Synthetic Seismic Data Interpretation And Study The Structural Features In The North Of Fangzheng Rift

Fang-zheng rift is a negative tectonic unit in the north-central part of Yi-Shu graben which limited by the fractures on the east and west side of the rift.It is a part of meso-cenozoic rift that developed from the ji-hei fold belt. On the basis of the latest 3D seismic data, we calibrate the seismic horizon utilizing the synthetic seismogram. By the application of sequence stratigraphy, Structural Geology and sedimentology, we can interpret the 3D seismic data more accurate. We can identify the regional unconformity interface and trace it exactly. And then establish the isochronal stratigraphic framework. We establish the 3D velocity field and extract the average velocity of the intended interval through the application of the velocity spectrum, the velocity logging and VSP data. We can divide the tectonic,study the spatial distribution of the faults and analysis the structural style. We discuss the the characteristics of the tectonic in different Evolutionary stages and the influence about the tectonic movement effects on the reservoir forming, then to predict the beneficial hydrocarbon accumulation area.According to the shape of basement, layer structure features and the distribution of fractures,etc, Fang-zheng rift can be divided into four Secondary structural units, just as the mid-west rift zone, the mid-east rift zone, the northwest fault uplift zone and the northeast fault uplift zone. The regional structure has the characteristics of east-west dividing zones and south-north dividing blocks. The distribution of formation is that the west part is thicker than the east, and the settlement center migrates frequently.The structural shape of the western part of the research area is controlled by the western boundary fault. In tension-shear stress field, its structural style dominate by extensional structures, and can be broken down into:shovel-like fan, rollover anticline and the step-fault zone. And the structural configuration of the mid-east part of the research region is controlled by the eastern boundary fault which is out of study area and the Yi-han-tong strike slip fault zone. In the torsional stress field, its structural style dominate by wrench structures,which has the characteristics of flower structure and dolphin effect in the seismic profile, and the en echelon fault zone.Tectonic evolution history analysis shows that the study area had experienced a strike slip pull apart stage, a twist compression uplift stage, a stable subsidence stage and a strike slip stage. The boundary faults control the distribution of the source rocks; the Yi-han-tong fault zone and the important unconformity interfaces are the main migration pathway for oil and gas; Traps beside the Yi-han-tong fault zone and the lithologic traps in the Da-lian-he group and the Xin-an-cun group are the main hydrocarbon accumulation area, and the shale in the Bao-quan-ling group can be a good cover, then we predict two favorable area for oil and gas accumulation.