The lower part of Denglouku Formation in northern Xujiaweizi area, Songliao Basin, consists of three main sedimentary facies: fluvial, braided delta, and lake facies. These facies can be further divided into 6 subfacies and 13 microfacies. The reconstructed palaeogeographic map shows a central lake surrounded by fluvial rivers and braided delta facies. The thick sandstone and conglomerate in the braided delta and fluvial facies are good reservoirs, while the dark mudstone in the lake facies serves as a source rock for hydrocarbons. This combination of reservoir and seal is favorable for oil and gas exploration in the area.