The Cenozoic in this area contains the Kongdian, Shahejie, Dongying, Guantao, Minghuazhen, and Pingyuan formations (Figure 2). The offshore Bohai Bay Basin experienced two tectonic episodes from the Proterozoic to the Mesozoic: (1) regional stable subsidence from the Middle to Late Proterozoic to the end of the Paleozoic and (2) the folding in the Mesozoic.