Bongor盆地BNE区块沉积特征及油气富集规律

Sedimentary characteristics and hydrocarbon accumulation regularity of BNE block in Bongor basin

BNE区块PI油层组沉积时期为陆相湖泊沉积,岩心资料分析表明,区内沉积物具有近物源、水体深、堆积快、粗碎屑和带有牵引流性质的重力流沉积特征。结合测井资料分析,明确了沉积相/微相类型及分布特征,水下分流河道和席状砂靠近断层呈南西–北东向展布,分布范围较大,分流河道间发育较少,扇三角洲前缘主体东侧可见小规模滑塌浊积砂。油气的富集受构造、沉积和储层的综合影响,白垩纪两期裂陷控制了烃源岩分布,构造与岩性的叠加圈闭为油气聚集提供了场所,幕式的沉积演化形成了完整的生储盖组合,水下分流河道砂体物性好,层多且厚,利于油气富集成藏。

PI pay set of BNE reservoir is a continental lacustrine deposit.The analysis of core data shows that the sediment has the characteristics of near provenance,deep water,fast accumulation,coarse debris and gravity flow with tractive flow property.Combined with the analysis of logging data,the sedimentary facies types and distribution characteristics are identified.Subaqueous distributary channel and sheet sand are distributed in SW-NE direction near faults,and the distribution range is large.The development of interdistributary channel is limited,and there is a small scale of slump-turbidite sand on the east side of the fan delta front.Hydrocarbon accumulation is affected by structure,sedimentation and reservoir.The distribution of source rocks is controlled by two periods of Cretaceous rifting.The superimposed traps of structure and lithology provide a place for hydrocarbon accumulation.Episodic sedimentary evolution formed a complete source-reservoir-cap assemblage.The subaqueous distributary channel sand bodies have good physical properties and thick layers,which are beneficial for hydrocarbon accumulation.