The distribution,the relative composition,and their variation of methylated chromans(MTTC) with maturation of organic matter in the source rocks from Mingjia 1 well,Jianghan hypersaline basin,have been analyzed and st...The distribution,the relative composition,and their variation of methylated chromans(MTTC) with maturation of organic matter in the source rocks from Mingjia 1 well,Jianghan hypersaline basin,have been analyzed and studied. There is a close relationship between the distribution of methylatd chromans and paleosalinity of depositional environment. In the Eq1-Eq3 source rocks deposited under hypersaline environment with lower Pr/Ph ratio,higher gammacerane index and abundant organic sulfur-containing compounds,methyl MTTC and dimethyl MTTC are main components,but in the Eq4 source rocks deposited non-hypersaline environment with relatively higher Pr/Ph ratio,lower gammacerane index and organic sulfur-containing compounds,trimethyl MTTC is a major compound in methylate chromans. Obviously,the distributions and the compositions of methylated chromans in the source rocks are in harmony with biomarker indicators indicating the paleaosalinity and redox of depositional environment. The relationship between the ratio of 5,8-dimethyl MTTC to 7,8-dimethyl MTTC(dimethyl MTTC ratio) and the maturity of organic matter in the source rocks from Mingjia 1 well has been discussed. The results show that dimethyl MTTC ratio increased with the burial depth and the maturation of organic matter in the source rocks,especially in immature level. It is noteworthy that this ratio is very susceptible to small variation in the maturity of organic matter in the source rocks when vitrinite reflectance Ro is less than 0.65%. It may imply that this ratio is a good and susceptible aromatic maturity indicator for the relative maturity of organic matter in immature source rocks.展开更多
A combined inorganic and organic geochemical study was carried out on marls and mudstones collected from the Lower Miocene Lopare Basin,Bosnia and Herzegovina.A total of 46 samples collected from two boreholes,Pot 1(d...A combined inorganic and organic geochemical study was carried out on marls and mudstones collected from the Lower Miocene Lopare Basin,Bosnia and Herzegovina.A total of 46 samples collected from two boreholes,Pot 1(depth of 193 m)and Pot 3(depth of 344 m),showed that element abundances like boron(B),lithium(Li),strontium(Sr),uranium(U),chromium(Cr),nickel(Ni),magnesium(Mg),sodium(Na)and calcium(Ca)are much higher than average than in the upper continental crust(UCC).Chemical composition indicates at least two sources:(i)Mesozoic ophiolites occurring in the north of the investigated area,and(ii)dacito-andesitic pyroclastics(Mesozoic to Cenozoic).Lopare Basin sedimentation was influenced by strong evaporation resulting in a partly hypersaline lake,which formed during a warm climatic period,probably during the Miocene Climatic Optimum.A brief episode of humid climate conditions resulted in the basin fillingup and deposition of felsic sediments enriched in thorium(Th).Organic geochemistry shows that the majority of studied sediments contains predominantly immature to marginally mature algal organic matter(OM).The biomarker patterns are generally in agreement with the geological history of the Lopare Basin and inorganic and mineralogical data.Conversely,the molecular distribution of n-alkanes as reliable climatic andδ-MTTC as paleosalinity indicators do not support this conclusion.展开更多
In geology we often revise theoretical models;upon finding new evidence,such as the discovery of methane hydrates,the initial model will be challenged immediately.Hereby the authors put forward two postulates:1)There ...In geology we often revise theoretical models;upon finding new evidence,such as the discovery of methane hydrates,the initial model will be challenged immediately.Hereby the authors put forward two postulates:1)There is a third,previously unexplored source of methane in the Transylvanian Basin,based on a new theoretical approach on methane hydrate formation;2)The dissociation of methane hydrates creates a strong chlorinity anomaly.Based on a recent analogy with the Black Sea basin model,we apply our statements to the Transylvanian Basin.Using direct and indirect indicators and the published system tract analysis,we claim that there are substantial grounds to believe that this model of methane hydrate formation applies to the Miocene Transylvanian Basin.Due to the increase of the geothermal gradient as a result of the volcanic activity from the Eastern Carpathians,the clathrates dissociated into methane and freshwater.This process of dilution resulted in a chlorinity anomaly that can be spotted in the formation waters of several gas fields from the Transylvanian Basin.展开更多
Crude oils from different basins in China, Anstralia and New Zealand were analyzed to character-ize aromatic hydrocarbons produced in different environments by means of GC/MS.The distributions of some conunon compound...Crude oils from different basins in China, Anstralia and New Zealand were analyzed to character-ize aromatic hydrocarbons produced in different environments by means of GC/MS.The distributions of some conunon compounds such as naphthalene, phenanthrene, chrysene, pyrene, fluoranthene,fluorene, dibenzothiophene and dibenzofuran were found to be related to sedimentary environments.Especially the relative contents of fluorenes, dibenzofurans and dibenzothiophenes can be used to di-vide the oils into three types: (1) saline or marine carbonate environment; (2) fresh -brackish water lake; (3 ) swamp and coal-bearing sequence.Aromahc biomarkers (e.g. retene, nor-abietene, derivatives of lupeol and β-amyrin) represent higher plant inputs with respect to the precursors of crude oils. High contents of sulphur-containing compounds like benzothiophene and dibenzothiophene series indicate a reducing sulphur-abundant diagenehc condition. The benzohopane series (C32-C35) was identified both in hypersaline and coal-bearing basins, and it is postulated to be the result of strong bacteria achvity. In all the sam-ples, a complete series of alkyl benzenes was analyzed. The similarity of its carbon-number distribu-tion with that of n-alkanes probably suggests their genetic relationship.The distribution of the methylphenanthrene series reflects the evolution degree of crude oils, MPI holding a positive correlation with C29 -sterane 20S/(20S+ 20R).展开更多
Not only the mudstones and carbonates deposited in hypersaline environments, but also evaporites can be source rocks of petroleum. They all have a peculiar composition of hydrocarbon such as the strong predominance of...Not only the mudstones and carbonates deposited in hypersaline environments, but also evaporites can be source rocks of petroleum. They all have a peculiar composition of hydrocarbon such as the strong predominance of phytane, the richness in gammacerane, the frequent preference of even carbon number n-alkanes, and have a generative potential for less mature oils in diagenesis of organic matter.展开更多
Gammacerane has been a common component of crude oils and organic matter of sedimentary rocks since it was found by Hills et al. in the Green River oil shale, Colorado, USA. For example, gammacerane was found in 42 cr...Gammacerane has been a common component of crude oils and organic matter of sedimentary rocks since it was found by Hills et al. in the Green River oil shale, Colorado, USA. For example, gammacerane was found in 42 crude oils of展开更多
基金Supported by Key Technologies R & D Programme (Grant No. 2004BA616A02-04-02-01)
文摘The distribution,the relative composition,and their variation of methylated chromans(MTTC) with maturation of organic matter in the source rocks from Mingjia 1 well,Jianghan hypersaline basin,have been analyzed and studied. There is a close relationship between the distribution of methylatd chromans and paleosalinity of depositional environment. In the Eq1-Eq3 source rocks deposited under hypersaline environment with lower Pr/Ph ratio,higher gammacerane index and abundant organic sulfur-containing compounds,methyl MTTC and dimethyl MTTC are main components,but in the Eq4 source rocks deposited non-hypersaline environment with relatively higher Pr/Ph ratio,lower gammacerane index and organic sulfur-containing compounds,trimethyl MTTC is a major compound in methylate chromans. Obviously,the distributions and the compositions of methylated chromans in the source rocks are in harmony with biomarker indicators indicating the paleaosalinity and redox of depositional environment. The relationship between the ratio of 5,8-dimethyl MTTC to 7,8-dimethyl MTTC(dimethyl MTTC ratio) and the maturity of organic matter in the source rocks from Mingjia 1 well has been discussed. The results show that dimethyl MTTC ratio increased with the burial depth and the maturation of organic matter in the source rocks,especially in immature level. It is noteworthy that this ratio is very susceptible to small variation in the maturity of organic matter in the source rocks when vitrinite reflectance Ro is less than 0.65%. It may imply that this ratio is a good and susceptible aromatic maturity indicator for the relative maturity of organic matter in immature source rocks.
基金partly financed by the Ministry of Education,Science and Technological Development,Republic of Serbia(Grant No.451-03-68/2020-14/200026 and Project 176006)。
文摘A combined inorganic and organic geochemical study was carried out on marls and mudstones collected from the Lower Miocene Lopare Basin,Bosnia and Herzegovina.A total of 46 samples collected from two boreholes,Pot 1(depth of 193 m)and Pot 3(depth of 344 m),showed that element abundances like boron(B),lithium(Li),strontium(Sr),uranium(U),chromium(Cr),nickel(Ni),magnesium(Mg),sodium(Na)and calcium(Ca)are much higher than average than in the upper continental crust(UCC).Chemical composition indicates at least two sources:(i)Mesozoic ophiolites occurring in the north of the investigated area,and(ii)dacito-andesitic pyroclastics(Mesozoic to Cenozoic).Lopare Basin sedimentation was influenced by strong evaporation resulting in a partly hypersaline lake,which formed during a warm climatic period,probably during the Miocene Climatic Optimum.A brief episode of humid climate conditions resulted in the basin fillingup and deposition of felsic sediments enriched in thorium(Th).Organic geochemistry shows that the majority of studied sediments contains predominantly immature to marginally mature algal organic matter(OM).The biomarker patterns are generally in agreement with the geological history of the Lopare Basin and inorganic and mineralogical data.Conversely,the molecular distribution of n-alkanes as reliable climatic andδ-MTTC as paleosalinity indicators do not support this conclusion.
基金This work was supported by Oil&Gas Development Central(O&GD C.)Ltd.Hungary.
文摘In geology we often revise theoretical models;upon finding new evidence,such as the discovery of methane hydrates,the initial model will be challenged immediately.Hereby the authors put forward two postulates:1)There is a third,previously unexplored source of methane in the Transylvanian Basin,based on a new theoretical approach on methane hydrate formation;2)The dissociation of methane hydrates creates a strong chlorinity anomaly.Based on a recent analogy with the Black Sea basin model,we apply our statements to the Transylvanian Basin.Using direct and indirect indicators and the published system tract analysis,we claim that there are substantial grounds to believe that this model of methane hydrate formation applies to the Miocene Transylvanian Basin.Due to the increase of the geothermal gradient as a result of the volcanic activity from the Eastern Carpathians,the clathrates dissociated into methane and freshwater.This process of dilution resulted in a chlorinity anomaly that can be spotted in the formation waters of several gas fields from the Transylvanian Basin.
文摘Crude oils from different basins in China, Anstralia and New Zealand were analyzed to character-ize aromatic hydrocarbons produced in different environments by means of GC/MS.The distributions of some conunon compounds such as naphthalene, phenanthrene, chrysene, pyrene, fluoranthene,fluorene, dibenzothiophene and dibenzofuran were found to be related to sedimentary environments.Especially the relative contents of fluorenes, dibenzofurans and dibenzothiophenes can be used to di-vide the oils into three types: (1) saline or marine carbonate environment; (2) fresh -brackish water lake; (3 ) swamp and coal-bearing sequence.Aromahc biomarkers (e.g. retene, nor-abietene, derivatives of lupeol and β-amyrin) represent higher plant inputs with respect to the precursors of crude oils. High contents of sulphur-containing compounds like benzothiophene and dibenzothiophene series indicate a reducing sulphur-abundant diagenehc condition. The benzohopane series (C32-C35) was identified both in hypersaline and coal-bearing basins, and it is postulated to be the result of strong bacteria achvity. In all the sam-ples, a complete series of alkyl benzenes was analyzed. The similarity of its carbon-number distribu-tion with that of n-alkanes probably suggests their genetic relationship.The distribution of the methylphenanthrene series reflects the evolution degree of crude oils, MPI holding a positive correlation with C29 -sterane 20S/(20S+ 20R).
文摘Not only the mudstones and carbonates deposited in hypersaline environments, but also evaporites can be source rocks of petroleum. They all have a peculiar composition of hydrocarbon such as the strong predominance of phytane, the richness in gammacerane, the frequent preference of even carbon number n-alkanes, and have a generative potential for less mature oils in diagenesis of organic matter.
文摘Gammacerane has been a common component of crude oils and organic matter of sedimentary rocks since it was found by Hills et al. in the Green River oil shale, Colorado, USA. For example, gammacerane was found in 42 crude oils of
