Wettability is a critical parameter that dictates various aspects related to the recovery of oil from reservoirs. Calcite rocks are used as minerals representative of carbonates to investigate the impact of surface roughness on wettability. Surface roughness was assessed using interferometry and atomic force microscopy (AFM). In this study, two case studies were investigated. The first case study characterizes the wettability of four different calcite samples with different surface roughnesses: naturally cleaved, and three samples grinded with diamond grit sizes of 1250, 1000 and 600. It is shown systematically that decreasing surface roughness results in acontact angle increases from 53 to 81° that is towards the more water wet. In the second case study, the consistency of wettability measurements and trends from different spots of the same calcite surface was studied. For the latter, a total of four different naphthenic acids are added to n-decane to form model oils (the non-aqueous phase) that in principle will alter the wettability differently. In conjunction, four different brines with 1.5 mol% of NaCl, KCl, CaCl2 and Na2CO3, respectively were used to represent the aqueous phase. Wettability was characterized by static and dynamic (advancing and receding) contact angle measurements using the sessile and captive-drop methods, respectively. The results did not reveal any clear trend. A surface roughness analysis for the naturally cleaved calcite sample shed light on the absence of structure in how the electrolytic composition influences the contact angle. The variation in contact angle measurement is found to be large when comparing two different spots on the sample. Therefore, it is only possible to single out a trend when the parameter in concern is very evident such as the oil composition. More subtle trends, such as those that are induced by a brine variation, are hardly apparent and this may be even more important at elevated temperatures because of fluid motion.