NEOGENE DEPOSITIONAL FEATURES AND FAVORABLE RESERVOIR-CAP COMBINATIONS IN THE DEEPWATER OF QIONGDONGNAN BASIN, NORTHERN SOUTH CHINA SEA

Abstract

The Qiongdongnan basin,northern South China Sea is a quasi passive continental margin in terms of its tectonic characteristics.There are favorable exploration perspectives in the deep-water area of the basin.According to the principle of sequence stratigraphy,integrated interpretation of depositional characteristics of reservoirs and reservoir-cap combinations in the Neogene has been made based on high resolution seismic data and well data.In the study area,there occur two types of reservoir-cap combinations in the Neogene sequence,one formed in the shallow water environment(the Epicontinental Sea) and the other in deep water environment(the Continental Slope).Depositional models for both the shallow water deposits and the deep water deposits were established in this research.The reservoir-cap combination formed in the shallow water environment include lowstand sandstone of the Meishan Formation or Huangliu Formation,shallow marine mudstone,organic reef limestone of the Meishan Formation and deep water mudstone,whereas the reservoir-cap combination formed in the deep water environment include turbidite channel sandstone of the Huangliu Formation or Yinggehai Formation,and deep water mudstone,highstand deltaic sandbodies of the Yinggehai Formation..Upon the study mentioned above,a reservoir prediction model was proposed and preliminary evaluation has been made.