Consecutive MRI images of the water–oil displacement in the model of polystyrene beads with the injection flow rate of 0.12 mL/min. The oil is yellow and the water is light blue. The acquisition of MRI signal was made each 15 minutes and shown here from the first water appearance in FOV. The dotted line on the first vertical section indicates the position of the horizontal sections (and vice-versa for the horizontal section below).