Upscaling of nonwetting phase residual transport in porous media: A network approach

Based on the volume averaging method, a macroscopic model is developed for the upscaling of NAPL transport in a porous medium idealised by a network m odel. Under the assumption of local mass non-equilibrium, a macroscopic equ ation involving a dispersion tensor, additional convective terms and a line ar form for the interfacial mass flux is obtained. The resolution of the tw o local closure problems obtained allow the determination of the local prop erties without adjustable parmeters. These problems are solved in a semi-an alytical, semi-numerical manner on the network. The originality of this wor k is the association of the upscaling by volume averaging method with the n etwork approach. The local properties, including the dispersion tensor and the mass exchange coefficient, can therefore be calculated over a large num ber of pore-bodies and pore-throats in a computationaly tractable manner, t hus leading to more significant results. Results are presented for 3D, spat ially periodic models of porous media.