Visible-micromodel technology was used to investigate multiphase flow in porous media because it allows watching the fluid flow under a microscope. However, most micromodels are made with glass media. A sandstone micromodel (SMM), manufactured from a thin sandstone slice, was used to study water injection in low-permeability rock. The main advantage of this micromodel was preservation of the original pore structure, clays, cements, and pore-surface properties. Oil recovery was proportional to the permeability of the model, suggesting that pore conductivity is key to water-injection efficiency. However, visibility was less than that of a glass micromodel (GMM). Thus, the combined results from both SMMs and GMMs are more valuable.