Genetic evolution and exploration strategy of submarine fan in the Meishan Formation, Qiongdongnan Basin

As the most striking large reservoir outside the central canyon channel, the submarine fan of the Meishan Formation is the next most important exploration object in the conventional clastic rock field of the Qiongdongnan Basin, especially in the deep-water area. The differential distribution of submarine fans in the Meishan Formation was revealed by the drilling data of various sags in the Qiongdongnan Basin. Based on the exploration of continental shelf and continental slope break in the study area, the provenance and source supply, dominant paleo-current direction, geological background differences and causes of submarine fans in different sags in the central depression of the Qiongdongnan Basin were analyzed in macro-pattern for the first time. It is proposed that the main material source of the large submarine fan of the Meishan Formation in Ledong Sag was from the Northeast Hainan Uplift. By anatomizing secondary sea-level cycles in the Middle Miocene regression, the accurate corresponding relationship between sequence filling and sea-level cycles of the Meishan Formation in this area was established, and the development and evolution of submarine fans in each sedimentation stage of the Meishan Formation and the favorable reservoir distribution at sag level were clarified from the perspective of sequence genesis. Therefore, the corresponding exploration strategies were put forward, from which the reservoir risk of Meishan Formation submarine fan in Ledong Sag was believed low and thus the submarine fan should be considered the first choice for breakthrough in the future exploration. Meanwhile, the early trap of the submarine fan in Lingshui Sag was effective, providing a favorable condition for large-scale reservoir formation of the Meishan Formation submarine fan. This study presented a new insight to the exploration deployment in the Meishan Formation submarine fan.