东海陆架盆地台北坳陷前第三系油气地质特征

PETROLEUM GEOLOGICAL CHARACTERISTICS OF THE PRETERTIARY IN TAIBEI DEPRESSION OF EAST CHINA SEA SHELF BASIN

东海陆架盆地是发育于华夏板块之上的中、新生代叠合盆地 ,其下地壳性质与浙闽隆起区一致。盆地前第三纪主要发育侏罗—白垩系沉积 ,沉积岩主要分布于南部的台北坳陷内。中生代构造演化可分为早中生代坳陷盆地发育和晚中生代断陷盆地发育两个阶段 ,为下坳上断形式的中生代陆相复合盆地。盆地中生界具有形成油气藏的基本地质条件 ,其中中下侏罗统暗色泥岩及煤层为主要生烃岩系 ;上白垩统砂岩具较好的储集性能 ,储集空间以孔隙—裂缝型为主。

East China Sea Shelf Basin is a Mesozoic—Cenozoic superposition basin formed on the Huaxia plate and its underlying crustal feature is similar to Zhe-Min Uplift.In the basin,the Pretertiary is mainly composed of Jurassic-Cretaceous and the sedimentary rocks are mainly distributed in Taibei Depression in the south part of the basin.The Mesozoic tectonic evolution may be divided into two stages,i.e.the Early Mesozoic-developed depressed basin and the Late Mesozoic-developed fault-depressed basin,thus forming a lower-depressed and upper-faulted Mesozoic continental superposition basin.The Mesozoic in the basin is of the basic geological conditions of forming oil/gas reservoirs,in which the Middle-Lower Jurassic dark mudstones and coal beds are the major hydrocarbon source rock series and the Upper Cretaceous sandstones are of fairly good reservoir quality,reservoir space being mainly pore-fracture type.