Abstract:

Each sag of Bohai Bay Basin has some comparability on tectonic characteristics and evolution, the overpressure distribution in vertical, the main distribution strata and the origin mechanism of overpressure. Firstly by making a qualitative analysis on the pressure field evolution of Doying, Zhanhua and Liaoxi sags, we discover that the overpressure of the three sags developed late. Then, by making a quantitative analysis on the pressure field evolution of Bonan sub-sag, a typical overpressure sag in Jiyang depression, we discover that the overpressure of Bonan sub-sag developed late as well. The overpressure of the main strata which are the third member and the upper of the fourth member of Shahejie Formation, developed after Dongying episode. From the above we conduct that the overpressure of Bohai Bay Basin developed late.

Key words: Bohai Bay Basin, overpressure, Bonan sub-sag, evolution of pressure field, late origin