Great quantities of light oil and gas are produced from deep buried hill reservoirs at depths of 5,641 m to 6,027 m and 190 ℃ to 201 ℃ in the Niudong-1 Well, representing the deepest and hottest commercial hydrocarb...Great quantities of light oil and gas are produced from deep buried hill reservoirs at depths of 5,641 m to 6,027 m and 190 ℃ to 201 ℃ in the Niudong-1 Well, representing the deepest and hottest commercial hydrocarbons discovered in the Bohai Bay Basin in eastern China. This discovery suggests favorable exploration prospects for the deep parts of the basin. However, the discovery raises questions regarding the genesis and accumulation of hydrocarbons in deep reservoirs. Based on the geochemical features of the hydrocarbons and characteristics of the source rocks as well as thermal simulation experiments of hydrocarbon generation, we conclude that the oil and gas were generated from the highly mature Sha-4 Member （Es4） source rocks instead of thermal cracking of crude oils in earlier accumulations. The source kitchen with abnormal pressures and karsted carbonate reservoirs control the formation of high-maturity hydrocarbon accumulations in the buried hills （i.e., Niudong-1） in conjunction with several structural-lithologic traps in the ES4 reservoirs since the deposition of the upper Minghuazhen Formation. This means the oil and gas exploration potential in the deep parts of the Baxian Depression is probably high.展开更多
The origin of the Jurassic low maturity natural gas in the Turpan-Hami Basin has attracted scientists’attention for some time,and it is known that radiogenesis may have played a role.However,little has been done on t...The origin of the Jurassic low maturity natural gas in the Turpan-Hami Basin has attracted scientists’attention for some time,and it is known that radiogenesis may have played a role.However,little has been done on the uranium-rich background of the whole basin.Based on plentiful logging and geological data for the Jurassic strata in the Turpan-Hami Basin,this research examined the features and factors controlling the distribution of rocks with high gamma reading.The results show that 70%-100%of the rocks with high gamma readings correspond to mudstones in the prodelta subfacies rather than those in semideep-deep lacustrine subfacies rich in mudstones.Therefore,we propose that the distribution of rocks with high gamma readings is mainly controlled by sedimentary facies rather than by lithology.Further analysis of the gamma spectrometry logging data shows that high gamma values are more strongly correlated with U content than with Th or K content.By comparing the U and Th contents of felsic rocks in peripheral provenances,we find that the Jueluotage Mountain and Harlik Mountain were the dominant uranium sources for the Jurassic Turpan-Hami Basin.Radiolysis due to high-level uranium in the prodelta subfacies can make the low maturity source rocks generate H2 and CH4,thus contributing to the production of low maturity natural gas in the Turpan-Hami Basin.展开更多
文摘Great quantities of light oil and gas are produced from deep buried hill reservoirs at depths of 5,641 m to 6,027 m and 190 ℃ to 201 ℃ in the Niudong-1 Well, representing the deepest and hottest commercial hydrocarbons discovered in the Bohai Bay Basin in eastern China. This discovery suggests favorable exploration prospects for the deep parts of the basin. However, the discovery raises questions regarding the genesis and accumulation of hydrocarbons in deep reservoirs. Based on the geochemical features of the hydrocarbons and characteristics of the source rocks as well as thermal simulation experiments of hydrocarbon generation, we conclude that the oil and gas were generated from the highly mature Sha-4 Member （Es4） source rocks instead of thermal cracking of crude oils in earlier accumulations. The source kitchen with abnormal pressures and karsted carbonate reservoirs control the formation of high-maturity hydrocarbon accumulations in the buried hills （i.e., Niudong-1） in conjunction with several structural-lithologic traps in the ES4 reservoirs since the deposition of the upper Minghuazhen Formation. This means the oil and gas exploration potential in the deep parts of the Baxian Depression is probably high.
基金supported by the National Natural Science Foundation of China(grant numbers 41330315,41402093)。
文摘The origin of the Jurassic low maturity natural gas in the Turpan-Hami Basin has attracted scientists’attention for some time,and it is known that radiogenesis may have played a role.However,little has been done on the uranium-rich background of the whole basin.Based on plentiful logging and geological data for the Jurassic strata in the Turpan-Hami Basin,this research examined the features and factors controlling the distribution of rocks with high gamma reading.The results show that 70%-100%of the rocks with high gamma readings correspond to mudstones in the prodelta subfacies rather than those in semideep-deep lacustrine subfacies rich in mudstones.Therefore,we propose that the distribution of rocks with high gamma readings is mainly controlled by sedimentary facies rather than by lithology.Further analysis of the gamma spectrometry logging data shows that high gamma values are more strongly correlated with U content than with Th or K content.By comparing the U and Th contents of felsic rocks in peripheral provenances,we find that the Jueluotage Mountain and Harlik Mountain were the dominant uranium sources for the Jurassic Turpan-Hami Basin.Radiolysis due to high-level uranium in the prodelta subfacies can make the low maturity source rocks generate H2 and CH4,thus contributing to the production of low maturity natural gas in the Turpan-Hami Basin.
