Study On The Structural Features And Evolution Of The North Of The Eastern Sag In Liaohe Basin

The northern area of the eastern sag of the Liaohe Basin is a typical dustpan-like structure,and it is an important oil and gas accumulation area in the Liaohe Basin.The basin structure and tectonic evolution in this area are both greatly influenced by the tectonic activities of the two boundary faults,the Tong'erpu fault and the Cidong fault.It has experienced various stresses such as extension,strike-slip,and squeeze in the geological history.The construction style is very complicated.In this study,the fine structural interpretation of the northern part of the eastern sag of the Liaohe Basin was carried out,and on this basis,the structural characteristics,structural evolution,and dynamic mechanism of the region were studied and analyzed.The research has achieved the following results:(1)After well-seismic calibration,the 3D seismic interpretation technology was used to explain the stratum in the study area in detail,and the identification of faults in the region through the identification technology of coherent volume production,dip scan,curvature,frequency division technology,etc.Reasonable combination.A total of 10 seismic reflection horizon interpretations and more than 30 fault interpretations have been completed.(2)On the basis of completing the 3D seismic interpretation,the structural pattern of the study area is divided according to the distribution from north to south based on the top surface structural form of Shahejie Formation.A series of typical sections are intercepted to systematically analyze the spatial distribution of large faults and their influence on the construction style and tectonic pattern,and divide the primary and secondary faults that play a major role.Combined with the relevant knowledge of structural geology and basin structural analysis,a comprehensive analysis of the stratum thickness in each area of the study area,as well as the combination of horizon and fault plane and profile,was divided into 4 types and 8types of structural styles.(3)On the premise of clarifying the fracture characteristics and main structural styles of the study area,a balanced profile of a typical survey line is made,and combined with the plane distribution map of stratum thickness of different sedimentary sections,the structural evolution process of the study area is analyzed.It is concluded that the third phase of Shahejie is a strong rift period in the study area,the extension is dominant,and the second phase ofShahejie is weakened,mainly by squeezing.In the first phase of Shahejie to Dongying period,the study area is in tension During the deposition period of superposition with strike-slip,the early period of Guantao was in the period of pressure-torsion strike-slip,and the later period of Guantao was a period of weak extension.These five different stages of evolution have created complex structural patterns in the study area.(4)Combined with the latest research results of the tectonic structure,from the aspect of plate kinematics,systematically analyzed the dynamical sources of each tectonic evolution stage: the strong extension of the third phase of the Shahejie is due to the subduction of the Pacific plate by the NW towards the Eurasian plate The stress during the squeezing period of the second member of the Shahejie Formation is derived from the subduction and turning of the Pacific plate;the superposition of the tension and torsion during the the first phase of Shahejie to Dongying period is due to the subduction and withdrawal of the Pacific plate and the right-handed slip of the Tan-Lu fault zone,and Combined with the extension of the study area;the early compression,torsion and slip of the Guantao were due to the northward movement of the Philippine plate,combined with the subduction and retraction of the Pacific plate;in the later period of the Guantao,the stress field tended to stabilize and the structure of the study area was basically shaped.