A Facies Analysis and Sedimentary Architecture of the Paleogene Dainan Formation in the Gaoyou Depression, North Jiangsu Basin, Eastern China

Sedimentary facies of Paleogene Dainan Formation in the Gaoyou Depression, North Jiangsu Basin, as well as their distribution and evolution, are studied based on comprehensive analysis of cores and logging data. The results show that fan delta, delta, near-shore subaqueous fan, and lacustrine facies deposited in the Dainan Formation. Fan delta and near-shore subaqueous fan deposited in the southern steep slope. Delta deposited in the northern gentle slope. The sedimentary evolution of the Dainan Formation could be divided into two periods, in which the lake changed from shallow to deep, and then to shallow, the sedimentary area gradually enlarged, fan delta, delta and near-shore subaqueous fan prograded first, then retrograded, and finally prograded. It also shows that the fan deltaic subaqueous distributary channel and deltaic subaqueous branch channel have sandstones with well physical properties, which are the major reservoir facies belt of hydrocarbon.