深水复合朵体内部沉积结构及其叠置模式——以尼日尔三角洲盆地Akpo油田中新统D油组为例

通过尼日尔三角洲盆地Akpo油田中新统D油组的岩心、测井和地震等资料，对其沉积单元构成、沉积微相、沉积演化及储层叠置模式进行了解剖，揭示了深水复合朵体内部的沉积结构。研究结果表明：①Akpo油田中新统D油组深水复合朵体由4期单一朵叶及3条分支水道组成，单一朵叶和分支水道交互作用，控制了深水复合朵体沉积演化；分支水道走向控制单一朵叶平面展布，单一朵叶生长影响分支水道的侧向迁移。②研究区深水复合朵体沉积微相可划分为朵叶主体、朵叶边缘、沉积性水道、侵蚀性水道和半远洋泥等5种类型。③根据各微相的空间接触关系，研究区深水复合朵体内部沉积结构可划分为边缘-边缘叠置、主体-主体叠置、上主体-下边缘叠置和上边缘-下主体叠置等4种模式，不同叠置模式的储层品质及连通性不同；分支水道对下伏朵体形成侵蚀改造，影响侧向连通性，影响程度取决于水道充填性质。该研究成果对尼日尔三角洲盆地Akpo油田的生产制度优化和井位部署具有指导意义，并取得了良好应用实效。

Internal sedimentary structure and stacking patterns of deep-water lobe complex:A case study of Miocene zone D in Akpo oilfield,Niger Delta Basin

Based on the core,well logging and seismic data of Miocene zone D in Akpo oilfield,Niger Delta Basin, the composition of sedimentary units,sedimentary microfacies,sedimentary evolution and reservoir stacking patterns were studied,and the internal sedimentary structure of deep-water lobe complex was revealed. The results show that:(1)The deep-water lobe complex of Miocene zone D in Akpo oilfield is composed of four stages of single lobe and three branch channels,and the sedimentary evolution of deep-water lobe complex is controlled by interaction between single lobe and branch channels. The trend of branch channels controls the plane distribution of single lobe, and the growth of single lobe affects the lateral migration of branch channels.(2)The sedimentary microfacies of deep-water lobe complex in the study area could be divided into five types:lobed axis,lobed margin,sedimentary channel,erosive channel and semi-pelagic mud.(3)Considering spatial arrangement of microfacies units,the internal sedimentary structure of deep-water lobe complex could be divided into four stacking patterns,including lobe margin with lobe margin,lobe axis with lobe axis,upper lobe axis with lower lobe margin and upper lobe margin with lower lobe axis,and different reservoir stacking pattern has different reservoir quality and connectivity. Branch channel erodes and transforms the underlying lobe,and then affects the lateral reservoir connectivity which is determined by the filling property of branch channel. The research results have guiding significance for the optimization of production system and well deployment in Akpo oilfield,and have achieved good application results.