The researchers studied the sedimentary microfacies of the Fuyu oil-bearing layer in the Songliao Basin. They used core observation, well-logging curve analysis, and other methods to analyze the rock types and lithofacies. The results showed that the reservoirs are meandering river-delta facies deposits, with different microfacies like gravel lag-deposit and river mouth bar. The best reservoir properties were found in meandering river and distributary channel sandbodies. The sedimentary facies changed from fluvial to river-delta as the lake transgressed, leading to broader meandering river channels and regional sandbody distribution.