A micromodel investigation of two‐phase matrix‐fracture transfer mechanisms

Abstract

[1] Micromodels employing a two-dimensional representation of pore space were used to observe directly (via microscope) water imbibition into a matrix and matrix-fracture interactions between wetting and nonwetting fluids. Within a single field of view, some pores are responsible for the uptake of water, whereas immediately adjacent pores expel nonwetting phase into the fracture. When water flow through fractures is relatively slow and fluid transfer from the fracture is relatively rapid, imbibition is microscopically cocurrent and micromodel observations teach that uptake of the wetting phase by the matrix correlates directly with the volume of water injected. This mode of transfer is coined a filling fracture. On the other hand, when fractures fill with water quickly relative to the rate of matrix-fracture transfer, the mass of water imbibed scales with the square root of time. Here imbibition is found to be countercurrent at the pore level. In the countercurrent mode, significant channeling of the nonwetting phase through the continuous wetting phase is observed that reduces the efficiency of water infiltration. Overall, it is found that the rate of water uptake from a fracture into an unsaturated matrix and the pore-level pattern of water infiltration depend critically on the rate of water infiltration through fractures.Citation: Rangel-German, E. R., and A. R. Kovscek (2006), A micromodel investigation of two-phase matrix-fracture transfer mechanisms, Water Resour. Res., 42, W03401,

Pore-scale interfacial dynamics and oil–water relative permeabilities of capillary driven counter-current flow in fractured porous media

“…This phenomenon has been observed in experiments using micro-models (Rangel-German and Kovscek, 2006). However, an in-depth understanding of the pore-scale capillary imbibition process under counter-current case is still missing.…”

Thermoplastic Micromodel Investigation of Two-Phase Flows in a Fractured Porous Medium

“…In the drainage process, the micromodel with a hydrophilic surface is first filled with dyed water. We drain the water out of the micromodel using two different methods: (1) injecting air into the model and (2) extracting water from the model. Since our syringe pump can provide a constant extraction rate, the extraction rates of both water and air are constant.…”

A Review of Micromodels and Their Use in Two-Phase Flow Studies

“…The micromodel is put under the objective lens of a microscope. The camera is mounted on the ocular of the microscope (Rangel‐German and Kovscek, 2006; Keller et al, 1997; Corapcioglu et al, 2009; Vayenas et al, 2002; Paulsen et al, 1998). The camera is connected to a computer to allow rapid data acquisition that can be stored in the computer.…”