东濮凹陷盐湖层序结构与隐蔽油气藏

东濮凹陷岩盐层序的低位体系域主要为厚层块状岩盐夹薄层泥岩和砂岩,地震上表现为强振幅连续反射;湖侵期为深湖-半深湖相泥岩夹薄层岩盐和重力流砂体;高位体系域为厚层块状岩盐夹薄层泥岩和砂岩。东濮凹陷沙河街组古生物化石资料显示,藻类生物发育,缺少淡水种类,介形虫成层出现,说明盐类沉积环境以潮湿和半干旱气候交替为主,在还原的深湖-半深湖的背景中仍有碎屑物供给。该区盐湖隐蔽圈闭多发育于盐类重力流扇体和盐湖碎屑重力流透镜体中。

SALINE LAKE SEQUENCE STRUCTURE OF DONGPU DEPRESSI ON AND SUBTLE RESERVOIR

Lowstand system tracts in rock salts sequence of Dongpu depression are predominantly composed of thick-massive rock salts intercalated by thin layers of mudstone and sandstone,showing in seism a continuous reflection with strong amplitude.The lacustrine transgression phase is characterized by sandstone with intercalation of thin layers of rocks salts and gravitational flow rock of deep and semi-deep lacustrine phase.Highstand system tracts are formed by thick-massive rock salts intercalated by thin layers of mudstone and sandstone.Palaeobiological fossil data collected from Shahejie Formation of Dongpu depression indicate that the development of algal-biologies,lack of freshwater biologies and mussel-shrimps appeared in layer have given a clear picture of the depositional environment of rock salts characterized chiefly and alternately by moisture and semi-arid climate,and with clastics supply even in the background of reduced deep lacustrine and semi-deep lacustrine phase.Subtle traps of Saline lake in this region are developed commonly in salt gravitational-flow fans and gravitational lenticular sandbodies of salt clastics.