The researchers analyzed sedimentary facies in the Bonan Sag of Bohai Bay Basin using GIS. They found that the main reservoir sandbodies in the area are braided fluvial deltaic deposits, with one sandy interval originating from deep-water turbidites. The sedimentary gradients varied between different sandy intervals, with the 9th interval having steeper gradients near the Gudao Uplift. This study helps us understand the depositional and tectonic settings of the basin and the characteristics of the reservoir sandbodies in the area.