Sedimentation and controlling factor of gravity flow channels in the Huangliu Formation in the western of the Qiongdongnan Basin

In recent years, the Miocene lithological traps in the Western of Qiongdongnan Basin have become hotspots for exploration in the South China Sea. Many medium- and large-scale gas fields have been discovered. The discovered gas fields are all closely related to submarine fans and gravity flow channels. To discover more oil and gas reservoirs and to increase the success rate of lithological trap exploration, it is necessary to strengthen the recognition of channels and study the controlling factors. Based on 3D seismic data, drilled cores, wall cores, logging data, Formation Microscanner Image (FMI) logging, and analytical tests, the seismic facies, litho-electric facies, and sedimentation of the channels of the Huangliu Formation in the west area of the Qiongdongnan Basin were analyzed. The structure, sedimentation characteristics, and their controlling factors have been comprehensively studied. The results show that the Huangliu Formation in the west area of the Qiongdongnan Basin developed two phases of watercourses, which mainly developed five types of sedimentary microfacies: main channels, overflow-natural dike, landslide mud, inter-channel and continental slope mud. The formation and evolution of the two-phase channels and the direction of the main provenance are mainly controlled by sea level changes, paleomorphology and tectonic activities. In the early Huangliu Formation, the channels are mainly developed in the Yingqiong junction, which are characterized by a large number, small scale, strong branching, and braided features; the late Huangliu Formation channels are restricted to the central canyon in the Ledong-Lingshui Sag. It is a characteristic of single-branch axial restricted channel and multi-stage development in the longitudinal direction.