationships are still unclear and require further study.
