Abstract: The research of flow units is the key of deepening and developing reservoir characterization, and it has important theoretical intention and practical value on revealing distribution of remaining oil. Based on establishing classification standard and discriminant of flow units in fluvial and delta facies, this paper classified the reservoir flow units of Triassic in block-1 of Tahe Oilfield, and analyzed the spatial distribution of flow units and its relationship with reservoir architectural structure and remaining oil. The result shows that flow units of the study area can be classified into E（excellent）, G （good）, M（medium） and P（poor） types, while E and G types have the most extensive distribution, and M and P types have smaller distribution area. Meanwhile, the interlayer and interwell flow units have distinct discrepancy. The E type flow unit has consistent distribution with lateral sandbar, and G type flow unit is corresponding to channel deposit and lengthwise sandbar that are sand reservoir bodies with high porosity and permeability, which means that reservoir architecture has favorable correspondence with flow units. E and G types of flow units are the main digging orientation of remaining oil, while M type is the secondary digging orientation. P type of flow unit has limited geological reserves of remaining oil, therefore has less digging potential.

Key words: low permeability sandstone, pore structure features, reservoir quality, Jiyuan area, Ordos Basin