The sandstone reservoirs within the 3

rd

and 4

th

members of Shahejie Formation in Dongying Depression

the Bohai Bay Basin are moderately to strongly overpressured with the maximum pressure coefficient of 2.0 and the maximum excessive pressure of 40 MPa calculated based on the measured pressures.Analysis indicates that oil-bearing properties of the reservoirs correlate to the development degree of overpressure

and current reservoir overpressure is mainly caused by the overpressured fluids from source rocks.Integrated with basin modeling and fluid inclusions analysis

this paper reconstructed the geo-pressure evolutionary history of the sandstone reservoirs in the 3

rd

and 4

th

member of Shahejie Formation.The first stage reservoir overpressure was mainly caused by the rapid subsidence during the deposition of the 3

rd

member of Shahejie Formation to the end of Dongying Formation that blocked pore fluid discharging.The overpressure might be released to hydrostatic pressure along with the tectonic uplifting during the late Dongying Formation to early Guantao Formation.From the late Minghuazhen Formation to the present

the bulk of the source rock is still at peak oil generation and large amount of oil/gas-bearing overpressured fluid generated by the source rocks charge into the sandstone reservoirs

leading to the second stage overpressure.