Abstract: The study area is located in the eastern slope of Fukang sag, Junggar basin, where the Permian reservoirs have a good exploration prospect. Through the approaches of cores observation, casting thin section identification, SEM and mercury intrusion analyses, we discussed the characteristics and controlling factors of the Permian reservoirs in the eastern slope of Fukang sag, and then conducted the reservoir evaluation and classification. The results show that, compared to the sedimentary and metamorphic rock debris, volcanic rock debris are the majority in Wutonggou Formation. The particle size is fine with poor sorting and grinding and low composition and structure maturity. Primary pores are the mainly reservoir spaces, the certain amounts of secondary dissolution pores and microfractures can also provide some spaces for hydrocarbon accumulation. The reservoir properties are dominated by moderate porosity and moderate-low permeability. Subsequently, we could recognize four types of diagenesis:compaction, dissolution, cementation and replacement in the research area. Eight types of diagenetic facies were identified through the quantitative analysis on diagenesis. The reservoir properties and pore throat structures in the research area are controlled by lithofacies and diagenetic facies, which were classified into 29 types. Based on the above analyses and combining with the actual oilfield production capacity, we divided the reservoirs into 4 types. From type 1 to type 4, the reservoir properties, pore throat structure and oil production capacity become worse and worse.

Key words: Fukang sag, Wutonggou Formation, reservoir physical properties, pore structure, diagenesis, controlling factor