陡坡带扇三角洲高分辨率层序地层学——以柳赞油田北区沙三~3亚段下部砂层组为例

High-resolution Sequence Stratigraphy for Fan Delta at Steep Slope Belt: Taking the Lower Sand Groups of the Third-submember Sedimentation of MemberⅢ of Shahejie Formation in the North Region of Liuzan Oilfield as an Example

在详细分析扇三角洲沉积相特征的基础上,结合地震、岩芯及测井资料,对柳赞油田北区沙三3亚段下部砂组进行了高分辨率层序地层学分析。结果表明:研究区发育典型的粒度向上变粗的水退型扇三角洲沉积,并可进一步划分为扇三角洲平原、扇三角洲前缘和前扇三角洲3个沉积亚相;以及辫状河道、辫状河道间、水下分流河道、分流间湾、河口坝和席状砂6个微相。采用"井震结合、模式指导、标志层控制、旋回对比"的方法建立了全区高分辨率层序地层格架。影响层序格架内扇三角洲储层砂体的几何特征与分布模式的主要因素为中期旋回A/S比值和古地形。研究对于油田开发中后期地层对比和井网调整具有重要指导意义。

Based on the detailed analysis of sedimentary facies features of fan delta,core,logging and seismic data are used to perform detailed high resolution sequence stratigraphy analysis of the lower sand groups of the third-submember sedimentation of MemberⅢ of Shahejie Formation in the north region of LiuZan Oilfield.The results show that progradational fan delta is well developed in the research area.Fan deltas there can be subdivided into three subfacies and six microfacies,showing coarsening upward succession.Based on the recognition of various grades of base-level cycles,high-resolution sequence stratigraphic framework is built.Geometric features and distribution pattern of the reservoir sand bodies of fan delta in stratigraphic framework are significantly controlled by A/S ratios in medium-term base level cycles and ancient landform.The study result has guiding significance for stratigraphic correlation and well pattern adjustment in middle and later period of oilfield development.