Studies On The Accumulation Mechanism And Main Controlling Factors Of The Paleogene Deep Condensate Gas In Dongpu Depression

Based on the hydrocarbon-generation evolution of Paleogene hydrocarbon source rocks and distribution characteristics of deep condensate gas in Dongpu depression,to explore the accumulation mechanism and main controlling factors of Paleogene deep condensate gas in Dongpu depression,by comparing the differences between temporal arrangement relationship of accumulation factors and the dynamic reservoiring processes in Duzhai area and Qiaokou area.By the means of cast thin,cathodoluminescence,fluorescence microscopy and other tests to analyzes the reservoir characteristics and porosity evolution in middle and lower submember of Es3 in Duzhai area and Qiaokou area.The study shows that both of the middle and lower sub-member of Es3 in Duzhai and Qiaokou area are develop tight-super tight sandstone reservoir.After a complex diagenetic process of continues compaction,three calcareous cementation and three dissolution,the porosity all present the evolution for primary pore loss?secondary porosity appear?secondary porosity decreases.Combined with mercury penetration test,interval transit time method,basin modeling and many other technical methods to research the gas migration paths,the relationship between filling dynamic and resistance.Research shows that the formation pressure can be vertically divided into three zones as following:normal pressure zone,over-pressure zone and ultra-high pressure zone.The deep tight sandstone oil and gas in Duzhai and Qiaokou area are influenced by pore and throat.Oil and gas occur short distance migration,and reservoiring in higher porosity and permeability sandstone,by the driving of source rock-reservoir pressure difference and sand body internal overpressure difference.Using fluid inclusion and fluorescent microscope to analysis the accumulation periods and time,then make a comprehensive comparison of space-time relationship between each accumulation factors in key accumulation periods.The results shows that early low maturity-mature hydrocarbon charging occurs in the late deposition of Ed.During this period Qiaokou area develops “ densifying after reservoiring ” type reservoirs,while Duzhai area develops “ reservoiring after densifying ” type reservoirs.Since the end of Nm,it occurs the late high mature oil and gas filling.Duzhai and Qiaokou area are all develops “ reservoiring after densifying ” type reservoirs,but compactness of Qiaokou is lower than Duzhai area.Comprehensive studies show that the accumulation mode of deep condensate gas in Dongpu depression for “ Temperature-pressure control phase,early as oil filling and late for gas filling,accumulate near the sag region,distribution in deep formation and quasicontinuous ”.The main controling factors include temperature and pressure environment control the petroleum filling phase in different accumulation period,and the reservoir densification process control the oil and gas filling capacity in different accumulation period,and the difference of lateral reservoir diagenetic control the migration dir-ection and position of gas.