关键词: 准噶尔盆地, 地质构造, 构造模式, 构造演化, 应力场, 应力分析, 油气运移, 油气聚集

Abstract: An analysis of piedmont structures and ground stress field in southerm margin of Junggar basin is made in this paper. It is suggested that the major factors restricting the exploration progress would include the complex structure, deep objective interval,and intensity of ground stress that mainly concentrated on the mudstone member of Anjihaihe formation,which is characterized by high pressure and undercompaction with NNE orientation of maximum major stress and big difference between two horizontal stresses. This often causes drilling damages in this area. The ground stress distribution within southerm margin of Junggar basin assumes that its compressing stress increases vertically with depth and . compatible with the structural layers, which can be divided into deep compressive belt,medium shear zone and shallow tensile fracture belt. The migration of hydrocarbon tends to take place from high pressure stress distribution area(hydrocarbon generation sag) towards low pressure stress distribution area(uplift). The piedmont, a compressive ground stress area, contains oil/ gas pools dominated by structure formed reservoirs. It is shown that deep abnormal high pressure confined area(abnormal pressure fluid compartment) at footwall in southern margin of the basin and uplift sector closely related to faulting should be as a domain or direction for exploration,and structural traps (like faulting barrier, anticline, etc.) along with original oil/ gas reservoirs at major faulting footwall as the main exploratary targets.

Key words: Junggar basin, Geologic structure, Structure model, Structure evolution, Stress field, Stress analysis, Hydrocarbon migration, Hydrocarbon accumulation