Tight sand gas plays were found in the Lower Cretaceous of Changling fault depression in the Songliao Basin. The sedimentary facies during the transition from a fault depression to a sag were braided river and braided river delta, with other facies like alluvial fan and fan delta. The distribution of fan deltas and depocenters was controlled by faulted steep slopes, while gentle slopes controlled braided rivers and deltas. In the late stage, only one depocenter remained in the north, with sediments moving from the south to the north. Braided rivers filled the main area of Changling Sag, forming potential reservoir belts in the Denglouku Formation and lower Quan I member.