Some natural pyrobitumens exhibit optical anisotropy similar to mesophase asphalt,potentially recording critical geological information.However,the significance of their distinctive optical textures remains understudi...Some natural pyrobitumens exhibit optical anisotropy similar to mesophase asphalt,potentially recording critical geological information.However,the significance of their distinctive optical textures remains understudied.Anisotropic pyrobitumen in the Ediacaran Dengying Formation(central Sichuan Basin,southwestern China)provides a key example.This study investigates controls on pyrobitumen optical texture evolution using petrography,scanning electron microscopy,and U-Pb dating.Then,it discusses the relationship between these textures and anomalous thermal events by analyzing their spatial distribution and their geological significance.Results reveal that anisotropic pyrobitumen in Dengying Formation formed from oil cracking caused by Late Permian hydrothermal activity.These pyrobitumen can be divided into two categories based on the optical textures:fibrous and mosaic,reflecting distinct internal physical structures.Fibrous pyrobitumen exhibits more ordered aromatic layers than the mosaic type.Temperature primarily controls optical textures by regulating polycondensation reactions and pyrobitumen viscosity.Although the Gaoshiti and Moxi areas share similar burial histories,Gaoshiti is dominated by highly evolved fibrous pyrobitumen,while Moxi contains predominantly low-evolved mosaic pyrobitumen.This disparity indicates formation of anisotropic pyrobitumen was unrelated to normal burial temperatures but to hydrothermal activity.This study demonstrates that anisotropic pyrobitumen cannot form below 240℃,even over extended durations.Consequently,in situ anisotropic pyrobitumen in deep strata serves as an indicator of paleo-thermal anomalies,with varying textures acting as proxies for relative temperatures within these events.Under identical geological settings,fibrous pyrobitumen typically records higher temperatures than mosaic pyrobitumen.展开更多
The Neoproterozoic-Lower Paleozoic dolostone gas reservoirs in the Chuanzhong Uplift in Southwestern China contain the mesophase pyrobitumen (pyrobitumen with mesophase). The mesophase in the pyrobitumen is mostly com...The Neoproterozoic-Lower Paleozoic dolostone gas reservoirs in the Chuanzhong Uplift in Southwestern China contain the mesophase pyrobitumen (pyrobitumen with mesophase). The mesophase in the pyrobitumen is mostly composed of a mixture of condensed macromolecule polycyclic aromatic hydrocarbons (PAH), and has been mostly converted to various grain, flow, and domain textures. The volcanic activity nearby the Chuanzhong Uplift may have generated very hot (over 300 °C) hydrothermal fluid, with migration of the fluid into the dolostone reservoir transforming the hydrocarbons in the reservoir into an anisotropic carbon by-product, which formed under high temperature and pressure conditions;over 300 °C and 200 MPa according to fluid inclusion analysis. The high temperature-pressure in reservoir was caused by sudden devolatilization of the hydrocarbons due to hydrothermal heating, which formed the unusual texture of the mesophase. The elliptical mesophase grains (EG), the honeycomb structure of pyrobitumen, and the occurrence of polarized classes of mesophase in single pyrobitumen deposits are all unusual textures. This study investigates the texture development of this pressure-affected pyrobitumen. Observation and study of the mesophase suggest that the class of mesophase in pyrobitumen is determined by temperature, while pressure (assessed from associated fluid inclusions) significantly affected the texture. Analysis of the texture of the pyrobitumen in conjunction with previous thermometry results from methane inclusions suggests that the high class mesophase of the pyrobitumen could be applied as a temperature indicator for geological conditions. Furthermore, the unusual textures of the pyrobitumen including elliptical mesophase grains (EG), the honeycomb structure of pyrobitumen, and the occurrence of polarized classes of mesophase in single pyrobitumen could reflect the abnormal high formation pressure.展开更多
Coke is the only solid charge component in the lower part of the blast furnace,and its strength is crucial to its production.Si and Al are the two most abundant elements in coke ash.The influences of these oxides on t...Coke is the only solid charge component in the lower part of the blast furnace,and its strength is crucial to its production.Si and Al are the two most abundant elements in coke ash.The influences of these oxides on the tensile strength of the coke matrix were studied by splitting tests.According to the Weibull analysis,with increasing Si and Al oxide concentrations,the fracture stress range of the coke widened,the upper and lower limits decreased,the probability of fracture under the same stress conditions increased,and the randomness and dispersion of strength increased.These results can be attributed to the inhibitory effect of ash during coal pyrolysis.Ash impedes the growth and contact of mesophase,leading to a decrease in graphitic carbon structures and an increase in edge carbon and aliphatic carbon structures in the resulting coke.Consequently,the overall ordering of the carbon structure is reduced.Moreover,SiO_(2)and Al_(2)O_(3)promoted the development of coke pores,thinned the coke pore wall,and significantly increased the proportion of large pores(>500μm).Moreover,Al_(2)O_(3)had more significant influences on the coke strength,carbon structure and stomatal ratio than SiO_(2).In addition,the position where the ash particles bonded to the carbon matrix easily produced cracks and holes,and the sharp edge of the matrix was likely to produce stress concentration points when subjected to an external force,leading to structural damage.Therefore,controlling the concentration of ash could effectively reduce the number of structural defects inside coke,which is conducive to improving the strength.展开更多
The coal petrography of 13 different rank single coals and the quality of cokes made on 40 kg pilot coke oven were measured and analyzed in the paper.The results indicated that the relationship between optical texture...The coal petrography of 13 different rank single coals and the quality of cokes made on 40 kg pilot coke oven were measured and analyzed in the paper.The results indicated that the relationship between optical texture index of coke(OTI)and vitrinite mean maximum reflectance of single coal was positive linear correlation.By multiple linear regression analysis,the quantitative relationship between vitrinite reflectance distribution and the component of coke optical texture were determined;The influence of composition of coke optical tissue on crushing strength for coke(M_(40))and coke reactivity index(CRI)can be summarized:the more mosaics texture proportion of the optical tissue,the better of crushing strength for coke(M_(40))and its coke reactivity index(CRI).展开更多
The microstructural characteristics including optical texture,porosity and pore structure and chemical structure of stamp-charged coke(SCC)and gravity-charged coke(GCC)with similar conventional macro-indicators were i...The microstructural characteristics including optical texture,porosity and pore structure and chemical structure of stamp-charged coke(SCC)and gravity-charged coke(GCC)with similar conventional macro-indicators were investigated,and the properties including micro-strength,reactivity of coke matrix and that after alkali enrichment were comparatively studied by various characterization methods.The anisotropic structure of SCC is composed of high content of fine mosaic texture,while the content of medium mosaic texture,coarse texture and fibrous texture is low.The statistical average shows that the fine mosaic average of SCC(24.89%)is 3.78 times the GCC average(6.58%),and the coarse mosaic average(1.24%)is only about 1/3 of the GCC average(3.43%).The porosity of SCC is lower than that of GCC,but tamping process does not lead to the fact that the number of closed pores of SCC is significantly lower than that of GCC.Although the structure of SCC is compact,its pore number is large and the pore wall is thin.Pores of coke with diameter less than 150 nm seem unaffected by tamping process.The aromatic structure of SCC was less ordered than that of GCC,which was speculated to be related to the addition of more low metamorphic coal in coking.The microscopic strength and structural strength of SCC are lower than those of GCC.The reactivity of coke matrix is affected by the specific surface area,but it is not the determining factor of its macro-reactivity.The improvement in dissolution reactivity of coke after potassium enrichment is independent of coke type.展开更多
Maturity evaluation of highly evolved organic matter is an important problem in oil and gas geochemistry,because conventional organic geochemical proxies are not applicable due to hydrocarbon generation and expulsion....Maturity evaluation of highly evolved organic matter is an important problem in oil and gas geochemistry,because conventional organic geochemical proxies are not applicable due to hydrocarbon generation and expulsion.In this study,we investigated the pyrobitumen in the reservoirs of the Sinian Dengying Formation in the Sichuan Basin,China.We focused on aromatic hydrocarbon biomarkers,and the calibration and application of aromatic maturity proxies using pyrobitumen reflectance and Raman spectral parameters.Our results show that only the thiophene compounds are effective maturity indicators,such as MDR(4-/1-MDBT),MDR′(4-MDBT/(1-MDBT+4-MDBT)),MDR1(1-MDBT/DBT),4,6-/(1,4+1,6)-DMDBT,(2,6+3,6)-/(1,4+1,6)-DMDBT,and[2,1]BNT/([2,1]BNT+[1,2]BNT),as these are largely independent of the optical anisotropy of pyrobitumen.The condensation and incorporation of thiophene compounds can lead to an increase in the reflectance of pyrobitumen,which means the thiophene compound parameters are positively or negatively correlated with pyrobitumen reflectance.New potential maturity parameters were proposed,including DMDBTs/MDBTs,TeMDBTs/(DBT+MDBTs+DMDBTs+TMDBTs+TeMDBTs),1-MDBT/MDBTs,and[2,1]BNT/BNTs.This method and these parameters are universally applicable to maturity characterization,especially in rocks that lack vitrinite,contain strongly anisotropic organic matter,and have high contents of thiophene compounds.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.42272161)Frontier Interdisciplinary Exploration Research Program of China University of Petroleum,Beijing(Grant No.2462024XKQY001)Science Foundation of China University of Petroleum,Beijing(No.2462023BJRC023)
文摘Some natural pyrobitumens exhibit optical anisotropy similar to mesophase asphalt,potentially recording critical geological information.However,the significance of their distinctive optical textures remains understudied.Anisotropic pyrobitumen in the Ediacaran Dengying Formation(central Sichuan Basin,southwestern China)provides a key example.This study investigates controls on pyrobitumen optical texture evolution using petrography,scanning electron microscopy,and U-Pb dating.Then,it discusses the relationship between these textures and anomalous thermal events by analyzing their spatial distribution and their geological significance.Results reveal that anisotropic pyrobitumen in Dengying Formation formed from oil cracking caused by Late Permian hydrothermal activity.These pyrobitumen can be divided into two categories based on the optical textures:fibrous and mosaic,reflecting distinct internal physical structures.Fibrous pyrobitumen exhibits more ordered aromatic layers than the mosaic type.Temperature primarily controls optical textures by regulating polycondensation reactions and pyrobitumen viscosity.Although the Gaoshiti and Moxi areas share similar burial histories,Gaoshiti is dominated by highly evolved fibrous pyrobitumen,while Moxi contains predominantly low-evolved mosaic pyrobitumen.This disparity indicates formation of anisotropic pyrobitumen was unrelated to normal burial temperatures but to hydrothermal activity.This study demonstrates that anisotropic pyrobitumen cannot form below 240℃,even over extended durations.Consequently,in situ anisotropic pyrobitumen in deep strata serves as an indicator of paleo-thermal anomalies,with varying textures acting as proxies for relative temperatures within these events.Under identical geological settings,fibrous pyrobitumen typically records higher temperatures than mosaic pyrobitumen.
基金funded by the National Natural Science Foundation of China for Young Scholars(No.41903059).
文摘The Neoproterozoic-Lower Paleozoic dolostone gas reservoirs in the Chuanzhong Uplift in Southwestern China contain the mesophase pyrobitumen (pyrobitumen with mesophase). The mesophase in the pyrobitumen is mostly composed of a mixture of condensed macromolecule polycyclic aromatic hydrocarbons (PAH), and has been mostly converted to various grain, flow, and domain textures. The volcanic activity nearby the Chuanzhong Uplift may have generated very hot (over 300 °C) hydrothermal fluid, with migration of the fluid into the dolostone reservoir transforming the hydrocarbons in the reservoir into an anisotropic carbon by-product, which formed under high temperature and pressure conditions;over 300 °C and 200 MPa according to fluid inclusion analysis. The high temperature-pressure in reservoir was caused by sudden devolatilization of the hydrocarbons due to hydrothermal heating, which formed the unusual texture of the mesophase. The elliptical mesophase grains (EG), the honeycomb structure of pyrobitumen, and the occurrence of polarized classes of mesophase in single pyrobitumen deposits are all unusual textures. This study investigates the texture development of this pressure-affected pyrobitumen. Observation and study of the mesophase suggest that the class of mesophase in pyrobitumen is determined by temperature, while pressure (assessed from associated fluid inclusions) significantly affected the texture. Analysis of the texture of the pyrobitumen in conjunction with previous thermometry results from methane inclusions suggests that the high class mesophase of the pyrobitumen could be applied as a temperature indicator for geological conditions. Furthermore, the unusual textures of the pyrobitumen including elliptical mesophase grains (EG), the honeycomb structure of pyrobitumen, and the occurrence of polarized classes of mesophase in single pyrobitumen could reflect the abnormal high formation pressure.
基金supported by the National Natural Science Foundation of China(No.51974212)the China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202116)+2 种基金the Science and Technology Major Project of Wuhan(No.2023020302020572)the Postdoctor Project of Hubei Province(No.2024HBBHCXA074)the Foundation of Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education(No.FMRUlab23-04).
文摘Coke is the only solid charge component in the lower part of the blast furnace,and its strength is crucial to its production.Si and Al are the two most abundant elements in coke ash.The influences of these oxides on the tensile strength of the coke matrix were studied by splitting tests.According to the Weibull analysis,with increasing Si and Al oxide concentrations,the fracture stress range of the coke widened,the upper and lower limits decreased,the probability of fracture under the same stress conditions increased,and the randomness and dispersion of strength increased.These results can be attributed to the inhibitory effect of ash during coal pyrolysis.Ash impedes the growth and contact of mesophase,leading to a decrease in graphitic carbon structures and an increase in edge carbon and aliphatic carbon structures in the resulting coke.Consequently,the overall ordering of the carbon structure is reduced.Moreover,SiO_(2)and Al_(2)O_(3)promoted the development of coke pores,thinned the coke pore wall,and significantly increased the proportion of large pores(>500μm).Moreover,Al_(2)O_(3)had more significant influences on the coke strength,carbon structure and stomatal ratio than SiO_(2).In addition,the position where the ash particles bonded to the carbon matrix easily produced cracks and holes,and the sharp edge of the matrix was likely to produce stress concentration points when subjected to an external force,leading to structural damage.Therefore,controlling the concentration of ash could effectively reduce the number of structural defects inside coke,which is conducive to improving the strength.
文摘The coal petrography of 13 different rank single coals and the quality of cokes made on 40 kg pilot coke oven were measured and analyzed in the paper.The results indicated that the relationship between optical texture index of coke(OTI)and vitrinite mean maximum reflectance of single coal was positive linear correlation.By multiple linear regression analysis,the quantitative relationship between vitrinite reflectance distribution and the component of coke optical texture were determined;The influence of composition of coke optical tissue on crushing strength for coke(M_(40))and coke reactivity index(CRI)can be summarized:the more mosaics texture proportion of the optical tissue,the better of crushing strength for coke(M_(40))and its coke reactivity index(CRI).
基金the National Natural Science Foundation of China(No.52374347)the China Postdoctoral Science Foundation(2021M702553)+2 种基金Natural Science Basic Research Program of Shaanxi(2022JQ-428)Shaanxi Provincial Department of Education Service Local Special Project(22JC042)Key Research and Development Program of Shaanxi(No.2021GY-128).
文摘The microstructural characteristics including optical texture,porosity and pore structure and chemical structure of stamp-charged coke(SCC)and gravity-charged coke(GCC)with similar conventional macro-indicators were investigated,and the properties including micro-strength,reactivity of coke matrix and that after alkali enrichment were comparatively studied by various characterization methods.The anisotropic structure of SCC is composed of high content of fine mosaic texture,while the content of medium mosaic texture,coarse texture and fibrous texture is low.The statistical average shows that the fine mosaic average of SCC(24.89%)is 3.78 times the GCC average(6.58%),and the coarse mosaic average(1.24%)is only about 1/3 of the GCC average(3.43%).The porosity of SCC is lower than that of GCC,but tamping process does not lead to the fact that the number of closed pores of SCC is significantly lower than that of GCC.Although the structure of SCC is compact,its pore number is large and the pore wall is thin.Pores of coke with diameter less than 150 nm seem unaffected by tamping process.The aromatic structure of SCC was less ordered than that of GCC,which was speculated to be related to the addition of more low metamorphic coal in coking.The microscopic strength and structural strength of SCC are lower than those of GCC.The reactivity of coke matrix is affected by the specific surface area,but it is not the determining factor of its macro-reactivity.The improvement in dissolution reactivity of coke after potassium enrichment is independent of coke type.
基金supported by the National Natural Science Foundation of China(Grant Nos.42230808 and 41830425).
文摘Maturity evaluation of highly evolved organic matter is an important problem in oil and gas geochemistry,because conventional organic geochemical proxies are not applicable due to hydrocarbon generation and expulsion.In this study,we investigated the pyrobitumen in the reservoirs of the Sinian Dengying Formation in the Sichuan Basin,China.We focused on aromatic hydrocarbon biomarkers,and the calibration and application of aromatic maturity proxies using pyrobitumen reflectance and Raman spectral parameters.Our results show that only the thiophene compounds are effective maturity indicators,such as MDR(4-/1-MDBT),MDR′(4-MDBT/(1-MDBT+4-MDBT)),MDR1(1-MDBT/DBT),4,6-/(1,4+1,6)-DMDBT,(2,6+3,6)-/(1,4+1,6)-DMDBT,and[2,1]BNT/([2,1]BNT+[1,2]BNT),as these are largely independent of the optical anisotropy of pyrobitumen.The condensation and incorporation of thiophene compounds can lead to an increase in the reflectance of pyrobitumen,which means the thiophene compound parameters are positively or negatively correlated with pyrobitumen reflectance.New potential maturity parameters were proposed,including DMDBTs/MDBTs,TeMDBTs/(DBT+MDBTs+DMDBTs+TMDBTs+TeMDBTs),1-MDBT/MDBTs,and[2,1]BNT/BNTs.This method and these parameters are universally applicable to maturity characterization,especially in rocks that lack vitrinite,contain strongly anisotropic organic matter,and have high contents of thiophene compounds.
