A study of Carboniferous structure characteristics and reservoir-forming conditions in the Xincun Oilfield, Chepaizi area, Junggar Basin

Through the analysis of Carboniferous structure characteristics, distribution characteristics of reservoir bed and hydrocarbon, major oil pool styles and reservoir-forming conditions in the Xincun oilfield in Chepaizi area of Junggar Basin, a synthetic hydrocarbon accumulation model was established. The results show that the study area is located on a tectonic slope on the whole, which has the tectonic characteristics of higher in the north and lower in the south, higher in the west and lower in the east, and south-north partitioning with gentle stratigraphic attitude. The study area mainly developed tensional faults in Carboniferous, which are in NE-SW direction and were formed in a regional tensional tectonic stress background. In the study area, the strata contour lines are mainly flat-straight, suggesting that the strata could not provide favorable conditions for the formation of anticline traps, but the study area has well-developed multi-order faults, which could provide favorable conditions for the formation of faulted block traps and pathways for oil-gas migration. Carboniferous faults can be divided into composite horst system, composite graben system and sporadic fault system based on their distribution, patterns and assemblies. The major geological factors controlling oil-gas migration and accumulation in the Xincun oilfield are the faults, fractures and lithologic changes or physical sealing.