Objective The natural gas exploration of the Sinian reservoirs in the central Sichuan Basin has made a significant breakthrough in recent years, and has thus attracted much attention among geologists. The Sichuan Bas...Objective The natural gas exploration of the Sinian reservoirs in the central Sichuan Basin has made a significant breakthrough in recent years, and has thus attracted much attention among geologists. The Sichuan Basin is known to have complicated geological settings, which has experienced multiple stages of tectonic evolution, fluid charging and hydrocarbon accumulation. This research aims to determine the geochemical characteristics of each stage of fluids, the features and time interval of fluid activity in different geologic periods, and further to restore the critical period and geological age of the hydrocarbon accumulation.展开更多
The Lower Cretaceous Yingcheng Formation in the southern Songliao Basin is the typical tight oil sandstone in China.In order to better predict the petrophysical properties of the tight sandstone reservoirs in the Lowe...The Lower Cretaceous Yingcheng Formation in the southern Songliao Basin is the typical tight oil sandstone in China.In order to better predict the petrophysical properties of the tight sandstone reservoirs in the Lower Cretaceous Yingcheng Formation,Songliao Basin,Northeast China,the diagenesis and porosity evolution was investigated using a suite of petrographic and geochemical techniques including thin section analysis,scanning electron microscopy,mercury intrusion and fluid inclusion analysis,on a set of selected tight sandstone samples.Combined with the histories of burial evolution,organic matter thermal evolution and hydrocarbon charge,the matching relationship between reservoir porosity evolution and hydrocarbon accumulation history is analyzed.The result showed that the tight sandstone reservoirs characterized of being controlled by deposition,predominated by compaction,improved by dissolution and enhanced by cementation.The hydrocarbon accumulation period was investigated using a suite of hydrocarbon generation and expulsion history,microfluorescence determination and temperature measurement technology.According to the homogenization temperature of the inclusions and the history of burial evolution,Yingcheng Formation has mainly two phases hydrocarbon accumulation.The first phase of oil and gas is charged before the reservoir is tightened,the oil and gas generated by Shahezi source rocks enter the sand body of Yingcheng Formation,influenced by the carrying capability of sand conducting layer,oil and gas is mainly conducted by the better properties and higher connectivity sand body and enriched in the east,which belongs to the type of densification after hydrocarbon accumulation.The second phase of oil and gas charge after densification,which belongs to the type of densification before the hydrocarbon accumulation.展开更多
Fluid inclusion analysis and testing were conducted to clarify the relationship between reservoir densification and hydrocarbon accumulation in the Paleogene Pinghu and Huagang formations in the Xihu Depression.The hy...Fluid inclusion analysis and testing were conducted to clarify the relationship between reservoir densification and hydrocarbon accumulation in the Paleogene Pinghu and Huagang formations in the Xihu Depression.The hydrocarbon accumulation stages of the reservoirs were studied in combination with the reconstruction results of burial and thermal evolution histories.Furthermore,the relationship between reservoir densification and accumulation charging was clarified in combination with the pore evolutionary history.In accordance with the time relation between reservoir densification and hydrocarbon charging,the reservoirs were classified into three types:pre-charging,syn-charging,and after-charging densification.Results indicated that large-scale hydrocarbon charging occurred in 11–0Myr.Reservoir densification was mainly caused by strong mechanical compaction and pore filling by well-developed siliceous and carbonate cements.Entering the middle diagenetic stage A1,the reservoir was under an acidic-diagenetic environment,resulting in the development of secondary dissolution pores.If large-scale hydrocarbon charging occurred during this period,then an after-charging densification reservoir,which is the most suitable type for hydrocarbon accumulation,might have developed.Entering the middle diagenetic stage A2,the reservoir was under an acidic-alkaline transitional diagenetic environment.During this stage,dissolution became weak,and compaction and cementation were enhanced,resulting in the continuous loss of pore space and reservoir densification.Entering the middle diagenetic period B,the reservoir was under an alkaline-diagenetic environment,and the reservoir had been largely densified.If large-scale hydrocarbon charging occurred during this period,a pre-charging densified reservoir,which is the worst reservoir type for hydrocarbon accumulation,might have developed.展开更多
基金supported by the Natural Science Foundation of China(grant No.41372141)
文摘Objective The natural gas exploration of the Sinian reservoirs in the central Sichuan Basin has made a significant breakthrough in recent years, and has thus attracted much attention among geologists. The Sichuan Basin is known to have complicated geological settings, which has experienced multiple stages of tectonic evolution, fluid charging and hydrocarbon accumulation. This research aims to determine the geochemical characteristics of each stage of fluids, the features and time interval of fluid activity in different geologic periods, and further to restore the critical period and geological age of the hydrocarbon accumulation.
基金The authors acknowledge sponsorship from China Petroleum Science and Technology Innovation Fund(2017d-5007-0101)China Geological Survey project(DD20191007)Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0207).
文摘The Lower Cretaceous Yingcheng Formation in the southern Songliao Basin is the typical tight oil sandstone in China.In order to better predict the petrophysical properties of the tight sandstone reservoirs in the Lower Cretaceous Yingcheng Formation,Songliao Basin,Northeast China,the diagenesis and porosity evolution was investigated using a suite of petrographic and geochemical techniques including thin section analysis,scanning electron microscopy,mercury intrusion and fluid inclusion analysis,on a set of selected tight sandstone samples.Combined with the histories of burial evolution,organic matter thermal evolution and hydrocarbon charge,the matching relationship between reservoir porosity evolution and hydrocarbon accumulation history is analyzed.The result showed that the tight sandstone reservoirs characterized of being controlled by deposition,predominated by compaction,improved by dissolution and enhanced by cementation.The hydrocarbon accumulation period was investigated using a suite of hydrocarbon generation and expulsion history,microfluorescence determination and temperature measurement technology.According to the homogenization temperature of the inclusions and the history of burial evolution,Yingcheng Formation has mainly two phases hydrocarbon accumulation.The first phase of oil and gas is charged before the reservoir is tightened,the oil and gas generated by Shahezi source rocks enter the sand body of Yingcheng Formation,influenced by the carrying capability of sand conducting layer,oil and gas is mainly conducted by the better properties and higher connectivity sand body and enriched in the east,which belongs to the type of densification after hydrocarbon accumulation.The second phase of oil and gas charge after densification,which belongs to the type of densification before the hydrocarbon accumulation.
基金This study was supported by the National Science and Technology Major Projects(No.2016ZX05027-002-006)the Research on the Key Technologies of Exploration and Development in the West of Xihu Depression(No.CNOOC-KJ135ZDXM39SH01).
文摘Fluid inclusion analysis and testing were conducted to clarify the relationship between reservoir densification and hydrocarbon accumulation in the Paleogene Pinghu and Huagang formations in the Xihu Depression.The hydrocarbon accumulation stages of the reservoirs were studied in combination with the reconstruction results of burial and thermal evolution histories.Furthermore,the relationship between reservoir densification and accumulation charging was clarified in combination with the pore evolutionary history.In accordance with the time relation between reservoir densification and hydrocarbon charging,the reservoirs were classified into three types:pre-charging,syn-charging,and after-charging densification.Results indicated that large-scale hydrocarbon charging occurred in 11–0Myr.Reservoir densification was mainly caused by strong mechanical compaction and pore filling by well-developed siliceous and carbonate cements.Entering the middle diagenetic stage A1,the reservoir was under an acidic-diagenetic environment,resulting in the development of secondary dissolution pores.If large-scale hydrocarbon charging occurred during this period,then an after-charging densification reservoir,which is the most suitable type for hydrocarbon accumulation,might have developed.Entering the middle diagenetic stage A2,the reservoir was under an acidic-alkaline transitional diagenetic environment.During this stage,dissolution became weak,and compaction and cementation were enhanced,resulting in the continuous loss of pore space and reservoir densification.Entering the middle diagenetic period B,the reservoir was under an alkaline-diagenetic environment,and the reservoir had been largely densified.If large-scale hydrocarbon charging occurred during this period,a pre-charging densified reservoir,which is the worst reservoir type for hydrocarbon accumulation,might have developed.
