溱潼凹陷西部内斜坡戴一段沉积相研究

根据溱潼凹陷西部内斜坡戴一段的岩石学、粒度分布、沉积构造及测井相特征,综合分析认为,该区戴一段主要发育水下分流河道、河口坝、分流间湾、远砂坝、席状砂、前三角洲泥6类沉积微相。水下分流河道自南东向北西方向展布,席状砂平面分布广泛。戴一段整体为一套正旋回沉积特征,从Ⅲ油组到Ⅰ油组,水体面积不断增大,反映了一个水体不断加深、沉积厚度不断减小的退积过程;沉积相序自下而上由三角洲前缘亚相逐渐演化为前三角洲亚相。

Sedimentary facies of the first member of the Dainan formation in western inner slope of Qintong Sag

According to the petrology, granularity distribution, sedimentary structure and well logging features of the first member of Dainan formation in the western inner slope of Qintong Sag, it is considered that there are 6 types of sedimentary microfacies including underwater distributary channel, interdistributary bay,channel mouth bar, distal bar, sand sheet and predelta mud in the study area. Underwater distributary channels are distributed from southeast to northwest, and the sheet sand is widely distributed. As a whole, the first member of Dainan formation is a positive cycle of sedimentary characteristics, from Ⅲ oil toⅠoil group, the water area is increasing, reflecting a deepening water falling, sedimentary thickness of retrogradation process.From bottom to top, the sedimentary facies sequence gradually evolved from delta front subfacies to predelta subfacies.