渤海湾盆地隐蔽油气藏

THE SUBTLE RESERVOIRS IN BOHAI BAY BASIN

渤海湾盆地隐蔽油气藏的形成与分布 ,总体上受控于裂谷断陷湖盆的生成演化。中新生代以来 ,多旋回的挤压、走滑与伸展作用 ,使华北地台解体 ,地壳薄化 ,并形成由一系列掀斜断块组成的裂谷盆地。在盆地内 ,常出现含油的潜山披覆背斜构造、拖曳构造、重力滑动构造、冲断构造和不同时期不同类型构造复合叠加而成的复杂隐蔽断裂构造。受老第三纪构造旋回与古气候旋回控制 ,在沉积建造上形成了 5个不整合或假整合界面和 4套层序叠覆的层序结构 ,以及富于岩相岩性变化的断陷湖盆沉积。在水进超覆层内或水进超覆层之间 ,建造的低水位扇砂体、浊积岩体、生物碎屑灰岩与火山岩体等 ,极易形成大量的地层岩性油气藏和岩性与构造复合油气藏。

The formation and distribution of the subtle reservoirs in Bohai Bay basin are usually controlled by originating and evolving of the rift lake basin.Due to multi cyclical extrusion, strike slip and extension since Mesozoic Cenozoic, the North China Platform was separated and the crust was thinned,and some rift basin constituted by a series of tilt block were formed. In Bohai Bay basin, there are some oil bearing structures, such as buried hill drape anticline structure, drag structure, gravity slumping structure, thrust structure and complex subtle fault structure combined by inhomogeneous and asynchronous structure.Controlled by the cycle of tectonization and palaeoclimate in Palaeogene, there are five unconformity (or parallel unconformity) surfaces, four covering sequence structures and rift basin deposition that lithofacies and lithology often vary.As a result, a lot of litho stratigraphic reservoir and litho structural reservoir presenting in LTS (low system tract) fan sand body, turbidity,bio calclithite and volcanic rock in/between progressive onlap sequence can be formed.