Extensive research work (examination of 161 limestone, dolomitic limestone, calcitic dolomite, and dolomite cores) on wettability of carbonate reservoir rocks by the writers indicate that 15 percent of these rocks are strongly oil-wet (θ = 160°-180°; some are bitumen coated), 65 percent are oil-wet (θ = 100°-160°), 12 percent have intermediate wettability (θ = 80°-100°), and 8 percent are water-wet (θ = 0°-80°). These results on carbonate reservoir rock cores from all over the world show that the majority of carbonates are oil-wet.