Abstract:

The main source rocks is Paleogene, including Kongdian Formation (Ek )-Member 4 of Shahejie Formation ( Es⁴ ), Member 3 of Shahejie Formation( Es ³ ), Member 1-2 of Shahejie Formation(Es^-2) and Member 3 of Dongying Formation (Es³) in Liaodong Bay, Bohai Basin. They are mainly distributed in several sub-sags in three sags (Liaoxi, Liaozhong and Liaodong) in the region.  Based on the depositional  and tectonic development history, with combination of  geochemical and thermal parameters, etc, maturity evolution of source rock is modeled. The results of typical wells show that it exhibits an  obvious difference among sub-sags in Liao zhong sag. The maturity evolution history modeled by Basinview software also shows that there are different times to reach thresholds of oil generation and oil generation peak and gas generation phases for the same set of source rock in different sags: Es⁴-Ek source rocks entered threshold of oil generation during the end of Dongying Formation deposition period generally and they are up to high-over maturity phase now; Es ³、Es ^-2 and part of Ed³ source rocks entered threshold of oil generation during the end of Guantao Formation deposition period generally, Es³ and Es ^-2   source rocks are up to oil generation peak phase in part of Liaozhong sag now. The results of this paper can provide important parameters in prediction and evaluation of source rock, calculation of volume of source rock, and the amount of hydrocarbon generation and expulsion, thus it has a guiding significance for petroleum exploration in this region.

Key words:  , Liaodong Bay, Paleogene, source rock, maturity, vitrinite reflectance