Similarity criteria are the control theory of physical simulation, which is very important to researches on
waterflooding mechanism of fractured reservoirs. With using equation analysis and taking into account gravity, viscous
force and matrix-fracture imbibition, similarity criteria of physical simulation about waterflooding in fractured reservoirs
are developed according to similarity theory. The similarity criteria include: ratio of fracture permeability in x, y and z
directions, oil-water viscosity ratio, matrix-fracture movable oil ratio, dimensionless half-cycle of imbibition, ratio of
gravitational pressure difference and injection-production pressure difference and ratio of well radius and injector
producer distance. These similarity criteria can be used as theory guidance for quantitative 3D physical simulation of
waterflooding in fractured reservoirs, and can be simplified to the case of 2D easily.