The fluid flow history during diagenesis of sandstones in the Upper Permian Black Jack Formation of the Gunnedah Basin has been investigated through integrated petrographic observations, fluid inclusion investigations...The fluid flow history during diagenesis of sandstones in the Upper Permian Black Jack Formation of the Gunnedah Basin has been investigated through integrated petrographic observations, fluid inclusion investigations and stable isotope analyses. The early precipitation of mixed-layer illite/smectite, siderite, calcite, ankerite and kaolin proceeded at the presence of Late Permian connate meteoric waters at temperatures of up to 60℃. These evolved connate pore waters were also parental to quartz, which formed at temperatures of up to 87℃. The phase of maximum burial was characterized by development of filamentous illite and late calcite at temperatures of up to -90℃. Subsequent uplifting and cooling led to deep meteoric influx from surface, which in turn resulted in dissolution of labile grains and carbonate cements, and formation of second generation of kaolin. Dawsonite was the last diagenetic mineral precipitated and its formation is genetically related to deep-seated mamagtic sourced CO2.展开更多
The characteristics, origin and injection history of the Dongfang gas field, the largest gas field found in the Yinggehai basin, are studied by integrated geological, geothermal and geochemical data. The gas field sho...The characteristics, origin and injection history of the Dongfang gas field, the largest gas field found in the Yinggehai basin, are studied by integrated geological, geothermal and geochemical data. The gas field shows considerable variation in hydrocarbon gas, nitrogen and carbon dioxide content, aud has been filled by at least four stage fluids. A strong thermal anomaIy caused by hydrothermal fluid flows occurs in the gas field, as evidenced rrom drill-stem test and fluid iuclusion homogenization temperatures, rock-eval tmax,vitrinite reflectance as well as clay-mineral transformation profiles. Such a thermal anomaly suggests focused, rapid flow of deeply-sourced hydrothermal rluids. The inter-reservoir heterogeneities, the strong migotion rractionation related to abrupt changes in pressure and temperature and tbe short-lived, transient nature of the thermal effect of fluid flow are evidences of episodic rluid injections from the overpressured systems into the reservoirs.展开更多
文摘The fluid flow history during diagenesis of sandstones in the Upper Permian Black Jack Formation of the Gunnedah Basin has been investigated through integrated petrographic observations, fluid inclusion investigations and stable isotope analyses. The early precipitation of mixed-layer illite/smectite, siderite, calcite, ankerite and kaolin proceeded at the presence of Late Permian connate meteoric waters at temperatures of up to 60℃. These evolved connate pore waters were also parental to quartz, which formed at temperatures of up to 87℃. The phase of maximum burial was characterized by development of filamentous illite and late calcite at temperatures of up to -90℃. Subsequent uplifting and cooling led to deep meteoric influx from surface, which in turn resulted in dissolution of labile grains and carbonate cements, and formation of second generation of kaolin. Dawsonite was the last diagenetic mineral precipitated and its formation is genetically related to deep-seated mamagtic sourced CO2.
文摘The characteristics, origin and injection history of the Dongfang gas field, the largest gas field found in the Yinggehai basin, are studied by integrated geological, geothermal and geochemical data. The gas field shows considerable variation in hydrocarbon gas, nitrogen and carbon dioxide content, aud has been filled by at least four stage fluids. A strong thermal anomaIy caused by hydrothermal fluid flows occurs in the gas field, as evidenced rrom drill-stem test and fluid iuclusion homogenization temperatures, rock-eval tmax,vitrinite reflectance as well as clay-mineral transformation profiles. Such a thermal anomaly suggests focused, rapid flow of deeply-sourced hydrothermal rluids. The inter-reservoir heterogeneities, the strong migotion rractionation related to abrupt changes in pressure and temperature and tbe short-lived, transient nature of the thermal effect of fluid flow are evidences of episodic rluid injections from the overpressured systems into the reservoirs.
