Sedimentary Genesis and Distribution of High Argillaceous Sandstone

Area A is located in the east of Yangjiang Sag in Zhusan Depression, Pearl River Mouth Basin. The Neogene Hanjiang Formation in this area has deposited a large number of sand, silt and mud mixed clastic sediments, with different particle sizes and complex composition. Predecessors have done some research on lithology, sedimentation and reservoir of this Formation, but the understanding of genesis and distribution of high argillaceous sandstone is not clear. In this paper, the genesis and vertical distribution of high argillaceous sandstone in Hanjiang Formation are analyzed by core, logging and analytical test data. Combined with high resolution seismic data, the density and seismic elastic parameters inversion method are used to clarify the plane distribution characteristics. The results show that high argillaceous sandstone is mainly distributed in deltaic front underwater distributary channel, interdistributary bay and distal bar. Sediment deposition rate of deltaic front underwater distributary channel is fast, low energy hydrodynamic can not be fully scoured sediment screening, resulting in high mud content. The hydrodynamic conditions of deltaic front interdistributary bay and distal bar are weak, and fine-grained and argillaceous sediments are deposited in large quantities, so the argillaceous content of sandstone is high.