Abstract: The faults controlled oil and gas accumulation in the North Block-faulted Belt of Qaidam Basin.In the section,the North Block-faulted Belt developed three sets of fault systems including lower thrust fault system,upper detachment fault system and top normal fault system.The lower thrust fault system controlled the distribution of source rocks and the formation of primary reservoirs.The upper detachment fault system controlled the formation of mid-shallow traps and secondary reservoirs.The top normal fault system could destroy oil and gas reservoirs.The qualitative analysis and quantitative estimation showed that in the static period of fault,the lateral seal-ability of fault got better from deep to shallow in depth,and the vertical seal-ability of fault got better from west to east.In the active period,the faults became the key vertical channels for hydrocarbon migration in the researched area.The vertical migration channels in the North Block-faulted Belt constituted three migration models including the upper and lower fault connective model,unitary model and disjunctive model.The hydrocarbon migration ability of the connective and unitary models was better than that of the disjunctive model,which resulted in the difference of hydrocarbon accumulation in the North Block-faulted Belt.

Key words: Qaidam Basin, North Block faulted Belt, fault system, oil gas accumulation, oil and gas migration, control factors

摘要： 柴达木盆地北部块断带断层对油气成藏有控制作用.在剖面上,该区发育3套断层系统,即下部冲断层系统、上部滑脱断层系统和顶部正断层系统.下部冲断层控制烃源岩的分布及深层原生油气藏的形成,上部滑脱断层控制中浅层圈闭和次生油气藏的形成,而顶部正断层对油气藏具有一定的破坏作用.定性分析和定量评价表明,在研究区断层静止期,侧向封闭性由深到浅变好,垂向封闭性由西向东增强;在活动期,断层构成油气垂向运移的关键通道.油气沿断层垂向运移具有上下连通、归一和分隔3种模式,其中上下连通和归一模式的输导能力强,分隔模式的输导能力差.这是造成该区主要构造油气富集程度差异的主要因素.

关键词: 柴达木盆地, 北部块断带, 断层系统, 油气成藏, 油气运移, 控制因素