柴北缘逆冲带侏罗系油气成藏主控因素分析

柴达木盆地北缘地区经过多年勘探,发现了以侏罗系为烃源岩的冷湖、南八仙及马北等油气田,通过对该地区石油地质条件综合分析,认为柴北缘侏罗系油气成藏主控因素具有以下特点:烃源岩的分布、成烃演化及生烃中心的位置控制着油气相态的分布格局;古近纪晚期和新近纪中期是柴北缘地区油气运聚的关键时刻,燕山期发育的古隆起和早第三纪发育的构造带是控制油气运聚的重要构造因素;中、新生界之间发育规模较大的区域性不整合面,第三系发育区域性分布的渗透性砂岩,为油气侧向运移提供了有利条件;晚喜马拉雅期盆内主控断裂及其派生断层的强烈活动,为油气垂向运移提供了有利条件。

Analysis on Main Control Factors of Jurassic Oil-gas Reservoir-forming in Thrusting Belt in Northern Margin of Qaidam Basin

The northern margin area in Qaidam Basin has been explored for many years, where some oil and gas fields such as Lenghu,Nanbaxian and Mabei ,whose hydrocarbon source rocks are mainly Jurassic sources, were discovered.Through comprehensive analysis of petroleum geological conditions in this area,it is considered that the main control factors of Jurassic oil and gas reservoir-forming in northern Qaidam Basin might be featured by as followings: a.The distribution of oil-gas phase state are controlled by the distribution of hydrocarbon source rocks, hydrocarbon evolution and hydrocarbon-generating center; b.Key time of oil-gas migration and accumulation in northern margin of Qaidam Basin is Later Eogene and Middle Neogene, the important structural factors that controlled oil-gas migration and accumulation are the paleouplift developed in Yanshanian period and structural belts developed in Eogene;b.The large-scale regional unconformity face developed between Mesozoic and Cenozoic eras and regional permeable sandstone distributed in Tertiary offer the favorable condition for oil-gas lateral migration;d. Violent activity of main-controlled faults and their derived faults in Later Himalaya period is helpful for oil-gas vertical migration.