江苏高邮凹陷马家咀-黄珏地区下第三系渐新统戴南组和三垛组一段含油气砂体沉积相特征

The Oil-Gas Sandbody Types and Sedimentary Facies Character of Eogene Oligocene Series Dainan Fm(Ed)Sanduo Fm(Es) about Majiazui-Huangjue area in Gaoyou depression Jiangsu Province

通过对马家咀-黄珏地区钻井岩心的系统观察和研究,作者认为,扇、湖组合是区内下第三系渐新统的主要沉积相。戴南组一段和戴二段下部砂体为近岸水下扇;戴二段上部砂体为滨湖冲积扇;三垛组一段为洪积扇,二段为河流相。砂体自下而上,有规律的相带演变,反映了本区湖体变浅、萎缩、衰亡、演变为河相冲积平原的过程。本区砂体由水下扇发展到洪积扇,其沉积机理一脉相承,受南缘江都-吴堡同生边界断裂的制约。各种扇体的扇中亚相是最有利于油气聚集的相带。

The Gaoyou depression is a faulted basin_p formed in Late Mesozoic. In Eogene sediment about 3000～4000M in thickness had been accumulated in it. On the southeast edge of the basin existed Jiandou-Wubao Synsedimentary fault. Along the foot of the fault a series of sandbodies of oligocene Dainan Formation(Ed)-Sanduo Formation (Es) are well depositional. Through investigation of the characteristics of the rocks and minerals, sedimentary struetures and sequences, grain size and electronic logs of the sandbodies of oligocene series, we find that they belong to four sedimentary facies as follows: 1. The subaqueous alluvial fan (main type of Ed1), 2. The lake-shore alluvial fan (main type of Ed2), 3. The diluvial fan (main type of Es1). 4. The fluvial facies (main type of Es2). In the sandbodies of above mentioned fans there have been fond oil and natural gas resource and the midfan subfaeies is the fittest subfacies for reserving the oil and gas resource.