鄂尔多斯盆地东缘韩城剖面下石盒子组沉积相

Sedimentary Facies of the Lower Shihezi Formation in the Hancheng Section of the Eastern Margin of the Ordos Basin

鄂尔多斯盆地东缘上古生界盒8段为主要含气层,沉积环境与储层息息相关,为明确下石盒子组沉积环境,通过对韩城剖面进行实测,结合剖面颜色、薄片鉴定、粒度分析、主微量元素特征、古生物特征、岩相特征等相标志分析,讨论下石盒子组沉积相。研究表明:盒5、盒6、盒7段沉积环境为辫状河三角洲沉积,发育分流间湾、水下分流河道、河口沙坝沉积微相;盒4段沉积环境为湖泊沉积,发育滨浅湖沉积微相。

Upper Paleozoic He-8 member in the eastern margin of the Ordos Basin as the main gas bearing layer,the sedimentary environment is closely related to the reservoir.In order to clarify the sedimentary environment of the Lower Shihezi Formation,the sedimentary facies of the Lower Shihezi Formation were discussed through actual measurement of the Hancheng section,combined with analysis of facies indicators such as section color,thin section identification,particle size analysis,major and micro element characteristics,paleontological characteristics,and lithofacies characteristics.Research has shown that through in-depth exploration of the Hancheng section,it has been identified that the sedimentary environment of the He5,He6,and He7 sections is braided river delta sedimentation,with the development of sedimentary microfacies such as inter distributary bays,underwater distributary channels,and estuarine sandbars;The sedimentary environment of the He4 section is lacustrine sedimentation,with the development of shoreline and shallow lake sedimentary microfacies.