西湖凹陷平湖斜坡带始新统平湖组碎屑沉积体系再认识

Reunderstanding of Clastic Rock Sedimentary Facies of Eocene Pinghu Formation in Pinghu Slope of Xihu Sag

西湖凹陷平湖斜坡带始新统平湖组(E2p)的沉积相类型还存在争议,为降低储层预测的风险,带动勘探开发研究深入开展,有必要对其进行更为深入的研究。目前主要观点认为平湖斜坡带E2p是受潮汐影响的三角洲和海湾-潮下带组合为主的沉积体系。通过对区域沉积背景的了解、层序地层划分及测井相研究,结合近两年地震解释和钻井成果,认为平湖斜坡带E2p是以砂岩为主的层段,砂体形态和沉积层序既不符合潮汐影响的三角洲体系,也不符合潮下带潮道等砂体微相,而是更接近浅水环境下辫状三角洲的沉积特征。

There existed dispute on the depositional types of Eocene Pinghu Formation(E2 p)in Pinghu Slope of Xihu Sag.In order to reduce the risk of reservoir prediction and promote a deep study of rolling exploration and development,it was necessary to carry out a deep study.At present the thick-bedded sandstone of Pinghu Formation(E2 p)is interpreted as delta gulf-subtidal deposit system influenced by tide.Through the understanding of regional deposit background,the sequence stratigraphic division and logging facies study,and in combination with seismic interpretation for recent 2 years and drilling results,it is considered that Pinghu Formation(E2 p)was a sandstone reservoir,where the sandstone shape and deposit sequence are not consistent with the delta system influenced by tide,and not consistent with the sandbodies of tidal channels in subtide,it is more likely a braid-delta deposit under shallow water environment.