GENERALIZED SCALING OF SPONTANEOUS IMBIBITION DATA FOR STRONGLY WATER-WET SYSTEMS

Mass transfer between fractures and matrix blocks is critical to oil r ecovery by waterflooding in fractured reservoirs. A scaling equation h as been used for rate of oil recovery by spontaneous imbibition and pr esented their results as oil recovery vs. dimensionless time. Many con ditions apply to this scaling equation, including identical core sampl e shapes and fluid viscosity ratios. Recent investigation by experimen t of these two factors has resulted in a more generalized scaling equa tion for strongly water-wet systems with a general definition of chara cteristic length and a viscosity ratio term included in the definition of dimensionless time. In this paper, published data on oil recovery hy imbibition have been analyzed and correlated through application of the new definition. These data sets were for different porous media, core dimensions, boundary conditions, and oil and water viscosities. A ll of the systems were strongly water-wet. The generalized correlation was fitted closely by an empirical mass transfer function with the ne w definition of dimensionless time as the only parameter. (C) 1997 Els evier Science B.V.