Abstract: Flow unit is a block of reservoir rock, in which the depositional features and the percolation flow behavior are same or similar. The flow unit index is a kind of comprehensive parameter of geology and reservoir engineering.Using it the reservoir heterogeneity can be more accurately described. In this article, the flow unit index is applied to evaluate the reservoir heterogeneity in Baobei block. The results show that the strongest intrastratal heterogeneity is inⅠ, Ⅰ₂and Ⅱ substratum, while the weakest intrastratal heterogeneity is in Ⅲ₁ and Ⅱ₂ substratum; the strongest in terlayer heterogeneity is in Ⅱ oil reservoir; the strongest plane heterogeneity is in Ⅰ₂ and Ⅱ₃ substratum, while the weakest plane heterogeneity is in Ⅲ₁ and Ⅱ₁ substratum. Because these heterogeneity features occur, they must be appreciated adequately in development.

Key words: Xinjiang, Yanqi, Baolang oilfield, reservoir, heterogeneity, Sedimentary characteristics, flowing characteristics