The Nanpu Sag in the Bohai Bay Basin underwent complex rifting evolution in the Paleogene period. The researchers identified two main phases, with the syn-rift stage having four episodes. During the fourth episode, intense faulting and subsidence occurred, affecting the deposition of the Dongying Formation. This stage had unique characteristics compared to other areas in the basin, with significant fault activity and subsidence migration. The findings highlight the importance of the Dongying Formation for hydrocarbon exploration in the Nanpu Sag.