A paper of Mr. Natanael Suwandi (M1, Tsuji Lab), Prof. Fei Jiang, and Prof. Takeshi Tsuji (Multiscale Science and Engineering for Energy and the Environment Thrust, I²CNER / University of Tokyo) has been published in “Water Resources Research.”

The relative roles of parameters governing relative permeability, a crucial property for two-phase fluid flows, are incompletely known. To characterize the influence of viscosity ratio (M) and capillary number (Ca), we calculated relative permeabilities of nonwetting fluids (k_nw) and wetting fluids (k_w) in a 3D model of Berea sandstone under steady state condition using the lattice-Boltzmann method. We show that k_nw increases and k_w decreases as M increases due to the lubricating effect, locally occurred pore-filling behavior, and instability at fluid interfaces. We also show that k_nw decreases markedly at low Ca (log Ca < −1.25), whereas k_w undergoes negligible change with changing Ca. An M-Ca-k_nw correlation diagram, displaying the simultaneous effects of M and Ca, shows that they cause k_nw to vary by an order of magnitude. The color map produced is useful to provide accurate estimates of k_nw in reservoir-scale simulations and to help identify the optimum properties of the immiscible fluids to be used in a geologic reservoir.

◆Paper

*Title : Relative Permeability Variation Depending on Viscosity Ratio and Capillary Number

*Authors : Natanael Suwandi, Fei Jiang, and Takeshi Tsuji

*DOI：10.1029/2021WR031501

*First published online : May 23, 2022