Development characteristics and genetic mechanisms of fault systems in Penglai 19-3 oilfield, Bohai Bay Basin

The main structure of the Penglai 19-3 oilfield in the Bohai Bay Basin is a large-scale transpressional anticlinal structure developed during the neotectonic period, characterized by a complex fault system. However, relevant targeted research is relatively limited. Based on the latest 3D seismic data, the structural characteristics of the study area were systematically analyzed using techniques such as detailed fault interpretation and equilibrium profile restoration. The research results indicated that the area primarily developed a near SN-trending strike-slip fault system and near EW-trending and NE-trending extensional fault systems, exhibiting a distinct east-west structural zoning pattern. The study suggested that the NEE-trending regional compressive stress during the neotectonic period was the core factor controlling this structural pattern. The stress not only reactivated the F1 and F2 branches of the pre-existing Tanlu fault, but also facilitated the development of NE-trending strike-slip pull-apart extensional faults (T-fractures) between the two strike-slip faults. Meanwhile, the derived NNW-trending extensional stress field in the area promoted the widespread development of near EW-trending extensional faults. The extensional and strike-slip fault systems formed contemporaneously, remained active, and interacted with each other during the neotectonic period, constituting the core characteristic of tectonic activity in the study area. The research findings provide references for studies on the regional strike-slip activity along the Tanlu fault and the characteristics of neotectonic movement.