A method of screening a plurality of fluids for an effectiveness in enhancing oil recovery comprises introducing a petroleum hydrocarbon into a plurality of separate fluid channels to saturate the fluid channels, each of the fluid channels having a porous structure configured to represent a condition of an earth formation; injecting a plurality of aqueous based fluids into the fluid channels; imaging the fluid channels to provide a plurality of images; analyzing the images to determine amounts of the petroleum hydrocarbon remain in the fluid channels after injection of the aqueous based fluids; and determining an effectiveness of the aqueous based fluids in forcing the petroleum hydrocarbon out of the fluid channels.