Study Of Strike-slip Structure Feature And Its Influence On The Hydrocarbon Accumulation In East Jiyang Depression, Bohai Bay Basin

The study area is located in the conjunction area of Middle Tan-Lu fault zone and Jiyang depression. Strike-slip structures are greatly developed. There are seven main strike-slip faults in the study area: East and West branch faults of Tan-Lu fault zone, Kendong fault, Gudong fault, Changdi fault, Chengdong fault and shallow strike-slip fault zone developed in the middle part of Kendong uplift. Strike-slip structural zones coincide with oil&gas accumulation zones in the study area.Based on the interpretation results of 2D and 3D seismic profiles and structural maps, the horizontal, vertical and spatial strucutural features of the main strike-slip faults are studied. According to their horizontal and vertical features, they are divided into three types: matured strike-slip fault, buried strike-slip fault and discontinuous strike-slip fault.On the basis of theoretical model research, the formula between the strike-slip rate and the subsidence rate in the pull-apart basin is derived. It is confirmed that the strike-slip moving rate has a steady relationship with the geometric parameters, max subsidence depth and the subsidence rate of the strike-slip basin. Based on the subsidence history analysis of the Weibei sag, the experiment relation between the Tan-Lu fault strike-slip rate and Weibei sag subsidence rate is obtained and the Cenozoic dextral strike-slip displacement of the Middle Tan-Lu fault in the Laizhou Bay is calculated for about 40km.Four typical seismic profiles in the study area are restored using 2DMove software. The extension parameters of every balanced cross-section in the different period are calculated.The intensity of tectonic evolution is quantitatively analyzed and the tectonic evolution history is revealed. The structural stress field and strain field of the study area during the late Late-Cretaceous to early Tertiary are rebuilt after finite element analysis using Ansys software. The results show that the transtension in study area at that time is the main reason for the trigger of the strike-slip faults strike-slipping movement.Based on the above analyses, together with the successful and failing oil&gas exploration and development cases during the recent year in the study area, the influence of the strike-slip movement on the important oil&gas accumulation factors: source rock, reservoir rock, cap rock, migration pathway, trap and preservation is carefully studied.