The northern shelf basins of South China Sea have the favorable conditions for the formation of non-structural reservoirs. In the geological history

frequent sea level fluctuations resulted in both vertical and lateral lithologic variations

leading to the formation of lithologic reservoirs

especially the low-level fans deposited on both the basin floor and slope during the lowstand. Frequent tectonic movements in the geological history resulted in many structural planes and structural unconformities

and so various types of unconformity reservoirs had correspondingly been formed. Exploration practices and research achievements show that the potential areas for non-structural reservoirs in offshore basins are as follows:(1) deep water areas where submarine fans are well developed

such as the central depression in Qiongdongnan basin

and Baiyun sag in Zhujiangkou basin; (2)frontal areas of large paleodeltas

such as Yingdong slope zone in Yinggehai basin and Yacheng 13-1 structural zone in Qiongdongnan basin; (3)sandbodies developed on the shelf

slope and basin floor around the diapiric structures in Yinggehai basin.