Structural Analysis And Analogue Modeling Of Fault Structures In Qiongdongnan Basin

The oil and gas reservoirs in the South China Sea account for about a third of total resources of our country,and most of which are located in deep water area.Since 2010,the gas reservoirs were found the deep valley of deep water area in Qiongdongnan Basin,the Qiongdongnan Basin became an important oil and gas production areas of South China Sea.Therefore,the study on the structure and tectonic evolution of Qiongdongnan Basin is helpful to advance the process of oil and gas exploration in the South China Sea.Combining with the geophysical data and characteristics analysis of the seismic profiles,this article is taking Qiongdongnan Basin as study area,to studying the differences of regional structure and the tectonic evolution of fracture system in Qingdongnan Basin.Combination of predecessors' point of view of basin tectonic evolution and tectonic features,a total of nine groups of physical simulation experiment was designed in this paper.Our experiment was designed for several aspects,including the basement lithology influence on fracture combination development,pre-existing faults' influence for the fracture and the sag development.The main achievements are as follows.(1)The position of pre-existing faults fracture and strike influence the evolution and the distribution of the depression located in the rift basin.The regional evolution formed by the preexisting fracture has formed the graben structure.The pre-existing fault is the normal fault of the depression boundary.In the region without pre-existing fracture,the formation of horst structure is formed.The faults in the sag are coincident with faults strike in the depression.(2)The overlying strata of the ductile basement is formed by the complex half-graben structure,while the overlying strata of the rigid basement is a shovel-like half-graben structure.The secondary and tertiary faults tend to be affected by basement stiffness and toughness.The main development in the upper depression of the rigid base is the tendency fault of the same tendency of stretching stress.On the upper part of the ductile base,there are multiple faults with the opposite tendency.Moreover,there are multiple secondary and tertiary faults located in the north and south area of the Baodao Depression,No.2 fault is located in the north of the Songnan Depression,a small number of secondary faults that tend to be NNW strike in the southern of the Qingdongnan Basin.