关键词: 数值模拟, 有限元, 应力场, 渤海海域

Abstract: The Bohai Sea, located in the northern part of North China, is an inland basin about 73 thousands km². Tectonically, it is one of the most active areas in eastern China since Late Tertiary. Meanwhile, it is also an area rich in oil and gas deposits. Previous studies have shown that faults and tectonic stress are important for oil and gas migration and accumulation. Based on the in-depth study on the tectonics of the Bohai Sea area and in the light of the geological and evolutional history, the authors simulate the stress field of the area using 2-D finite element method. In the simulation, the studied area is assumed as a rigid block that has been divided into 1347 finite elements, 1339 nodes. The tectonic field stress is calculated using SAP5 procedure. Some significant results are achieved. In light of the calculations and the evolutional history of the area, we firstly divide the Bohai sea tectonic stress field into four regions, namely the east Liaoning Bay, the central Bohai Sea, the east Bohai Sea and the west Bohai Sea. The stress characteristics are different in different regions, e.g. the central Bohai Sea has the maximum average normal stress value and shear stress value compared with other regions,while its minimum principal stress is lower. Secondly, the stress distribution of the whole study area shows that the faulting in the west is more intense than that in the east since Late Tertiary. The faults in the east Bohai Sea region have a higher degree of development and gaping along the Tanlu Fault belt, while in the middle Bohai Sea area, the faults have a low degree of displacement and development.

Key words: mathematical simulation, finite element model, stress field, Bohai Sea