Coupling relationship between structure and sedimentary of the Paleogene Wenchang Formation in Panyu 4 Sag, Pearl River Mouth Basin

The Panyu 04 Area is located in the gentle slope zone of Panyu 4 Sag in the Pearl River Mouth Basin. Panyu 4 Sag has found having many oil fields in the Neogene, which is a "small and fat" hydrocarbon generating depression. However, no breakthrough has been made in the exploration of the Paleogene. Combining the well recording and logging, and 3D seismic data, the structural characteristics and evolution, provenance system, and sedimentary filling characteristics of the study area were systematically studied, the development and distribution of high-quality reservoirs explored, and their exploration potential analyzed. The results show that the NW-trending F1 fault controlled the structure of the Panyu 04 Area. The Wenchang Period experienced a tectonic evolution from the initial to the peak stage of rifting, and to the shrinkage stage of rifting. The provenance is mainly from the middle-low uplift of the Xijiang River in the north, the parent rock is granite, the transportation distance of clastic materials is average, and the composition maturity is high. Influenced by the Huizhou Movement and the clockwise transformation of regional stress field, the main faults in the study area are highly active in early Wenchang Period. The fault-controlled fan delta depositional system was developed in the lower Wenchang Formation, and was in overall inactive in late Wenchang Period. The slope-controlled braided river delta deposition system was developed in the upper Wenchang Formation, which favored high-quality reservoir development. Based on the restoration of prototype basin, we considered that the study area developed structural sedimentary pattern from early fault-control to late slope-control model. The upper and lower parts of Wenchang Formation show obviously different sedimentary filling characteristics, and there is a transition from fault-controlled fan delta to slope-controlled braided river delta. The research results provide an important basis for the Paleogene exploration in the gentle slope zone of Panyu 4 Sag.