Network modeling of multiphase flow in fractures

We develop a pore-scale model of wetting in a single fracture. A variable f racture aperture distribution is represented as a square lattice of concept ual pores connected by throats. We borrow concepts from network modeling of flow in porous media to generate a fracture model that includes the effect s of flow in wetting layers, snap-off, and cooperative piston-like advance. Cooperative filling accounts for both the curvature of the wetting front i n the fracture plane and the effect of the fracture aperture itself. Viscou s forces are accounted for using a perturbative method and simulations are performed for horizontal flow, as well as gravity stable and gravity unstab le displacements. The wetting phase relative permeability and the trapped n on-wetting phase saturation are computed for a fracture whose aperture dist ribution has been measured using CT scanning. (C) 2001 Elsevier Science Ltd . All rights reserved.