This paper presents a comparative study of two wettability modifiers with different characteristics for enhancing water imbibition from a fracture into the surrounding matrix. One is 3-pentanone, a symmetric short ketone, and the other is 2-ethylhexanol -4 propylene oxide-15 ethylene oxide, a non-ionic surfactant with an ultrashort hydrophobe. They were used as lowconcentration additives (approximately 1 wt %) to reservoir brine in this research. The coreflooding experiments using fractured limestone cores showed that the 3-pentanone solution resulted in more rapid oil recovery by water imbibition than the surfactant solution. The difference in oil recovery response between the two chemical solutions was attributed to the main difference between them as wettability modifiers; that is, the 3-pentanone solution keeps the original water/oil interfacial tension, but the surfactant solution lowers it by 2 orders of magnitude.