An embodiment of a method of evaluating fluid trapping in an earth formation includes injecting a water-based fluid into at least one fluid channel fabricated on a substrate, the at least one fluid channel having a pore structure configured to represent a condition of an earth formation. The method also includes injecting oil into an inlet of the at least one fluid channel until at least a selected amount of the injected oil exits the channel, imaging the fluid channel and determining an amount of remaining fluid in the fluid channel after injection of the oil, the remaining fluid being an amount of the oil and/or an amount of the water-based fluid, and estimating a proportion of the total volume of the fluid channel occupied by the remaining fluid to determine an amount of fluid trapping in the pore structure. The method further includes analyzing the amount of fluid trapping.