吐哈盆地红台地区辫状河三角洲沉积体系研究

Depositional system of braided river delta in Hongtai Area of Tuha Basin

通过对研究区内11口探井的岩心进行观察分析,结合粒度特征、测井电性特征及地震属性等相关资料,认为研究区主要发育2种沉积相:辫状河三角洲和滨浅湖。三间房组底部的红色泥岩段主要发育滨浅湖相;从三间房组S4砂层组到七克台组的中下部均发育辫状河三角洲相。在三间房组S1—S4砂层组和七克台组Q1—Q2砂层组辫状河三角洲平原亚相和前缘亚相详细研究的基础上,建立了适合工区的辫状河三角洲沉积相模式,平原亚相进一步划分出辫状河道、河漫滩、心滩和河漫沼泽4种沉积微相;前缘亚相分为水下辫状分流河道、水下分流间湾、河口坝3种微相。

Through the core analysis of 11 exploration wells in research area,combined with the study of size characteristics,electric characteristics,seismic attribute,it is believed that there are two types of sedimentary facies： braided river delta and shore-shallow lake.The shore-shallow lake facies developed in the red mudstone section of the bottom of Sanjianfang Formation and the braided river delta developed from the S4 sands of Sanjianfang Formation to middle and lower part of Qiketai Formation.On the basis of detailed research of the braided river delta plain subfacies and front subfacies in the S1-S4 sands of Sanjianfang Formation and the Q2-Q1 sands of Qiketai Formation,we established the sedimentary facies model of braided river delta in the area.The braided river delta plain subfacies can be divided into four kinds of depositional microfacies： braided channel,flood plain,piont bat and flood swamp.And the front subfacies of braided river delta can be further divided into three types of depositional microfacies： underwater braided distributary channel,underwater distributary interchannel and mouth bar.