Research On Structure Stress And Controlling On Structure In Western Gaoyou Depression Of Subei Basin

Geology chrematistic of western Gaoyou Sag is complex. We emulated the tectonic stress field which is in main migration and accumulation period and nowadays by numerical simulation technology. We made definite that the structural styles were controlled by tectonic stress, so was the structural evolution. We analyzed the law which the tectonic stress field controlled the hydrocarbon migration and accumulation. The aim is to guide hydrocarbon exploration.Based on the paleostructure recovering and hydraulic fracturing data and acoustic emission data, we emulated the tectonic stress field of Funing, Sanduo and present stages with Ansys 10.0. The result showed that maximum principal stress was main of tensile stress in Funing stage. The direction is near NE. At the same time there was low compressing stress, too. Minimum principal stress was NS direction. It showed high numeric value. Shear principal stress was main of dextrorotation. There was laevorotation at the same time in some area, too. Maximum principal stress was tensional in Sanduo stage, high numeric value, near NE direction. Minimum principal stress was low numeric value and compressive, near EW direction. Maximum principal stress was NS direction and compressive at present stage. It distributed average and stable. So was the minimum principal stress.Some classic sections were elucidated by Schlumberger Geoframe 4.3 Version. We made known the structural styles and faults group characteristic. We recognized that there were normal fault, anticline, block and faulted nose, etc group structural styles . We analyzed systematically the reason that structural styles were formed by tectonic stress. Tectonic stress chrematistic is different between different area, and that is the reason why the structural styles is different in different area.We analyzed the structure evolution history by structure restoration of balancing cross section and back-stripping in inversion of original stratum thickness with tectonic stress emulation. Zhenâ‘ fault was formed in Taizhou stage . Zhenâ‘¡and Hanliu fault were formed in Funing stage. Faults of grade four and below is mainly formed in Dainan and Sanduo stage. Faults'evolution in this area suffered three stages"forming-active-stable". The process was good coincide with tectonic stress emulation results.Tectonic stress controlled the palaeostructure in Sanduo stage. Structural tendency of west high and east low caused the hydrocarbon migrating to the west almost. Tectonic stress controlled the traps. In Weizhuang area, there developped faulted-nose, block traps. In Huangjue and Majiazui area, there developped fault, fault-lithology traps. Tectonic stress controlled hydrocarbon accumulation. In Sanduo stage, maximum principal stress was main of tensile stress and high numeric value. Then any levels of faults were of activity. Sealing of them was bad almost. Validity of fault pathway system was good. Fault pathway system was the most important kind in the area. Tectonic stress in present stage was that the maximum principal stress was compressive and stable. It distributed average. Fault activity came down and trended to still. It was good for hydrocarbon storage.