靖边气田二叠系石盒子组盒8段沉积微相研究

摘要

靖边气田二叠系的主要含气层为石盒子组盒8段,为了查明该区砂体展布特征,笔者在资料收集、岩心观察和测井曲线综合解释的基础上,对研究区60余口井的石盒子组盒8段沉积微相进行了详细研究,认为1）三角洲-湖泊沉积体系是靖边气田二叠系主体沉积类型之一。2）砂体分布明显受沉积微相的控制：本区北部,砂体受河道、分流河道和水下分流河道控制,砂体呈近南北向展布;本区南部,砂体主要为滨浅湖滩坝和席状砂,砂体呈近东西向展布。3）频繁的脉动式的湖平面升降和湖岸进退控制了相带的迁移和砂体的展布,湖平面下降,三角洲作用活跃时期,砂体相对发育。因此,盒8下2段、盒8上2段水下分流河道砂体、河口坝砂体是本区最有利的储集层段。%The main gas-bearing reservoir of Permian in the Jingbian gas field is He8 of the Shihezi Formation.In order to identify the sand body distribution characteristics of this area,sedimentology,petrography and paleogeography,logging geology are used in this article.On these bases,the sedimentary microfacies are studied in detail.It is suggested that delta-lake depositional system is one of the main types of sedimentation in the Jingbian gas field.The distribution of sand body is clearly controlled by the sedimentary microfacies.In the north of this area,controlled by the channel,distributary channel and underwater distributary channel,sand body lanes are near north-south spread.In the south of this area,the sandbody is belong to shore shallow sandbeaches and sheet sand,sand body lanes are near east-west spread.Frequent pulse of the lake level and shoreline advance and retreat movements controls the migration of facies and sand body distribution,when the lake level drops,the role of delta actives,the sand bodies are relatively developed.So the sandbody in subaqueous distributary channel and channel-mouth bank are the most favorable reservoir sections in this area.