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延吉盆地是吉林省东部的一个山间断陷盆地，其东部坳陷下白垩统大拉子组一、二段为天然气的区域性盖层，盖层的排替压力在１１～１３ＭＰａ范围内，属强封闭能力盖层。研究区断层发育，断层在大一、二段内封闭性好，在下白垩统铜佛寺组内封闭性差；边界断层封闭性差，盆地内部断层封闭性从古至今逐渐变好。研究区主要储层为铜佛寺组和大一、二段，均属低孔、低渗储层。通过对古流体势场的恢复发现，德新凹陷的油气运移以汇聚流形式为主，清茶馆凹陷的油气运移以发散流和平行流形式为主。根据生、储、盖、断层及流体势场等特征的研究，总结出东部坳陷油气运聚模式有３种，即背斜聚敛型油气运聚模式、断层部分截流型油气运聚模式和汇聚流运移断层泄漏型假聚集模式。

OIL GAS MIGRATION AND ACCUMULATION MODES OF THE EAST DEPRESSION IN THE YANJI BASIN,

??Located in the east part of Jilin Province,Yanji Basin is an intermontane rift-subsidence basin.The member 1 and member 2 in the Lower Cretaceous Dalazi Formation in the east depression of the basin act as regional caprocks with threshold pressure of 11??13 MPa.Faults are development in the researched area.The faults in Da 1 and Da 2 members are well closed,but those in the Lower Cretaceous Tongfusi Formation are poorly closed.The boundary faults are also poorly closed,and the sealing ability of the internal faults of the basin gradually increased through geologic time.Tongfusi Formation,Da 1 and D2 members are the main reservoirs with low porosity and low permeability in the area of interest.Rebuilt palaeofluid potential field indicates that petroleum in Dexin Sag is migrated in the form of convergence flow,and the oil-gas migrations in Qingchaguan Sag are mainly in divergence flow form and in parallel flow form.According to the characteristics of source-reservoir-cap,faults and fluid potential field,it is concluded that there are three oil-gas migration and accumulation modes in the east depression,that is anticline convergence mode,fault partial intercepting flow mode and the convergence flow migration and fault leakage mode.