The application of carbon dioxide is becoming increasingly important for enhanced oil recovery (EOR) processes. In view of combined EOR and carbon dioxide capture and storage technologies (CCS), knowledge must be gained on relevant properties of the participating fluid mixtures. The solubility of carbon dioxide is significant in many hydrocarbon materials, which affects the capillarity and migration of fluids in oil reservoirs via the interfacial tension (IFT) and wetting of the rock surfaces. For EOR the capillarity is decisive in view of the pressure that has to be overcome within the rock pores. The present study is dedicated to a thorough experimental description of a gas-crude oil-reservoir water system and its behavior under CO(2) pressure including oil density and interfacial properties. The experimental results of decreasing IFT in a three-phase system, increasing density and diminishing wettability, show an important influence of the presence of carbon dioxide.