Influence of simple fracture intersections with differing aperture on density‐driven immiscible flow: Wetting versus nonwetting flows

[1] We conducted laboratory experiments to evaluate the effects of simple fracture intersections with differing aperture on density-driven immiscible wetting (water into air) and nonwetting (Trichloroethylene into water) flows, and analyzed them quantitatively. The experimental systems consisting of vertical and horizontal fractures were fabricated with glass for easy visualization. The aperture variation between intersecting fractures and the viscous force of the injected fluid were considered to be critical system parameters. Experimental results show the critical difference between the wetting and nonwetting flows by the intersection and viscous force, and subsequent mathematical analyses explain well our observations: The intersection acts as a capillary barrier (CB) for the wetting and capillary bridge for the nonwetting flows, and the viscous force of flowing fluids reduces the strength of CBs. The results of both laboratory experiments and mathematical analyses suggest that the fracture intersection with differing aperture can be a more significant factor controlling the network-scale phase structure for the nonwetting than the wetting flows.