Wettability study using the potential technique is a novel approach proposed for carbonate reservoir rocks. As opposed to other existing industrial and laboratory methods, such as the Amott-Harvey, United States Bureau of Mines (USBM), and contact angle methods, the potential technique provides a complete wettability profile of limestone versus relative water/oil content in the presence of water for different oil samples. In addition, the study is extended for oil derivatives (i.e., asphaltenes and maltene). A case study was carried out to understand the effect of asphaltenic solutions on wettability of limestone rocks. From the obtained wettability profiles, it was found that different oil samples show the wettability transition, from water-wet to oil-wet. Moreover, the adsorption of maltenes was limited to the water-wet region whereas asphaltenes were found to be the main reason for heavy-fraction deposition.