The application of the distributive fluvial system in the South Xihu depression, East China Sea and its indication of oil and gas potential

Taking the South Xihu depression as a study case, the authors applies the research idea of distributive fluvial system (DFS) to the study of the sedimentary system of the East China Sea Basin. By summarizing the forming conditions of large DFS, it is concluded that the south Xihu depression is near the source and under stable tectonic condition, and there also exists large basin and mountain systems, which is favorable for forming large DFS. Based on the characteristics of the core and paleontology of Huagang Formation, the author divided branch channels into some types, and indicated that the main types of FS are braided bifurcating and single braided channels. Different types of channels have the potential for developing thick sand bodies. Combined with the features of the paleotopography and sedimentary system distribution, the study of the patterns of DFS distribution shows that the study area has developed two sets of DFS, which are distributed respectively from western slope to the northeast and southeast. The DFS end belongs to "the axial end" type, suggesting that the axial limited rivers of Xihu depression and DFS has formed a convergence zone with reservoir exploration potential.