塔里木盆地库车河-克拉苏河地区白垩系储集砂体特征精细研究

A Fine Study on Deposition Characteristics of the Cretaceous Reservoirs of Kuqa River-Kelasu River Area in the Northern Tarim Basin

基于塔里木盆地北缘库车河与克拉苏河地区白垩系系统的野外观察和沉积地质学的精细描述,在巴西盖组和巴什基奇克组分别识别出陆相冲积体系的辫状河三角洲-湖泊沉积体系及扇三角洲沉积体系。通过对三角洲主要砂体的实测与写实,特别是基于对复合砂体和单砂体大比例尺(1∶50)的精细研究和系统的实测数据,研究结果表明:在研究区白垩系地层中,三角洲大型复合砂体和单砂体规模大,垂向上,砂体呈现出规律的正粒序渐变与反粒序的旋回叠置;在横向上,砂体均发生侧向减薄或尖灭,反映三角洲环境下河道由西至东的迁移发展及叠加,砂体侧向接触关系分为突变接触和渐变接触关系。

Based on field observations and detail studies of Cretaceous of sedimentary geology in Kuqa River-Kelasu River Region of the northern Tarim Basin,an alluvial depositional system of fan-delta and braided delta and lacustrine facies were recognized in the continental allvial system in Baxigai Formation and Bashijiqike Formation.By field detecting the delta sand,especially by using the data of high scale(1∶50)and fine description based on the composite sandbodies and single sandbody,the result indicates that in the Cretaceous system,the big delta composite sandbodies and single sandbody are large scales,vertically the sandbodies present regular and normal particle order that is gradually turned into opposite particle order of cyclic superposition,horizontally the sandbodies are thinned or pinched out laterally,it represents that the channel is migrated and superposed from the west to east,the relation of lateral sand contact is presented as abrupt contact and gradational contact.