The greyscale image of the 0fw experiment. The nitrogen is the darkest phase and brine is the lightest phase in the pore space. The scan lasted 40 minutes, such that locations where intermittency occurred are blurred in the tomographic images (resulting in an intermediate greyscale, which is the average of the brine and nitrogen). For the segmented image, the rock grain = 0, stable brine = 1, stable nitrogen = 2 and intermittent locations = 5.