Genetic mechanism and quantitative evaluation of fault traps in Xicaogu structural belt, Shulu Sag, Bohai Bay Basin

The fault traps in the Xicaogu structural belt in the Shulu Sag of the Bohai Bay Basin were studied. They are mainly synthetic fault traps and antithetic fault traps. A displacement-distance curve was drawn according to the variation of displacement. In this way, the segmental growth process of faults was restored, and the genetic mechanism of faults was determined. The synthetic fault traps were developed at the segmental growth point of the hanging wall of the fault. The antithetic fault traps were developed between the segmental growth points of the head wall of the fault during fault nucleation, with the largest displacement in the head wall of the fault. Some parameters such as the correlation between faults and strata (synthetic or antithetic faults), the maximum displacement, fault dip angle and strike, stratigraphic dip angle, fault segment length and formation rotation angle were selected to quantitatively evaluate their controls on fault physical properties. A model and a quantitative calculation method for the area of synthetic and antithetic fault traps were established, and were applied in the Jin 93 fault trap. The calculated error value is only about 2%, which indicates that the quantitative evaluation of fault traps is feasible.