THE DISTINGUISHING OF FAULT AGE STAGE AND ITS CONTROLING ON HYDROCARBON ACCUMULATION IN JIYANG DEPRESSION，EASTERN CHINA

The age and mode of activity of faults are significant factors affecting hydrocarbon accumulation in sedimentary basins. Based on the theory of Analytical Tectonics, Sedimentology, and Petroleum Geology, considering the geological data of drilling, well logging, seismic profiles, the age stage of the fault is distinguished in Jiyang Depression, by using the methods of data analysis and indoor physical simulation, qualitative description and quantitative analysis. Based on the analysis of geometric and kinematic characteristics of Jiyang Depression, typical faults are selected for age discrimination, and then the relationship between the fault age and activities of faults and basin structure, sedimentary sandstone body and oil and gas distribution is discussed.

The horizontal uniform stretch model and extensional model of flexural basement faults were established to simulate the process of fracture development. The life process of faults occurring in plane and profile, from simple to complex is presented. The evolution process of faults was simulated by discrete element model, and it was found that with the growth of fault age, the internal structure of fault zone gradually transited from fracture to local fracture, fracture penetration, sliding fracture with displacement and derived fracture. Taking Chennan fault in Dongying Depression for instance, the relationship between fault zone structure, strata and sedimentation during the evolution was analyzed. The life cycle of fracture development is divided into six stages: embryo stage, infancy stage, youth stage, maturity stage, old age stage and extinction stage.

Based on the study of the stage of fault development and the mode of fault activity, the hydrocarbon-controlling ability, reservoir-controlling ability, source-reservoir-cap assemblage, hydrocarbon transmission and sealing ability, reservoir-controlling type, trap and reservoir type of faults of different ages are discussed. In general, as the age of faults growing, the types of reservoir control of faults became more complex, and the types of controlled traps became more, and the size of traps became larger. Eight types of reservoir control modes are proposed in the study area.