Distribution of stratigraphic and lithologic reservoirs in sequence framework of rift-subsidence basin

The characteristics of stratigraphic and lithologic reservoirs distributed in sequence frameworks of Dongying, Zhanhua, Nanpu and West Depressions of Bohai Bay Basin were analyzed by using sequence stratigraphy. The sequence boundaries controlled distribution of stratigraphic reservoir. Good source rocks of lake expanding systems tract in the third-level sequences of the main rifting episode controlled horizons of lithologic reservoirs. The lowstand systems tract and highstand systems tract sand-body controlled by basin edge valleys and the structural slope-break zones are the main lithologic reservoirs. Good arranged regions of sand-body horizons and good source rocks of lake expanding systems tract are the main distribution zone of lithologic reservoirs. The original and secondary pores, fluid fracturing, episodic hydrocarbon fluid flow and high fluid overpressure are favorable for overcoming capillary force in the abnormal overpressure compartment and make sand bodies under the control of structural slope-break zone in high-pressure compartment have high oil saturation and productivity.