Fig. 3

a Thin section of sample with pore-dominated porosity and only one minor fracture visible; b thin section under fluorescent light; c TS3 binary image with the connected voids in black and unconnected voids and minerals in white. In the bottom right of the image, there are visibly fewer fractures surrounding the vug in c than in a due to the white intensity selected for the image. If the intensity was set to allow for the microfractures surrounding the vug in c to be visible, several falsely identified “void spaces” in the background would also be identified. While there are small areas of voids that are not identified in the final image, in c, there is a high degree of confidence that all identified void spaces are true pore spaces