叠覆式浅水三角洲储层结构分析——以东濮凹陷文79南断块沙二下亚段为例

Reservoir architecture analysis of overlying shallow water delta: a case study of lower Member of Sha2 in south block of W79 in Dongpu Sag

采用传统的分流河道型浅水三角洲储层构型模式,难以表征文79南断块局部大面积连片分布的砂体。文中以叠覆式浅水三角洲沉积模式为指导,利用岩心、三维地震、测井以及生产动态资料,结合现代沉积调查和沉积数值模拟,综合应用层次分析和建筑结构要素法,对研究区浅水三角洲砂体进行精细解剖:将储层内部结构划分为叠覆复合朵体、单期复合朵体、复合朵体内部单朵体3个主要的层次格架;识别出叠覆复合砂体、单个复合砂体、复合朵体内部单砂体和薄层砂等4种结构要素及朵体主体和主体侧缘2种岩相。根据目的层大量的解剖实例,提出了紧密叠覆型和分离叠覆型朵体2种储层构型发育模式,初步建立了叠覆式浅水三角洲储层构型模式,为剩余油研究提供了新思路。

It is difficult to characterize the partial extensive sand of the south W79 fault block by using traditional distributary channel-type shallow-water delta reservoir architecture model. Guided by the overlying shallow-water delta sedimentary model, using cores, 3D seismic data, well logging and production dynamic data, combined with modern sedimentary survey and sedimentary numerical simulation, the fine architecture of shallow water delta sand in the study area has been analyzed by applying hierarchy analysis and architecture-element analysis process;the internal architecture of the reservoir is divided into overlapping composites, single-stage composites, and single-lobe inside the composite three main hierarchies. Four architecture-elements of overlapping composite sand, single composite sand, internal single-lobe inside the composite sand and thin sand layers have been identified, and the main part and the lateral edge of the lobes also have been distinguished by lithofacies characteristics. According to a large number of anatomical examples of the target layer of the study area, two reservoir development patterns are proposed: tightly overlaid and separated overlaid lobes. The reservoir architecture model of overlying shallow water delta is preliminarily established, which provides a new geological idea for the study of remaining oil.