Abstract: Selecting discretion parameter is the key of multi-parameters to identify flow units. Taking reservoir of fluvial facies of Yanchang Formation in the area of well W93 in Ordos Basin as an example, utilizing SPSS statistical analysis software, through analyzing the discretions and their correlation between eleven parameters of reservoirs and choosing permeability, effective thickness, filtrational coefficient, storage energy coefficient,FZI, RQI as discretion parameters, the discretion function of flow units has been established, the characters of flow units have been investigated. The results show that the flow units consist of type A, B, C and D which distribute in sedimentary microfacies of subaqueous distributary channel, mouth bar, crevasse splay, interdistributary bay and subaqueous natural levee, respectively. Different flow units have different filtrational and reservoir ability,so different methods should be adopted according to the different flow units of reservoir.

Key words: flow units, discriminator function, multi-parameters, fluvial facies, Yanchang Formation