Structural features and impact on hydrocarbon accumulation in Yangjiang Sag of Zhu Ⅲ Depression

The structural unit of Yangjiang Sag and its southern low uplift were redivided on the basis of fine seismic interpretation. The northern part of the low uplift vSeparated Yangjiang Sag into two sags, east and west, and the east one can be further divided into east 1 sub-sag and east 2 sub-sag. As the main controlling fault of east and west sags, the Yangjiang north fault can be divided into three parts, the west, the middle and the east according to the fault strike and the boundary of east and west sags. The west part controls the west sag, the middle part controls the east 1 sub-sag and the east part controls the east 2 sub-sag. Different parts of the Yangjiang north fault have different activity periods. The late Eocene and early Oligocene is the main activity period of the middle part, which controls the lacustrine sedimentation of Wenchang Formation and Enping Formation and has the best hydrocarbon potential. The inherited and superimposed extensional structural style is the main structural style of Yangjiang east and west sags, and the fault trap and drape-anticline trap are the main trap types. The exploration indicated that vertical migration and near-source accumulation are main accumulation patterns of Yangjiang east and west sags.