近岸水下扇相油气分布规律及控制因素研究——以友谊油田沙三上亚段储层为例

大港友谊油田沙三上亚段为近岸水下扇沉积,具有3套独立的油水系统。由于油气分布规律复杂,且对储层认识不清,导致油藏开发效果一直很差。结合区域地质特征分析,以岩心分析资料、测井资料为基础,确定了沙三上亚段油气分布规律及控制因素。研究表明,岩相、沉积微相和成岩作用是沙三上亚段油气分布的主要控制因素,辫状沟道微相内砂岩发育的构造高部位是近岸水下扇储层油气分布的最有利区域。通过地层精细划分对比、相带及砂体展布研究以及岩相识别等技术,认为沙三上亚段有利油气分布区主要集中于庄42井—庄1605井—庄1604井—庄47井区以及庄93X1井区和东北部的辫状沟道砂岩分布区。

Hydrocarbon Distribution Patterns and Control Factors in Nearshore Subaqueous Fans System-With Es31 Reservoir in Youyi Oilfield as an Example

The Es31 of Youyi oilfield consists of nearshore subaqueous fans, and it can be subdivided into three microfacies: braided channel, sheet sandstone and middle channel, as three independent oil-water systems. The development of that part is not very ideal due to its complex hydrocarbon distributions and reservoir characteristics. Combined with regional geological features, the hydrocarbon distribution patterns and control factors were analyzed based on core and logging data. According to the sedimentary environment and physical properties, the lithofacies of Es31 can be divided into four types: conglomerate, sandstone, siltstone and mudstone. The sandstone type serves as high-quality reservoir. It is shown that lithofacies, microfacies and diagenesis are the main control factors for hydrocarbon distribution in Es31. In brief, the braided channel with sandstones in high position tectonically is the favorable region for oil accumulation. And the favorable regions of Es31 are mainly concentrated in Zhuang42-Zhuang47 and Zhuang93X1 well blocks, and the braided channel with sandstones in the northeastern part.