Faulted basins are important oil and gas production bases in China. With the progress of hydrocarbon exploration

the proportion of the proved conventional oil and gas resources in the shallow and middle layers (depth3 500 m)has exceeded 60 %

and hydrocarbon resources in tectonic traps of the uplift area are exhausted after years of exploration. There is an increasing difficulty in exploring large-scale oil and gas reservoirs

and the focus is shifted to the exploration of middle and deep layers. Based on the researches of hydrocarbon generation

sedimentation

reservoirs and source-reservoir matching relationship in the Bohai Sea area

the paper systematically summarizes the petroleum geological conditions for tight oil and gas accumulation

which

in combination with the exploration practice of tight oil and gas

an analysis is conducted on the exploration potential of shale oil. The results show that under the control of fault activity

lake level rise and fall

and source supply intensity

there are four types of tight reservoir sedimentation in the middle and deep Paleogene layers

including near-source fan delta in steep slope zone

saline medium braided river delta

sublacustrine fan in slope and depression zone

and carbonate deposition in arid and uncompensated lake basin. When the burial depth exceeds 3 500 m

the reservoir is gradually densified under compaction

and the tight reservoir mainly exhibits the physical characteristics of low and ultra-low porosity and permeability. Deep burial depth

complex composition

and carbonate cementation are the main reasons for the development of tight reservoirs

and dissolution pores and fractures are the main storage spaces. There is relatively large accommodating space in deep depression areas during the pan-lake period

which is conducive to the formation and preservation of organic-rich shale

boasting of superior source rock conditions. The exploration practice of tight oil and gas in the Paleogene reservoirs has confirmed that the Bohai Sea area has the potential for large-scale exploration of tight lithological oil and gas reservoirs

and superior conditions for the development of shale oil as well as enormous resource potential. These unconventional oil and gas resources can provide an important foundation for sustainable exploration and discovery in Bohai oilfield.