Developmental Characteristics of Post-Rift Faults and Palostress Field Inversion in the Bozhong 19-6 Structural Belt

The faults in the post-rift period have an important controlling effect on the migration and accumulation of oil and gas in the shallow strata of Bohai Bay Basin. Based on the seismic interpretation data of Bozhong 19-6 Structural Belt, this paper analyzes the geometric characteristics and growth history of the faults in the post-rift period and inverts the tectonic paleostress that caused the fault activities in the post-rift period. Finally, the developmental characteristics of the faults in the post-rift period are deeply understood from three aspects: fault geometry, kinematics, and dynamics. In the study area, the trend of post-rift faults are mainly east–west, followed by NEE. According to the fault activity, it can be divided into three types: newly formed faults, long-term active faults, and deep-linked faults. The latter two types are faults that existed before and then reactivated during post-rifted period. The inversion result of the Neogene is the strike-slip stress field, showing that the intermediate principal stress axis (σ₂) is oriented vertically, the minimum principal stress (σ₃) is oriented N170°, the maximum principal stress axis (σ₁) is oriented N80°, and σ₃/σ₁ = 0.24, σ₂/σ₁ = 0.62. The data used in this inversion method is easily obtained in the oil and gas industry, and the inversion results can provide an important reference for analyzing the regional tectonic evolution and clarifying the fault activity at the key moment of oil and gas accumulation.