Abstract: Channel sandstone is the most important oil and gas reservoir type in deep-water sedimentary systems. A large-scale axial channel deposition system is present in the Yinggehai and Huangliu Formations in the Ying-Qiong Basin. Axial channels are considered an important area for oil and gas exploration in the Ying-Qiong basin, and are valued by domestic and international companies. However, due to a lack of systematic understanding of the formation mechanism and distribution of sandstones in such axial channels, exploration thus far has been unable to yield a commercial breakthrough. This study aimed to resolve issues of provenance and reservoir distribution, which have restricted the exploration of axial channel depositional systems. The central valley, which is the most representative axial channel in the Qiongdongnan Basin, was taken as an example. Combined geological and seismic analysis, multi-attribute integration technology, seismic sedimentology, and other new technologies suited to canyon channel systems were applied in this study. We then carried out targeted research on the provenance system, sedimentary evolution, and reservoir distribution, thereby clarifying the provenance, sedimentary evolution and quality reservoir distribution patterns of the central valley channel. We have also established a sedimentation model and channel sandstone superimposition method for the central valley, which could be used to predict the structure of the reservoir. Our results revealed the existence of four potential large lithologic traps, such as in the Ledong 10-1 Valley channel. These areas are favorable for the next step of exploration of axial channels, thus greatly enhancing their exploration potential.

Key words: Ying-Qiong Basin, axial channel, central valley, filling evolution, reservoir distribution