渤海湾盆地黄河口凹陷SC7区块古近系东营组二段下亚段滩坝储集体构型特征

Architectural characteristics of beach-bar reservoirs in the lower submember of the 2 member of the Paleogene Dongying Formation in block SC7， Huanghekou Sag， Bohai Bay Basin

邵长印 宋璠 张世奇 王秋月

Changyin SHAO Fan SONG Shiqi ZHANG Qiuyue WANG

渤海湾盆地黄河口凹陷SC7区块滩坝是滨浅湖区的重要储集体，厘清其砂体内部结构特征对油气开发具有重要指导意义。根据现代沉积和岩心、录井、测井资料研究，对SC7区块古近系东营组二段下亚段（东二下亚段）砂体进行构型解剖，将厚泥-薄砂式滩坝划分为坝中心、坝侧缘、内缘滩、外缘滩和湖相泥5种沉积微相类型。基于厚泥-薄砂式滩坝成因和内部结构特征分析，研究了滩坝沉积特征、沉积模式和生长过程。将滩坝构型分为复合砂坝、单一坝和增生体3个级别，探讨各滩坝砂体构型单元空间展布特征。提出了单一坝坝间泥岩、测井曲线特征、相对高程差和单一坝侧向相变4种识别标志。用识别标志对密井网区单一坝进行划分，分析了单一坝规模、演化过程及连通性。在单一坝内部划分出4期增生体，最终确定了4级构型界面、单一坝侧向相变和单一坝内部增生体对油气分布的影响。

Beach bars in block SC7 of the Huanghekou Sag， Bohai Bay Basin are identified as important reservoirs in the shore-shallow lacustrine area. Figuring out the internal structural characteristics of the beach-bar sand bodies can offer significant guidance for hydrocarbon exploitation. Based on the examination of modern analogs and data on cores and logs， we carry out architectural dissection for sand bodies in the lower submember of the 2 member of the Dongying Formation （the Dong 2 lower submember） in block SC7， segmenting the beach-bar facies featuring thick mudstones and thin sandstones to five sedimentary microfacies： bar center， bar lateral margin， inner marginal beach， outer marginal beach， and lacustrine mud. By analyzing the origin and internal structural characteristics of the thick-mudstone and thin-sandstone beach bars， we investigate the sedimentary characteristics and pattern and growth process of the beach bars. Consequently， the beach-bar architectures are categorized into three levels， namely composite sand bar， single bar， and accretionary body， along with the exploration of the spatial distributions of these architectural units of beach bars. To identify single bars， we propose four indicators： inter-bar mudstone， logging curve characteristics， relative elevation difference， and lateral phase change of a single bar. Using these indicators， we identify single bars in the area with a dense well pattern， analyzing their scales， evolution process， and interconnectivity. Furthermore， four phases of accretionary bodies within single bars are determined， finally ascertaining the effects of 4-level architectural interfaces， single-bar lateral phase change， and accretionary bodies within single bars on hydrocarbon distribution.

10.11743/ogg20240213