It is well known that oil generated from source rocks of saline-lake facies is characteristic of low Pr/Ph ratio and high contents of gammacerane.The authors found that gas generated from the same source rocks was hig...It is well known that oil generated from source rocks of saline-lake facies is characteristic of low Pr/Ph ratio and high contents of gammacerane.The authors found that gas generated from the same source rocks was high in benzene and cyclohexane contents and had light carbon isotope compositions.In this study,a series of thermal simulations of gas generations on source rock with/without evaporites(such as carbonate,gypsum,and sodium chlorite,respectively),were conducted.It was found that the gypsum played an important role on the catalyzsis of gas generation in the thermal simulations.Compositions of the gaseous hydrocarbons generated from source rocks with evaporites are very similar to those of natural gases discovered from northern Dongying Depression.Meanwhile,in the thermal simulations,it was found that the carbon isotopic compositions of gaseous hydrocarbons generated from source rocks with evaporites are lighter than those of the gases from source rocks without evaporites.Therefore,it is concluded that natural gases discovered from northern Dongying Depression are the product of interaction between source rocks and evaporites(especially gypsum) of the saline facies.展开更多
Basalts interbedded with oil source rocks are discovered frequently in rift basins of eastern China, where CO2 is found in reservoirs around or within basalts, for example in the Binnan reservoir of the Dongying Depre...Basalts interbedded with oil source rocks are discovered frequently in rift basins of eastern China, where CO2 is found in reservoirs around or within basalts, for example in the Binnan reservoir of the Dongying Depression. In the reservoirs, CO2 with heavy carbon isotopic composition (δ13C>-10‰ PDB) is in most cases accounts for 40% of the total gas reserve, and is believed to have resulted from degassing of basaltic magma from the mantle. In their investigations of the Binnan reservoir, the authors suggested that the CO2 would result from interactions between the source rocks and basalts. As the source rocks around basalts are rich in carbonate minerals, volcanic minerals, transition metals and organic matter, during their burial history some of the transition metals were catalyzed on the thermal degradation of organic matter into hydrocarbons and on the decomposition of carbonate minerals into CO2, which was reproduced in thermal simulations of the source rocks with the transition metals (Ni and Co). This kind of CO2 accounts for 55%-85% of the total gas reserve generated in the process of thermal simulation, and its δ13C values range from -11‰- -7.2‰ PDB, which are very similar to those of CO2 found in the Binnan reservoir. The co-generation of CO2 and hydrocarbon gases makes it possible their accumulation together in one trap. In other words, if the CO2 resulted directly from degassing of basaltic magma or was derived from the mantle, it could not be accumulated with hydrocarbon gases because it came into the basin much earlier than hydrocarbon generation and much earlier than trap formation. Therefore, the source rocks around basalts generated hydrocarbons and CO2 simultaneously through catalysis of Co and Ni transition metals, which is useful for the explanation of co-accumulation of hydrocarbon gases and CO2 in rift basins in eastern China.展开更多
A fluid inclusion fluorescence and microthermometric study was performed on sandstones from the deep Es4 reservoir rocks of the Minfeng （民丰） sag, north of Dongying （东营） depression. Two types of oil inclusions ...A fluid inclusion fluorescence and microthermometric study was performed on sandstones from the deep Es4 reservoir rocks of the Minfeng （民丰） sag, north of Dongying （东营） depression. Two types of oil inclusions （yellow and blue white fluorescence）, one type of gas inclusions （blue white fluorescence）, and bitumen inclusions （no fluorescence） were detected within quartz and feldspar minerals. The evolution of hydrocarbon fluid inclusions in the lower Es4 sequence indicates that present oil accumulation was predominantly thermal stress controlled. Homogenization temperatures of aqueous fluid inclusions coexisting with gas-bearing and bitumen-bearing fluid inclusions indicate that oil cracking occurred at temperatures up to 160 ℃, primary condensate or wet gas genera- tion occurred during 170-195℃. Oil has cracked into condensate or wet gas in the depth of 4 300- 4 410 m and dry gas and abundant pyrobitumen in the depth of more than 4 410 m in the geological history based on the fluid inclusion extrapolation. Secondary oil cracking is undergoing in present day when the depth of reservoir is more than 4 150 m whose temperature is the threshold temperature of oil cracking （160 ℃）. However, because of the consumption of oil in the first oil cracking process, it may have few chances to find liquid petroleum, and only natural gas can be found when the depth of reservoir is more than 4 410 m, where oil cracks into condensate gas or wet gas according to present-day formation temperature. This study is preliminary but foreshadows a new insight into oilcracking using natural fluid inclusions to trace hydrocarbon evolution in sedimentary basins.展开更多
基金prepared under the permission of the authorities of the Shengli Oilfield,and funded by the National Natural Science Foundation of China (No. 40572084)SINOPEC (No. P07008)
文摘It is well known that oil generated from source rocks of saline-lake facies is characteristic of low Pr/Ph ratio and high contents of gammacerane.The authors found that gas generated from the same source rocks was high in benzene and cyclohexane contents and had light carbon isotope compositions.In this study,a series of thermal simulations of gas generations on source rock with/without evaporites(such as carbonate,gypsum,and sodium chlorite,respectively),were conducted.It was found that the gypsum played an important role on the catalyzsis of gas generation in the thermal simulations.Compositions of the gaseous hydrocarbons generated from source rocks with evaporites are very similar to those of natural gases discovered from northern Dongying Depression.Meanwhile,in the thermal simulations,it was found that the carbon isotopic compositions of gaseous hydrocarbons generated from source rocks with evaporites are lighter than those of the gases from source rocks without evaporites.Therefore,it is concluded that natural gases discovered from northern Dongying Depression are the product of interaction between source rocks and evaporites(especially gypsum) of the saline facies.
基金This research project is funded by the National Natural Science Foundation of China （Grant No. 40272061）.
文摘Basalts interbedded with oil source rocks are discovered frequently in rift basins of eastern China, where CO2 is found in reservoirs around or within basalts, for example in the Binnan reservoir of the Dongying Depression. In the reservoirs, CO2 with heavy carbon isotopic composition (δ13C>-10‰ PDB) is in most cases accounts for 40% of the total gas reserve, and is believed to have resulted from degassing of basaltic magma from the mantle. In their investigations of the Binnan reservoir, the authors suggested that the CO2 would result from interactions between the source rocks and basalts. As the source rocks around basalts are rich in carbonate minerals, volcanic minerals, transition metals and organic matter, during their burial history some of the transition metals were catalyzed on the thermal degradation of organic matter into hydrocarbons and on the decomposition of carbonate minerals into CO2, which was reproduced in thermal simulations of the source rocks with the transition metals (Ni and Co). This kind of CO2 accounts for 55%-85% of the total gas reserve generated in the process of thermal simulation, and its δ13C values range from -11‰- -7.2‰ PDB, which are very similar to those of CO2 found in the Binnan reservoir. The co-generation of CO2 and hydrocarbon gases makes it possible their accumulation together in one trap. In other words, if the CO2 resulted directly from degassing of basaltic magma or was derived from the mantle, it could not be accumulated with hydrocarbon gases because it came into the basin much earlier than hydrocarbon generation and much earlier than trap formation. Therefore, the source rocks around basalts generated hydrocarbons and CO2 simultaneously through catalysis of Co and Ni transition metals, which is useful for the explanation of co-accumulation of hydrocarbon gases and CO2 in rift basins in eastern China.
基金supported by the National Natural Science Foundation of China (No. 40372068)
文摘A fluid inclusion fluorescence and microthermometric study was performed on sandstones from the deep Es4 reservoir rocks of the Minfeng （民丰） sag, north of Dongying （东营） depression. Two types of oil inclusions （yellow and blue white fluorescence）, one type of gas inclusions （blue white fluorescence）, and bitumen inclusions （no fluorescence） were detected within quartz and feldspar minerals. The evolution of hydrocarbon fluid inclusions in the lower Es4 sequence indicates that present oil accumulation was predominantly thermal stress controlled. Homogenization temperatures of aqueous fluid inclusions coexisting with gas-bearing and bitumen-bearing fluid inclusions indicate that oil cracking occurred at temperatures up to 160 ℃, primary condensate or wet gas genera- tion occurred during 170-195℃. Oil has cracked into condensate or wet gas in the depth of 4 300- 4 410 m and dry gas and abundant pyrobitumen in the depth of more than 4 410 m in the geological history based on the fluid inclusion extrapolation. Secondary oil cracking is undergoing in present day when the depth of reservoir is more than 4 150 m whose temperature is the threshold temperature of oil cracking （160 ℃）. However, because of the consumption of oil in the first oil cracking process, it may have few chances to find liquid petroleum, and only natural gas can be found when the depth of reservoir is more than 4 410 m, where oil cracks into condensate gas or wet gas according to present-day formation temperature. This study is preliminary but foreshadows a new insight into oilcracking using natural fluid inclusions to trace hydrocarbon evolution in sedimentary basins.
