Two-phase flow in correlated pore-throat random porous media

Abstract

We have constructed a porous media model in which there are percolation clusters with varying percolation probability P and correlated site-bonds.Taking into account both the pore and the throat geometry,the viscous fingering (VF) in porous media has been investigated by using the standard over-relaxed Gauss-Seided scheme.The simulation results show that the VF structure varies with the correlation parameter e,the viscosity ratio M and the percolation probability P.The smaller the correlation parameter e,the greater the deviation of the normalized size distribution of the invaded throat Ninv(r) from the truncated Rayleigh distribution.For a larger viscosity ratio M,the VF pattern looks like a diffusion-limited-aggregation structure in percolation clusters.The fractal dimension D increases with the increase of the percolation probability P and the correlation parameter e.the velocity distribution f(α) of VF in percolation clusters is of a parabola-like curve.The tail of the distribution (large α) is longer for a larger correlation parameter e.For a smaller e,the distribution is very sharp.The sweep efficiency E decreases along with the decrease of the correlation parameter e and the increase of the network size Lnz.E has a minimum as Lnz increases up to the maximum no matter what the values of P,M and e.The E-Lnz curve has a frozen zone and an active zone.The geometry and the topology of the porous media have strong effects on the displacement processes and the structure of VF.