Plate shaped sandstones containing two fabricated circular holes that were filled with gypsum and high-strength concrete respectively were prepared for studying the effects of ligament length L ligament incline angle ...Plate shaped sandstones containing two fabricated circular holes that were filled with gypsum and high-strength concrete respectively were prepared for studying the effects of ligament length L ligament incline angle α, as well as filling modes on their strength properties and failure modes. The results show that the initial cracks can be categorized as wing crack, axial tensile crack and curved tensile crack. The failure modes of ligaments can be categorized as mode of single inclined crack, mode of single axial crack and mode of two parallel cracks. The final failure modes of all specimens can be categorized as the tension-shear mixed failure and shear failure. The strength of inclusions shows little influence on the final failure modes of specimens, while the failure modes vary with L and α. When α is a fixed value, the peak strength σc and elastic modulus Ec of tested specimens increase firstly with increasing L and reaches to the maximum value at L of 16 mm, then declines. When L is a fixed value, σc declines firstly and then turns to increase as α increases to 75° from 45°, while Ec increases linearly. The axial stress σp performs the similar variation trends with those of σc versus increasing L and α when ligaments fail.展开更多
Chemical inclusions significantly alter shock responses of crystalline explosives in macroscale gap experiments but their microscale dynamics origin remains unclear.Herein shock-induced energy localization,overall phy...Chemical inclusions significantly alter shock responses of crystalline explosives in macroscale gap experiments but their microscale dynamics origin remains unclear.Herein shock-induced energy localization,overall physical responses,and reactions in a-1,3,5-trinitro-1,3,5-triazinane(a-RDX)crystal entrained various chemical inclusions were investigated by the multi-scale shock technique implemented in the reactive molecular dynamics method.Results indicated that energy localization and shock reaction were affected by the intrinsic factors within chemical inclusions,i.e.,phase states,chemical compositions,and concentrations.The atomic origin of chemical-inclusions effects on energy localization is dependent on the dynamics mechanism of interfacial molecules with free space volume,which includes homogeneous intermolecular compression,interfacial impact and shear,and void collapse and jet.As introducing various chemical inclusions,the initiation of those dynamics mechanisms triggers diverse decay rates of bulk RDX molecules and hereby impacts on growth speeds of final reactions.Adding chemical inclusions can reduce the effectiveness of the void during the shock impacting.Under the shockwave velocity of 9 km/s,the parent RDX decay rate in RDX entrained amorphous carbon decreases the most and is about one fourth of that in RDX with a vacuum void,and solid HMX and TATB inclusions are more reactive than amorphous carbon but less reactive than dry air or acetone inclusions.The lessdense shocking system denotes the greater increases in local temperature and stress,the faster energy liberation,and the earlier final reaction into equilibrium,revealing more pronounced responses to the present intense shockwave.The quantitative models associated with the relative system density(RD_(sys))were proposed for indicating energy-localization mechanisms and evaluating initiation safety in the shocked crystalline explosive.RD_(sys)is defined by the density ratio of defective RDX to perfect crystal after dynamics relaxation and reveals the global density characteristic in shocked systems filled with chemical inclusions.When RD_(sys)is below 0.9,local hydrodynamic jet initiated by void collapse dominates upon energy localization instead of interfacial impact.This study sheds light on novel insights for understanding the shock chemistry and physical-based atomic origin in crystalline explosives considering chemical-inclusions effects.展开更多
Marmarosh massif is an important structural element of the Eastern Carpathians,which differs by the geological features from the other structural-facial zones of Carpathian fold belt.Metamorphic rocks of the massif ha...Marmarosh massif is an important structural element of the Eastern Carpathians,which differs by the geological features from the other structural-facial zones of Carpathian fold belt.Metamorphic rocks of the massif have been formed under the influence of the processes of medium-and low-temperature meta-morphism and metasomatism.Within the Marmarosh massif the stratiform gold ore has展开更多
Non-metallic inclusions,especially the large ones,within P/M Ni-base superalloy have a major influence on fatigue characteristics,but are not directly measurable by routine inspection.In this paper,a method,automatic ...Non-metallic inclusions,especially the large ones,within P/M Ni-base superalloy have a major influence on fatigue characteristics,but are not directly measurable by routine inspection.In this paper,a method,automatic image analysis,is proposed for estimation of the content,size and amount of non-metallic inclusions in superalloy.The methodology for the practical application of this method is described and the factors affecting the precision of the estimation are discussed.In the experiment,the characteristics of the non-metallic inclusions in Ni-base P/M superalloy are analyzed.展开更多
Crystal of lithium boric oxide(LBO)crystallizes in the orthorhombic system with a=8.446,6=7.380 and c=5.147A in the unit cell.Large transparent crystals were grown in flux on seeding.Only dislocations occur in the hig...Crystal of lithium boric oxide(LBO)crystallizes in the orthorhombic system with a=8.446,6=7.380 and c=5.147A in the unit cell.Large transparent crystals were grown in flux on seeding.Only dislocations occur in the high quality crystal with density ranging from 30 to 100/cm^(2) and they run all in straight.展开更多
The density of CO<sub>2</sub> inclusions in minerals is commonly used to determine the crystallizing conditions of the host minerals.However,the conventional microthermometry method is difficult to apply f...The density of CO<sub>2</sub> inclusions in minerals is commonly used to determine the crystallizing conditions of the host minerals.However,the conventional microthermometry method is difficult to apply for inclusions that are small in size（【5-10μm） or low in density.Raman analysis is an alternative method for determining CO<sub>2</sub> density,provided that展开更多
The Shuiyindong and Yata Carlin-type gold deposits, located in Southwestern Guizhou, China, are hosted by Permianbioclastic limestone in the form of stratabound mineralization and Middle Triassic calcareous clasti... The Shuiyindong and Yata Carlin-type gold deposits, located in Southwestern Guizhou, China, are hosted by Permianbioclastic limestone in the form of stratabound mineralization and Middle Triassic calcareous clastic rocks as fault-controlled mineralization, respectively. In these deposits, quartz crystals in the veins or veinlets associated with mineralization have contained several populations of fluid inclusions with relatively quite big size and clear paragenetic relationship of entrapment. Petrography, microthermometry, Raman and LA-ICPMS of fluid inclusions analyses are used to characterize fluids chemistry and their evolution of Carlin-type system in Guizhou.……展开更多
This paper summarizes recent data about magnesite and talc genesis in Carboniferous host rocks of Western Carpathians (Slovakia) , which occur in two distinct belts in tectonic superunit Veporicum and its contact zone...This paper summarizes recent data about magnesite and talc genesis in Carboniferous host rocks of Western Carpathians (Slovakia) , which occur in two distinct belts in tectonic superunit Veporicum and its contact zone with Gemericum. The northern Sinec magnesite and talc belt (with main deposits Kokava, Sinec, Samo, Hnust'a-Mutnik) contains economic accummulation of magnesite and talc, while in the southern Ochtina belt ( main deposits in Dubrava massif-Dubrava, Mikova, Jedl'ovec; Lubenik, Ochtina, Kosice-Bankov, Banisko, Medvedia) the magnesite is dominating.The magnesite genesis by successive replacement of Carboniferous calcite to dolomite and magnesite during metamorphic process Ml (northern belt 280-400℃; , southern belt 370-420℃: ; Radvanec & Prochaska, 2001; Kodera & Radvanec, 2002) , being supplied by Mg from Permoscythian evaporitic bittern brines, relates to Variscan post-collisional (post-VD) evolution. The extensional tectonics and the high heat flow facilitated the generation of a hydrothermal system.The time-separated later metamorphic and sourcely different fluid flow event (M2; 1. c. ) produced talc. Tectonic, microtectonic, metamorphic and geochronological data relate the talc origin with the Alpine Upper Cretaceous (88-84 Ma; Maluski in Kovacik et al. , 1996) tectonothermal event AD2. This event, being the consequence of Alpine collisional ( AD1 ) crustal thickening and metamorphic core complex origin, meant regional extension and pervasive fluid flow of open system in crustal discontinuities. This process was prominent in the northern belt ( Sinec shear zone) located more closely to Veporic thermal dome, while towards its peripheral parts (southern Ochtina belt) the M2 metamorphic process and steatitization gradually weakened.Studies from Sinec shear zone (being the prominent AD2 -AD3 structure of northern Sinec belt) , where the dolomite/magnesite lenses (replacement in M1) and their accompanying lithology were in AD1 sandwitched between more competent basement blocks, proved in AD2 the pervasite steatitization, the talc and dolomite 2 origin in extensional microstructures ( metamorphic process M2; 490 -540℃, 240-330 MPa, 1. c. ).The economic accummulations of talc in Sinec belt are the products of antithetic shearing during the AD3 phase, being the gradual continuation of AD2 ( change of kinematics from unroofing to regional transpressional shearing). Contrary to the northern Sinec belt having located the AD3 deformation into narrow shear zone with soft lithology surrounded by hard lithology, in southern Ochtina belt the deformation AD3 was accommodated by wide soft rock column with rigid carbonate blocks floating inside. The lower P-T ( M2)conditions and deformational gradient in Ochtina belt during AD2 and AD3 phases caused why no economic talc accummulations developed there.The results of presented study can be used as general criteria for magnesite and talc prospection in Alpine type terranes.展开更多
The types, composition and physico-chemical conditions of primary fluid inclusions were researched. The results show that the primary fluid inclusions contain vapor and liquid phase type （Type I）, daughter mineral-b...The types, composition and physico-chemical conditions of primary fluid inclusions were researched. The results show that the primary fluid inclusions contain vapor and liquid phase type （Type I）, daughter mineral-bearing type （Type II） and pure liquid phase type （Type III）. The compositions of vapor are mainly H20 and CO2 with a tiny amounts of CH4 and H2; the liquid phase mainly contains Mg2＋, Ca2＋, Na＋, K＋, CI- and SO]-, and w（Na＋）/w（K＋）〉l; the homogenization temperatures of the primary fluid inclusions can be divided into 190-250 ℃, 250-340 ℃ and 360-420 ℃, corresponding to the salinities of 4%-9%, 9%-14%, and 14%-20.43% （NaC1 equivalent mass fraction）, respectively. The mineralization process can be divided into three episodes： the silicatization stage, the quartz-sulfide stage, and the carbonatization stage, and all of them are associated with the ore-forming hydrothermal fluid activity. The origin of the hydrothermal fluid is from magrnatic water mainly, and later it mixes with the groundwater and meteoric water, which lead to the decrease of temperature and salinity. The decrease of salinity, temperature and pressure are the main causes of the metallogenic elements unloading and enriching in the favorable position.展开更多
Melt inclusions in primitive olivine phenocrysts,which has been thought to represent the primitive melts(Schiano,2003),have increasingly been applied to studies of igneous processes(Audétat and Lowenstern,2014;Ke...Melt inclusions in primitive olivine phenocrysts,which has been thought to represent the primitive melts(Schiano,2003),have increasingly been applied to studies of igneous processes(Audétat and Lowenstern,2014;Kent,2008),including lunar magmatism(Chen et al.,2015;Hauri et al.,2011;Saal et al.,2013).However,some melt inclusions in primitive olivine phenocrysts in various tectonic settings。展开更多
Samples in the two oil fields with reported gas-washing and water-washing were collected for fluid inclusion analysis.Micro-fluorescence and Fourier infrared spectra of single oil inclusions were measured to study the...Samples in the two oil fields with reported gas-washing and water-washing were collected for fluid inclusion analysis.Micro-fluorescence and Fourier infrared spectra of single oil inclusions were measured to study the different effects of gas-washing and water-washing on oil compositions.The results show that spectral parameter QF_(535)values of the oils altered by gas-washing were expanded toward decreasing and increasing,respectively.The CH_(2)/CH_(3)distribution range ratio does not expand significantly,but the peak values are averaged.And the distribution of H_(2)O/Alkanes has no change.The QF_(535)values of the oils affected by water-washing increased towards the increase direction,and the distribution ranges of both CH_(2)/CH_(3)and H_(2)O/Alkanes increase significantly.The changes of QF_(535)in light oil reservoirs altered by gas-washing and CH_(2)/CH_(3)in heavy oil reservoirs by water-washing are not obvious.Therefore,two spectral parameter distribution trend charts of light and heavy oil reservoirs are summarized to discriminate the gas-washing and water-washing processes.This study is of great practical significance to utilize fluid inclusion analysis to restructure stages and processes of petroleum accumulation.展开更多
The sequence of the densification and hydrocarbon charging of the Xu2 reservoir in the Anyue–Hechuan area of Central Sichuan Basin is discussed.The diagenetic sequence is considered a time line to determine the histo...The sequence of the densification and hydrocarbon charging of the Xu2 reservoir in the Anyue–Hechuan area of Central Sichuan Basin is discussed.The diagenetic sequence is considered a time line to determine the historical relationship between the densification process and the hydrocarbon charging of the Xu2 reservoir in the study area:Early diagenetic stage B(the first stage of hydrocarbon charging,which was about 200–160 Ma ago,with a porosity of about 20%,consolidated and not tight)→middle diagenetic stage A(the second stage of hydrocarbon charging,which was about 140–120 Ma ago,with a porosity of 10%–20%and relatively tight)→middle diagenetic stage B(the third stage of hydrocarbon charging,which was about 20–5 Ma ago,with a porosity of 6%–10%and tight;However,fractures have developed).The study results prove that large-scale hydrocarbon charging and accumulation completed before the densification of the Xu2 reservoir,showing that the Upper Triassic Xujiahe Fm unconventional tight reservoir in the Sichuan Basin is prospective for exploration.展开更多
基金Project(2017YFC0603001)supported by the High-tech Research and Development Program of ChinaProject(51374198)supported by the National Natural Science Foundation of China
文摘Plate shaped sandstones containing two fabricated circular holes that were filled with gypsum and high-strength concrete respectively were prepared for studying the effects of ligament length L ligament incline angle α, as well as filling modes on their strength properties and failure modes. The results show that the initial cracks can be categorized as wing crack, axial tensile crack and curved tensile crack. The failure modes of ligaments can be categorized as mode of single inclined crack, mode of single axial crack and mode of two parallel cracks. The final failure modes of all specimens can be categorized as the tension-shear mixed failure and shear failure. The strength of inclusions shows little influence on the final failure modes of specimens, while the failure modes vary with L and α. When α is a fixed value, the peak strength σc and elastic modulus Ec of tested specimens increase firstly with increasing L and reaches to the maximum value at L of 16 mm, then declines. When L is a fixed value, σc declines firstly and then turns to increase as α increases to 75° from 45°, while Ec increases linearly. The axial stress σp performs the similar variation trends with those of σc versus increasing L and α when ligaments fail.
基金the financial support from National Natural Science Foundation of China(Grant Nos.11872119,12172051,and 11972329)Natural Science Foundation of Hubei Province(Grant No.2021CFB120)。
文摘Chemical inclusions significantly alter shock responses of crystalline explosives in macroscale gap experiments but their microscale dynamics origin remains unclear.Herein shock-induced energy localization,overall physical responses,and reactions in a-1,3,5-trinitro-1,3,5-triazinane(a-RDX)crystal entrained various chemical inclusions were investigated by the multi-scale shock technique implemented in the reactive molecular dynamics method.Results indicated that energy localization and shock reaction were affected by the intrinsic factors within chemical inclusions,i.e.,phase states,chemical compositions,and concentrations.The atomic origin of chemical-inclusions effects on energy localization is dependent on the dynamics mechanism of interfacial molecules with free space volume,which includes homogeneous intermolecular compression,interfacial impact and shear,and void collapse and jet.As introducing various chemical inclusions,the initiation of those dynamics mechanisms triggers diverse decay rates of bulk RDX molecules and hereby impacts on growth speeds of final reactions.Adding chemical inclusions can reduce the effectiveness of the void during the shock impacting.Under the shockwave velocity of 9 km/s,the parent RDX decay rate in RDX entrained amorphous carbon decreases the most and is about one fourth of that in RDX with a vacuum void,and solid HMX and TATB inclusions are more reactive than amorphous carbon but less reactive than dry air or acetone inclusions.The lessdense shocking system denotes the greater increases in local temperature and stress,the faster energy liberation,and the earlier final reaction into equilibrium,revealing more pronounced responses to the present intense shockwave.The quantitative models associated with the relative system density(RD_(sys))were proposed for indicating energy-localization mechanisms and evaluating initiation safety in the shocked crystalline explosive.RD_(sys)is defined by the density ratio of defective RDX to perfect crystal after dynamics relaxation and reveals the global density characteristic in shocked systems filled with chemical inclusions.When RD_(sys)is below 0.9,local hydrodynamic jet initiated by void collapse dominates upon energy localization instead of interfacial impact.This study sheds light on novel insights for understanding the shock chemistry and physical-based atomic origin in crystalline explosives considering chemical-inclusions effects.
文摘Marmarosh massif is an important structural element of the Eastern Carpathians,which differs by the geological features from the other structural-facial zones of Carpathian fold belt.Metamorphic rocks of the massif have been formed under the influence of the processes of medium-and low-temperature meta-morphism and metasomatism.Within the Marmarosh massif the stratiform gold ore has
文摘Non-metallic inclusions,especially the large ones,within P/M Ni-base superalloy have a major influence on fatigue characteristics,but are not directly measurable by routine inspection.In this paper,a method,automatic image analysis,is proposed for estimation of the content,size and amount of non-metallic inclusions in superalloy.The methodology for the practical application of this method is described and the factors affecting the precision of the estimation are discussed.In the experiment,the characteristics of the non-metallic inclusions in Ni-base P/M superalloy are analyzed.
文摘Crystal of lithium boric oxide(LBO)crystallizes in the orthorhombic system with a=8.446,6=7.380 and c=5.147A in the unit cell.Large transparent crystals were grown in flux on seeding.Only dislocations occur in the high quality crystal with density ranging from 30 to 100/cm^(2) and they run all in straight.
文摘The density of CO<sub>2</sub> inclusions in minerals is commonly used to determine the crystallizing conditions of the host minerals.However,the conventional microthermometry method is difficult to apply for inclusions that are small in size（【5-10μm） or low in density.Raman analysis is an alternative method for determining CO<sub>2</sub> density,provided that
文摘 The Shuiyindong and Yata Carlin-type gold deposits, located in Southwestern Guizhou, China, are hosted by Permianbioclastic limestone in the form of stratabound mineralization and Middle Triassic calcareous clastic rocks as fault-controlled mineralization, respectively. In these deposits, quartz crystals in the veins or veinlets associated with mineralization have contained several populations of fluid inclusions with relatively quite big size and clear paragenetic relationship of entrapment. Petrography, microthermometry, Raman and LA-ICPMS of fluid inclusions analyses are used to characterize fluids chemistry and their evolution of Carlin-type system in Guizhou.……
文摘This paper summarizes recent data about magnesite and talc genesis in Carboniferous host rocks of Western Carpathians (Slovakia) , which occur in two distinct belts in tectonic superunit Veporicum and its contact zone with Gemericum. The northern Sinec magnesite and talc belt (with main deposits Kokava, Sinec, Samo, Hnust'a-Mutnik) contains economic accummulation of magnesite and talc, while in the southern Ochtina belt ( main deposits in Dubrava massif-Dubrava, Mikova, Jedl'ovec; Lubenik, Ochtina, Kosice-Bankov, Banisko, Medvedia) the magnesite is dominating.The magnesite genesis by successive replacement of Carboniferous calcite to dolomite and magnesite during metamorphic process Ml (northern belt 280-400℃; , southern belt 370-420℃: ; Radvanec & Prochaska, 2001; Kodera & Radvanec, 2002) , being supplied by Mg from Permoscythian evaporitic bittern brines, relates to Variscan post-collisional (post-VD) evolution. The extensional tectonics and the high heat flow facilitated the generation of a hydrothermal system.The time-separated later metamorphic and sourcely different fluid flow event (M2; 1. c. ) produced talc. Tectonic, microtectonic, metamorphic and geochronological data relate the talc origin with the Alpine Upper Cretaceous (88-84 Ma; Maluski in Kovacik et al. , 1996) tectonothermal event AD2. This event, being the consequence of Alpine collisional ( AD1 ) crustal thickening and metamorphic core complex origin, meant regional extension and pervasive fluid flow of open system in crustal discontinuities. This process was prominent in the northern belt ( Sinec shear zone) located more closely to Veporic thermal dome, while towards its peripheral parts (southern Ochtina belt) the M2 metamorphic process and steatitization gradually weakened.Studies from Sinec shear zone (being the prominent AD2 -AD3 structure of northern Sinec belt) , where the dolomite/magnesite lenses (replacement in M1) and their accompanying lithology were in AD1 sandwitched between more competent basement blocks, proved in AD2 the pervasite steatitization, the talc and dolomite 2 origin in extensional microstructures ( metamorphic process M2; 490 -540℃, 240-330 MPa, 1. c. ).The economic accummulations of talc in Sinec belt are the products of antithetic shearing during the AD3 phase, being the gradual continuation of AD2 ( change of kinematics from unroofing to regional transpressional shearing). Contrary to the northern Sinec belt having located the AD3 deformation into narrow shear zone with soft lithology surrounded by hard lithology, in southern Ochtina belt the deformation AD3 was accommodated by wide soft rock column with rigid carbonate blocks floating inside. The lower P-T ( M2)conditions and deformational gradient in Ochtina belt during AD2 and AD3 phases caused why no economic talc accummulations developed there.The results of presented study can be used as general criteria for magnesite and talc prospection in Alpine type terranes.
基金Project(200911007-04) supported by the Special Funds for Scientific Research of Land and Natural Resources, ChinaProject (2007CB411405) supported by the National Basic Research Program of ChinaProject(20109901) supported by the National Crisis Office of China
文摘The types, composition and physico-chemical conditions of primary fluid inclusions were researched. The results show that the primary fluid inclusions contain vapor and liquid phase type （Type I）, daughter mineral-bearing type （Type II） and pure liquid phase type （Type III）. The compositions of vapor are mainly H20 and CO2 with a tiny amounts of CH4 and H2; the liquid phase mainly contains Mg2＋, Ca2＋, Na＋, K＋, CI- and SO]-, and w（Na＋）/w（K＋）〉l; the homogenization temperatures of the primary fluid inclusions can be divided into 190-250 ℃, 250-340 ℃ and 360-420 ℃, corresponding to the salinities of 4%-9%, 9%-14%, and 14%-20.43% （NaC1 equivalent mass fraction）, respectively. The mineralization process can be divided into three episodes： the silicatization stage, the quartz-sulfide stage, and the carbonatization stage, and all of them are associated with the ore-forming hydrothermal fluid activity. The origin of the hydrothermal fluid is from magrnatic water mainly, and later it mixes with the groundwater and meteoric water, which lead to the decrease of temperature and salinity. The decrease of salinity, temperature and pressure are the main causes of the metallogenic elements unloading and enriching in the favorable position.
文摘Melt inclusions in primitive olivine phenocrysts,which has been thought to represent the primitive melts(Schiano,2003),have increasingly been applied to studies of igneous processes(Audétat and Lowenstern,2014;Kent,2008),including lunar magmatism(Chen et al.,2015;Hauri et al.,2011;Saal et al.,2013).However,some melt inclusions in primitive olivine phenocrysts in various tectonic settings。
基金National Science and Technology Projects(2011ZX05023-004-010)National Science Foundation of Hubei Province(2020CFB372)。
文摘Samples in the two oil fields with reported gas-washing and water-washing were collected for fluid inclusion analysis.Micro-fluorescence and Fourier infrared spectra of single oil inclusions were measured to study the different effects of gas-washing and water-washing on oil compositions.The results show that spectral parameter QF_(535)values of the oils altered by gas-washing were expanded toward decreasing and increasing,respectively.The CH_(2)/CH_(3)distribution range ratio does not expand significantly,but the peak values are averaged.And the distribution of H_(2)O/Alkanes has no change.The QF_(535)values of the oils affected by water-washing increased towards the increase direction,and the distribution ranges of both CH_(2)/CH_(3)and H_(2)O/Alkanes increase significantly.The changes of QF_(535)in light oil reservoirs altered by gas-washing and CH_(2)/CH_(3)in heavy oil reservoirs by water-washing are not obvious.Therefore,two spectral parameter distribution trend charts of light and heavy oil reservoirs are summarized to discriminate the gas-washing and water-washing processes.This study is of great practical significance to utilize fluid inclusion analysis to restructure stages and processes of petroleum accumulation.
基金Project(41372141) supported by the National Natural Science Foundation of ChinaProject(2008ZX05001–05–01) supported by Special and Significant Project of National Science and Technology,China
文摘The sequence of the densification and hydrocarbon charging of the Xu2 reservoir in the Anyue–Hechuan area of Central Sichuan Basin is discussed.The diagenetic sequence is considered a time line to determine the historical relationship between the densification process and the hydrocarbon charging of the Xu2 reservoir in the study area:Early diagenetic stage B(the first stage of hydrocarbon charging,which was about 200–160 Ma ago,with a porosity of about 20%,consolidated and not tight)→middle diagenetic stage A(the second stage of hydrocarbon charging,which was about 140–120 Ma ago,with a porosity of 10%–20%and relatively tight)→middle diagenetic stage B(the third stage of hydrocarbon charging,which was about 20–5 Ma ago,with a porosity of 6%–10%and tight;However,fractures have developed).The study results prove that large-scale hydrocarbon charging and accumulation completed before the densification of the Xu2 reservoir,showing that the Upper Triassic Xujiahe Fm unconventional tight reservoir in the Sichuan Basin is prospective for exploration.
