Due to the depletion of conventional hydrocarbon resources,both China and Russia are giving more attention to the exploration and production of unconventional oil and gas resources,especially those generated and accum...Due to the depletion of conventional hydrocarbon resources,both China and Russia are giving more attention to the exploration and production of unconventional oil and gas resources,especially those generated and accumulated within source rocks.In an attempt to further understand the mechanisms of these resources,detailed mineralogical,lithological,and geochemical studies were performed to compare source rock samples from i)the Longmaxi Formation of the Lower Silurian in the Sichuan Basin(China),and ii)the Semiluksk Formation of the Frasnian Stage of the Upper Devonian in the Volga-Ural region of the East European Platform(Russia).The results showed that the main mineral of the source rocks of both formations is chalcedony that formed during an outpouring of deep fluids onto the sea bed.Simultaneous thermal analyses of this mineral indicated similar thermophysical properties to those of the hydrothermal-sedimentary chalcedony from jasper.Moreover,a direct relationship between the chalcedony content and the total organic matter content in the samples from the two formations was established.The presence of biophilic chemical elements in the siliceous component of the source rock samples indicate that high total organic content values were likely due to the presence of biophilic chemical elements in deep fluids,which led to the large-scale development of biota and subsequent accumulation of organic matter during sedimentation.The findings also revealed that the organic matter in the source rocks of the two regions was at different stages of maturity.The organic matter in samples from the Volga-Ural region was less mature and only at the early stage of oil generation,whereas the organic matter in samples from the Sichuan Basin reached both oil and gas generation stages.The Longmaxi Formation is already in the shale gas exploration and development stage,and the Semiluksk Formation could also be regarded as an exploration target for shale oil reservoirs.展开更多
Despite its significant exploration potential,the origin of natural gas in the tectonically complex southwestern Tarim Basin remains controversial due to multiple potential source rocks.This study identifies the genet...Despite its significant exploration potential,the origin of natural gas in the tectonically complex southwestern Tarim Basin remains controversial due to multiple potential source rocks.This study identifies the genetic types and sources of natural gas by integrating gas molecular and isotopic compositions with the geochemical characteristics of potential source rocks.The results indicate that the Kekeya gas field mainly contains coal-derived gas sourced from the Permian Pusige Formation,whereas the Akemomu field and the QT-1 well contain highly overmature gas from the Permian Qipan Formation with some mantle-derived He and inorganic CO_(2).Furthermore,the oil-associated gas in the FS-8 well originates from Permian sapropelic source rocks,while the KS-6 well contains a mixed,oil-associated gas predominantly sourced from the Jurassic Yangye Formation.These findings reveal a complex gas accumulation scenario with multiple genetic types and sources in the southwestern Tarim Basin,providing critical insights for future exploration.展开更多
基金supported by grants from the Russian Foundation for Basic Research(project No.18-35-00136)the Chinese NSFC(project No.41811530094)+1 种基金the Government of the Republic of Tatarstan(project No.18-45-160003)supported by subsidies allocated as part of the state’s support for the Kazan Federal University in order to increase its global competitiveness in leading research and educational centers.
文摘Due to the depletion of conventional hydrocarbon resources,both China and Russia are giving more attention to the exploration and production of unconventional oil and gas resources,especially those generated and accumulated within source rocks.In an attempt to further understand the mechanisms of these resources,detailed mineralogical,lithological,and geochemical studies were performed to compare source rock samples from i)the Longmaxi Formation of the Lower Silurian in the Sichuan Basin(China),and ii)the Semiluksk Formation of the Frasnian Stage of the Upper Devonian in the Volga-Ural region of the East European Platform(Russia).The results showed that the main mineral of the source rocks of both formations is chalcedony that formed during an outpouring of deep fluids onto the sea bed.Simultaneous thermal analyses of this mineral indicated similar thermophysical properties to those of the hydrothermal-sedimentary chalcedony from jasper.Moreover,a direct relationship between the chalcedony content and the total organic matter content in the samples from the two formations was established.The presence of biophilic chemical elements in the siliceous component of the source rock samples indicate that high total organic content values were likely due to the presence of biophilic chemical elements in deep fluids,which led to the large-scale development of biota and subsequent accumulation of organic matter during sedimentation.The findings also revealed that the organic matter in the source rocks of the two regions was at different stages of maturity.The organic matter in samples from the Volga-Ural region was less mature and only at the early stage of oil generation,whereas the organic matter in samples from the Sichuan Basin reached both oil and gas generation stages.The Longmaxi Formation is already in the shale gas exploration and development stage,and the Semiluksk Formation could also be regarded as an exploration target for shale oil reservoirs.
基金supported by the National Natural Science Foundation of China(Grant No.41903013)university—enterprise cooperation projects(041021090118)the Hubei Key Laboratory of Petroleum Geochemistry and Environment at Yangtze University(Grant No.HKLPGE-202308).
文摘Despite its significant exploration potential,the origin of natural gas in the tectonically complex southwestern Tarim Basin remains controversial due to multiple potential source rocks.This study identifies the genetic types and sources of natural gas by integrating gas molecular and isotopic compositions with the geochemical characteristics of potential source rocks.The results indicate that the Kekeya gas field mainly contains coal-derived gas sourced from the Permian Pusige Formation,whereas the Akemomu field and the QT-1 well contain highly overmature gas from the Permian Qipan Formation with some mantle-derived He and inorganic CO_(2).Furthermore,the oil-associated gas in the FS-8 well originates from Permian sapropelic source rocks,while the KS-6 well contains a mixed,oil-associated gas predominantly sourced from the Jurassic Yangye Formation.These findings reveal a complex gas accumulation scenario with multiple genetic types and sources in the southwestern Tarim Basin,providing critical insights for future exploration.
