中国近海含油气盆地新构造运动和油气成藏

新构造运动的成因主要是由于近代板块运动或地球深处壳幔物质交替、位移,以及陆架陆坡转折带沉积体的滑塌陷落、盆地快速沉降等因素诱发地壳区域应力场改变,在某些应力集中而失去平衡的区域,产生地体形变,或形成断裂。中国近海新构造运动的表现形式主要体现在:中新统末、上新统与第四系之间存在着不整合;中新统和第四系的沉降、沉积中心偏移;晚期断裂极其发育;天然地震比较活跃;具有新构造运动形成的各种晚期构造圈闭。中国近海新构造运动调整和控制了各含油气盆地的油气成藏和油气田的分布:渤海新构造运动控制渤中坳陷及其周围油气晚期成藏;莺歌海盆地底辟活动控制天然气晚期成藏;珠江口盆地新构造运动控制珠二坳陷北坡天然成藏;东海西湖坳陷新构造运动部分破坏了油气藏。

Neotectonic movement and hydrocarbon accumulation in petroliferous basins,offshore China

Neotectonic movements in offshore China are mainly represented by unconformities that occurred by the end of Miocene and between Pliocene and Quaternary, subsidence and migration of depocenter during Miocene and Quaternary, well development of late faulting,active earthquake,and various structural traps resulting from Neotectonism.Neotectonism is contributed to changes of regional stress field caused by various factors,such as recent plate movement,replacement and migration of crust and mantle in deep earth,slumping and depressing of sedimentary bodies in transitional zone between shelf and continental slope,and rapid subsidence of basins.Terrain deformation or faulting occurred in some areas where stress concentration resulted in losing equilibrium. Neotectonism in offshore China adjusted and controlled hydrocarbon accumulation and field distribution in each petroliferous basin.Neotectonism in Bohai Bay basin controlled late hydrocarbon accumulation in Bozhong depression and surrounding areas;diapirism in Yingehai basin controlled late gas accumulation;neotectonism in Zhujiangkou basin controlled gas accumulation in the northern slope zone of Zhu Ⅱ depression;while that in Xihu depression partially disrupted oil and gas reservoirs.