Sedimentary, geochemical and reservoir characteristics of the Quaternary submarine fan in the Qiongdongnan basin

The South China Sea holds significant marine oil and gas resources, with the Qiongdongnan Basin being a key area. Submarine fans, as major marine reservoir systems, are crucial for storing natural gas and gas hydrates. However, research on the large Quaternary submarine fan in this basin is limited. Our study examines the importance of Quaternary submarine fans in the Qiongdongnan Basin, South China Sea, with a focus on their development. By utilizing 3D seismic data and core samples, our research aims to analyze submarine fan features and their developmental processes. The submarine fans are divided into four units, with Unit 1–2 submarine fans and internal waterways gradually increasing in size, and Unit 2 to Unit 4 submarine fans and waterway development decreasing in size. Through major and trace element analysis of core samples, we discovered that each major and trace element has different characteristics in different units, such as higher relative contents of Zr and Ti in Units 3 and 4, and higher relative contents of K in Unit 2. Simultaneously microscopic observations and reservoir characteristic parameters are utilized to evaluate the quality of submarine fan reservoirs. We reveal that Unit 2 has the best reservoir quality, followed by Unit 1, and that Units 3 and 4 have poor reservoirs quality This research enhances understanding of the sedimentary evolution of submarine fans in the Qiongdongnan Basin, offers insights into regional geological processes and contributes to global deep-water basin exploration and management.