庙西北洼西部陡坡带断裂特征与油气成藏

庙西北洼是渤海湾盆地东部一箕状洼陷,其西部陡坡带在剖面上具有不同的组合特征,发育不同的边界断裂结构类型,分为简单式和复式两种类型,其中复式断裂结构又包括座椅式、马尾式、阶梯式及复杂断阶带。该区在断裂控制下发育正牵引、逆牵引和滚动背斜构造样式,形成的圈闭类型包括断鼻、断块、逆牵引背斜和滚动背斜。断裂结构控制油气运移、富集成藏,马尾式和阶梯式断裂结构有利于油气的垂向疏导,座椅式断裂结构由于受坡坪的影响,运移能力稍差。断裂结构和圈闭的合理匹配是形成油气富集区块的关键。

Fracture characteristics and hydrocarbon accumulation of western steep slope in northern sag of Miaoxi

Northern sag of Miaoxi is a loop-shape sag in the east of Bohai bay basin.The western steep slope belt in profile presents different combination features,and develops different boundary fracture structure types(simple type and compound type).The compound fracture structure includes seat type,horsetail type,cascade type and complex fault terrace zone.Under the fracture control,different structural styles have been developed,namely normal drag structure,reserve drag structure and rolling anticline structure.The formed trap types include fault nose,fault block,inverse traction anticline and the rolling anticline.The hydrocarbon migration and accumulation are controlled by fracture structure,while the horsetail and cascade structure type are advantageous to vertical hydrocarbon channeling.Affected by Poping,the migration ability of seat structure type is poor.Therefore,the reasonable matching between fracture structure and trap matching is the key to the formation of hydrocarbon enrichment blocks.