The flow of oil phase in the gas/oil two-phase region in fractures is a key to production performance of fractured petroleum reservoirs where gravity drainage is the dominant mechanism. In this study, data on a set of experiments that center on flow of the oil phase in the fractures are presented. The experiments cover fracture apertures ranging from 50 to 1,200 mu m, and the contact area is varied by a factor of 16. The data reveal that the rate of oil drainage across a stack of matrix blocks is very sensitive to fracture aperture size.