On the basis of reviewing the petroleum exploration history of the Bohai Sea Basin(the offshore part of the Bohai Bay Basin)and the related petroleum geologic theories

we summarized the Cenozoic tectonic-sedimentary evolution of the Bohai Sea Basin

and analyzed its petroleum geologic conditions

with focus on their significant differences from that of the onshore part of the Bohai Bay Basin.First of all

two sets of high-quality source rocks of the Shahejie Formation and Dongying Formation are developed as the results of two tectonic cycles of the Bohai Sea Basin.The distribution of source rocks of the Dongying Formation is limited to this basin

and the rapid subsidence in late stages contributes to its maturity

both of which manifest the more favorable hydrocarbon source conditions in the Bohai Sea Basin.On the other hand

shallow-extremely shallow-water deltas

a unique series of strata for exploration in the offshore part

are widely developed in the Neogene of the Bohai Sea Basin.In addition

the long-term sustained activities of the Tanlu fault zone in the offshore part eventually resulted in the play fairway with several large-and medium-sized oil and gas fields in the Bohai Sea Basin

which is an important field for oil and gas exploration in the Bohai Sea at present.It's of referential value for future Bohai Sea exploration and related studies to fully understand the particularity of evolution of the Bohai Sea Basin and its unique petroleum geologic conditions and oil and gas accumulation patterns.