The researchers studied different types of sediment in the Shahejie Formation in the Gudong area. They found braided river delta, meandering river delta, and lake sediment. The braided river delta was a new discovery in the area. The sediment changed over time, with different types developing during different periods. The main areas for hydrocarbon sources were in the southeast and west. During one period, the source area moved back, leading to a large amount of lake sediment forming in the area.