惠民凹陷沙河街组三段岩性油藏勘探方向

EXPLORATION TREND FOR LITHO-OIL RESERVOIR IN 3rd MEMBER OF SHAHEJIE FORMATION OF HUIMIN DEPRESSION

惠民凹陷沙河街组三段经井 -震标定后 ,可以识别出 7个层序界面 ,其中T7,T6,T4和T3 为最大湖泛面 ;T6′,T4′,T3 ′为沉积作用转换面。据此 ,将沙河街组三段划分为 3个中期基准面旋回 (C3 ,C2 ,C1)。C3 期 ,盆地强烈沉积 ,形成小型浊积扇 ;C2 期 ,中央隆起带形成 ;C1期 ,控边断裂活动减弱 ,形成了分布稳定的泥岩段。根据以上层序分析 ,基山砂体和江家店地区有可能发育岩性油气藏 ,基山砂体主要形成于C2 旋回期 ,发育浊积扇砂体 ;江家店地区在C3 ,C2 旋回时期 ,在惠民凹陷西南部发育双丰三角洲 -滑塌浊积扇岩性圈闭 ,在夏口断层下降盘发育曲堤三角洲或近岸水下扇体

sequence interfaces can be identified through demarcation by well drilling and seismic detection in 3rd member of Shahejie Formation of Huimin depression,of which T7,T6,,T4,T3 are believed to be maximum lake flooding plane and T6-1,T4-1,T-3 are discovered to be transitional plane of sedimentary process.Therefore,3rd member of Shahejie Formation can be divided into 3 middle basic level cycles(C3,C2,C1).During C3 period,small-scale of turbidite fans were formed due to intensely deposition of the basin.During C2 period,central uplift belts were formed.In C1 period,wide spread of stable mudstone intervals were developed due to gradually weakening of fault-controlled activities.Litho-hydrocarbon reservoirs might have been developed in Jishan sandbody and in the area of JiangJjiadian on the basis of above sequence analysis.Jishan sandbody was largely formed in the period of C2 cycle,developing in turn turbidite fan sandbodies,delta of twist embankment( offshore underwater fan body)-turbidite fan litho-traps were developed along down-dropped blocks of Xiakou fault.