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

During the last 25 to 30 yr, micromodels have been increasingly used to study the behavior of fluids inside microstructures in various research areas. Studies have included chemical, biological, and physical applications. Micromodels have proven to be a valuable tool by enabling us to observe the flow of fluids and transport of solutes within the pore space. They have helped to increase our insight into flow and transport phenomena on both micro‐ and macro‐scales. In this review, we have considered only the application of micromodels in the study of two‐phase flow in porous media. Various methods exist for generating patterns used in micromodels. These include perfectly regular patterns, partially regular patterns, fractal patterns, and irregular patterns. Various fabrication methods and materials are used in making micromodels, each with its own advantages and disadvantages. The major fabrication methods include: Hele–Shaw; glass beads; optical lithography; wet, dry, and laser or plasma etching; stereo lithography, and soft lithography. The distribution of phases in micromodels can be visualized using (confocal) microscopes, digital cameras, or their combination. Micromodels have been applied to the study of two‐phase displacement processes, measurements of fluid–fluid interfacial area and phase saturation, measurements of relative permeability, and the study of enhanced oil recovery.