The Features Of Fluid Inclusions And Their Contained Information On Hydrocarbon Migration And Accumulation Among Permian Systems In Zhongguai Area,Northwestern Junggar Basin

Adjacent to several hydrocarbon generation kitchens, the hydrocarbon resource is rich in Zhongguai area in the northwest margin of Junggar basin, but it is still lack of exploration. Additionally, because of the features of hydrocarbon multiple source and multi-period migration, accumulation and mixing, complex transport, the types, distribution and charging stages of oil are still not definite in this area. Combining the analysis of geological structure background and sandbody-unconformity-fault constituted transport, with the methods of thin section researching, inclusion temperature measurement and fluorescence spectrum analysis etc., the fluid inclusion characteristics are studied systematically in the Permian system (Jiamuhe Fm, Xiazijie Fm and Wuerhe Fm, etc.) in order to establish an available classification of oil types and its charge stages in Zhongguai area, then clarify the modes of oil charge and migration in this paper.With the analysis of the petrography and fluid inclusion characteristics, it is showed that the fluid inclusion is captured mainly at microcracks of stripped quartz grain in Zhongguai area, secondly it is captured at calcite cements. Secondary gas-liquid two-phase inclusions (aqueous and oil inclusions) are selected as major studying object. With the analysis of the Grains containing Oil Inclusions (GOI), it is showed that there is high GOI value in the southwest margin and northeast area, mainly distributed to 1.28%-5.96 and% 1.00%-9.75% respectively, illustrated that the southwest margin and northeast area are preferential path of hydrocarbon migration and palaeo-oil zones. Compared to the different fluorescence colors of oil-bearing inclusion's GOI values, it is verified the charging areas of yellow fluorescence hydrocarbon were extensive and massive. The fluorescence spectrum analysis of oil-bearing inclusion showed that there were mainly two types of hydrocarbon developed in Zhongguai area. Category ? was yellow fluorescence hydrocarbon with low maturity and Q650/500 of 0.3-1.3, ?max of 525nm-590nm, while category ? was blue-and-white fluorescence hydrocarbon with high maturity and Q650/500 of 0.1-0.35, ?max of 480nm-520nm. And the hydrocarbon in the reservoir of Permian systems mainly belonged to category ? with blue-and-white fluorescence hydrocarbon and high maturity.It is showed that there were two stages of fluid activity mainly developed in Zhongguai area from the homogenization temperature characteristic analysis of the fluid inclusion, the homogenization temperatures belonged to two groups at 80?-100? and 110?-120?, and its characteristics were similar in the central and north area, while it was clearly different from in the south. By way of the homogenization temperature characteristic analysis in symbiotic aqueous inclusions of two types respectively, it is concluded that the hydrocarbon charging stages were mainly developed in late Triassic epoch, middle -late Jurassic epoch and middle of early Cretaceous epoch respectively in Zhongguai area.Combining the time-space distribution of transport and other factors of petroleum geology, it is established the hydrocarbon charging mode in Zhongguai area:The category ? hydrocarbons were found in the south and central north area, they were generated by charging from Shawan sag at the late Triassic epoch and from Mahu sag at the middle-late Jurassic epoch respectively. Hydrocarbon charge and migration were influenced by unconformity transport, and controlled jointly by sandbodies and unconformities. The category ? hydrocarbons were developed by migration from nearby Mahu sag, Penyijingxi and Shawan sag at the middle of early Cretaceous epoch. At that time, petroleum migration in central and north parts showed longer distance controlled by unconformity transport effect, while the petroleum migration in south part showed shorter distance controlled by relay mode and joint effect of sandbody, unconformity and fracture. And the category ? and ? hydrocarbon mixed during later migration.