Abstract:Drag reducer is the key additive of fracturing fluid for unconventional reservoir reconstruction, such as tight sandstone and shale, and its performance will directly influence on the fracturing operation effect. The advantages,disadvantages and application of different drag reducers were analyzed. The turbulent drag reduction and drag reduction failure mechanism of drag reducers were emphatically described. The research progress of nanomaterials in fracturing drag reduction was summarized. This paper points out that in unconventional reservoir fracturing environment such as high temperature, high shear and complex medium, the new type of multi-functional composite drag reducers with the advantages of stability, high efficient drag reduction, low reservoir damage, strong sand carrying capacity, easy flowback and easy recycling will be an important research direction in future.