Structure Describing Methods On Complex Fault-block Structure In South Fault-belt Of Gaoyou Sag

Using well logs, well drilling and seismic data, combing the direction of new theories such as structural dynamics and geometry, applying structural evolution to analyse the active characters of faults, applying numerical simulation of tectonic stress field and physics simulation of structure to forecast the developing area and distributing rule of low-sequence faults, applying seismic forward modeling to analyse the characters of seismic waves. Combing the upwards research, directing by the structural mode analysis, applying seismic interpretation methods such as coherent、 slices、3-D visualization to describe the small complex fault structures.Through the analysis of structural evolution:zhen① fault is the earliest fault in South fault-belt of Gaoyou Sag, active before the deposition of Funing formation. The faults between zhen ① and zhen ② fault were formed in the first member of the Funing sedimentary period, the second and third member of the Funing sedimentary period were the main developing period of zhen① 、 zhen② fault. The active period of zhen② fault was late, began to develop in Dainan sedimentary period. In late sedimentary period of Yancheng, the activity of faults in South fault-belt of Gaoyou Sag were very weak.Through the analysis of distributing rule of low-sequence faults:the third and forth-class faults were formed under common action of the shearing stress and tensile stress in the third and forth member of the Funing sedimentary period. The characters and the vertical 、 plane combination pattern of these faults differ in different area.Through the forward modeling:affected by the interference of large faults, false reflections can be found in local area, according to this,the effects of the interference of large faults were reduced during the seismic interpretation.Under the recognition of upwards research,carrying on fine structural interpretation,nineteen traps were found in Huangjue area, fifty-two traps were found in Xuzhuang area,benefits were obtained during the late well-drilling.