Researchers studied sedimentary systems in the north Songliao Basin to predict hydrocarbon reservoirs. They used modern sedimentology, sequence stratigraphy, and geophysics methods, analyzing cores, logs, seismic data, and fossils. The fourth-grade sequence1 transgressive tract in the Qingshankou Formation contains delta and lacustrine facies, with sand bars and muddy beaches. Sandstone bodies are found in condensed sections, making them ideal for reservoir development.