惠民凹陷临南地区古近系沙三下亚段沉积特征

Sedimentary characteristics analysis of the lower part of the third member of Paleogene Shahejie formation,Linnan area,Huimin depression

惠民凹陷临南地区古近系沙三下亚段沉积相类型及砂体展布规律复杂,制约该地区进一步中深层勘探.根据岩心观察、录井、测井及地震等资料对研究区进行沉积学研究,分析各沉积微相的识别标志、沉积特征及分布规律.结果表明:临南地区古近系沙三下亚段广泛发育三角洲前缘沉积,在三角洲前缘细粒沉积的大背景下,发育下切谷充填沉积.三角洲前缘沉积主要以细粒沉积为主,划分为三角洲前缘水下分流河道、分流间湾、河口砂坝和远砂坝4种微相;下切谷充填沉积以粗粒沉积为主,划分为下切谷水道、水道天然堤和水道间漫溢3种微相.该研究成果为该地区下一步勘探提供指导.

The sedimentary characteristics and sandbody spatial distribution of the lower part of the third member of Palaogene Shahejie formation,Linnan area,Huimin depression were unclear and this seriously hampered the further exploration of this area.Based on the core observation,logging and seismic data,the sedimentary facies,identification mark,sedimentary characteristics and the distribution of each microfacies of the lower part of the third member of Palaogene Shahejie formation,Linnan area,Huimin depression were detailed studied.The results showed that:delta front deposits were widely developed in this area and incised valley was existed under the background of the fine grained sediments of the delta front.Delta front deposits were dominated by fine grained sediments which contained microfacies of the underwater distributary channel,the channel mouth bar,the distal bar,and the interdistributary estuary.The incised valley deposits were mainly composed by coarse grained sediments which contained microfacies of the incised valley channel,the channel levee and the channel overflowing.The research results will serve as a guidance for the next step of the exploration in this area.