Abstract:

There are evident characteristics of vertical pressure segmentation in Bohai Bay Basin, that is, normal hydrostatic pressure exists in shallow part;overpressure layers appear in deep part,and transitional pressure belts lie between the first two parts. The thickness of transitional pressure belts and the depth of overpressure belts increase from east to west, existing apparent mirror image relationship with geotemperature field,and the depth of overpressure belts and the thickness of transitional belts are controlled by aerial geotemperature fields.On the other hand, the Transitional pressure belts are related to diagenesis. Excess pressure is higher in depressions than that in uplifts.Furthermore, excess pressure is higher in gyprock and salt developed areas than that in other lithologic areas.The formation of overpressure in mud sand caprock area is mainly controlled by the degradation of organic matter and sealing ability of faults;the formation of overpressure in the areas with gyprock/salt caprock is controlled by sealing ability of gyprock rock and faults.