Study On The Development And Evolution Of Shengli Offshore Strike-slip Area

Shengli offshore strike-slip area is located in the east of Jiyang depression in the Bohai bay basin.The strike-slip shearing is obvious and the basin structure is complicated.In order to analyze the geometric characteristics and dynamic evolution process the study area,the latest 3-D seismic data was processed to interpret the faults and the basin structure.The fault activity analysis and balanced-section restoration are used to reflect the tectonic evolution of the study area.The dynamics of the discrepancy evolution of the study was analyzed by combined analysis of the regional geological setting and the local stress changes.This study would be important for the oil and gas exploration in this area.Three groups of faults are developed in the study are,including the NW-,NNE-,and NE-trending faults.The NW-trending faults are formed during Cenozoic and present left-lateral shearing extension.The four NNE-trending basin controlling faults are right-lateral strike-slip faults,which parallel to the Tan-lu fault zone.The NE-trending faults are normal faults,which developed in Paleogene.The strike-slip shearing stress is stronger in the upper formations than in the lower formations.The strike and the property of the faults in the study are is coincide with the right-lateral strike-slip stress field of the Tan-lu fault zone.Strike-slip shearing and its associated strucures are the mostest important deformation of the study area.According the classification of the associated structures,sevseral associated stress are recognized in the study area,including restraining bend,releasing bend,restraining bend,releasing bend,horsetail splay.Pre-existing Mesozoic NW-trending structure induced the Cenozoic basin divide into several parts,including the inheritied faulting rift area,coherent faulting rift area,and the strike-slip transformation area.The evolution of the inheritied faulting rift area is controlled by NW-trending faults,such as Chengbei,Chengnan region.The evolution of the strike-slip transformation area is controlled by the NW-trending faults in the deposition period of the Ek-Es₄ formation,whereas controlled by the NNE-trending faults in the deposition period of Es₃ formation,and this area include Changdi,Gudong,Kendong region.The evolution of the coherent faulting rift area is controlled by the NW-trending faults in the Mesozoic,while controlled by the NE-trending faults in the Cenozoic,and this area include the Bonan,Kenxi,Gubei,Gudao,Gunan and Fulin region.